WO2005098635A2

WO2005098635A2 - Systems and methods for receiving data in a wireless communication network

Info

Publication number: WO2005098635A2
Application number: PCT/US2005/009807
Authority: WO
Inventors: Ismail Lakkis
Original assignee: Pulse-Link, Inc.
Priority date: 2004-03-26
Filing date: 2005-03-23
Publication date: 2005-10-20
Also published as: WO2005098635A3

Abstract

A radio receiver comprises a band pass filter (4104) configured to filter a combined signal, a clocked comparator (4110) coupled with the band filter, a digital-to-analog converter (4106) coupled with the clocked comparator, and a combiner (4102) configured to receive a RF signal and combine the RF signal with the analog signal generated by the digital-to-analog converter in order to generate the combined signal. The clocked comparator is configured to compare the filtered combined signal to a ground reference when the comparator is enabled by a clock signal. The digital-to-analog converter is configured to convert the output of the clocked comparator to an analog signal.

Description

SYSTEMS ATWMETHODS FORRECEIVT^^ COMMUNICATION NETWORK BAC^GROIJT^OFTEIEINVENΠON

1. Field of the Invention The invention relates generally to wireless communication and more particulariy to systems and methods for wireless ccmmumcation over awide bandwidth (Λannel using apluraUty of sub-channels.

2. I3ackground Wireless communication systems are proliferating at the Wide Area Network (WAN), Local Area Network (LAN), and Personal Area Network (PAN) levels. These wireless communication systems use a variety of techniques to allow simultaneous access to multiple users. The most common of these techniques are Frequency Division Multiple Access (FDMA), which assigns specific frequencies to each user, Time Division Multiple Access (TDMA), which assigns particular time slots to each user, and Code rJivision Multiple Access (CDMA), which assigns specific codes to each user. But these wireless communication systems and various modulation techniques are afflicted by a host of problems that limit the capacity and the quality of service provided to the users. The following paragraphs briefly ctesαibe a few of Ihese problems for the purpose of illustration Olieproblem to can exist mawirelesscorrπnura Multipaminterfeιence,or multirjaih, occurs because some of the energy in a transmitted wireless signal bounces offof obstacles, such as buildings or mourήains, as it travels from source to destination The obstacles in effect create reflections of the transmitted signal and the more obstacles mere are, the more reflections they generate. The reflections then travel along their own transmission paths to the destination (or receiver). The reflections will contain the same infbrmation as the original signal; however, because of the differing transmission path lengths, the reflected signals will be out of phase with the original signal As a result, they will often combme destructively with the caiginal signal in e receiver. This is referred to as fading To combat fading, current systems typically try to estimate the multipa effects and then compensate for mem in the receiver using an equalizer. In practice, however, it is very difficult to achieve effective inultipath compensation A second problem mat can affect the operation of wireless ccβrnmunication systems is mterference from adjacent communication cells within the system In FDMA/TDMA systems, is type of interference is prevented through a frequency reuse plan Under a frequency reuse plan, available communication frequencies are allocated to cceimunicaticn cells within the communication system such mat the same frequency will not be used in adjacent cells. Fϊssentially, the available frequencies are split into groups. The number of groups is termed the reuse factor. Then the communication cells are grouped into clusters, each duster containing me same numr-β" of cefc Each frequency group is then assigned to a cell in each cluster. Thus, if a frequency reuse factor of 7 is used, for example, men aparticular communication

As a result, in any group of seven communication cells, each cell can only use l/V¹ of the available frequencies, ie., each cell is only able to use 1/7⁸¹ of the available bat-dwidth. " In a CDMA con^unϊcatiόn" sfit ϊti, έach cell uses the same wideband communication channeL In order to avoid interference with adjacent cells, each communication cell uses a particular set of spread spectrum codes to differentiate cornmumcations within the cell from those originating outside of the cell Thus, CDMA systems preserve the bandwidth in the serise to mey avoid limitaticins But as will be discussed, there are ether issues that limit the r>andwidth in CDMA systems as well Thus, in overcoming interference, system bandwidth is often sacrificed 13andwidth is becoming a very valuable commodity as wireless communication systems contiriue to e-φatxi by adding more and more users. Therefore, trading off bandwidth for system performance is a costly, albeit necessary, proposition to is inherent in all wireless communication systems. The foregoing are just two examples of the types of problems that can affect conventional wireless ccnimunication -^sterns. The examples also illustrate to mere are many aspe^

Not only are conventional wireless ccπnmunication systems effected by problems, such as those described in the preceding paragraphs, but also different types of systems are effected in different ways and to different degrees. Wireless communication systems can be split into three types: 1) line-of-sight systems, which can include point-to-point or point-to- multipoint systems; 2) indoor non-line of sight -^sterns; and 3) oiώdoαr systems such as wireless WANs. line-of-sight systems are least affected by the problems described above, while indoor systems are more affected, due for example to signals bouncing off of building walls. Outdoor systems are by far the most affected of the three systems. Because these types of problems are lirniting factors in the design ofwirelesstran-mtters and receiver^ such d specific types of system in which it will operate. In practice, each type of system implements unique communication standards to address the issues unique to the particular type of system Even if an indoor system used the same ccnimunication protocols and modulation techniques as an outdoor system, for example* the receiver designs would still be different because multipath and other problems are unique to a given type of system and must be addressed with unique solutions. This would not necessarily be the case if cost efficient and effective methodologies can be developed to combat such problems as described above that build in programmability so that a device can be reconfigured for diffeient types of systems and still maintain superior performance. SUMMARY OFTHE INVENTION In order to combat the above problems, the systems and methods described herein provide a novel channel access technology that provides a cost efficient and effective methodology that builds in programmability so to a device can be reconfigured for different types of systems and still maintain superior perfcamance. In one aspect of the invention, a method of (xanmuracating over a wiclebaτ-d-ccmmuracation channel divided into a plurality of -nib-channels is provided The method comprises dividing a single serial message intended for one of the plurality of communication devices into a plurality of parallel messages, encoding each of the plurality of parallel messages onto at least some of the plurality of sub-channels, and transmitting the encoded plurality of parallel messages to the communication device over flie wideband communication channel ^"When^' symbols are^' restricted fo 'pafficύlar range of values, the transmitters and receivers can be simplified to eliminate high power consuming components such as a local oscillator, synthesizer and phase locked loops. Thus, in one aspect a trarismitter comprises a plurality of pulse converters and differential amplifiers, to convert a balanced trinary data stream into a pulse sequence which can be filtered to reside in the desired frequency ranges and phase. The use of the balanced trinary data stream allows conventional components to be replaced by less costly, smaller cornponents that consume less power. Similarly, in another aspect, a receiver cornprises detection of the magnitude and phase of the symbols, which can be achieved with an envelope detector and sign detector respectively. Thus, converώcnal receivα components can be replaced by less costly, smaUercomponentstocσnsume less power. Other aspects, advantages, and novel features of the invention will become apparent from the following Detailed Description ofPreferred Emboαment-^whmccrøderedmccηurc BRIEFDESCRIPΠON OFTHE DRAWINGS Preferred emlxxliments of the present irwenti limitation, in the figures of the acccmpanyirigclrawings, in which: Figure 1 is a diagram illustrating an example embodiment of a wideband channel divided into a plurality of -αib-channels in accordance with Ihe invention; Figure 2 is a diagram illustrating the effects of multipatti ma wireless cornmunication system; Figure 3 is a diagram illustiating another example embodiment of a wideband communication channel divided into a plurality of sub-channels in accordance with the invention; Figure 4 is a diagram iUustrating the appUcati Figure 5 A is a diagram illustrating flie assignment of sub-channels for a wideband ccnimunication channel in accordance with the invention; Figure 5B is a diagram illustrating the assignment of time slots for a wideband communication channel in accordance with the invention; Figureό is a diagram illustoting an example embodiment of a wireless communication in accordance with the invention; Figure 7 is a diagram illustrating the use of synchronization codes in the wireless communication system of figure 6 in accordance with the invention; Figure 8 is a diagram illustrating a correlator to can be used to correlate syrx^ronization codes in the wireless commurrication system of figure 6; Figure 9 is adiagram illustratirig syncl^ Figure 10 is a diagram ilhistrating the cross-correlation properties of synchronization codes configured in accordance with the invention; Figure 11 is a diagram illustrating another example embodiment of a wireless communication system in accordance with Ihe invention; Figure 12A is a diagram illustrating how sub-channels of a wideband communication channel according to the present invention can be grouped in accordance witii the present invention; Figure 12B is a diagram illustrating the assignment of the groups of sub-channels of figure 12A in accordance with the invention; Figure 13 is a diagram illustrating the group assignments of figure 12Bm the time ctomairr, Figure 14 is a flow chart illustrating the assignment of sub-ctoinels based on SIR measurements in the wireless communication system of figure 11 in accσrdancewith the invention; Figure 15 is a logical block diagram of an example embodiment of transmitter configured in accordance with the invention; Figure 16 is a logical block diagram of an example einbodiment of a lnodulator configured in accordance with the preserit ventionforuseinmetrarisniitleroffigure 15; Figure 17 is a diagram illustrating an example eml-odiment of a rate controller configured in accordance with the mveritionforuse theinodulatoroffigure 16; Figure 18 is a diagram illustrating anomer example ernkxliment of a rate ccn^ memventicnfcruse themodulatoroffigure 16; Figure 19 is a diagram iflustrating an example embodiment of a fiequerκ;y encoder cc«ώ themve cmforuseintiiernodulatoroffigure 16; Figure 20 is a logical block diagram of an example emlxjdiment of a TDM/FDM block configured in accordance VΛmmeinventionforuseinthemoQ\to offigure 16; Figure 21 is a logical block diagram of another example embodimαit of a TDM/FDM block configured in accordance wim the invention for use in the modulator of figure 16; Figure 22 is a logical block diagram of an example embodiment of a frequency shifter configured in accordance with the invention for use in the modulator of figure 16; Figure 23 is a logical block diagram of a receiver configured in accordance wim me invention; Figure 24 is a logical block diagram of an example embodiment of a demodulator configured in accordance with the invention for use in the receiver of figure 23 ; Figure 25 is a logical block diagram of an example e-nbodimerit of an equalizer configured in accordance with the present invention for use in the demodulator of figure 24; Figure 26 is a logical block diagram of an example embodiment of a wireless communication device configured in accordance wim the invention; Figure 27 is a flow chart illustrating an exemplary method for recovering bandwidth in a wireless communication network in accordance with the invention; Figure 28 is a diagram illustrating an exemplary wireless communication network in which the method of figure 27 can be implemented; Figure 29 is^' a logical block diagrarri illustrating an exenplary transmitter to c^ to implement tie method of figure 27; Figure 30 is a logical block diagram illustrating another exemplary tran-anitter that can be used in the network of figure 28 to implement the method of figure 27; Figure 31 is a diagram illustrating another exemplary wireless communication network in which the method of figure 27 can be implemented;

15; Figure 33 is a diagram of an example radio tran-anitter module that can be used in the transmitter of figure 15 in accoπlance with one embodiment of the invention; Figure 34 is a waveform illustrating erκ - _^ Figure 35 is a diagram illustrating one example embodiment of a pulser that can be used in the radio trarismitter module of figure 33; Figure 36 is a diagram illustrating an example embedment of apassive cornbiner that can be used in the radio transmitter module of figure 33; Figure 37 is a diagram illustrating arrøther example emb^ module of figure 33; Figure 38 is a diagram illustrating an example embodiment of a passive combiner to can be used in the radio transrnitter module of figure 33; Figure 39 is a diagram illustrating an exemplary radio rec vertocanbe used in ti e receiver of figure 23; Figure 40 is a diagtam of an example radio receiver that can be used m me receiver offigure 23 m accordance with one ernbodiment of the invention; Figure 41 is a diagram illustrating another example eintoαfa-ent of a receiver that can be used in the receiver of figure 23 in accordance with one emrxxfenent of the invention; and Figure 42 is a table illustrating me effective number ofbits for various implementations of the radio receiver offigure 41. DETAΗJ-DDESCRIPπONOFTHE PREFERRED EMBODIMENTS 1. htroduction In order to improve wireless communication system perfccmance and allow a single device to move from one type of system to another, while still maintaining siiperiorperformance, the systems andmethods described herein provide various communication methodologies that enhance performance of trarismitters and receivers with regard to various common problems that afflict such -^sterns and to allow the transmitters arxlorrec vers to b^ ina variety of systems. Accordirιgty,te systems and md common wideband communication channel for all cornmunication cells. The wideband channel, however, is then divided into a plurality of su- -harrnels. ]-)ifferentsιιb-chaπnels are then a-agned to one or more users wilh each ∞l l it me base station, or service access point, within each cell tr-ttisni s one message to occupies the entire bandwidfti of the wideband channel Each user's communication device receives the entire message, but only decodes those portions of the message to reside in sub-channels assigned to the user. For a point-topoint system, for example, a single user may be assigned all sub-channels and, therefore, has the full wide band channel available to them. In a wireless WAN, on the other hand, the sub-channels maybe divided among apiurality of users. In the (iescriptiσns of example embodiments that follow, implementation α Terences, or unique concerns, relating to

described herein are applicable to any type of communication systems. In addition, terms such as communication cell, base station, service access point, etc. are used hτjχ-τi]angeablytoreiertotheccmm To begin illustrating the advantages of the systems and methods described herein, one can start by looking at the multipath effects for a single wideband communication channel 100 of bandwidth B as shown in figure 1A Communications sent over channel 100 in a traditional wireless ccnimunication system will comprise digital data symbols, or symbols, that are encoded and modulated onto a RF carrier that is centered at frequency /_c and occupies tendwidthR. Generally, the width of the symbols (or the symbol duration) Tis defined as 1/B. Thus, if the bandwidth B is equal to 100MHz, then the symbol duration is defined by the following equation: T=W = 1/lOOMHZ = 10ns. (1) When a receiver receives the communication, demodulates i and men deco ies i twifl re clatasymbols 106 as illustrated in figure 2. But the receiver will also receive multipath versions 108 ofthe same data stream. Because multipalh data streams 108 are dekyed time relative to data stream 104 by & theymaycxmbmedestriictivelywitiidatastream 104. A delay spread a is defined as the delay from reception of data stream 104 to the reception ofthe last multipath data stream 108 that interferes with thereception of data stream 104. Thus, inthe example illustrated in figure 2, the delay spread d_s is equal to delay d4. The delay spread d, will vary for dif-ferentenviror-ments. An environment wim a lot of obstacles will create a lot of multipalh reflections. Thus, the delay spread a will be longer. --Experiments have shown that for outdoor WAN type envtemments, the delay spread a can be as long as 20μs. Using the 10ns symbol duration of equation (1), this translates to 2000 symbols. Thus, with a very large randwidth, such as 100MHz, multipath interference can cause a agnificant amount of terterence at the symbol level for which adequate compensation is difficult to achieve. This is true even for indoor environments. For indoor LAN type systems, the delay spread d, is significantly shorter, typically about 1 μs. Fora 10ns symbol duration, this is equivaleπtto 100 symtels, wMch is rncre manageable but stiflsignffi By segmenting the bandwidth B into a plurality of - Mtomels 200, as illustrated in figure 3, and generating a distinct data stream for each sub-channel, the multipalh effect can te reduced to a much more manageable leveL For example, if the bandwidm B of each sub-channel 200 is 500KHz, then the symbol duration is 2μs. Thus, the delay spread for each surκhannel is equivalent to only 10 symbols (outdoor) or half a symbol (indoor). Thus, by breaking up a message that occupies the entire bandwidth B into discrete messages, each occupying the bandwidthR of sub-channels 200, a very wideband signal to suffers from relatively minor multipath effects is created Before discussing further features and^' advantages of using a wideband communication channel segmented into a plurality of sub-channels as described, certain aspects ofthe -ajd-Htomels will te explained in more detaϋ Inferring back to figure 3, the overall tøndwidthR is segmented into Nsub-charmels center at frequencies fo to fop Thus, the s κtoιnel 200 that is immediately to the right of fc is offset from fc by b/2, where b is the bandwidth of each saib hannel 200. The next sub-channel 200 is oflset by 3b/2, the next by 5 b/2, and so on To the left of fc, each sub<-hannel 200 is oflset by -b/s, -3b/s, - 5b/2,dtc. Preferably, sαib-charmels 200 are røn-overlapping as this allows each sub-channel to te processed inderxndentry in the receiver. To accomplish this, a roll-off factor is preferably applied to the signals in each sub-channel in a pulse-shaping step. The effect of such a pulse-shaping step is illustrated in figure3 by the r-on-rectangular shape ofthe pulses in each s channel200. Tlιus,mebarx dtiιRofeachsιιb-charmelca^ b = (l+ryT; (2) Wherer=meroU-offfactor, and T= the symbol duration Without the roll-off factor, i.e., b = 1/T, the pulse shape would te iectangular in the frequency domain, which corresporιclstoa(tø;^/ftfur-ctionm The time domain signal for a (sinx)άsgxa\ 400 is shown in figure 4 in ordertoillustiate the problems associated wit^ As can te seen, main lobe 402 comprises almost all of signal 400. But some ofme signal also resides in side lobes 404, which stretch out indefinitely in bom directions from inam lobe 402. Side lobes 404 make processing signal 400 much more difficult, which increases the complexity of e receiver. Applying a roll-off factor r, as in equation (2), causes signal 400 to decay faster, reducing the number of side lobes 404. Thus, increasing the roll-off factor decreases the length of signal 400, i.e., signal 400 becomes shorter in time. But including the roll-off factor also decreases the available bandwidth in each s channel200. Therefore, r must te selected so as to reduce tte number ofside lobes 404 to a suffiderl number, e.g, 15, while still rnaximizing the available bandwidth in each sub-channel 200. Thus, the overall bandwidth B for communication channel 200 is given by the following equation: B =N(l+r)/T; (3) or B =MT; (4) Where M=(l+r)N. (5) For effiάency purposes related to transmitter desigrt, it is preferable tor is chosen so to in equa^ integer. Choosing r so mat M is an integer allows for more efficient transmitters designs using, for example, Inverse Fast

Fourier Transform (1F 1) techniques. Since ^N+N^ andNis always an integer, this meaικ tor must te chosen so that N(r) is an integer. Gmerally, it is preferable for r to te between 0.1 and 0.5. Therefore, if Nis 16, for example, then .5 could be selected fbrrso thatN(rJ is an integer. Alternatively, if a value forris chosen in the above example so fhatNi^) is not anir-tegff,Rcanternaα s-ightiywidfftl^ In this case, ftisstifl preferable tortecho is approximately an integer. 2. Example Fjrirxxffinent of a Wireless Ccmmunication System With the above in mind, figureό illustrates an example cornmumcation system 600 comprising a plurality of cells 602 that each use a common wideband communic^onctomel to communicate with ccmmura each cell 602. The common cornmumcation channel is a wideband commimication charmel as desmTjed above. Each communication cell 602 is defined as the coverage area of abase station, or service access point, 606 within the cell One such base station 606 is shown for illustration in figureό. For purposes of mis specification and the claims that follow, the term base station will te used generically to refer to a device that provides wireless access to the wireless communication system for apiurality of communication devices, whe tiiesyεlemisaMe of sight indoor, or out o^ Because each cell 602 uses the same communication charmeL

signals in adjacent cells 602. To d-ffαentiate signals from one cell 602 to anolher, adjacent base stations 606 use different syneliranization codes according to a codereuseplan In figure 6, system 600 uses a syrxnronizaticn cede raise factor of 4, although the reuse factor can vary deperxling cm tiie application Preferably, the synchronization code is periodically inserted into a communication from a base station 606 to a communication device 604 as illustøiedm figure 7. Afterapredetermmednumberofdatapackets7C2,inte particular synchronization code 704 is inserted into the information being transmitted by each base station 606. A synchronization code is a sequence of data bits lαiown to torn me base station 606 and any cc ^ which it is communicating The synchronization coo^aUows such a cornmunication device 604 to syn^ toof oa-«sMon6O6,wlιiclι,inturrι,aUowsdevice604todβ Thus, incell l (see lightly shaded cells

602 in figure 6), for example, synebrorazation cocte l (SYNCl) is inserted into data sdream station 606 in cell 1, after every two packets 702; in cell 2 SYNC2 is inserted after eveiy two packets 702; m inserted; andincell 4 SYNC4 is inserted

In figure 5 an example wideband communication channel 500 for use in communication system 600 is divided into 16 sub-channels 502, centered at freque^ transmits a single packet occupying Ihe wtelebarxlwidmRofwidebarxi channel 500. Such apacket is illustrated bypacket 504 in figure 5B. Packet 504 comprises sub-packets 506 to are encoded with a frequency oflset ccαiesponding to one of sub-channels 502. Sub-packets 506 in effect define available time slots in packet 504. Si i y, sub-channels 502 can te said to define available fiequency bins in ccmmunication channel 500. Therefore, the resources available in cornmuricaticn cell 602 are time slots 506 and frequency bins 502, which cante assigned to different communication devices 604 within each cell 602. Thus, for example, frecμency bins 502 and time slots 506 can te assigned to 4 different communication devices 604 within a cell 602 as shown in figure5. Each cornmumcation device 604 receives the entire packet 504, but only processes those frequency bins 502 and/or timeslots 506 that are assigned to it Preferably, each device 604 is assigned non- adjacent frequency bins 502, as in figure 5. This way, if iriterference corrupts the information in a portion of communication channel 500, then the effects are spread across aH devices 604 within a cell 602. Hopefully, by spreading out the effects of iriterference in this manner the effects are rnirami--edaώ the entire infoimationsert from the unaffected informatiori received in other frequency bins. For example, if iriterference, such as fading, corrupted the information in bins (r ^ then each user 1-4 loses one packet of data But each user poteritMy receives three unaffected packets from the other bins assigned to them Hopefully, the imaffected data in the other three bins provides enough information to recreate ftie entire message for each user. Thus, bins to each of multiple users. Eri-a-tring mat the bins assigned to one user are separated by mcae than me coherence baridSvidth a diversity. As discussed above, the coherence bandwidth is approxiinately equal to i - For outdoor systems, whae ds is

least 1 MHz, It can te even more preferable, howevα, if the coherence banc dfh plus some guard band to ensure suffi frequency diversity separate the non-adjacent bins assigned to each user. For example, it is preferable in certain irnplementations to ensure to at least 5 times the coherence aα aceπtbins. Another way to provide frequency diversityis to repeat blocks of data in frequency bins assigned to a particular user to are separated by more than the coherence bandwidth. In otter words, if 4 sub-channels 200 are assigned to a user, then data block a can te repeated in the first and third sub-charmels 200 and data blcκ-kb can te repeated in tte sub-channels 202, provided the sub-channels are sufficiently separated in frequency. In this case, the system cante said tote usingadiversitylaιgthfactorof2. The system can similariyte configured to irnplementofl acfiversity lengths, e.g, 3,4, ..., /. lt shouldbe noted that spatial diversity can also te inducted deper lirιg on 1te Spatial diversity can comprise transmit spatial diversity, receive spatial diversity, or both, transmit spatial drversity, the transmitter uses a plurality of separate transmitters and a plurality of separate ariterrnas to transmit each message. In other words, each transntittertrar)-5mits1hesamemessageinparalleL The messages are then received from the tiansnitters and combined in the receiver. Because the parallel transmissions travel different paths, if one is affected by fading, the others will likely not te affected Thus, when they are combined in the receiver, the message should te recoverable even if one or more ofthe other trarismission paths experienced severe lading Receive spatial diversity uses a plurality of s-ϊparaterecdvers arxi a pluraHty of separate antennas to message. If an adequate distance separates the antennas, then the transmission path for the signals received by the antennas willbe different AgairL,1hisdiffererx« in the transmission D the receivers are combined Transmit and receive spatial diversity can also te combined within a system such as system 600 so that two ar-tennas are used to transmit and two ariteririas are used to receive. Thus, each base station 6C)6transmitta can include two antennas, for transmit spatial diversity, and eaΛ ccnimunication device 6O4recaver can irr spatial diversity. If only trar-smit spatial diversity is implemented in system 600, then it can te implemented in base stations 606 or in communication devices 604. Similarly, if only receive spatial diversity is included in system 600, then it can te iinplementedinbase stations 606 or cornmumcation devices 604. The niimber^'όfccmrrairήcation devices 604 assigned frequency bins 502 and/or time slots 506 in each cell 602 is preferably programmable in real time. In otter words, the resource allocation within a communication cell 602 is preferably programmable in the face of varying external conditions, i.e., multipalh or adjacent cell ir-terference, and varying requirements, i.e, bandwidth requirements for various users within the cell Thus, if user 1 requires the whole bandwidth to download a large video file, for example, then the aUocation oftøns5Q2canteadjιιsttoprovi<-teιι^ of bins 502. Once user 1 no longer requires such large amounts ofT-αnctwidth, the allocation ofbins 502 can te readjusted among all of users 1-4. It should alsote noted that all of the bins assigned to a particular usre can te used for tethtte forward aώ link Alternatively, some bins 502 can te assigned as the forward lirik and some can te assigned for use on me reversely defending on the irnplementation To increase capadty, the entire bandwidthR is preferably reused in each ∞mmunication cell 602, with each cell 602 being differentiated by a unique syr Aranization code (see discussion below). Thus, system 600 provides increased immunity to multipalh and fading as well as increasedtend width (i etomeelirnir-a^ 3. Synchronization

When a device 604 in cell 1

(see figure 6), for example, recdves an incoming commiinication from the cell 1 base station 606, it compares the incoming data with SYNCl in correlator 800. Essentially, the device scans the incoming data trying to correlate the data with the

Once correlator 800 matches the incoming data to SYNCl itgeneratesa correlation peak 804 at the output Multipath versions ofthe data will also generate correlation peaks 806, although these peaks 806 are generafly smaller than coπelation peak 804. Thedevice can then use thecoπelation peaks to perform charrnd estimation, which allows the device to adjust for Ihe multipalh using, eg., an equalizer. Thus, in cell 1, if correlator 800 receives a data stream comprising SYNCl , it will generate correlation peaks 804 and 806. Iξ on the other hand, the data stream comprises SYNC2, for example, then no peatewiflte generated arri the device wift ess ccnimunication Even though a data stream to comprises SYNC2 will not create any correlation peaks, it can create noise in correlator 800 that can prevent detection of coπelation peaks 804 and 806. Several steps can te taken to prevent this from occurring Cne way to minimize fl erioise created mccn^latOT

600sotoeachbasestation606transmteat1te This way, the εync^nizaticn cedes can in such a maπnσ to only the synchronization codes 704 of -djacenl cell data streams, e.g., streams 708, 710, and 712, as opposed to packets 702 within those steams, will interfere with detection ofthe correct syrchronization code 704, e.g, SYNCl.

For example, the noise or iriterference caused by an incorrect synchronization code is a function ofthe cross correlation of that synclironization code with respect to the correct code. The better the cross correlation between the two, the lower the noise level When the cross coπelation is ideal, then the noise level wiUtevirtuaUy--ero as illustrated m figure 9 by noise level 902. Therefore, a preferred erntectiment of system 600 uses synchronization codes to exhibit ideal cross correlation, -.e, zero. Preterably, the ideal cross correlation ofthe synchronization codes covers aperiod 1 that is suffident to aflow accurate detecfim of miΛipathα This is important so that accurate channel estimation and eqiializaticn can take place. Outside of period 1, the noise level 908 goes up, because the data in packets 702 is random and will exhibit low cross correlation with the synchronization code, e.g., SYNCl . Preferably, period 1 is actually slightly longer then the multipalh length in oidαtoensuretothemultipatiicantedetected a Synchronization code generation Conventional systems use orthogonal codes to achieve cross coπelation in correlator 800. In system 600 for example, SYNCl, SYNC2, SYNC3, and SYNC4, corresponding to cells 14 (see lightly shaded cells 602 of figure 6) respectively, wiflaU need tote generated In one embodiment, if the data streams involved comprise liigh and low data bits, thente bits and "-1" to the low data bits. Orthogonal data sequences are then those to produce a "0" output when they are exclusively ORed (XORed) together in correlator 800. The following example illustrates this point for orthogonal sequences l and2: sequence 1: 1 1 -1 1 sequence^ 1 1 1 -1 1 1 -1 -1=0 Thus, when the results ofXORing each bit pair are added, the result is 'O." But in system 600, for example, each code must have ideal, or zero, cross correlation with each ofthe other codes used in adjacent cells 602. Therefore, in one example embodiment of a method for generating syncliionization codes exhiDiting the properties clesciibedatevei the process begins by select^ codes. A perfect sequence is one that when correlated with itself produces a number equal to the iiumber of bits in the sequence. For example: Perfect sequence 1: 1 1 -1 1 1 1 -1 1 1 1 1 1 =4 But each time a perfect sequence is cyclically shifted by one bit, the new sequence is orthogonal wim the original secjuenee. Thus, for example, ifperfect sequence 1 is cyctically shifted by cne bit and thm correlated wil^ correlation produces a"0" as in the following example: Perfect sequence 1: 1 1 -1 1 1 1 1-1 1 1 -1-1 = 0 If the perfect sequence 1 is again cyclically sifted by one bit, and again correlated with the original, then it will produce a "0".

shifted sequence with the original to obtain a ' f '. Once aperfed sequence of the correct length is selected me fir-isyrxhrorιi--aticn code is prefe embodimentbyrepealirιgthesequence4times. Thus, tfpertect sequence 1 is being used, then a first ε;yndιrc zaticmcxdey wouldtethe following: y=l l -1 1 1 1 -1 1 1 1 -1 1 1 1 -1 1. ϋrrngenenc'torm y=x(0)x(l)x(2)x(3)x(0)x(l)x(2)x(3)x(0Kl)x(2K3)x(0)x(lM2W3 For a sequence oflength L: y=x(0Kl)..Λ(TK0)x(l)..Λ(LK0)xG)..Λ(L)x(0)x(l). Λ(L). Repeating the perfect sequence allows correlator 800 a better opportunity to detect the syrchranization code and allows generation of other uricorrelated fiequendes as well Repealing has the effect of sampling in the frequency domain This effed is illustrated bythegraphs in figure 10. Thus, intrace l, which ccπesponds to synchronizatimccde , a sample 1002 is generated every fourth sample bin 1000. Each sample bin is separated by l/(4LxT), where -Tis the symbol duration Thus in the above example, where E = 4, each sample bin is separated by 1/(16x1) in the fiequency ckπnain Traces 2-4 illustrate the next three synchronization codes. As can te seen, the samples for each subsequent syrxhronization code are shifted by one sample bin relative to the samples for the previous sequence. Therefore, none of sequences interfere with each other. To generate the subsequent seqijjaxes,corresp This can te accomplished using the following equation: £(m) =y(m)*exp(j*2 *π*r*m/(n*L)), (6) forr= 1 toE(#< εequenees)andm=0to4*E-l (time); and where: i(m) = each subsequent sequence, y(m) = the first sequence, and n = the riurnter of times the sequence is repeated It will be imdastood to multiplying by an eφ(j2π(r*m/N)) factor, where N is equal to flie nurnter of times the sequence is repeated (n) multiplied by the length of the imderiying perfed sequence Z, te flie -requency domain liquation (6) results in the desired shift as illustrated m figure 10 for each of syrc reMveto syr-chronizatic code l. The final step in generating each syr-chrom-_aticmαxteisto samples, where is the length ofthe multipalh, to flie front of each code. This is done to make the convolution with flie multipath cyclic and to allow easier detection of fl e multipalh. It shouldte noted that synchronization coo s rantegenerated from more than o methodology. For example, a perfect sequence can te generated and repeated for times ard then a secxMl perfed sequent can te generated and repeated four times to gd a n factor equal to dght The resulting sequence can then te shifted as described above to create the synchronization codes. b. Signal Measurements Using Synchronization Codes Therefore, when a ccmmunication device is at the edge of a cell, it will receive signals from multiple base stations and, therefore, will be decoding several synchronization codes at flie same time. This can te illustrated with the help of figure 11, which illustrates anoflier example ernbodiment of a wireless communication system 1100 cornprising communication cells 1102, 1104, and 1106 as well as cxjmmunication device 1108, which is communication with base station 1110 of cell 1102 but also receiving communication from base stations 1112 and 1114 of cells 1104 and 1106, respectively. If ccnimunications from base station 1110 comprise synchronization code SYNCl and ccmmunications from base station 1112 and 1114 comprise SYNC2 and SYNC3 respectively, then device 1108 will effectively receive flie sum of these three synchronization codes. This is because, as explamedatove, base sMcms 1110, 11 π^ tran-anit at the same time. Also, the synchronization codes arrive at device 1108 at almost the same time because they are generated in accordance with the description above. Again as described above, the synchronization cxxles SYNCl, SYN^ Therefore, when device 1108 correlates the sumx of codes SYNCl, SYN(-2, arid SYN(-3, the latta two wiU not int ^ with proper detection of SYNCl by device 1108. Importantly, the sumx can also te used to detemtine irnportant signal (toacteristics, because the sumx is equal to the sum of flie synehionizaticn code signal in accordance with flie following equation: x = SYNCl +SYNC2+SYNC3. (J) Therefore, when SYNC 1 is removed, the sum of SYNC2 and SYNCS is left, as shown in the following: x- SYNCl =SYNC2+SYNC3. (8)

Siixe the purpose of collating flie s^nchra has the energy in the signal from base station 1110, i.e., the energy represented by SYNC 1. Therefore, device 1106 can use the energy of SYNCl and of (SYNC2 + SYNC3) to perform a sagnal-teHπterferenee measurement for the communication channel ova which it is cxjmmunicatirig with base station 1110. The result ofthe measurement is preferably a sdgnal-to- interfaence ratio (SIR).

tedisαissedtelow. The ideal cross correlation ofthe synchronization codes also allows device 1108 to perform extremely accurate detenninations ofthe Channel Impulse Response (CIR), or channel estimation, from the correlation produced by correlator 800. This allows for highly accurate e ualization using low cost, low complexity equalizers, thus overcoming a significant draw back of conventional systems. 4. Siib-channel Assignments As mentioned, the SIR as determined by device 1108 cante ccnimumcatedbadctobase station lllOfor use in the assignment of slots 502. In one embodiment, due to flie fad that each sub-channel 502 is processed independaitly, flie SIR for each sah-channel 502 cante measured and communicated back to base station 1110. sαich an αnlxxliment, therefore, sub<hannels 502 c^tectivided into gro Thisis illustrated in figure 12A which shows a wideband cxmmunication channel 1200 segmented into sub-channels jo to fc.

Thus, m one emboctimeni, device 1108 and base station 1110 commum∞teovaachannelsudi as channel 1200. Sub-charmels in flie same group are preferably separated by as many sub-channels as possible to ensure diversity. In figure 12A for example, sub-channels within the same group are 7 sutκhaπnels apart, e.g., group GI coinprises ø and/₅. Device 1102 reports a SIR measurement for each of the grourxGl to G8. These SIR measurements are preferably ∞rnparedwifliaflin-stoldvatuetodeter^ This comparison can occur in device 1108 or base station 1110. ffit occurs in device 1108, thendevice 1108 canεarrplyrepcrttobasestation 1110 whichsub-charmelgroupsareuseableby device 1108. SIR reporting will te samultaneously occurring for a plurality of devices within cell 1102. Thus, figure 12B illustrates the situation where two communicaticn devices corresponding to uεerl and user2 report SIR levels above the threshold for groups GI, G3, G5, and G7. Base station 1110 preferably then assigns sub-channel groups to useri and user2 based on the SIR reporting as illustrated in Figure 12B. When assigning the "good" sub-channel groupstousal anduseώ, base station 1110 also preferably assigns them based on the principles of frequency diversity. In figure 12B, therefore, usal anduser2 are alternately assigned every otha "good" εnι1-κharιnel The assignment of sub-channels in the fre uency domain is equivalent to the assignment of time slots in flie time αbmai Therefore, as iflustrated in figure 13, two users, used and user2, receive packd 1302 transmitted ova cornmumcation channel 1200. Figure 13 also illustrated flie saib-channel assignment offigure 12B. While figure 12 and 13 illustrate sιιr> harmeltime slot assignment based on SIR for two users, the principles illustrated can te extended for any number of users.

Although, as the numter of available sub-charmebisreduc^duetoMghSIl^soistheavaii^ faothawords, as available sub-channels are reduced,

Poor SIR can te caused for a variety of reasons, but frequerώy it results from a ά^ce at the ed^ ccmmunication signals from adjacent cells. Because each cell is using the same bandwidth B, flie adjacent cell signals will eventually raise the noise level and degrade SIR for certain sadκhannels. In certain embcxliments, therefore, saib-channel assignment can te ccoidinated between cells, such as c«lk 1102, 1104, arxl 1106 m fi from adjacent cells. Thus, if commumcation device 1108 is near the edge of cell 1102, and device 1118 is near the edge of cell 1106, then flie two can interfere with each otha. As a result, the SR measurements to device 1108 and 1118 report back to base stations 1110 and 1114, respectively, will indicate to the interference level is too high Base station 1110 can then te configured to assign only the odd groups, i.e, GI, G3, G5, c^., to device 1108, wMe base ε on 1114 cante configured to assign the even groups to device 1118 a coordinated i -ion The two devices 1108 and 1118 will then not interfere with each otha due to the ccoidinated assignment of sub-channel groups. Assigning the sub-channels in this manna reduces the overall bandwidth available to devices 1108 and 1118, respectively. Infliiscas lhebandvvic-thisieduce^ But it should te remembered that devices operating closer to each base station 1110 and lll4, respectively, will still te able to use all sub-channels if needed Thus, it is only

Contrast this with a CDMA system, for example, in which the barxrwidthfcraUusersisreduc^duetotheεpreadr^ systems, by apj-roxnriately a factor of 10 at a times. It can te seen, therefore, that flie systems and methods for wireless communication over a wide bandwidth channel usingaplura ofsub-charmelsnotc^yimprov can also increase the available bandwidth agnificantly. When there are three devices 1108, 1118, and lllόnearthe edge of flieir respective adjacent cells 1102, 1104, and 1106, the sub-channels cantect ded by three. Thus, device 1108, for example cante assigned groups GI, G4, etc., device 1118 cante assigned groups G2, G5, etc., and device 1116 cante assigned groups G3, G6, etc. In this case fl e available bandwidth for these devices, i.e., devices near flie eclges ofcells 1102, 1104, arκl 1106, is reduced by a fad^ still better than a CDMA system, for example. The manna in which such accxjrdrnated assignment of s κharmels <^n wcrt is illiistratedby the flow chart in figure 14. First in step 1402,

G8. The SIRs reported are then coinpared, in step 1404, to a thresteM to determine tfthe SIR is

group. Alternatively, device 1108 can make the deteπninatiσn and simply report which groups are above or below the SIR threshold Ifthe SIR levels are good for each group, then base station 1110 can make each group available to device 1108, in step 1406. Periodically, device 1108 preferably measures the SIR level and updates base station 1110 in case the SIR as deteriorated For example, device 1108 may move from near the center of cell 1102 toward the edge, where interference from an adjacent cell may affect the SIR for device 1108. If the cornparison in step 1404 reveals to the SIR levels are not good, then base station 1110 can te preprogrammed to assign άthertheodd groups or the even groups only to device 1108, whichitwill do instep 1408. Device 1108 then reports flie SIR measurements for the odd or even groiφs it is assigned in step 1410, and they are again compared toaSlRlhreεholdinstep 1412. It is assumed to the poor SIR level is due to the fad to device 1108 is operating at flie edge ofcell 1102 and is therefore being interfered with by a device such as device 1118. Butdevice 1108 will teiriterfering with device 1118 at flie same time. Therefore, the assignment of odd or even groups in step 1408 preferably corresponds with fl e assignment of flie opposite groups to device 1118, by base station 1114. Accordingly, when device 1108 reports flie SIR measurements for whicheva groups, odd or even, are assigned to it, the cornparison in step 1410 should reveal to flie SIR levels are now below the threshold level Thus, base station 1110 makes the assigned groups available to device 1108 in step 1414. Again, device 1108 prefer-hlyperiodically updates the SIR measurements byretumrng to step 1402. It is possible for flie cornparison of step 1410 to reveal that the SIR levels are still above the threshold, which should indicate that a third device, e.g, device 1116 is still interfering with device 1108. m fliis case, base station 1110 can te preprogrammed to assign everythird group to device 1108 in step 1416. This should correspond with the corresponding assignments of non-interfering channels to devices 1118 and 1116 by base stations 1114 and 1112, respectively. Thus, device 1108 should te able to operate on the sub-channel groups assigned, i.e., GI, G4, etc., wilhout undue interference. Again, device 1108 preferably periodically updates flie SIR measurements by returning to step 1402. Optionally, a third comparison step (not shown) can te irnplemeπted after step 1416, to ensu^ an adequate SIR level for propa operation Moreover, if there are more actøacent cells, i.e, if it is possible for devices in a 4^th or even a 5°' adjacent cell to^' interfere ^'witfrαϊvice 1108, then flie process offigure 14 would continue and the sub-channel groups would te divided even further to ensure adequate SIR levels en the sιjl>charmels assignd Even though the process of figure 14 reduces the bandwidh availabletodevices at the edge of cells 1102, ^ 1106, the SIR measurements can te used in such a manna as to inαease the data rate and therefore resto^ bandwidth To accomplish this, the transmitters and recάversusedin base stations 1102, 1104, and 1106, and in devices in ccmmunication therewith, e.g, devices 1108, 1114, and 1116 respectively, must te capable of dynamically changing the symbol mapping schemes used for some or all of the sub-channel For example, in some en-hodiments, the symbol mapping scheme can te dynamically changed among BPSK, QPSK, 8PSK, 16QAM, 32QAM, etc. As flie symbol mapping scheme moves higha, i.e, toward 32QAM, the SIR level required for proper operation moves higha, i.e., less and less iriterference cante withstood Therefore, once the SIR levels are determined for each group, the base station, eg, base station 1110, can then determine what symbol mapping scheme can te supported for each sub-channel group and can change the modulation scheme accordingly. Device 1108 must also change the symbol mapping scheme to correspond to that ofthe base stations. The change can te effected for all groups uπifoimly, or it can te effected for individual groups. Moreover, the symbol mapping scheme can te changed cnjust flie forward link,jusi flie revere theemrxxiiment Thus, by ma tainrng the capability to erynamically assign sub-<-hannels and to dynamically change the symbol mapping scheme used for assigned sub-channels, the systems and methods described herein provide the ability to rnaintain higha available bandwidths with higha perfeirmance levels than conventional systems. To fully realize the benefits clescnted, however, the systems and methods described thus far must te capable of irnplementation in a cost effect and convenient manner. Moreova, the irnplementation must include ieconfigurability so that a single device can move between clifferent types of ccmmunicaticHi systems and still maintain optimum performance in accoidance with the systems and methods described herein The following clesxripticns detail example high level embcxiimeπts ofhardware irnplementations configured to operate in accordance with fl e systems and methods described herein in such a manna as to provide flie capabilityjust described above. 5. Sample Transmitter F-mrxx-iments Figure

cornmumcation in accordance with the systems and methods clescribed above The transmitter could for example te within a base station, e.g., base station 606, or within a commionic^cneiewc^suchaseievi(x604. Transmitter 1500 is provided to illustrate logical ccmponents that can te irøludedm a transmitta configure described herein It is not intended to limit the systems and methods for wireless communication over a wide bandwidth channel using a plurality of sub-channels to any particular transmitter configuration or any particular wireless commixnication system. With this in mind, it can te seen to transmitter 1500 comprises a serial-toparallel converter 1504 configured to receive a serial datastream l 502 exπnprising a data iateR. Serial-topara converter 1504 converts data stream 1502 intoN parallel data streams 1504, where Nis the number of sub-channels 200. It should te noted that while the discuss cai to follows assumes that a Srngle Serial data stream is used, more than one serial data stream can also te used if required or desired fri any case, the datarate of each parallel data stream 1504 is flienRN. Each data stream 1504 is then sent to a scrambla, encoder, and interleaver block 1506. Scrambling, encciding, and interleaving are common techniques irπplemented in many wireless ∞rnmumcaticn transmitters and help to provide robust, secure communication Examples of these teclmicfues will te briefly explained for illiistrativepurposes. Scrambling breaks up the data to te transmitted man effort to smooth oirtte For example, if the data comprises a long string of 'T 's, there will te a spike in the spectral density. This spike can cause greater interfaence within flie wireless communication system. By breaking up the data, the spectral clensity can te smoothed outto avcidany suchpeaks. Often, seiπnblingisacHevedbyXOI^ingthedataw Encoeiirig,orcoelmgtheparaUelbitsu^arns 15M The purpose of EEC is to improve the capacity of a communication channel by adding some carefully designed redundant irfomiatim to the data being 1ran-m^ The process of addingfliis redundant iπfoπnationisknownas channel coding CcmvoMoιτalcodirιgandbloc- cχχ^ ⁽Evolutional codes operate on serial data, one or a few bits at a time. Block codes operate on relatively large (typicaUy,uptoacoupleofhundred bytes) message blocks. There are a variety of useful convolutional and block codes, and a variety of algorithms for decoding the received exxiedinformatien sequences to recovathecriginalciata For example, convo orial encoding or turto coding with Viterbi decocting is a FEC tcx imcruetoispartiαilariysuitedto

mainly by additive white gaussian noise (AWGN) or even a channel that simply experiences fading Convolutional codes are usually described using two parameter: the cede rate ar l fl e con^ rate, k/n, is expressed as a ratio ofthe numter ofbits into flie convolutional encoder (k) to the number of channel symbols (n) output by the corrvo onal ericoder ina given erccder cycle. Ac»inmcncx>cteiateis 2, Vvbic^ proctuced for every 1-bit input into the coda. The constraint length parameter, K, denotes the 'length" ofthe convolutional encoder, i.e. how many k-bit stages are available to feed the combinatorial logic to produces the output symbols. Qosely related to ΛTis the parameter m, which indicates how many encoda cycles an input lit is retained and ιιs^ it first appears at the input to the convolutional encoder. The m parameter can te thought of as the memory length ofthe encoder. Interleaving is used to reduce flie effects of fading. Interleaving mixes up flie order ofthe data so that if a fade interferes with a portion ofthe transmitted sagna the overafl message wifl not te effected This is because once the message is de-interleaved and decoded in the recdver, the data lost will comprise non-ccntiguous portions of flie overall message. In otha words, flie lade will interfere with a contiguous portion ofthe interleaved message, but when the message is de- interieaved, the interfered with portion is spread througteirt Are overaU message. Using t information can then te filled in, or the irnpad ofthe lost data may just te negligible. After blocks 1506, each parallel data stream 1504 is sent to

1508. Symbol mappers 1508 apply the requisite symbol mapping, eg, BPSK, QPSK, etc, to each parallel data stream 1504. Symbol mappers 1508 are preferably programmable so to the mcdulation apptied to paraUel data streams can teetoiged, for e an^ the SIR reported for each siib-channel 202. It is also preferable, to each εymtelm-ipp l 508 tese so to the optimum symbol mapping scheme for each εaib-charmel cante selected and appKed to each pa^

1504. Aftasymtelιnappas l508,paraUeldatasheams l50^ Irnportarit aspects and features of example eml-odments of rnodulators 1510 are described telow. After modulators 1510, parallel data streams 1504 are sent to summa 1512, which is configured to sum flie para daføstaearris and thereby genα^ 1518 eornprisrngeach ofthe inαιvicιua processed paraM dak 1504. Serial data stream 1518 is then sent to radio module 1512, where it is modulated with an RF carria, arnplified, and transmitted via antenna 1516 according to known technic[ues. RaclionxxMee^nbcdiments that cante used mccnjunc^cnwifli fl e systems and mefliodsde-ented described telow. The transmitted signal occupies the entire ter-dwidth B of communication channel 100 and cornprises each ofthe discrete parallel data streams 1504 encoded onto their respective sub-channels 102 within bandwidth B. lE-ncoding parallel data streams 1504 onto the appropriate sub-channels 102 recjuires to each paraUel data stream 1504 by an appropriate offset This is acMeved modulator 1510. Figure 16 is a logical block diagram of an example embodiment of a modulator 1600 in accordance with the systems and methods described herein Irnrxjrtaπtly, modulator 1600 takes parallel data streams 1602 performs Time Division Modulation (TDM) or Frequency KvisicnMoαnlation (TOM) on each data stream 160^ 1612, and then shifts each data stream in frequency using frequency shifter 1614 so that they occupy the appropriate sub-channel Filters 1612 apply flie required pulse shaping, i.e, they apply the roll-off factor described in section 1. The frequency shifted parallel data streams 1602 are then summed and transmitted Moctulator 1600 can also include rate controlla 1604, frecjuency encoder 1606, and interpolators 1610. All ofthe components shown in figure 16 are clescribed in moredetailin the foUowingparagraphsandin conjunction withfigures 17-23. Figure 17 illustrates one example emtediment of a rate controlla 1700 in accordance with the systems and methods described herein Rate control 1700 is used to control the data rate of each parallel data stream 1602. In rate ccntrolla

forexar wltichα((^isttes-measfl(^,αt7^isflιesameasα(^),etc. Figure 17 illustrates that flie effed of repeating the data streams in this manna is to take the data streams that are encoded oritotte first 8 sub-(-harrnels 1702, and duptieateth sulKhannels 1702. As can te seen, 7 siib-channels separate sub-channels 1702 cxmprising the same, or duplicate, data streams. Thus, tffMng effects one sub-channel 1702,fcτexarnpleitteo1hαεwb-channels 1702 carrying the same data will likely not te effected, i.e, there is frecjuency diversity between the duplicate data εrtrearns. So by sacrificing data rate, in this case half the data rate, more robust transmission is achieved Moreover, the robustness provided by d ticating the data

It should te noted to the data rate cante reduced by more than half eg, by four or more. Alternatively, the data rate can also te reduced by an amount otha than half For example if iritbrmation from n data stream is encoded onto m sub<hannels, where m >n. Thus, to clecrease the rate by 2/3, information from one data stream can te encoded on a first sub-charmel iriformaticn from a second data s thetwodatastreamscanteencciό^OTathMchanneL In which case, propa scaling will need to beapplied to thepowain theflώdchanneL Otherwise, fOTe- anple;flιepowainfl eflιirdcharmele^ Preferably, rate controlla 1700 is programmable so that the data rate can te changed responsive to certain operational factors. For example, if flie SIR reported for sub-channels 1702 is low, then rate controller 1700 can te programmed to provicle mere robust transmission Additionally, different types of wireless communication system, e.g, indoor, outdoor, line-of-sight, may require varying degrees of robustness.

communication system. This type of programmability not only ensures robust corrimunicaticn, it can also te used to allow a

Figure 18 illustrates an alternative example emrxxlrmeπt of a rate controlla 1800 in accordance with the systems and methods dctscrited In rate controller 1800 flie data rate is increased instead of decreased This is accornplished using serial-to-parallel converters 1802 to convert each data streams d(0) to d(15), for exarnpte, into two data streams. Delay circuits 1804 then delay one ofthe two data streams generated by each sεrial-to-parallel converter 1802 by ^lA a symbol, period Thus, data streams d(0) to d(15) are transformed into data &em α(0) to α(31). The data streams generated by a particular serM-to-parallel converter 1802 and associate delay circuit 1804 must then te summed and encoded onto the appror-riatesnib-channeL Forexample, data strearnsαf^ andαtT must te summed ard encoded onto tte first εair^ Preferably, flie data streams are summed subsequenttoeachclata stream beingpu^ Thus, rate controlla 1604 is preferably programmable so that the data rate can te increased, as in rate controller 1800, or decreased, as in rate controller 1700, as required by a particular type of wireless cornmumcation system, or as required by the communication channel conditions or sub-channel conditions. In the event that flie data rate is increased, filters 1612 are also preferably programmable so to they can te configured to apply pulse shaping to data streams α(0) to α(31), for example, and then sum flie appropriate streams to generate the appropri to frequency shifter 1614. The advantage of increasing the data rate in the matmα illustrated in figure 18 is to Hghasymtelm

Once the data streams are summed, the summed streams are shifted m frequency so to they reside m the But because the niπnberofbitsper each symbol has been αbuble4 flie symtelm-ipping rate has been do Thus, forexample, a4QAM symbol mapping can te converted to a 16QAM symbol rnar ingevmtftheSIRist∞WghfOT to otherwise beapplied oth words, programming rate cxntroU figure 18 can increase the symbol mapping even when channel conditions would otherwise not allow it, which in turn can allow a communication device to maintain adequate or even superior performance legardless ofthe type of communicaticn system. The draw back to increasing the data rate as ilhistrated in figure 18 is that intej-ference is inαeased, as is receiver complexity. The former is due to the increased amount of data The latter is due to flie tad that each symbol cannot te processed indepenelently because ofthe 1/2 symbol overlap. Thus, these concerns must te balanced against the increase syrntelrnapping ability when irnpl^ 1800. Figure 19 illustrates one example emboctimc^ of a frequency encxida 19^ methods clescribed herein Similar to rate encoding, frequency encoding is preferably used to provide increased communieation robustness.

subchannel This is accomplished using adders 1902 to sum data streams dφ) to d(7) with data streams d(8) to d(15), respectively, while adders 1904 subtrad data streams d ) to d(7) from data streams d(8) to d(15), respectively, as shown Thus, data streams a(0) to a(15) generated by adders 1902 and 1904 comprise information related to more than one data streams dφ) to d(15). For example, a(0) comprises the sum of dφ) and d(8), i.e, dφ) + d(8), while a(8) ccnprises d(8) - dφ). Therefore, if dtha aφ) or a(8) is not received due to fading, for example, then both of data streams dφ) and d(8) can still te retrieved from data stream a(8). lE-s-entially, the relationship between data stream dφ) to d(15) and aφ) to a(15) is amatrix relationship. Thus, if flie recdva knows the correct matrix to apply, it can recover flie sums and differences of dφ) to d(15) from aφ) to a(15). Inferably, frequency encoder 1900 is programmable, so to it can te enabled and disabled in order to provided robustness when required Preferable, adders 1902 and 1904 are programmable also so that diflereπt matrices cante applied to -/(Q) to d(15) . Afta frequency erxxxling^ TDM/FDM blocks 1608 perform TDM or FDM on flie data streams as required by the particular embcxliment Figure 20 illustrates an exanpleenιrxxiimentofaTDM/FT Mblock2000configure^ TDM/FDM block 2000 is provided to illustrate the logical components to can teirrlud d a TDM/FDM block configured to perform data strea Depending on the actual irnplementation, some ofthe logical cxmponents may or may not te included TDM FDM block 2000 comprises a sub-block repeater 2002, a sub-block scrambler 2004, a sub-block terminator 2006, a sub-blockrepeater2008, andaSYNC inserter 2010. Sub-block repeater 2002 is configured to recάve a sub-block of data, such as block 2012 comprising bits aφ) to a(3) for example. Sub-block repeater is then configured to repeat block 2012 to provide repetition, which in turn leads to more robust communication Thus, sub-block repeater 2002 generates block 2014, which comprise 2 blocks 2012. Sub- block scrambla 2004 is then configured to receive block 2014 and to scramble it, thus generating block 2016. One method of scrambling can te to invert half of block 2014 as illustrated in block 2016. But other scrambling methods can also te implemented defending on the embodiment Siib-block terminator 2006 takes block 2016 generated 2034 to the front of block 2016 to form block 2018. Termination block 2034 ensures that each block can te processed independently in the receiver. Without termination block 2034, some blocks may te delayed due to multipath, for example, and they would therefore overlap part of flie next block of data But by including termination block 2034, the delayed block canteprevented frcmoveriapping any ofthe actual data in the next block 1 errntnation block^"2034 can be a cy iC prefix termin-ition 2036. A cyclic prefix terminaticn 2036 simpfy repeats the last few symbols ofblock 2018. Thus, for example, if cyclic prefix termination 2036 is three symbols long, then it would simply repeat the last three symbols ofblock 2018. Alternatively, terminaticn block 20254 can comprise a sequence of symbols that are known to both the transmitter and recdver. The selection of what type ofblock termination 2034 to use can irnpad what type of equalizer is used in the receiver. Therefore, receiver complexity and choice of equalizers must te considered when cletermining what type of teιminationbloc-k2034toυsemTDM/roMblcck2000. After sub-block terminator 2006, TDM/FDM block 2000 can include a sub-block repeater 2008 configured to perform a second block repetition step in which block 2018 is repeated to form block 2020. In certain emtediments, sub- block repeater can te configured to perform a second block scrambling step as well After sub-block repeater 2008, if included, TDM/FDM block 2000 comprises a SYNC inserter 210 configured to periodically insert an appropriate synchronization code 2032 after a predetermined πumba of blocks 2020 and/or to insert known symbols into each block. The purpose of synchronization code 2032 is discussed in section 3. Figure 21, on the otha hand, illustrates an example embcdime ιtofaTDM/FDMblock2100corιfiguredforFDM which exjmprises sub-block repeater 2102, sub-block scrambla 2104, block coda 2106, saib-blcck transformer 2108, sub- block terminator 2110, and SYNC inserter 2112. Sub-block repeater 2102 repeats block 2114 and generates block 2116. Siib-blockscCTnbl thmscramM Sub-block coder 2106 takes block 2118 and codes it generating block 2120. Coding block correlates the data symbols togeflia and generates symbols b. This requires joint demodulation in flie recdver, which is more robust but also more complex. Sub-block transforma 2108 then performs a transformation on block 2120, generating block2122. Preferably, the transformation is an IFFT ofblock 2120, which allows for more effidait equalizers to te used in flie recdver. Next, sub-block terminator 2110 terminates block 2122, generating block 2124 and SYNC inserter 2112 periodically inserts a synchronization code 2126 after a certain number ofblocks 2124 and/or insert known symbols into each bloc Preferably, sub-block terminator 2110 only uses cyclic prefix te-mination as described above. Again this allows for more effident receiva designs. TDM/FDM block 2100 is provided to illustrate the logical components to cante irc^ configured to perform FDM on a data stream, ---^pending on the actual iinplcrnentaticn, some ofthe logical components may or may not te included Moreover, TDM/FDM block 2000 and 2100 are preferably programmable so to the appropriate logical components can te included as lεquired by a particular implementation This allows a device to incorporates one ofblocks 2000 or 2100 to move between elifferent systems with different reqtώements. Flutter, it is preferable to TDM/FDM block 1608 in figure 16 te programrnable so to it cante programmed to perfoπn TDM, such as described in conjunction with block 2000, or FDM, such as described in conjunction with block 2100, as required by a particular communicaticn system. After TDM/FDM blocks 1608,infigure 16,theparaMclatas-reamsarepreferablypa 1610. After interpolators 1610, theparaUeldatastreamsarepassεdtofilters 1612, which apply the pulse shφingefcscribed in c»rgurxΛc wiflι the roU-off factor of equation (2) insecticn 1. Then theparallel data streams are sent to frequency shifter 1614, whichls configured fo^" shift each parallel data stream by flie frequency offsd associated with the εur^ flie particular parallel data stream is associated Figure 22 illustrates an example emboclimerit of a frequency shifter 2200 in acccadance with the systems and methods described herein As cante seen, frequency shifter 2200 comprises miώipHers 2202 configured parallel data stream by tiie appropriate exponents to achieve flie required frequency shώ Each exponential is of flie for eψ( 2^7 Λ-9, where c is the corresponding sub-channel ^ in figure 16 is programmable so to various channel/sub-channel cxnfiguraticns can te acccmmoclated for various different systems. Alternatively, an 1FFT block can replace shifter 1614 and filtering can te done after the JJ bT block Thistypeof implementation can te more effident depending on the irπplementaticn After the parallel data streams are shifted, they are summed eg, in summa 1512 offigure 15. The summed data stream is then transmitted iiεing the enlire barx^ stream also comprises each of the parallel data streams shifted in frequency such to they occupy flie appropriate sαibcharmeL Thus, each sub-charmel may te asag^ different users. The assignment of sub-channels is described in section 3b. Regardless ofhow the sub-channels are assigned, however, each user will receive the entire bandwidth, cornprising all the subchannels, but will only decode those sub-channels assigned to the user. 6. Sample Receiver Embodiments Figure 23 illustrates an example embodiment of a receiver 2300 to can te configured in acccadance with the present invention Recdva 2300 ∞mprises an antenna 2302 configured to rec^e a message transrnitted by a to such as transmitter 1500. Thiis,antenrra23CCisccnfiguredtoreceiveawi&

B of a wide band channel to is divided into saib-channels of bandwidth B. As described above, the wide band message comprises a plurality of messages each encoded onto each of a corresponding sub-channel All ofthe sub-channels may or may not te assigned to a device to includes recdver 2300; therefore, receiva 2300 rnaycrirøy riot te re all ofthe εurκhaπnels. After the message is recdved by antenna 2300, it is sent to ι^o recdver 2304, which is corifigured to remove the carrier associated with the wide band communication channel and extrad a baseband signal comprising the data stream transmitted by flie transmitter. Exarnple radio recdva embodiments are elescrited in more detail telow. The baseband signal is then sent to correlator 2306 and demodulator 2308. Qjrrelator 2306 is configured to correlated with a syrxhranization code inserted in the data stream as clescnted in section 3. It is also preferably configured to perform SIR and multipalh estimations as

-Demodulator 2308 is configured to extrad the parallel data streams from each sub-channel assigned to the device comprising recdva 2300 and to generate a single data stream therefrom. Figure 24 illustrates an example crnbcKΪrmentofa demodulator 2400 in ac

the baseband data stream so that parallel data streams corrprisang the baseband data stieam can teinde^ m receiva 2400. Thus, the output of frequency shifter 2402 is a plurality of parallel data streams, which are then preferably filtered by filters 2404. Filters 2404 apply a filter to each paraflel data stream to correspcncls to Ihe pirlse shape ap^ transmitter, eg, transmitter 1500. Alternatively, an IFFT block can replace shifter 1614 and filtering can te done after the IFFTblock. Thistyr_eofiιnplemer cncaιtemcre Next, recdva- 2400 preferably includes dedmators 2406 configured to decimate the data rate ofthe parallel bit streams. Sampling at higha rates helps to ensure accurate recreation of Ihe data But the higher the data rate, the larger and more complex equalizer 2408 becomes. Thus, the sampling rate, and therefore the number of samples, can te reduced by

Equalizer 2408 is configured to reduce the effects of multipath in receiva 2300. Its operation will te discussed more fully telow. After equalizer 2408, the parallel data streams are sent to de-scrambler, decoder, and de-interieaver 2410, which perform the opposite operations of scrambla, axoda, and interleaver 1506 so as to leproduce the original data generated in the transmitta. The parallel data streams are then sent to parallel to serial converter 2412, which generates a single serial data stream from the parallel data streams. lE iualizer 2408 uses flie multrpath estimates provided by coπelator 2306 to equalize the effects of multipath in recdva 2300. In one embodiment, equalizer 2408 rørπprises Single-In Single-Out (SBO) equalizers operating on each parallel data stream in demcκiulator 2400. mtiiis case, each SISO equali-- comprisirιg equalizer 2408 rec^ and generates a single equalized output Alternativdy, each ecjualizer can te a Multiple-In Multiple-Out (MMO) or a Multiple-Si Single-Out (MISO) equalizer. Multiple inputs can te required for example, when a frequency encoder or rate controlla, such as fiequency encoder 1900, is hxluded in the transmitta. Because frequency encoder 1900 encodes information from more than one parallel clata stream onto each sub<harm^ to equalize more than one s xhanneL Thus, forexample, if a parallel data stream in clemodulatar 2400 comprises ^ 7,) + d(8), then equalizer 2408 will need to

together. Equalizer 2408 can then generate a single output correspcndingto ( ord(8) (MISO) or it can generate both d(l) ztύd ) (MMO). 1- ιualizer 2408 can also te a time domain eqιιalizer(TDE) era frequency dom the en±odiment Generally, equalizer 2408 is aTDE ffthe modulator in the transmitter paforms TDM on the parallel data streams, and a FDE if the rnoα ιlator performs FDM But equalizer 2408 can te an FDE even if TDM is used in the toansrnitter. Therefore, the preferred equalizer type should te taken into consideration when deciding what type ofblock termination to use in flie transmitta. l-tecaiiseofpowarec[Lriremerit^ and TDM on the reverse link in a wireless ccnimunication syste As with transmitter 1500, the various cornpcnents con that a single device can operate in a plurality of cbfferentsystcrnsardstiflrnairtta^ advantage ofthe systems and methods described herein Accordingly, the above discussion provides systems and methods for irnplementing a channel access protocol to allows flie transmitter and receiver hardware to te reprogrammed slightly depending on flie eommunicaticn system. Thus, what a device moves from one system to anotha, it preferably reconfigures the harά ^^ receiver, as required and switches to a protocol stack con spcnding to the new syste An impcrtart part of reconfiguring the recdva is leconfiguring, ca-prograrnming, the equalizer bexause multipalh is a main problem for each type of system The multipalh, however, varies expending on the type of system, which previously has meant that a different equaliza is required for different types of communication systems. The channel access protocol described in the preceding sections, however, allows for equalizers tote used that need σrilyterecorifiguredsHghtfyfOT operatic^ systems. a SanφlelE τualizεrIEriτbc<iiment Figure 25 illustrates an example embodiment of arecdva 2500 illustrating cnewayto configure equals acccadance with the systems and methods described herein Before discussing the configuration of receiva 2500, it should te noted that one way to configure equalizers 2506 is to simply include one equalizer per channel (for the systems and methods described herein, a channel is flie equivalent of a s κhannel as described above). A correlator, such as correlator 2306 (figure 23), can then provide equalizeis 2506 with an estimate ofthe number, arrplitude, and phase of any mult-paths present, up to some maximum nurnba. This is also known as the Channel Impulse Response (CIR). The maximum numbαofmultipathsisdeteπnm^ Thernoremultipalhsirxluded in the CIR the more path diversity the receiva has and the more ιcbιιstcxnτmunicatimm the system discussed a little mere fully telow. If fl ere is one equaliza 2506 per channel, the QR is preferably provided directly to equalizers 2506 from the correlator (not shown), ffsuch a ccαrelator configuration is iised equalization process is relatively fast For systems with a relatively small number of channels, such a configuration is therefore preferable. The problem, however, is that fliere is large variances in flie number of channels used in different types of ccmmunication systems. For example, an outdoor system can have has many as 256 channels. This would require 256 equalizers 2506, which wouldmal-eti erecdverdeagntooc»mplexardcc»sfly. Thus,forsysternswi1halotofd]anneis,the configuration ilhistrated in figure 25 is preferable. In recdva 2500, multiple channels share each equalizer 2506. For example, each equalizer can te shared by 4 channels, e.g, CH1-Ch4, Ch5-CH8, etc, as illustrated in figure 25. In which case, receiver 2500 preferably comprises amemory25Q2ccnfiguredtostoreirιformatimamvingonea^ Memory 2502 is preferably divided into sub-sections 2504, which are each configured to store iriforrnation for a particular subset of channels. Mcnnation for each channel in each subset is then alternately sent to the appropriate equalizer 2506, which equalizes the information based on the CIR provided for that channel Si this case, each equalizer must run much faster than it would if fliere was simply one equalizer pa channel For example, equalizers 2506 would need to run 4 ormoretimesasfast cadertoeflec^^ haddMcn,extramemoι 2502isrequiredto buffer the channel information But overall, flie complexity of recdva 2500 is reduced, because there are fewer equalizers. This should also lower the overall cost to implement receiva 2500. Relerabl memcHy 2502 arri the numb ^ In this way, recdva 2500 can te reconfigured for the most optimum operation for a given system. Thus, if receiver 2500 were moved lrom an outdcor system to m indoor system so that there are^' fewer, evefl as low as^" l, ciia el per equalizer. The rate at which equalizers 2506 are run is also preferably programmable such that cquatizeis 2506 can te run at fl e optimum rate for the num^ In addition, if each equalizer 2506 is equalizing multiple channels, then flie CIR for those multiple paths must alternately te provided to each equalizer 2506. Preferably, therefore, a memory (not shown) is also ii luded to buffer the QR information for each channeL The appropriate QR information is then sent to each equalizer from the CIR memory (not shown) when the corresponding channel information is being equalized The QR memory (not shown) is also preferably programmable to ensure optimum cperation regardless ofwhat type of system receiver Rduming to the issue of path ctiversity, the numba of paths used by equalizers 2506 must account for the delay spread 4 in the system. For example, if flie system is an outdoor system cpeiating in flie 5G^ range, fl e commiinication channel can comprise a bandwidth of 125MHz, e.g, the channel can extend from 5.725GHz to 5.85GHz, If flie channel is divided into 512 sub-charmels with a roll-off factor r of .125, Ihcri each subchannel will teve a banα^ 215KHz, which provides approximately a4.6μs symtel duration Sirxe the worst case

ofpathsιιsedbyequalizeιs2504cantesettoamaximumof5. Thus, fliere would tea first path PI at Oμs, a second path P2 al4.6μs,aflώdpathP3 at92μs,afour1hpathP4al 13.8μs,arrifii1h path P5 at 18.4μs, which is close to^ In another emlxxirment, a sixth path can te irxluded so as to coπpletely cover the efelay spread^ the worst case. In fact, a delay spread of 3μs is a more typical value, most instance^ flieret ie, the de y spread actually te shorter and an extra path is not needed Altematively, fewer siib-channels can te iised, thus provicling a larger symbol duration, instead of using an extrapafh I3ut again, this wou typi<aUynotteneeded As explained above, equalizers 2506 are preferably configurable so that they can te reconfigured for various ccmmunication systems. Thus, for example, the numba of paths used must te suffident regardless of flie type of commiimcaticn system. Bιrttiώisal∞deperκlenlc ttenιιnte from operating in flie above described outdoor system to an indoor system, where flie dekyεpre-d is ∞ then recdva 2500 can preferably te reconfigured for 32 subchannels and 5 paths. Assuming the same overall bandwidth of 125 MHz, the bandwidth of each sub-charrnel is approximatefy4Mføandttesymtelciu^ Therefore, there will be a first path PI at Oμs and subsequent paths P2 to P5 at 250ns, 500ns, 750ns, and lμs, respectively. Thus, the delay spread shouldte covered for tte indoor environment Again, the lμsds is worst case so flie lus ds provided in tte above example will often te more than is actually required This is preferable, however, for indoor systems, because it can allow operation to extend outside ofthe inside environment, e.g, just outside the building in which the inside environment operates. For campus style environments, where a user is likely to te traveling between buildings, this can te advantageous. 7. Sample Embodiment of a Wireless Commimicaticn Device Figure 26 illustrates an example embodiment of a wireless communicaticn device in acccttdance with flie systems aidmedTOC-sdescnted herein Device 2600 is, for example, a portable communication device configured for oper^c m plurality of indoor and oiitdoOT communication systems. Thus, device 2600 comprises an anterιrø26O21br transmitting and receiving wireless communication signals ova a wireless cornmumcation channel 2618. Duplexa 2604, or switch, can te included so that transmitta ^'2606 and receiva 2608 can both use antenna 2602, while being isolated from each otha. Duplexers, or switches used for this purpose, are well known and will notte explained herein. Transmitter 2606 is a configurable transmitter configured to implement the channel access protocol c-escribed above. Thus, transmitter 2606 is capable of transmitting and encoding a wideband cαmmunicaticn signal ∞mprising a plurality of subchannels. Moreova, transmitter 2606 is configured such that flie various subcorriponents to comprise transmitter 2606 can te leconfigured, or programmed, as descnted in section 5. Similarly, recdver 2608 is configured to implement the channel access protocol described above and is, therefore, also configured such that flie various sub- n cnents coinprising receiva 2608 canteieccnfigured, orreprogrammed, as descnted in section 6. Transmitter 2606 and recdva 2608 are intei-faced with processor 2610, which can comprise various prrxessing, controller, and or Digital Signal Processing (DSP) drcuits. Processor 2610 controls flie operation of device 2600 including cricxxiirig signals tote transmit^ Device 2610 can also include memory 2612, which can te ccnfigured to store operating instructions, e.g, firmware/software, used by processor 2610to control the operation of device 2600. Processor 2610 is also preferably configured to lEprogramtiHismitter 2606 arid rerøva 26^ 2614and2616,respextivdy,asreqιιiredbyttewireι^ Thus, for example, device 2600 cante configured to periodcaflyaaertamflx availability Ifthe system is detected, then processor 2610 can te configured to load the ∞rrespcnding operating instruction from memory 2612 and reconfigure tiansmitta 2606 and receiva 2608 for operation in the preferred system. For example, it may preferable for device 2600 to switch to an indoor wireless LAN if it is available. So device 2600 may te operating in a wireless WAN where no wireless LAN is available, while periodically searching for the availability of an appropriate wireless LAN. Once the wireless LAN is detected, processor 2610 will load the operating ir-structions, e.g, the appropriate protocol stack, for the wireless LAN environment and wifl reprogram transmitta 26C)6 and receiver 2608 accordingly. In this manner, device 2600 can move from one type of ccmmunicati(-n system to another, while maintaining saφericrperfoimance. It should te noted that a base station configured in acccadarκ«wifl the systems ardmemodsheremwffl similar manner as device 2600; however, because tte base station does not move from one type of system to another, fliere is generally no need to configure processor 2610 to reconfigure transmitter 2606 ard recdver 2608 IOT with the cperating instruction for a clifferent type of syste But processor 2610 can still te configured to reconfigure, or reprogram the

of tiansmitta 2606 anαVcriecdvα 2608 as reqiώed by the operating co system as reported by cc mimication devices m communication with flie base station Moreova, such abase station cante ccnfigured m accordance with the systems aώ which case, controlla 2610 cante configured to reprogram transnitta 2606 and receivα 2608 to rrnplement Ihe appro mode of operation

As described above in relation to figures 11-14, when a device, such as device 1118 is near flie edge of a communicaticn cell 1106, it may experience interference from base station 1112 of an adjacent cornmumcation cell 1104. In this case, device 1118 will report a low SIR to base station 1114, which wifl cause base εtaticm 1114 to reduce the numbα of subchannels assigned to device 1118. Asexplamedmre αntofigιιιes l2aιdl3,fl-isred 1114 assigning oriy wen snibcharmels to Prelerably,bases cm lll2iscxnespondir^ sub-channels to device 1116. In this maπnα, base station 1112 and 1114 perform ccn-plernentaryreciucticns in tte channels assigned 1116 and 1118 oιd to prevcτtf intαfcrence ai 1116 and 1118. The reduction in assigned channels reduces the overall bandwidth available to devices 1116 and 1118. But as described above, a system irnplementing such a corrplementary reduction of siib-charmels will still maintain a highα bandwidth than conventional systems. Still, it is preferable to recovα the unused sub-channels, or unused tendwidth, created by the leducticn of sιiκhannels in response to a low reported SIR One method for re∞vering the unused bandwidth is illustrated in the flow chart of figure 27. First, in step 2702, basestatic lll4recdvesS!Rrepcrtsfcffclifføτe^ Ifthegroup

SIR reports are good, then base station 1114 can assign all subchannels to device 1118 in step 2704. If, howevα, some of the group SIR reports received in step 2702 are poor, then base s^on 1114 can reduce the numter of sur>charmelsas^ to device 1118, e.g, by assigning only even subcfiannels, in step 2706. At the same time, base station 1112 is preferably perfcnning a complementary reducticn in the subchannels assigned to device 1116, e.g, by assigning only odd subchannels. At this point, each base station has unused bandwidth wifli respect to devices 1116 and 1118. To recovα this bandwidth, base station 1114 can, in step 2708, assign flie unused odd εub-<-h-ιrmels to device 1116 a^ It should te noted that even though cells 1102, 1104, and 1106 are illustrated as geometrically shaped, non-oven^pping coverage areas, the actual coverage areas do not resemble these shapes. The shapes are essentially fictions used to plan and describe a wireless commumcaticn system 1100. Therefore, base station 1114 can in fad ccmmunicate with αevice 1116, even though it is in adjacent cell 1104. Once base station 1114 has assigned flie odd sub harmels to device 1116, in step 2708, base s c lU^ communicate with device 1116 sάnidtaneously ova the odd sub-channels in step 2710. Preferably, base station 1112 also assigns the unused even sub-channels to dewce lll8mordαtorecovαthe unused banc In essence, spatial diversity is achieved by having toth base station 1114 ard 1112 communicate with (levice 1116 (and 1118)ovathesameεub<hannels. Spatial diversity occurs when flie same message is transmitted s-muttaneously ova statistically independent cornmunication paths to the same recdva. The indepenclence ofthe two paths improves flie overall immunity ofthe system to fading. This is because the two paths will experience different f &ig effects. Therefore, if the recdv cannot receive the signal ova one path due to fMrig, then it wifl probabfystiflte able to othα path, because the fading that effected the first path will not effect flie second As a result, spatial diversity improves overall system performance by irnproving the Bit Error Rate (BER) in the receiva, which effectively increases the deliverable data rate to flie receivα, Le, increase the bandwidth For effective spatial eliversity, base stations 1112 and 1114 ideally transmit the same information at the same time ova the same subchannels. As mentioned above, each base station in system 1100 is configured to transmit sdmultaneously, Le, system 1100 is a TDM system with synchrcnized base stations. Base stations 1112 and 1114 also assigned flie same sub-channels to device 1116 in step 2708. Therefore, all to is left is to ensure that base stations 1112 and 1114 send flie same information Accordingly, the information commumcatedtodevice lllόbybasestaticns iπ coordinated so to fl e same information is transmitted at flie same time. The mexharasm for enabling this coordination is discussed mere fully telow. Such coordination, howevα, also allows encoding to can provide furthα perforrnanee enhancements withm system 1100 ard aflow a gteatαp One example coordinated encoding scheme that can teirnplcrnerited between base stations 1112 and 1114 wifli respect to ccmmunications with device 1116 is Space-Time-Coding (ST diversity. STC is illustrated by system 2800 in figure 28. Si system 2800, transmitta 2802 transmits a message ov channel 2808 to recdva 2806. Simultaneously, trananitter 2804 transmits amessage ova channel 2810 to recdva 2806. Because channels 2808 and 2810 are independent, system 2800 will have spatial diversity with resped to communications from transmitters 2802 and 2804 to recdva 2806. In addition, howevα, the data transmitted by each transmitta 2802ard2804canteencocledtoalsor^ The

First, channel 2808 cante denoted hi and channel 2810 cante denotedg_B where:

Second, we can look at two blocks of data 2812a and 2812b to te transmitted by transmttα 2802 as iflustrated in figure 28. Blo&2812acxn prise«N5yιτιtekd^ Block 2812b transrnitsNsymbols of data denoted b(0:N-l). Transmitter 2804 simijltaneousfytransmils two block of data 2814^ Block 2814a is the negative inverse ccnjugate ofblock 2812b and can flierefbre te described as -b*(N-l:0). Block 2814b is the inverse conjugate ofblock 2812a and can therefore te described as a*(N-l:0). It should te noted that each block of data in the forgoing description will preferably comprise a cyclical prefix as αesxribed above. When blocks 2812a, 2812b, 2814a, and 2814b are received in receiva 2806, they arecxπnbmedandeiecodedinthe following manna First, the blocks will te combined in the recdva to form the following blocks, after discarding the cyclical prefix: Blockl = :N-l) ®h_n-b*(N-l:0) <5>&;and (3) Block2 = b(0:-N-l) ®h_n + a*(N-l:0) Θ& (4) Where the symbol <8> represents a cyclic convolution Second, by taking an IFFT of the blocks, the blocks cante described as: Blockl =A„_*H_n-B_n*_*G_n,arύ (5) Bbck2^B_n*H_n- *_*G„ (6) Where«=(7toN-7. In equations (5) and (6) H„ and G_n will te known, or can te estimated But to solve the two equations and determine A_n and B_m it is preferable to turn equations (5) and (6) into two equations with two unknowns. This can te achieved using estimated signals-^ and Y„ as follows: X, =A„ *H_n-B_n*_*G_n;arή (1) Y_n=B_n *H_n +A *_*G_n. (8) To generate two equations and two unknowns, the conjugate of Y_n can te used to generate the following two equations: ^=A *H,-R„*.G„;and (9) Y_n*=B **H *+A_*G *. (10) Thus, the two unknowns are. andR„* and equations (9) and(l0)defineamatr re onsr mtemιsof1hesetwo unknowns as follows:

Wliich can te rewritten as:

Signals-^andR_Mcantedeterminedιιs-^ It should te noted, that the processjust described is not the only way to implement STC. Otha methods can also te implemα-ted in acccadance with the systems and methods described herein BnrxMtantly, howevα, by adding time diversity, such as described in the preceding equations, to flie space diversity already achieved byusing base stations 1112 and 1114 to ccnm unicate with device 1116 samultaneouslytheBER can te reduced even furfhα to recova even more bandwidth An example transmitter 2900 configured to communicate using STC in acccarJancewiflιflκ s stem described herein is illustrated in figure 29. Transmitter 2900 irxludes a block storage device 2902, a serial-toparallel converter 2904, encodα 2906, and antenna 2908. Block storage device 2902 is included in ti rsrnittα 2900 because a 1 block delay is necessary to implement the coding ifliistrated in figure 28. This is because tCTismittα 2804 first transmits -b„* (n =N-lte>0). I b„ is flie second block so tftransmito and b_m and then generate block 2814a and 2814b (see figure 28). Serial-topatallel convertα 2904 generates parallel bit streams from the hits ofblocks 0_nWάb_n. Encoda 2906 then encodes the bit streams as required, eg, encodα 2906 can generate -b„* and α„* (see blocks 2814a and 2814b in figure 28). The mcoded blocks are then combined into a sang-etrans-nitagrial as decribed^ Transmitter 2900 preferably uses TDM to transmit messages to recdv 2806. An alternative transmitter 3000 ernbodimenttousesFDMisillustra^ Transmitta 3000 als»irκlude«blcκ-ks*cnιgp device 3002, a se d parallel convertα 3004, encodα 3006, and antenna 3008, which are configured to perform in the same mannα as flie correspcnctϊrigcoinpcnerfcmtran^ Butm addition, transmitta 3000 irxlucles IF s3010totake the 1FF1 ofthe blocks generated by encodα 2906. Thus, transmitter 3000 transmits -B_n* and A„* as opposed to -b_n* and a„*, which provides space, freα^ieney, and time diversity. Figure 31 illustrates an alternative system 3100 to also uses roMbirt to elimm^ with transmitters 2900 and 3000. In system 3100, transmitta 3102 transmits ova channel 3112 to recdv 3116. Transmitta 3106 transmits ova channel 3114 to receivα 3116. As wifli transrnitters 2802 and 2804, transmitters 3102 and 3106 implement an encoding scheme designed to recovα tendwidfh in system 3100. In system 3100, howeva, the ccoidinated encoding occurs at the symbol level instead ofthe block level Thus, forexample, transmitter 3102 can transmit bloe^ 3104 cornprisirig symtels OQ, «_/, ₂, and ΪJ. In which case, tiHi-anittα 3106 wifl transmit a block 31C⁾8 comprising symbols -α/*, «o* -α , and α . As cm te seen, this is flie same encoding scheme used by transmitters 2802 and 2804, but implemented at flie symbol level instead of flie block level As such, there is no need to delay one block before tiHismittirig AnlFFl of each block 3104 and3108 can then betaken and transmitted using FDM An FT 3110 ofblock 3104 is shown in figure31 for purposes ofilluslration Channels 3112 and 3114 can te described by Ft, and G_» respectively. Thus, in receivα 3116 the following symbols will te formed: (A₀.H₀)-(A₁* .G) (A₁.H,)+(Ao* .G₁) (A₂.H₂)-(A₃* .G2) (A_3*H₃)+(A₂* .G₃). In time, each symbol a„ (n = 0to3) occupies a sKghflycϊfferent time location Infreqiiency, eaehsymbolΛ (n = 0 to 3) occupies a slightly different frequency. Thus,eachsymtel.4„istransmittedovαasfig^ =

0 to 3) or G„ (n = Oto 3), which results in flie cornbinaticos above. As cante seen, the symbol combinations fcnned the leceivα are ofthe same form as eq^ therefore, can te solved in the same maπnα, but without flie one block delay. Inordα to implement STC or Space Frequency Coding (SFQ diversity as described above, bases stations 1112 and 1114 must te able to coordinate encoding ofthe symbols to are simultaneously sent to aparticular device, such as device 1116 or 1118. Fortunately, base stations 1112 and 1114 are preferably interfaced with a cornir network i^ servα. For example, in a LAN, base stations 1112 and 1114 (which would actually te service access points in the case of a LAN) are interfaced with a common network interface servα to ∞nnects the I-A^

Switched Telephone Network (PSTN). Similarly, in a wireless WAN, base stations 1112 and lll4 are typically interfaced with a common base station control center or mobile switching center. Thus, coordination of flie encoding can te enabled via the common connection with flie network interface servα. Bases station 1112 and 1114 can then te configured to share information Ihrough this common connection related to communications with devices at flie edge of cells 1104 and 1106. The sharing ofinfcamaticn, in turn, alfows time or frcqueix diversity CCK.^ It should te noted that σthα for s ot drvαsity, such as polarization ctiversity or delay άvαsity, can also te combined with the spatial d-vasity in a communication system designed in accordance with the systems and methods describe herein The goal being to combine alternative forms of diversity with the spat divert in ordα to recovα largα amounts of bandwidth. It should also te noted, to flie systems and methods ciescribed can te applied regardless of he number ofbase stations, devices, and ccnimunication cells involved Briefly, delay diversity can preferably te achieved in acccffdance with flie systems and methods described herein by cyclical shifting the trarisrnitted blocks. For example, one transmitter can transmit a block comprising A^A^ A^ and A₃ in that orάer, while the otter transmitter transmits the symbols in the following ordα A^ Ac A_1} and A₂. Therefore, it cante seen to the second transmitta transmits a cyclically shifted version of flie block transmitted by the first transmitter. Furtter, the shifted block can te cyclically shiftedby mere then one symtelofieqiώedbyapartiαilariinplcn er^ 9. Transmitter Radio Module Figure 32 is a diagram

In certain crnbodiments, such a conventional radio transmitta module can, for example, te used to implement radio transmitta module 1514. As can te seen, baseband carcuitry 3202 can te configured to provide a digital transmit signal to radio trar-smitta module 3200 for transmission Baseband circuitry 3202 can, for example, comprise the components ciescribed above in relation to figures 15- 23. The digital transmit data provided by baseband drcdtiy 3202 cante separated into a pluraHty as the -hphase (I) and Quadrature phase (Q) data streams illustrated in figure 32. The I and Q data streams can then te encoded onto two orthogonal waveforms. The divisicn of baseband data stream 1518 to I and Q channels can take on a variety of schemes. For example, if data stream 1518 is complex, then flie I-(±annel can represent the real part of data stream 1518ardtheQ hannelcanιeprescntflιeimagjnaryt^ Separation of digital tr-tnεmit data into I and Q data streams is well known and will not te discussed in furflia detail here. In many conventional radio transmit modules, flie digital I and Q data stoeams are converted to analog signals by digital to analog (D/A) converters 3204 and 3254 respectively. The resultant analog signals can each te filtered with low- pass filters 3206 and 3256, respectively. The filtered signals can then te mexlulated by modulators 3208 and 3258 with a local oscillator (LO) signal centered at flie carria frequency COQ. A synfliesizα 3210 coupled to alocal oscillator 3210cante used to generated the O signals used by teth mixers 3208 and 3258. The modulated sagriak supplied by flie mixers cante ccml-αriedbyccmbinα3212. The corrihined signal cante filtered throiigh band pass filter 3214. The filtered signal is then ampMedbypowαarnplifi 3216 and broadcast with antenna3218. The irnplementation illustrated in figure 32 is commonly referred to as a dired conversion transmitta, because the baseband

carria frequency c-< Inoflι emlxx_iments, astaged approach to frequency conversden in which the baseband signal is first stepped up to one pr more intermediate fiequendes before being converted to an RF signal can te implemented Such multi-staged transmitters often comprise adciitional mixers, synthesizers, local oscillators, etc. The synthesizers, local oscillators, andϋ/A converters required by ccnveritional radio transmit modules cante large and expensive and can have relative large powα requirements, especially when they are run at higha data rates. As ∞rnmimicaticn data rates for new systems increase, flie powα consumption -equired by such cornpcnents can te prohibitive. Figure 33 iflustrates an example embodiment of a radio transmit module 3300 configured in accordance with the systems and methods described herein Unlike radio Iransmit module 3200, radio transmit module 3300 does not include D/As, synthesizers, local osdllators or modulators. As a result, radio transmit module 3300 can avoid the expense, size constraints, and powα constraints that are inherent in cx venticnal radio Iransmit module designs. In ordα to achieve such benefits, baseband ciuritiy 3202 can, fOTexarnp^ "0", and "-1" for both the I and Q data By using two signals for each data stream, howevα, radio transmit module 3300 onfyseesaseriesoflsandOs. For example, as illusteatedin figure 34, the 1+ data stream can teccxledsaieh to it goes high when a "1" is bang transmitted and stays low when eithα a 'V' or a "-1" is bdiig transmitted The I- data stream cante coded such that it goes high when a "-1" is being trarismitted and stays low when erthαa'^'ora"!" is being tran^^ The Q andQ- data streams can tecoded in flie same mannα. The data streams can then te passed through pulsαs 3322- 3328, whiώcanteccnfiguredtocxnvcrttheeiatabitsin each data stream into natrowα pulses. The narrow pulses can then te combined in combiners 3320 and 3322 such that

Q = (Q )-(Q-). ₍₂₎ The combined signals can then te band pass filtered using band pass filters 3334 and 3336, which in addition to confining the signal to a narrow bandwidth for transmission, can also shape the pulse sequences in effect mochilating the signals. The resultant shaped signals are flienready for trari-mi-sicmm the appropriate freqi^ The shaped signals can then te combined in addα 3338, amplified by arnplifiα 3340, and transmitted via antenna 3342. Band-pass filters 3334 and 3336 can also te configured to control phase, mord toiriaiπlamorttegonalwavefo configured to only allow sin coot components to pass and band-pass filter 3336 can te configured to allow cos αtf coinponents to pass which are orthogonal waveforms.

Thirst by constraining the digital d implemented without costly, powα ccnsαiming D/As, synthesizers, modulatoisriiixers, etc. Aexordrngly, radio transmit modules configured in accordance wifli the systems ardmeflx lsclescnhedherdn can provi to cannot be achieved by conventional transmitta designs. Figure 35 is a diagram illustrating an example ernboctimeritofapiilsα configured m accords and methods ciescribed herein In the example offigure 35, ttepuls cornprises an AND gate 3506 and a delay module 3504. A data stream 3502 is coupled to oneinputofAND gate 3506 as well as to flxcte ymcx e3504,wHchproclucesa delayed version 3508 of data stream 3502. Delayed data stream 3508 is then coupled to the oflia input of AND gate 3506. As cante seen on the right side of figure 35, when data stream 3502 is ANDedwiftictelayed data stoeam 3508, a data stream 3510 comprising narrowα pulses can be created The amount of delay applied by delay module 3504 must, of course, te controlled so as to produce satisfactory pulse wiclthsmdata stream 3510. As illustrated in figure 35, an inverted output can te used to generate outouls fcr the I- ardQ- data εtoearns so to they can te combined with the 1+ and Q+- data streams in acxx lance wifli equations (1) and (2). In such embcxliments, exnibiners 3320 and 3322 can te passive combiners such as flie one illustrated in figure 36. The combinα illustrated in figure 36 sirrpfy comprises fliree res ve components R1,R2, and R3. The resistive value ofcornponentsRl,R2, and R3 can te selected on an irnplementation by iinplementation bases. For example, in certain embodiments the resistive values canteselectedsuchtoRl=R2=R3. Forexarnple;avalueofl7ohrnscaιteusedforeachofRl,R2,andR3. Figure 37 illustrates an alternative emlxxlmert of a piilsα to In this embodiment a (-apadtorCl ard resisted Whena data stream 3708 is passed through the capacitcff-res-stor combination, the rising and felting edges ofthe various bits will create narrowa positive and negative pulses as illustrated by waveform 3710. In oidα to eliminate the negative pulses, a diode DI can te irxluded so to waveform 3710 is converted into waveform 3712, which comprises a narrow pulse for each "1" in data stream 3708. The decay rate ofthe pulse cornprising waveform 3712 is deteimined by the capadtance of capadtor Cl and flie resistance of resistor Rl. To produce narrow pulses, the circuit decay rate 1/RCεteddte much less than the data rate. The pulsα offigure 37 can also te referred to as a differentiator detector. For a diffeientiator cletector to work, the irput data stream must adhere to a "return to zero" convention, that is regardless ofthe value ofaα^l m tte agrial a before the transmission ofthe next datum. When pursers such as the one iUustrated in figure 37 are used, an active combinα can te used to combine 1+ and Q+- with I- and Q-, respectively, in accordance wifli equations (1) and (2). An active cornhinα can comprise an Operational Amplifiα (OP-AMP) 3802 as illustrated in figure 38. 1+ or Q can te coupled to the positive irput of OP-AMP 3802, while I- orQ-cantecoupledtoflie negative irput 10. Radio Recdva Figure 39 is diagram illustøating an exemplary ra&o recdvα to cante used, for example, to implement radio receivα2304. As cante seen, a radio signal is first received by anterma 3902 ard filtered by bard-pass filtα 3904. The filtered signal can then te amplified by amplifiα 3906, which can comprises a low noise amplifiα ( NA) and in some embodiments include additional amplifiers. The amplified signal can then te split into I and Q ccmponents and down converted by mixers 3910 and 3960 which have an LO signal supplied to them by the combination of syπthesizα 3908 and local oscillator 3970. Or e the signals are cbwrκxmvcrte4 low pass fitters 3912 ard artifacts from the downconverted signals. The resultant filter signals can then, for example, te converted to digital signals by analog-to-digital (A/D) converters 3914 and 3964. The digital I and Q signals can then te supplied to baseband circuit 3920 for furfl aprrxessing. In some irnplementatiσns, additional mixas, and frequency filters can te employed to perform the

frequency. As with flie radio transmitter module offigure 32, it is well known to flie synthesizα, local oscillator, mixers, and A/D converters can te large, expensive, and consume a relatively large amount of powα. If a transmitter such as the one illustrated in figure 33 is irscd en the transmft s^ the need for such corrrponents in the receivα. Figure 40 is a diagram of an example radio receivα 4000 that can te configured to work, for example, with the radio transmit module offigure 33. In radio receivα 4000, a signal is received by antenna 4002, filtered by band ass filter 4004, and amplified by amplifiα 4006, in amannα samilar to that ofthe recdv described in figure 39. The signal can fliente processed in two ccncurrentprrxesses. In the first process, the envelope, for example, ofthe signal can tedetected using detector 4010. -Depending on flie embodiment, for example, cletecto 4010 can bean envelop detector or apowαcletector. Envelope eletectors are wellknownand can, for exan le^teirnplementedasasiiTpledodeor a tricde with the propα biasing The output of eπvelφ detector 4010 can then tefiltαed by filtα 4012 ard converted to a digital signal Filter 4012 can te implcrnented as a low pass filter with DC removal, e.g, a single pole notch filter. The conversion process can te achieved, for example using A/D converter 4014, wliich then forwards the digital signal to base band circuitry 4018. Sign detector 4020 can then te used to detect flie sign ofthe bit being decoded Thus, when the output of A/D converter 4014 is combined with flie output of sign detector 4020, flie original "1", "0", "4" values can te recovered by baseband circuitry 4018. Sign detecticncan, depending on the embodimaιt,te irnplana-tedιιsdngalimita ar^ configured to deted adoublepositive, or doublenegative, in the resulting bit stream. Figure 41 is a diagram illustrating an alternative emrxx-iment of a radio receivα 4100 that can te used in cxn-juncticn,fOT example^ mradiorecdvα4100,ansigma-dellaA Dccnvertαisfcranedby combinα 4102, band pass filter 4104, precision, clocked comparator 4110, and D/A converter 4106. Thus, flie incoming signalisfilteredbyfiltα4104ar thenconrparedto The output of comparator 4110 is then fed to D/A converter 4106, the output of which is then subtracted form the incoming signal by combinα 4102. The output if comparator 4110 is also sent to filter and dexirnatim circuitry 4108, the output of wlich is sentto 4112. The incoming signal is ova sampled The ova sampling facftff-tndcm-l ofhaidpas fite effective nurnbα ofhits at the output of filtering and decimation circuitry 4108. The table in figure 42 illustrates the effective numbαofbits for each sanφlingfreqiiency, Le, the rate at which cxmparafor 4110 is clocked, the filter carter for band pass filter 4104, and fl e ova sampling factor, for a partiαilar implementation In an alternative embodiment, ova sampling can te achieved iisang a plιιra of comparator different phase ofa clock signal Tteoiitoulofttecomparatcascanthentec filtenrigadedmaticncarcuitry4108. While ernbodrments arid Driplemenlatϊons ot e invention have been shown and described, it should te apparent that many more embocriments and πnplementations are within the scope ofthe invention Accordingly, the invention is not to te restricted, except in light of the claims and their equivalents.

Claims

What is claimed: 1. A radio leccrvα, comprising: an envdcpe detedor configured to detect an arrplitude of a received signal and generate a waveformrepresentativeof an envelope ofthe received signal; and a sign detector configured to determine a sign associated signal 2. Theradorecάvαofclaiml,furtiια∞r^^ envelope detector, the filter configured to filterthe waveform generated by the envelope detector. 3. The radio recdva ofclaim 2, fiirthαccmpriarig an analog-to-ctigi converter cornmunicating wifli flie filter, flie analog-to-digital convertα configured to convert the filtered waveform to adigital agnal 4 Theι orecdvaofclaim l,whereintheagncletectorcorrrm to generate abit stream 5. Theradiorecdvαofclaim6,whαein1hesigncιete^ coupled wifli the limiter, the cirxidtry configured to acted a cfouble poative, or a double negative^ in the bit stream 6. A recdva, ∞rnprising: an antenna configured to receive a signal; a filter rømmirmcating with the antenna, the filtα ccnfigutedtofiltα flie leceived signal; an amplifiα coupled with tte filter, the ampMαccnfiguredtoarrφliJ thefiltαedagrτal;and an envelope detector commuricating with the amplifiα, the envelope cletector configured to detect an ainplitude ofthe signal and generate a waveform representative of an envelope ofthe signal; and a sign detector configured to determine a sign assc atedwifti each data tit encoded en flie signal 7. Thereceivaofclaim6,fuιthαcx>mD^ elcrector, the filtα configured to filterflie waveform generated by the envelope αetector. 8. Therece-vαofclaim7,fLrrflταccmpris--^ eommunicating with the filter, the analog-to-digital converter configured to convert the filtered waveform to a digital signal 9. The receivα ofclaim 6, wherein the sign detector cc prisesalirmtαcc guredto generate abit stream. 10. The recdva ofclaim 9, wherein the sign αetedOT with flie limiter, the circuitry configured to detect a ctaiMe poative^ cr a doihlene 11.

receiving a signal; gendating'a v^elo-m^'bia-eooh an envelope associated with flie signal; and detecting a sign for data bits encoded en the signaL 12.

signal 13. Thememodof claim 11, fiπfl αeornpri-ϊtng low pass filtαing the w^ the envelope associated with flie signal 14. Themeflιodofclam l3,turthαcompris^ digital signaL 15. The method ofclaim 14, flirthαcMriprising decoding datab^ using the digital signal and a sign information related to the databits. 16. A radio receivα, corrrpriarig: abandpass filter configured to filtα a combined signal; a clcκkedcxmparator communicating with flie band pass fitter, the clocked cotnparator configured to compare flie filter combined signal to a reference; a digital-to-analog converter cxnimumcating with the clocked comparator, the digital-to-analog converter configured to convert flie output ofthe clocked ∞nparator to an analog agnal; and a cx bina configured to receive a signal and cx-mbine ft with flie analog agnal mordα to generate the combined agnal 17. The radio recdva ofclaim 16, furthαcorriprising a filtering ar^ configuredto filter and decimate flie output of the clocked ccnparator. 18. The radio recdva ofclaim 16, iutlhαcc prisingaclcckagrialcc^ clocked ccnparator. 19. The radio recdva of claim 16, lutfliαccnpriarig: a plurality of clocked cc parators cemmuricat-ng with the band pass fitter, each of the clocked cornparators configured to te activated on a differentphaseofaclock signal; and a combinα ccmmimicating with flie plurality of clocked ccnpatators, the combinα configured to combine an outputs ofthe clocked coinparators. 20. Theradiorecdvαofclaim 19,whereinttedgital-to-aιιalogconvertαcornmumcates with the plurality of clocked ∞mparalors via flie combinα. 21. A lecdvα, comprising: an antenna configured to receive a signal; a filter cxnimumcating with flie antenna, the filter configuied to filtα the signal;

aband pass filter configuredto filtα a combined signaL wherem the combined signal at least fl e filtered signal; a clocked cxmparator coupled with the band pass filter, the clocked comparator configured to conpare the filtered combined agnal to areference; a digital-to-analog coπvertα communicating with flie clocked cxjnparator, that converts the output ofthe clocked ccnparator to an analog agnal; and a combina configured to receive the signal and cxmbine it wifli flie an-dogsignalmordαto genaate the combined signal 22. Thereceivαofclaim21,fur1hαeornprisangafilteri^ configuredto filtα ard decimate the output of tte clocked comparator. 23. Therexeivαofclaim21,furthαc<3rnprisirιgaclex a clocked ccnparator. 24. The receiva of claim21,fuιthacornprιsirιg: apluralityof clocked ccnparators commiimcatrrig with the bard pa^ cxnparators ccnfigured to te activated onadu erentriiaseofaclockagrial; and acc rm cornmuric-atirigvvithtte to combine an outputs ofthe clocked ccnparators. 25. The receivα ofclaim 24, wherein the dgital-to-ar-alogccnvertαccrø flieplurality of clocked cornparators viaflie ccmbinα. 26. A method of ^receiving data in a wireless communication network, comprising: bandpass filtering a combined signal; gaierating a digital signal from flie filtered cxnibmed signal by comp agnal to areference; converting the digital signal to an analog signal; and cxmbrning the analog signal with a signal in order to generate Ihe combined signal 27. The method ofclaim 26, furthα cornprising cxnparing the combined signal to the reference at arateeieagr-edtoproduce a riurriterofbits from tte combined signaL