WO2002015602A2

WO2002015602A2 - Method and apparatus for determining the radiation location of active mobile stations

Info

Publication number: WO2002015602A2
Application number: PCT/IB2001/001852
Authority: WO
Inventors: Shmuel Miller; Joseph Shapira
Original assignee: Celletra Ltd.
Priority date: 2000-08-15
Filing date: 2001-08-15
Publication date: 2002-02-21
Also published as: AU9216501A; WO2002015602A3

Abstract

Provided is a system and method for determining and classifying the radiation location of active mobile stations within a wireless communication network. Identifiers such as predetermined delays or power/amplitude adjustments are inserted in the forward or reverse link between a base station and the active mobile stations comprising beam patterns covering a sub-sector. The identifiers are inserted (152) in each of the beam patterns according to a predetermined sequence. Reports generated between the active mobile stations and the base station are examined (154) for information relating to the inserted identifiers. The examined information is then correlated (156) with the predetermined sequence of inserted identifiers. Based on the correlation, the active mobile stations are classified (158) as corresponding to a radiated beam pattern or associated sub-sector.

Description

METHOD AND APPARATUS FOR CLASSIFYING WIRELESS NODES WITHIN CELLULAR COMMUNICATIONS NETWORKS

BACKGROUND OF THE INVENTION

1. Reservation of Copyright

The disclosure of this patent document contains material, which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone ofthe patent document or the patent disclosure, as it appears in the U.S. Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever.

2. Related Application Data

The present application claims priority to the U.S. Provisional Application No. 60/225,390, entitled "Method and Apparatus for Classifying Wireless Nodes within Cellular Communications Networks", filed on August 15, 2000, in the name of Joseph Shapira. The content of the aforementioned provisional application is hereby expressly incorporated herein by reference in its entirety.

3. Field of the Invention

This invention generally relates to the field of cellular communications. More particularly, the present invention relates to classifying wireless nodes within cellular communications networks. 4. Background Information

Today's cellular communication systems are subjected to ever-increasing user demands. Current subscribers are demanding more services and better quality while system capacities are being pushed to their limits. The challenge, therefore, is to provide feasible and practical alternatives that increase system capacity while achieving better grades of service.

Typically, for each geographic cell, cellular communication systems employ a base station (BS) with an omni-directional antenna that provides signal coverage throughout the cell. One way to increase the communications capacity, is to split the geographic cell into a plurality of smaller cells (i.e., cell-splitting) by deploying additional BSs within the cell, thereby increasing the number of frequencies that can be re-used by the system. This cell- splitting, however, can be both cost-prohibitive and environmentally-deterred as conventional BS equipment include antenna arrangements that are expensive and often too bulky and unaesthetic for prevailing community standards.

An alternative approach to improve system capacity and maintain service quality is to angularly divide the geographic cells into sectors (i.e., sectorize) and deploy BS antennae that radiate highly-directive narrow beam patterns to cover designated sectors. The directive beam patterns can be narrow in both the azimuthal and elevation plane and, by virtue of their directional gain, enable mobile stations (MSs) to communicate with the BS at longer distances. In addition, system capacity increases as the sectorized cells are not as susceptible to interference from adjacent cells. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 A illustrates a receive portion of a BS antenna beam system in accordance with an embodiment ofthe present invention;

FIG. IB illustrates a classification process in accordance with an embodiment of the present invention;

FIG. 2A illustrates a classification process in accordance with another embodiment ofthe present invention;

FIG. 2B illustrates a multi-sector cell configuration; and

FIG. 3 illustrates a classification process in accordance with another embodiment ofthe present invention.

DETAILED DESCRIPTION

The narrow radiated beams used to form radiated beam patterns over forward (FWD) and reverse (RVS) links for given coverage areas may be optimized to improve overall performance of the wireless network. For example, optimization schemes may improve performance by matching FWD and RVS link coverage, abating pilot pollution, and reducing soft hand-off zones. In addition, optimization schemes may be applicable to local optimization of a single beam shape as well as global optimization of multiple beam shapes within the wireless network.

Optimization of wireless network performance requires the ability to establish, modify, or fine-tune transmission controls for the transmitted radiated beam patterns. As such, optimization schemes can benefit from knowing the location of active MSs within the sectors in order to monitor performance parameters on a per sector or even sub-sector basis and derive suitable optimization controls for the radiated beams. For example, optimization schemes may monitor the angular load distribution of active MSs within a sector coverage area in an effort to optimize overall network performance. To acquire load distribution information, an optimization scheme may determine the location information of the active MSs to determine relevant network traffic and load information, such as, for example, load distribution within a sector or sub-sector. This information may then be exploited to allow a BS to control and enhance the transmission characteristics of the radiated beam patterns.

Possible approaches for determining the location of active MSs include methods based on FCC E911 emergency services or employing global positioning system (GPS) technology. These approaches are tailored to determining the geographical coordinate location information of active MSs. However, determining active MS location based on geographical coordinate information and its use as a performance parameter to optimize wireless network performance may be limited. For example, the accuracy, efficacy, or procurement of geographical location information may be compromised by active MSs operating along the fringe areas of radiated beam patterns (e.g., beam pattern roll-off or outskirts). Similarly, active MSs operating within holes of the coverage areas due to obstacles or terrain fluctuations may also compromise the accuracy or efficacy of geographical location information.

Accordingly, there exists a need to optimize wireless network performance by employing active MSs location information without relying on geographical location information for active MSs.

The embodiments described herein provide active MS location information by determining the "radiation or electromagnetic location" of active MSs. That is, each active MS is classified as belonging to a radiated beam pattern or sub-sector and may be tracked accordingly. In addition, radiation location provides for better performance monitoring because communications service between BSs and MSs is more dependent on the electromagnetic radiation in the FWD and RVS links, as well as the interference between signals traveling across these links, than by mere geographic position. It is to be noted that radiation location generally differs from geographical location information along the areas that generally compromise service to MSs, such as the fringe areas and coverage holes, noted above. Thus, wireless network performance, and the optimization thereof, is better correlated to radiation location than to geographical location information.

Moreover, optimization schemes based on the radiation location of active MSs requires minimal BS hardware and/or software reconfiguration, and may be configured to be compatible with CDMA systems, such as IS-95 and 3G system (e.g., W-CDMA, CDMA2000, etc.).

FIG. 1A depicts a receive portion of a BS antenna beam system 100, constructed and operative in accordance with an embodiment of the present invention. The details of BS system 100, and the associated optimization schemes, may be as described in co- pending U.S. Application Nos. 09/357,845 and 09/357,844 (each filed July 21, 1999 in the name of Dr. Joseph Shapira), the contents of which are hereby expressly incorporated by reference in their entirety.

As depicted in FIG. 1A, the receive portion of system 100 may include receive antenna elements 102A-102K that are electrically coupled to receive band-pass filters BPF 104A-104K to filter out noise accompanying the signals collected by antenna elements 102A-102K. Receive BPFs 104A-104K are subsequently coupled to low-noise amplifiers (LNAs) 106A-106K to amplify the received signals. In turn, LNAs 106A-106K are coupled to a receive transform matrix 108 to transform the received signals into a form suitable for subsequent processing. On the beam side of transform matrix 108, time delay elements 110A-110K and amplitude/gain attenuation adjustments (i.e., weights) 112A- 112K may be introduced to adjust, vary, or otherwise manipulate the characteristics ofthe received signals. The beam port signals are then combined by combiner 114 to form a received beam pattern. Although not shown, a transmit portion of BS system 100 operates as the transmit analog ofthe illustrated receive portion.

The BS antenna arrangement and associated components provide for beam pattern radiation configuration and power management within a cellular sector. Based, in part, on the optimization schemes employed, the antenna arrangement may independently optimize cellular transmission in the FWD and RVS links. For example, along the FWD link, the antenna arrangement may control the effective isotropic radiated power (ETRP) including its angular distribution. Along the RVS link, the antenna arrangement may control the gain (G/T) including its angular distribution. The antenna arrangement is also capable of allowing a sector to be divided into sub-sectors (e.g., 3, 4 and 6 sub-sectors) and provides for independent transmission control of the sub-sectors, as well as the FWD and RVS links. In addition, the antenna arrangement may be configured to dictate the transmission characteristics of the FWD and RVS links of sub-sectors that are complementary to each other and that angularly span an entire sector.

FIG. IB illustrates classification process 150, constructed and operative in accordance with an embodiment of the present invention. Classification process 150 is configured to determine the radiation location of active MSs. The radiation location may then be used to assist in the performance assessment and corresponding optimization controls for radiated beam patterns, sectors, or sub-sectors. In other words, process 150 identifies the radiation location of active MSs and classifies the MSs as belonging to a radiated beam pattern or a particular sub-sector. Consequently, optimization schemes may evaluate performance parameters within the sub-sector and optimize the control of transmission characteristics accordingly.

Classification process 150 operates in the delay domain by introducing an identifier, such as a known delay, into each radiated beam pattern, which serves to determine the radiation location of the active MSs. Specifically, as indicated in block B152, process 150 switches-in known delays within the radiated beam patterns of the FWD link. The delays are inserted during a predefined sequence or switching-in cycle. Although process 150 may equally insert the delays in the RVS link without loss of functionality, for purposes of clarity, the following description will be limited to FWD link delays.

In block B154, the BS examines the reports generated by the active MSs for delay information. It is to be noted that CDMA and related wireless systems provide for the transfer and reporting of certain management and control information between MSs engaged in an active calls and the corresponding BSs. Such information may include link performance measurements, such as Frame Error Rates (FERs) and Bit Error Rates (BERs), power control command information, and timing information. With respect to timing information, a MS rake receiver measures the arrival time of each pilot signal reported to the BS and the time of the earliest arriving usable multipath component of the pilot signal is used to measure timing relative to the MS's time reference in units of pseudo-noise (PN) chips. Such timing information is included in the information reported to the BS by being tagged or time-stamped to indicate a time-of-day (TOD) reference.

However, because MSs do not distinguish between multipath propagation delays and the switched-in delay identifiers, the BS deduces the relative delay values based on reported delays. Specifically, when a delay is switched-in, active MSs operating within the delayed beam pattern experience a delay shift in its signal by a corresponding amount (in integer number of PN chips). The BS then exploits the TOD reference accompanying the MS reports, which is a common timing reference, to deduce the relative delay values from the reported delays.

In block B156, the BS correlates the relative delay values with the switch-in delay sequence. As will be described in greater detail below, process 150 synchronously monitors the timing sequence or switching-in cycle of the delay operations. The BS may then correlate the timing sequence of the switched-in delays with the deduced relative delay values.

In block 158, process 150 classifies the active MSs as belonging to a particular sub-sector or radiated beam pattern based on the correlation between the switch-in delay sequence and the relative delay values. Such classification identifies the radiation location ofthe MSs while allowing for seamless communications to continue between the MS and the BS, without interrupting service.

Returning to FIG. 1A, the switched-in delay of process 150 may be achieved by incorporating time-delay elements 110A-110K, such as, for example, a surface-acoustic- wave (SAW) device, with a 1-bit control adjustment on the beam-plane side of transformation matrix 108. In such a configuration, time-delay elements 110A-110K provide a delay for each radiated beam in a sector, where N beams span the entire sector.

The delay may be configured as either a 0 sec. delay (i.e., no delay) or a τ sec. delay (e.g.,

2.5 μsec, equivalent to 3 PN chips). For CDMA and similar wireless networks, where PN

chips = 813.8 nsec, setting τ « 2/3 PN chip duration is adequate for decorrelating the signals of different beam outputs and provides for a small, but well defined, delay shift in communications path.

As noted above, process 150 inserts the delays during a predefined switching-in cycle. The switching-in cycle comprises serially repeating the insertion of delays for N-l sub-sectors out of N beams/sub-sectors to successfully classify the active MSs into any of the N sub-sectors for a particular interval of time. For example, if a sector comprises N=4 sub-sectors, with 1 radiated beam per sub-sector, then the switching-in cycle only needs to be repeated for N-l =3 sub-sectors to successfully classify the MSs into any of the N=4

beams within the sector at an instant in time. Upon switching-in a delay τ in one beam, it

is possible to resolve the group of MSs that are serviced from that beam if their reported

delay shifts by amount τ (measured in PN chips). A possible timing sequence for such a

scheme is to switch-in a delay in each sub-sector beam path for 1 sec. Then, a basic switch-in cycle maybe completed in N-l seconds (i.e., 3 seconds) for N=4 sub-sectors.

It will be appreciated that the switched-in delays may be switched in/out per one or more beams simultaneously, and that the delays may be inserted according to a switch-in rule. Such a rule may be pre-programmed into the BS system 100. If the MS delay reports occur once per second, for example, then the beam delays may be switched at least every 3 - 5 sees. Additionally, if a switching matrix at the beam space side of transformation matrix 108 is used and measurement time is not a limitation, a single serially switched delay unit may be used. If the reported delay is based on FWD link measurements in the MS, which is reported back to the BS, the delay units should be incorporated in the FWD link (in this case FIG. 1A applies with the directions of all horizontal arrows reversed). As noted above, the MS measures the relative pilot signal delays and reports them to the BS. In such cases, the switched-in delay identifier may be implemented in the FWD link. Otherwise, the delay units may be placed in the RVS link as depicted in FIG. 1 A.

It will be appreciated that MSs incur delays from signal propagation, including multipath influences, as well as BS transceiver processing, such as narrow-band filtering.

When MSs move, delay changes of ±1 PN chip variations are possible. Larger delay

changes may occur in situations where there is a loss in the direct path and a secondary multi-path signal having a larger delay becomes the major finger correlator in the MS rake receiver. Fortunately, such occurrences are not often encountered and are usually not experienced simultaneously by all the active MSs to pose any significant risk to the aforementioned scheme.

Moreover, the BS rake receiver along the RVS link and the MS rake receiver along

the FWD link are capable of handling delay-shifts by τ, with no SNR deterioration. The

serial delay unit may preserve a fixed gain in both 0 sec. and τ sec. settings. Such a gain

allows for a steady constellation or metric determination at the CDMA modem.

It is to be noted that when a MS signal is served by more than one radiated beam, such as in soft hand-off (SHO) zones where there exists an overlap or crossover area

between pairs of adjacent beam patterns, switching-in the delay τ in one beam may delay-

spread the MS rake receiver finger correlators (see, e.g., FIG. 2B). Conventionally, the cross-over boundaries of the SHO zones are determined by the BS, based on MS reports, which contain various BS pilot signal measurements including the energy per PN chip relative to noise and interference (E_c/I₀).

Naturally, by switching-in delays in only one ofthe overlapping beams, the signals within the beam having the inserted delays experience a corresponding delay but the signals in the adjacent beam do not. Such asymmetry may translate into a deterioration of link performance (e.g., BER and FER), if the number of significant, comparable level signals received by the MS rake receiver exceeds the number of available finger correlators. For example, if there were only a single signal, then the undelayed signal component and its delayed counterpart would operate to spread the signal allowing two finger correlators to create delay-diversity that the rake receiver uses to enhance reception. However, if there are 3 or more significant signals, then splitting the signals into 6 signal components (i.e., 3 undelayed signal components and 3 delayed signal components) would not enhance reception because the rake receiver cannot process more than 4 signal components.

To avoid the delay-spreading phenomenon of the rake receiver finger correlators for situations where an MS signal is served by more than one radiated beam, classification

process 150 may switch-in delay τ for the two adjacent beam patterns.

FIG. 2A illustrates classification process 200, constructed and operative in accordance with another embodiment of the present invention. Like process 150, process 200 determines the radiation location of active MSs and also operates in the delay domain. Process 200 is configured as an iterative switch-in delay scheme that converges to identify the radiation location of active MSs. As noted above with respect to process 150, the delays may be inserted according to a rule. To this end, process 200 requires that the switched-in delays for each radiated beam or sub-sector conform to predetermined pattern or format in order to optimize radiation location operations. The format ofthe switched-in delays are defined in State Tables 1-4, illustrated below, and a description of each of the State Tables 1-4 is presented as follows: STATE TABLE 1

State Table 1 illustrates switch-in delay formats for a single sector comprising 4 sub-sectors. The format of the switched-in delays for the present state correspond to the top row of the State Table. The format of the next switched-in delays correspond to the second row representing the next state. Thereafter, the format of the switched-in delays are determined by subsequent rows of the State Table. This sequential switched-in delay scheme wraps around back to the top row after the row ofthe State Table is reached.

As described above and depicted in FIG. 2B, switching-in a delay τ for two

adjacent beams avoids the delay spread phenomenon for active MSs in the crossover area between the pair of beams (see, e.g., rows 4 and 5 of State Table 1). In row 4 of State

Table 1, active MSs within sub-sectors 1 and 2 post similar delays (i.e., τ). From this

information, process 200 may classify MSs that do not post delays (i.e., τ) as occupying

sub-sectors 3 and 4. In row 5 of State Table 1, active MSs within sub-sectors 2 and 3 post

similar delays (i.e., τ). From this information, process 200 may classify MSs that do not

post delays (i.e., τ) as occupying sub-sectors 1 and 4. Examining this information in light

of the prior gathered information and present information, process 200 may classify the active MSs within sub-sector 2 (the intersection between group 1 and 2 and group 2 and 3). As shown, process 200 examines prior and present information to iteratively classify the performance of active MSs within sub-sectors. STATE TABLE 2

State Table 2 illustrates switch-in delay formats for two adjacent sectors, each comprising 4 sub-sectors. It is to be noted that sub-sector 4 of sector 1 is adjacent to sub- sector 1 of sector 2 (see, e.g., FIG. 2B).

STATE TABLE 3

State Table 3 illustrates switch-in delay formats for 3 sectors such that each sector contains adjacent sectors on both sides. For example, sub-sector S4 of sector 1 is adjacent to sub-sector SI of sector 2, sub-sector S4 of sector 2 is adjacent to sub-sector SI of sector 3, and sub-sector S4 of sector 3 is adjacent to sub-sector SI of sector 1 (see, e.g., FIG. 2B).

State Table 3 is implemented with 3 delay values (i.e., 0, τ, 2τ). If the adjacent sectors

have equal (or similar) delays, then crossover among the beams of the sectors results in delay-spreading. In order to avoid the effects of delay-spreading, State Table 3 incorporates non-equal delays at the sub-sectors that interact among adjacent sectors, such

that the non-equal delays manifest a difference of at least one τ.

STATE TABLE 4

State Table 4 illustrates another implementation of switch-in delay formats having

only 2 delay values are (i.e., 0 and τ). State Table 4, like State Table 3, illustrates switch-

in delay formats for 3 sectors such that each sector contains adjacent sectors on both sides and incorporates non-equal delays at the sub-sectors that interact among adjacent sectors. It is to be noted that the delay format of State Table 4 requires a cycle of 7 rows as opposed to State Table 3, which requires a cycle of only 6 rows.

Returning to FIG. 2A, the classification ofthe active MSs within the sub-sectors is unknown. In block B210, process 200 sets the index i to correspond to row 1 of a selected State Table. The selection ofthe State Table depends, in part, on the number of sectors to be monitored (e.g., State Table 1 may service 1 sector, State Tables 3 and 4 may service 3 sectors).

In block B220, process 200 sets the state to correspond to index i. In block B230, the delays of the indexed state are switched-in. In block B240, process 200 examines the reports generated by the active MSs for regarding the incurred delays and BER/FER information. hi block B250, process 200 determines whether the relative delays incurred by the active MSs due to the switched-in delays and the associated BER/FER information are acceptable. In other words, process determines whether a correlation exists between the switched-in delays versus the relative delays and BER/FER performance. Acceptability may be determined by providing an acceptable tolerance threshold level for the relative delay values and BER/FER information.

If the reported delay shifts and BER/FER information are acceptable, then in block B260 process 200 classifies the active MS into beam(s). If either the reported delay shifts or BER/FER infoπnation are not acceptable, process 200 does not classify the MSs. Rather, in block B270, process 200 stores the information and classifies the active MSs as potentially belonging to the boundary of kj. For example, if a delay is switched-in sub- sector SI and no delay shift is determined in sub-sectors S1-S4, then the active MSs are classified as belonging to the boundary of kj, which comprises the immediately adjacent neighbors of sub-sector SI; namely, sub-sector S4 of sector 1 and sub-sector S2 of sector 3. h other words, this feature accounts for the possibility that the active MSs could be located at the intersection of two beams.

In block 280, process 200 increments the index i to correspond to the next row of the selected State Table. Process 200 then returns to block B220 to set the state to correspond to index i and switches-in the delays of the indexed state in block B230. As noted above, process 200 then assesses the delays and BER/FER reports from the active MSs and determines whether the reports are acceptable, in blocks B240 and B250, respectively. Process 200 iterates until it converges to classify the active MSs in any of radiated beam patterns covering a sector, thereby identifying the radiation location of each active MS. If the end ofthe State Table is reached, then the index is reset to correspond to row 1.

BSs that service several sectors (e.g., 3 sectors) may include multiple antenna arrangement systems (e.g., 2 or 3 BS antennas). For a multi-sector implementation, the State Table delay formats may be synchronized in order for the two outermost sub-sectors of the State Table and adjacent sub-sectors belonging to different but adjacent sectors

experience different delays (i.e., 0/τ vs. τ/0). Such synchronization allows for smooth

transition between radiated beam patterns belonging to one sector into those of an adjacent sector, regardless ofthe phase difference between the radiated beam patterns produced by the antennas ofthe two sectors.

State Tables 2 and 3 illustrate such synchronized delay formats. In the 3-sector

implementation, a fixed additional delay τ is employed to allow such condition to hold true for all boundaries. State Table 4 illustrates another implementation of such synchronized delay format for the 3-sector case. However, as noted above, because the

delays in State Table 4 comprise either 0 or τ, State Table 4 requires an extra row to complete the delay cycle

The BS antenna arrangement may be configured to perform with a minimum ripple pattern (in the FWD and RVS links) for any signal, including continuous wave (CW) signals. The antenna arrangement may also be configured to match phases, delays, and attenuation along parallel signal arms, as well as insertion of optimized preset offset phases, in the beam paths. Thus, the antenna arrangement achieves pattern shaping operation on orthogonal multi-beams that serve all common-air-interfaces, including CDMA and similar wireless communication services. Moreover, classification processes 150 and 200 are compatible with a multi-beam array shaping operations of CDMA waveforms. For example, processes 150 and 200 are capable of switching-in delays greater than the PN chip duration, which allows the matched filters ofthe rake receivers to perform coherent summation ofthe relevant beams complex envelopes. As such, processes 150 and 200 are amenable to a multi-beam array shaping operations.

In addition, classification process 150 and 200 are also compatible with 3G wireless systems. For example, 3G systems employ dedicated pilot signals per beam, which active MSs utilize. Classification processes 150 and 200 may be used with dedicated pilot signals when antenna arrangements are used on a per sector basis.

Furthermore, BSs may utilize antenna arrangements without the combiner/divider components. In such implementations, processes 150 and 200 may operate without affecting system performance when the radiated beam pattern is one of the 4 sub-sector beams because the delay variations affect (in FWD link) the dedicated pilot signal per the specific beam without affecting the receiver modem performance. Also, system performance is not affected when the radiated beam is based on weighted multiple sub- sector beams because the switched-in delay in one beam spreads the pilot fingers in the modem's RAKE receiver.

Accordingly, the switched-in delays in multiple antenna beam patterns sorts out the active MSs utilizing specific antenna radiation beams from MSs utilizing broader sector radiation beams, of which the specific antenna radiation beam comprises a subset.

FIG. 3 illustrates classification process 300, constructed and operative in accordance with another embodiment of the present invention. Like classification processes 150 and 200, process 300 is configured to determine the radiation location of active MSs. However, unlike processes 150 and 200, which operate in the delay domain, process 300 operates in the power domain. As such, classification process 300 switches-in an identifier, such as a known amplitude or power adjustment, into each radiated beam pattern, which serves to determine the radiation location ofthe active MSs.

Specifically, as indicated in block B302, process 300 switches-in known amplitude/power adjustments into each radiated beam pattern ofthe FWD link occupying a sub-sector for a predetermined interval of time. For example, the sub-sector EIRP in the FWD link may be increased by 2dB for 1 second. These adjustments may be performed by manipulating amplitude/gain attenuation weights 112A-112K on the beam plane side of transformation matrix 108. Although process 300 may also insert the amplitude/power adjustments in the RVS link (e.g., adjust the G/T in the RVS link) without loss of functionality, for purposes of clarity, the following description will be limited to FWD link adjustments.

In block B304, process 300 switches out the known amplitude/power adjustments inserted into each radiated beam pattern. In block B306, process 300 examines the response of the power-control commands reported by the active MSs used to control and/or equilibrate signal levels. In the above-noted example, the active MSs would report to the BS to decrease the EIRP by 2dB, when the 2dB amplitude/power adjustments are inserted.

In block B308, process 300 correlates the switched-in amplitude/power adjustments for each beam pattern with the the power-control commands reported by the active MSs. In other words, process 300 determines which of the observed sub-sector power control commands statistically match the switching-in/out sequence of the power adjustments. In block B310, process 300 classifies the active MSs into beam patterns or sub- sectors. Specifically, based on the correlation of the MSs power-control up/down command statistics and power adjustment switching-in/out sequence, process 300 identifies which active MS belongs to a particular beam pattern or sub-sector.

Classification process 300 may be repeated sequentially over N-l sub-sectors out of an N sub-sector sector to classify the active MSs into any of the sub-sectors within a sector.

It is to be noted that classification process 300 modifies the transmitted EIRP, which may impact system performance. However, wireless communications signals fade continuously and require fast power control. Such power control may be updated 800 or 1600 times per second. Thus, slow changes (e.g., such as once per second) by a limited amount (e.g., 2dB) does not appreciably affect overall network performance.

The foregoing description of the embodiments of the present invention provides illustration and description, but is not intended to be exhaustive or to limit the invention to the precise form disclosed. Modifications and variations are possible consistent with the above teachings or may be acquired from practice of the invention. For example, the various features of the invention, which are described in the contexts of separate embodiments for the purposes of clarity, may also be combined in a single embodiment. Conversely, the various features of the invention which are, for brevity, described in the context of a single embodiment may also be provided separately or in any suitable sub- combination. Accordingly, it will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention is defined only by the attached claims and their equivalents.

Claims

WHAT IS CLAIMED IS:

1. A method of determining the radiation location of active mobile stations in a wireless communication network, comprising: inserting an identifier into one of a forward link and receive link of a base station, said forward link and reverse link comprising a plurality of beam patterns spanning a predefined coverage area of said wireless communication network, said identifier being inserted in each of said beam patterns in accordance with a predetermined insertion sequence; examining reports generated during communications between said base station and said active mobile stations for information responsive to said insertion of said identifier; correlating said responsive information with said predetermined insertion sequence; and classifying each of said active mobile stations as corresponding to any of said beam patterns based on the correlation of said responsive information with said predetermined insertion sequence, wherein said classification identifies the radiation location of each of said active mobile station within said predefined coverage area of said wireless network.

2. The method of Claim 1, wherein said identifier comprises a delay identifier having a predetermined value.

3. The method of Claim 2, wherein said reports between said base station and said active mobile stations additionally include at least one of timing information and link performance information.

4. The method of Claim 3, wherein said information included in said reports responsive to the insertion of said identifier comprises information indicating transmission delays experienced by said active mobile stations.

5. The method of Claim 4, wherein said base station determines the relative delay values of each of said active mobile station due to the insertion of said delay identifier based on the transmission delays and the timing information reported by said active mobile stations.

6. The method of Claim 5, wherein said coverage area of comprises at least one sector divided into a plurality of N sub-sectors and each of said beam patterns substantially spans at least one of said N sub-sectors.

7. The method of Claim 6, wherein said predetermined insertion sequence comprises serially inserting, at discrete time intervals, said delay identifier into each beam for N-l sub-sectors.

8. The method of Claim 7, wherein said predetermined insertion sequence further includes concurrently inserting said delay identifier into two adjacent beam patterns that overlap in coverage.

9. The method of Claim 6, wherein said predetermined insertion sequence further includes implementing a delay insertion format defimng the insertion of said delay identifier for each beam pattern.

10. The method of Claim 9, wherein said delay insertion format is configured in accordance with at least one of State Tables indicated below, wherein S1-S4 represent said sub-sectors and kj, k_j, and k represent a first sector, a second sector, and a third sector, respectively:

STATE TABLE 2

STATE TABLE 4

11. The method of Claim 10, wherein said examining reports further includes determining whether the relative delay values of each of said active mobile station due to the insertion of said delay identifier and said link performance information are within a predetermined tolerance threshold.

12. The method of Claim 11, wherein said active mobile stations are classified as corresponding to the beam patterns for each of said sectors upon determining that said relative delay values and said link performance information are within said tolerance threshold.

13. The method of Claim 12, wherein said active mobile stations are classified as corresponding to an intersection of overlapping beam patterns upon determining that said relative delay values and said link performance information are outside of said tolerance threshold.

14. The method of Claim 1, wherein said identifier comprises one of an amplitude identifier comprising adjusting signal amplitudes by a predetermined value and a power identifier comprising adjusting signal power levels by a predetermined value.

15. The method of Claim 14, wherein said coverage area of comprises at least one sector divided into a plurality of N sub-sectors and each of said beam patterns substantially spans at least one of said N sub-sectors.

16. The method of Claim 15, wherein said predetermined insertion sequence comprises serially inserting said amplitude identifier or power identifier into each beam pattern for N-l sub-sectors for a predetermined time interval and then extracted for a predetermined time interval.

17. The method of Claim 16, wherein said reports between said base station and said active mobile stations additionally include power control command information.

18. The method of Claim 17, wherein said information included in said reports responsive to the insertion of said amplitude or power identifier comprises power control command information indicating requests to compensate for said inserted amplitude or power identifier.

19. The method of Claim 18, wherein said examining reports further includes evaluating power control command information indicating requests to compensate for said inserted amplitude or power identifier.

20. The method of Claim 19, wherein said correlating further includes determining which of said sub-sectors' power control command information matches the predetermined insertion sequence of said amplitude or power identifier.

21. A system for determining the radiation location of active mobile stations in a wireless communication network, comprising: a base station including, an antenna arrangement configured to collect, in a reverse link, and radiate, in a forward link, a plurality of beam patterns spanning a predefined coverage area of said wireless communication network, a transformation matrix coupled to said antenna arrangement and configured to transform received signals into a form suitable for processing and to transform transmitting signals into a form suitable for radiation, a plurality of delay elements coupled to said transformation matrix configured to generate delays of a predetermined value, and a plurality of amplitude or gain adjustment elements configured to adjust signal amplitude or signal gain by a predetermined value; wherein said base station inserts an identifier into each of said beam patterns in accordance with a predetermined insertion sequence, examines reports generated during communications between said base station and said active mobile stations for information responsive to said insertion of said identifier, correlates said responsive information with said predetermined insertion sequence, and classifies each of said active mobile stations as corresponding to any of said beam patterns based on the correlation of said responsive information with said predetermined insertion sequence, and wherein said classification of each of said active mobile stations identifies the radiation location of each of said active mobile station within said coverage area of said wireless network.

22. The system of Claim 21, wherein said identifier comprises a delay identifier having a predetermined value generated by said delay elements.

23. The system of Claim 22, wherein said reports between said base station and said active mobile stations additionally include at least one of timing information and link performance information.

24. The system of Claim 23, wherein said information included in said reports responsive to the insertion of said identifier comprises information indicating transmission delays experienced by said active mobile stations.

25. The system of Claim 24, wherein said base station determines the relative delay values of each of said active mobile station due to the insertion of said delay identifier based on the transmission delays and the timing information reported by said active mobile stations.

26. The system of Claim 25, wherein said coverage area of comprises at least one sector divided into a plurality of N sub-sectors and each of said beam patterns substantially spans at least one of said N sub-sectors.

27. The system of Claim 26, wherein said predetermined insertion sequence comprises serially inserting, at discrete time intervals, said delay identifier into each beam for N-l sub-sectors.

28. The system of Claim 27, wherein said predetermined insertion sequence further includes concurrently inserting said delay identifier into two adjacent beam patterns that overlap in coverage.

29. The system of Claim 26, wherein said predetermined insertion sequence further includes implementing a delay insertion format defining the insertion of said delay identifier for each beam pattern.

30. The system of Claim 29, wherein said delay insertion format is configured in accordance with at least one of State Tables indicated below, wherein S1-S4 represent said sub-sectors and k;, k_j, and kh represent a first sector, a second sector, and a third sector, respectively:

STATE TABLE 2

STATE TABLE 4

31. The system of Claim 30, wherein said examining reports further includes determining whether the relative delay values of each of said active mobile station due to the insertion of said delay identifier and said link performance information are within a predetermined tolerance threshold.

32. The system of Claim 31, wherein said active mobile stations are classified as corresponding to the beam patterns for each of said sectors upon determining that said relative delay values and said link performance information are within said tolerance threshold.

33. The system of Claim 32, wherein said active mobile stations are classified as corresponding to an intersection of overlapping beam patterns upon determining that said relative delay values and said link performance information are outside of said tolerance threshold.

34. The system of Claim 21, wherein said identifier comprises one of an amplitude identifier comprising adjusting signal amplitudes by a predetermined value via said amplitude adjustment elements and a power identifier comprising adjusting signal power levels by a predetermined value via gain adjustment elements.

35. The system of Claim 34, wherein said coverage area of comprises at least one sector divided into a plurality of N sub-sectors and each of said beam patterns substantially spans at least one of said N sub-sectors.

36. The system of Claim 15, wherein said predetermined insertion sequence comprises serially inserting said amplitude identifier or power identifier into each beam pattern for N-l sub-sectors for a predetermined time interval and then extracted for a predetermined time interval.

37. The system of Claim 36, wherein said reports between said base station and said active mobile stations additionally include power control command information.

38. The system of Claim 37, wherein said information included in said reports responsive to the insertion of said amplitude or power identifier comprises power control command information indicating requests to compensate for said inserted amplitude or power identifier.

39. The system of Claim 38, wherein said examining reports further includes evaluating power control command information indicating requests to compensate for said inserted amplitude or power identifier.

40. The system of Claim 39, wherein said correlating further includes determining which of said sub-sectors' power control command information matches the predetermined insertion sequence of said amplitude or power identifier.