WO2006047993A1 - Access control for a wireless local access network (wll) comprising an air interface working with ds-cdm/cdma, embedded tdm/tdma and tdd - Google Patents

Abstract

The invention relates to CDMA-based radio communication system of access control by means of a central access channel and enables acess in the data part of various free uplink channels. Inactive subscriber stations select a free uplink channel at random and transmit the access request for IP transfer or an outgoing POTS link. In the case of Internet transfers, uplink/downlink access/allocation occur independently from each other, requiring a minimum amount of time and transfer capacity such that packet-oriented setting up of a link is effective even for short IP packets. The uplink /downlink capacity ratio is controlled in a dynamic manner and good compatibility with access/allocation for POTS links is achieved. The subscriber stations receive a bearer control channel (BCCH) in a code channel 0, wherein the base station subscriber transmits the subscriber call-in and channel allocation for IP downlink transfers or a forthcoming POTS link. Minimum capacity control channels are respectively installed in the other direction channel scheme in order to control uplink and downlink IP transfers.

Description

ZUGRI FFS CONTROL FOR A WIRELESS, LOCAL ACCESS NETWORK (WLL) INCLUDING AN AIR INTERFACE WORKING WITH DS-CDM / CDMA, EMBEDDED TDM / TDMA AND TDD

The present invention relates to the field of methods enabling stationary subscribers to wirelessly access the Internet and the PSTN, particularly the type that both access to the Internet and access to the PSTN are direct accesses, and one subscriber both accesses simultaneously and independently can use each other. In detail, the invention relates to the methods of channel construction, the switching of services and access control in the air interface of such radio systems and the effective use of the resource air interface. Wireless local access networks to the PSTN have become more and more popular in the past decade and a half and are now commonly known as WLL (Wireless Local Loop). These access networks were originally developed with the aspect that they offer the subscriber the basic telecommunications service as POTS (Piain Old Telephone Service). They differ in this respect from the mobile radio networks, which implement the feature of mobility in addition to a basic service that already exists elsewhere, without wanting to replace or being able to replace it. A resulting distinguishing feature is that with WLL the subscriber stations do not represent terminal devices, but rather

Have interfaces for the connection of terminals at the subscriber's choice, while in mobile radio networks the subscriber stations have terminal functions.

A typical representative of the first generation of WLL are the facilities and processes described in [1]. In the meantime, various further developments have taken place, which as a second generation primarily include the transition from analog to digital transmission in the air interface, the increase in data rates for modem and fax transmissions and the expansion of the range of services. Although the WLL of this second generation allow access to the Internet by means of a modem via the PSTN, this is ineffective due to the low bandwidths / data rates which are adapted to the voice transmission in the air interface of the WLL. In addition, access to the PSTN is in the

Areas of application of the WLL are usually the participant's only communication connection and the occupancy of an Internet access is annoying and hindering and the acceptance of WLL is detrimental. Accordingly, third-generation WLLs have now been developed that overcome the shortcomings of the existing facilities with new solutions. In this regard, [2] describes the concept of a DECT-based WLL system, which has the task of uniting an access network to the Internet and an access network to the PSTN in one system. DECT (Digital European Cordless Telephone) is a system for cordless telephony standardized by the ETSI. It is intended for short ranges up to 300 m and voice transmission. DECT already has a low frequency effectiveness in the standard version, which can be specified as 0.226 bit / sΗz (duplex operation). In this version, the runtime-related range is 5 km. In the concept mentioned, a range of 15 km is specified without specifying that in this case only every second slot can be used in the channel scheme in order to create sufficient distances for the runtime compensation. In this case, the frequency effectiveness is reduced to 0.113 bit / s * Hz. In addition, DECT is neither equipped with an error protection method such as FEC or another, nor with an equalizer to compensate for interference caused by multipath propagation.

REPLACEMENT LEAF Both facts in the network have the consequence that DECT only reaches a BER of 10 ^'3 , which is sufficient for the transmission of speech by means of 32 kbps ADPCM, but is insufficient for the data transmission. In particular, interference due to multipath propagation and the resulting intersymbol interference are no longer negligible for transmission distances up to 15 km. The reason for this is that a detour length of 500 m is a product of

Π _DS = symbol rate * detour time = 1, 5 results, see also the explanations below.

The concept presented in [2] further assumes that a layer 2 security is used for the transmission of Internet traffic (see [2], page 8), which, since no subsegmentation of the IP packets is provided, only can be effective at the package level. This has considerable disadvantages, since with packet lengths of up to 1500 bytes corresponding to 12,000 bits with the above-mentioned error rate, the probability of incorrectly transmitted packets is very high and frequent repetitions of the transmission of entire packets can be expected. For practical reasons, all attempts to use DECT for WLL applications with ranges greater than 1 km and for data transmission have been problematic in practical use. It is advantageous in [2] that DECT has a fast access procedure and is therefore possible to set up a new physical connection between a base station and the subscriber station for each packet to be transmitted. It is largely coordinated with current requirements [3] in which patent a solution is presented that combines access to the PSTN and the Internet in one system. It is disadvantageous in this system that, as the traditional state of the art, the capacities for useful data, signaling and radio overhead are linked to each other in a rigid relationship and therefore, when higher transmission capacity is allocated, the absolute amount for signaling and radio overhead are increased proportionally, and thus transmission capacity is not used or is used redundantly.

A typical representative of this third generation of WLL is described in [4]. Wireless access to the Internet and the PSTN are implemented as direct access in such a way that the subscriber can use both access simultaneously and independently of one another. An FEC for error protection and an equalizer or preequalizer are used for transmission in the air interface. Furthermore, the IP packets, OA&M data packets and signaling data packets of POTS connections are subsegmented for transmission in the air interface. The subpackets formed in this way are multiplexed and transmitted with a layer 2 security via the air interface. If the length of the sub-packets is on average one order of magnitude shorter and the error rate of this solution is three orders of magnitude smaller, the probability of incorrectly transmitted sub-packets is very low and the second

Repetition of the transmission of subpackets with regard to the effectiveness of the transmission and the resulting data rate has less influence than can be expected with a solution according to [2]. In [4] there is also a load-dependent dynamic capacity distribution between the PSTN and the Internet access network. The disadvantage is the lack of a load-dependent dynamic capacity distribution between the upward and downward direction. Another disadvantage is a slow connection establishment and disconnection. That is owed to

REPLACEMENT LEAF Internet connections do not immediately clear the connection after a packet has been transmitted, in order not to have to disconnect and reconnect for a further packet that follows within a defined waiting time. The object of the present invention is to overcome the disadvantages of the aforementioned methods. This concerns, based on the facilities and general methods according to [4], methods that combine a load-dependent dynamic capacity distribution between upward and downward direction with a fast connection setup and clearing. The object is achieved by the method according to the features of claim 1. An embodiment of the invention is explained in more detail with reference to the accompanying drawings. Show it:

Figure 1 The architecture of the radio communication system in its entirety. Figure 2 Structure of the duplex frame in the general code channels 1 to (n-1) Figure 3 Structure of the duplex frame in a special code channel_0 Figure 4 Structure of the up-control channel UCCH Figure 5 Structure of the access control of the subscriber station

FIG. 6 state machine for controlling the upward direction in the subscriber station,

Inactive state

FIG. 7 state machine for controlling the upward direction in the subscriber station, state "access" FIG. 8 state machine for controlling the upward direction in the subscriber station,

Send state

FIG. 9 state machine for the control of the downward direction in the subscriber station. Both the preceding general descriptions and the following detailed description have only exemplary character as possible embodiments of the methods according to the invention and do not limit the claims for the invention.

Figure 1 describes the architecture of the radio communication system in its entirety. A base station 1 has an interface to the air interface 3 for the wireless connection to a plurality of subscriber stations 4.1 to 4.i. Access to the air interface 3 takes place via an antenna 2, which is used equally for the transmitting as well as the receiving operation. The base station 1 also has a PCM interface 10 which is designed as one or more E1 or T1 PCM trunk lines and which connects the base station 1 to a local exchange 12 of the PSTN 13. If required, optional connection devices 11 are switched into the connection between the base station 1 and the local exchange 12 if the local exchange 12 does not support a concentrated interface, but only subscriber-related connections such as

TIP / RING (a / b) or V5.1 offers or a protocol is offered by the local exchange 12, which is not supported by the base station 1.

The base station 1 also has an interface 14, which is designed as an Ethernet interface. A router or proxy server 15 is connected to the Ethernet, which is connected via a data line 16 to a network access of an ISP (Internet service provider) 17, via which there is access to the Internet 18. A local OA & M is also connected to the Ethernet.

REPLACEMENT LEAF Device 21 connected. A component of the device is also an OA&M center 19, which is connected to the Internet 18 via a router / proxy server 20 (via an Internet service provider, not shown here, which does not have to be identical to the former). The OA&M center 19 may be reserved for a plurality of remote base stations 1. The subscriber stations 4 have an interface to the air interface 3 for the wireless connection to the base station 1. Access to the air interface 3 takes place via an antenna 5, which is used equally for the transmitting and also for the receiving operation. Furthermore, the subscriber stations 4 each have a PSTN subscriber interface 6, which is designed for POTS (TIP / RING, a / b) or ISDN (basic connection, 2B + D), and an Ethernet interface 8, which is intended for Internet access. The PSTN subscriber interface 6 allows the connection of

Terminals 7 according to the type of service and at the customer's choice. The Ethernet interface 8 allows the connection of computers 9 for direct access to the Internet, which may be individual computers or, in the case of computer networks, routers, proxy servers or computers with a proxy server emulation. In this configuration, the radio communication system realizes independent access networks to the PSTN and the Internet. In the air interface, the capacity distribution between the access network to the PSTN and the access network to the Internet is controlled and adapted as required. Furthermore, the participants connected via radio enable simultaneous access to the PSTN and the Internet. This property correlates with the aforementioned aspect in that the capacity distribution between POTS and the Internet is controlled as required within the maximum capacity of the subscriber station, the requirements of the POTS taking precedence. Furthermore, an effective use of resources takes place in the access network to the PSTN, in that the POTS subscribers are provided with a compressed voice transmission as the standard connection and higher transmission capacity for fax or modem transmissions is assigned on request and all service features are applied to the POTS subscribers using the "off-hook" principle are guaranteed, the digital local exchanges as standard also offer analog wired participants. Furthermore, a direct access to a gateway of an ISP (Internet service provider) is made available to the subscriber via the Ethernet interface of his computer or his computer network via the wireless access network to the Internet, so that the route via the PSTN by dialing an access number of an Internet Service providers and use of transmission via modem is not required. Regardless of this, the latter route can be used alternatively or simultaneously by the subscriber via his POTS connection.

In the air interface of the radio communication system, the particularly interference-free multiplex / access method DS CDM / CDMA (Direct Sequence Code Division Multiplex / Code Division Multiple Access, hereinafter referred to as CDMA) is used. With a sequence length n, orthogonal codes are made available by appropriate selection, data spread with these can be transmitted in an additively superimposed manner and separated again at the receiving end. In the following, the term "code channel" is used in this regard. Furthermore, TDD (Time

REPLACEMENT LEAF Division duplex) is used, ie an RF channel is used alternately for both transmission directions.

FIG. 2 shows the duplex frame 22 of the general code channels j (i = 1 to (n-1)) for a TDD period. The duplex frame 22 consists of a down period 23 for broadcasts of the base station in the downward direction, an up period 24 for broadcasts of the

Subscriber stations in the upward direction and a protection time 25 for the runtime compensation of the transmissions of the subscriber stations 4.

The downward period 23 consists of an upward control channel UCCH 26 and a maximum number of i time slots 27, which are used for downward data transmission. The upward period consists of a guard time 28 for the synchronization of the subscriber stations in the special code channel 0 in accordance with FIG. 3, a downward control channel DCCH 29 and a maximum number of j time slots 30, which are used for upward data transmission. The duplex frame 22 is shown from the perspective of the base station 1. This means that the transmissions of the subscriber stations 4, including the DCCH 29 and the timeslots 30, are received synchronously in the base station, so that the orthogonality of the codes is ensured.

The number of time slots 27 and time slots 30 can vary. The variation takes place in such a way that the sum of the two numbers is constant and thus a variable ratio of upward to downward capacitance can be set with a constant duration of duplex frame 22. The setting is made by the signal "VerhJC 42 in UCCH 26 (see FIG. 4). A duplex frame 22 of the special code channel_0 is shown in FIG. 3. The duplex frame 22 consists of a down period 23, an up period 24 and one, identical to the general code channels Protection time 25 for the runtime compensation of the programs of the subscriber stations 4. The duplex frame is shown from the perspective of the base station 1. This means that the programs 29 of the subscriber stations 4 are received synchronously in the base station, so that the orthogonality of the codes is guaranteed.

The down period 23 consists of the up control channel UCCH 26, a call channel BCCH 31 and a maximum number of (i-1) time slots 32, which are used for the downward data transmission. The up period consists of a synchronization channel SCCH 33 for the synchronization of the subscriber stations, the down control channel DCCH 29 and a maximum number of j time slots 30, which are used for the upward data transmission. The location of the SCCH 33 is shown for the case of a synchronized subscriber station. In the case of a subscriber station which has not yet been synchronized, the SCCH 33 can appear to be leading and overlapping with the protection time 25. The BCCH 31 is used for the subscriber call for the purpose of initiating a downward transmission and the synchronization of inactive subscriber stations and comprises at least the signals

- Subscriber call with the elements subscriber number, service request and number of the assigned code channel, where the service request can contain the information IP, POTS or synchronization, and

- Sync_2, which contains the number of certain time units by which the start time of the transmission of a subscriber station is to be shifted in order to achieve an optimal synchronous one

To ensure reception in the base station.

REPLACEMENT LEAF The structure of the UCCH 26 is shown in FIG. The UCCH is transmitted by the base station 1 in the down period 23 of each code channel and is used by the subscriber stations 4 to control the access and transmission of IP data packets, data packets of other services in the up period 24 or to set up outgoing POTS connections in the respective Code channel. The UCCH includes at least the following signals:

- "Occupancy" 35. The signal "occupancy" 35 can contain the information "free" 51, "acceptance" 55 or "rejection" 38. The "occupancy" 35 applies to the time slots 30 of the upward period, taking into account the restriction given by "offset_1" 36.

- "Offset_1" 36 and "Offset_2" 37. "Offset_1" 36 indicates from which of the time slots 30 the signal "occupancy" 35 is valid. "Offset_2" 37 indicates after how many duplex frames 22 a new one

Value of "Offset_1" 36 is valid, the value is therefore counted down by the base station from duplex frame to duplex frame to zero.

- "Repetition" 39. "Repetition" 39 is a layer 2 signal and indicates which subpacket or from which subpacket, depending on the selected Layer 2 protocol, is to be repeated.

- "ADD_K" 40 and "Versatz_3" 41. "ADD_K" is the number of another code channel which is assigned to the subscriber station for upward data transmission, if the subscriber station has requested one, "Offset_3" indicates after how many duplex frames 22 the assignment is valid, the value is therefore counted down by the base station from duplex frames to duplex frames to zero. Further channels are requested and assigned in accordance with the method steps in claim 6.

- "Verh_K 42" and "Versatz_4" 43. "Verh_K" 42 is the number of time slots 27 in the downward period 23 and thereby characterizes the position of the switching time between the downward period and the upward period 24. "Versatz_4" 43 indicates after how many duplex frames 22 a changed value of "Verh_K" 42 is valid, the value is therefore counted down by the base station from duplex frame to duplex frame to zero. The application for controlling the ratio of downward to upward period is as described in claim 11.

- "Syncjl" 44. "Sync_1" is the number of certain time units by which the start time of the transmission of the active subscriber station is to be shifted in order to achieve an optimal synchronous one

To ensure reception in the base station. The application for synchronizing the subscriber station is as described in claim 12.

According to the invention, the design of the UCCH 26 implies that a subscriber station has a

Access for an IP transmission in the up period 24 or an outgoing POTS connection in a randomly selected code channel, in which the UCCH

"Occupancy" 35 contains the information "free", and transmits its identification and the service request in the timeslot specified by "Versatz_1" 36.

The UCCH is received by all subscriber stations regardless of their operating state in at least one of the code channels (see FIGS. 6 to 9), which ensures that global, non-subscriber-related information is observed by all subscriber stations.

The structure of the access control of the subscriber station is shown in FIG

REPLACEMENT LEAF For the sake of clarity, one channel each for access control in the uplink and the

Downward direction is shown.

State machine 46 for controlling the upward direction in the subscriber station

- UCCH 26 receives a plurality of consecutive code channels in numbering, - sends access requests in the uplink in one of time slots 30, and

communicates with the internal control 48 of the subscriber station, which logically and physically implements the transmission of data to the base station.

The state machine 47 for controlling the downward direction in the subscriber station

- receives the special code channel_0 BCCH 31 - receives the special code channel_0 UCCH 26 and / or other code channels assigned by the base station for downlink transmission,

- transmits in the DCCH 29 the code channels assigned for the downward transmission, and

communicates with the internal control 48 of the subscriber station.

According to the invention, subscriber stations therefore receive the signals from this plurality of code channels simultaneously.

IP transmission in the upward direction

Since in the case of an IP transmission in the upward direction, it is not mandatory that the

Subscriber station receiving downlink data transmission at the same time, the UCCH 26 minimizes both access and control during the uplink

If the access is successful, all time slots 30 are assigned to the subscriber station from the time slot specified by "Offset_1" 36.

The mode of operation in the case of an IP transmission is explained on the basis of the state machine 46 (FIG. 5) for controlling the upward direction in the subscriber station. This state machine can assume the states "inactive" 50 (FIG. 6), "access' 70 (FIG. 7) and" send "80 (FIG. 8). The state" inactive "50 is shown in FIG Subscriber station receives the occupancy signal "free" 51 or "rejection" 38 in a freely selected code channel in the UCCH 26. If a query "N = O?" 52 delivers the value zero, "L_Search" 67 resets the search state and "returns" "53 for the" inactive "state 50. Here, as generally in the following," return "53 means the return to the respectively active state. The input signal" rejection "38 is treated like a free code channel, since it can be assumed that an external assignment of the code channel starts the following duplex frame 22. If the occupancy signal "Acceptance" 55 is detected in the UCCH 26, the block 54 for channel search is processed, and the block 54 ensures that if a code channel is occupied by another, the subscriber station is looking for a channel free code channel skips a number of free code channels determined by a random number and only remains in the following free code channel. This results in the unbundling of the plurality of subscriber stations which were together in the code channel which is now externally occupied in the “inactive” state 50. When "Acceptance" 55 is received for the first time, the query "Search?" 65 the value No, "Search" is set 66, a random number RND> 0 is generated and

"N: = RND" 56, an increase in the number of the code channel to be received with "K: = K + 1" 57 and

REPLACEMENT LEAF "Return" 53. If "Acceptance" 55 is received further, the query "Search?" 65 then the value yes, there is an immediate increase in the number of the code channel to be received with "K: = K + 1" 57 and "return" 53. Each time after receiving "free" 51 or "rejection" 38 if the query "N = O?" 52 provides a value not equal to zero, the amount "N: = N-1" 58 is reduced and the number of the code channel to be received is increased with "K: = K + 1" 57. Only when N = O is reached with "L_Search" 67 Reset the search status and remain in the code channel.

The method of searching for a free code channel illustrated in this way would have the disadvantage, when receiving only one code channel, that block 54 is only run through once per duplex period 22. With a high number of occupied code channels and a high random number RND, many duplex periods could therefore be required and the method could be time-consuming until the abovementioned conditions were met. For this reason, the subscriber stations are equipped to receive the UCCH 26 in parallel in the case of a plurality of successive code channels. The occupancy signals 35 received at the same time are stored in the sequence of the code channels in the input stack of the state machine and then processed immediately within the current duplex period in block 54, which means an acceleration factor corresponding to the number of code channels received in parallel.

The input signals "Repetition" 39, "Sync_1" 44 and the input signal 59, comprising "ADD_K" 40 and "Offset_3" 41, are ignored. The input signal 60, comprising "offset_1" 36 and "offset_2" 37, as well as the input signal 61, comprising "Verh_K" 42 and "offset_4" 43, are transferred as unchanged output signals 62, 63 to the internal control 48 for further consideration.

The input signal "access" 64, coming from the internal control, triggers the transition to the state "access 70. The state" access "70 is shown in FIG. The starting point is that the

Subscriber station in a freely selected code channel in the UCCH 26 receives the occupancy signal "free" 51. If a query "N = O?" 52 supplies the value zero, "L_Search" 67 resets the search, the "Access 71" signal is sent to the internal control 48 and a "Mark_A" 72 is set. The "Access 71" signal allows the internal control 48 in which subsequent upward period 24 to send an access request to the base station. A successful access in the following duplex frame 22 in the UCCH 26 is answered with "acceptance" 55 or, in the case of a hazard, due to the simultaneous access by another subscriber station or other faults with "rejection" 38. The access request can already include the request for higher-rate bundled data transmission in more than one code channel. The establishment of such a connection is carried out in accordance with the method steps in claim 6. Upon receipt of the "acceptance" occupancy signal 55

- If the query "Brand_A?" is positive 73 the "Send" signal 74 is sent to the internal control as confirmation of the successful access attempt and the transition to the "Send" state 80 takes place. The "Send" signal 74 allows the internal control to send data in the subsequent upward period 24 to start,

REPLACEMENT LEAF respectively

- If the query "Brand_A?" is negative 73 the search for a free code channel started.

When the "Repetition" signal 39 is received - if the result "Query_A?" 73 a jump into the path to "free" 51 and a new access attempt is initiated, or

- If the query "Brand_A?" is negative 73 ignored the signal. When the "Rejection" signal is received 38

- after a negative result of the query "Marke_A?" 73 evaluates the signal as a free code channel and there is a jump into the path to "free" 51, or

- If the query "Marke_A?" is positive 73 with "L_Marke_A" 75 the reset of Marke_A and the search for a free code channel is started.

A free code channel is searched for in accordance with the explanations for block 54 (FIG. 6). In this search process, an input signal "rejection" 38 if the subsequent query "Mark__A?" 73 is treated negatively as a free channel, since in this case "rejection" refers to another subscriber station that leaves this channel from this point in time. The input signal 59 and the input signal "Sync_1" 44 become

- if the query "Brand_A?" 73 is positive, passed to the internal control as signals 76 and 77 for further attention, or - if the query "Marke_A?" 73 is negative, ignored

The input signal 60 and the input signal 61 are processed identically to the explanations for FIG. 6.

The state "Send" 80 is shown in FIG. The initial consideration is that it is still in a state

"Access' 70 to the internal control 48 an output signal" Send "74 was sent, which is the release for a data transmission to the base station in the following

Represents upward period 24. The data transfer is carried out by the internal control during this

Transmission, and subsequently with each further of these transmissions, with a signal

"Send" 81 confirmed at the state machine 46.

After the signal "Send" 81 received by the internal control, "L_Marke_A" 75 is used to reset the Marke_A. After an input signal "Acceptance" 55, "Marke_A" 72 is set and the signal "Send" 74 is transmitted to the internal controller 48, with which the latter is released again for data transmission to the base station in the following

Up period 24 receives.

The subscriber station sends an end signal in the data channel to the base station when an IP packet has been completely transmitted and no further packets are to be transmitted. After recognizing this end signal, the base station continues to send “acceptance” 55 until from the layer 2 instance of the

Base station

- The end of the connection is avoided, whereupon "free" 51 is sent in the UCCH 26, which is evaluated in the subscriber station as the correct completion of the transmission, or - a retry request is reported, whereupon "acceptance" 55 and additionally "retry" 39 in the UCCH 26 be sent.

REPLACEMENT LEAF In the waiting time that occurs after the end signal, the internal control 48 of the subscriber station sends dummy data to the base station and continues to send the signal “send” 81 to the state machine 46. An input signal “repetition” 39 - if the query “Marke_A?” 73 passed to the internal control 48 (FIG. 5) as an unchanged output signal 82 for further attention, or - if the result of the query "Mark_A?" 73 ignored. After the input signals "rejection" 38 or "free" 51, the output signals "abort" 83 or "end" 84 are sent to the internal control and the system returns to the "inactive" state 50 (FIG. 6).

The input signals 44, 59, 60 and 61 are processed identically to the explanations for FIG. 7.

Access for setting up an outgoing POTS connection In the case of an outgoing POTS connection, the UCCH 26 only represents the return channel for the access. After the access has been confirmed by the base station, further signals in the signaling part of the allocated time slots are transmitted in the up and down direction . For POTS connections, both outgoing and incoming connections, time slots are always assigned in the order starting with the first timeslot of the up period 24 and the down period 23 in the same code channel. The method ensures that POTS connections can maintain their relative timeslot position if the ratio of the upward to the downward period changes.

To set up a POTS connection, the base station in UCCH 26 increases the value of "offset_1" 36 by one and the assignment 35 is then set to "free" again, which permits further access to the still free timeslots. Because POTS connections

Duplex connections, "offset_1" 36 also applies to the IP transmissions to be set up or existing in the downward direction in order to also clear or keep the allocated time slot for the POTS connection in the downward direction. The access to set up an outgoing POTS connection is also controlled by the state machine 46 (FIG. 5) already described above for controlling the

Upward direction in the subscriber station. The functions in the "Inactive" state 50 (FIG. 6) and the "Access" state 70 (FIG. 7) are completely identical. The operation in the "Send" state 80 is shortened. The same initial consideration applies, but from the internal Control of the subscriber station transmit the signal "transmit" 81 only until the time slot is provided by the base station in the downward direction, thereby signaling that in the UCCH 26 "offset_1" 36 has been increased by 1 and "offset_2" has the value zero After validity of the changed value of "offset_1" 36, "free" 51 is transmitted in the UCCH 26, which causes the state machine 46 to return to the "inactive" state 50.

IP transmission in the downlink

Since in the case of an IP transmission in the downward direction, it is not mandatory that the

REPLACEMENT LEAF If the subscriber station carries out an upward data transmission at the same time, the DCCH 29 additionally represents a minimized return channel for controlling the set-up and during the downward transmission. If the access is successful, all time slots 27 or 32 from the one specified by "Versatz_1" 36 are assigned Downslot 23 time slot assigned.

The IP transmission for a subscriber station is carried out by the base station in accordance with the method steps in claim 7. The transmission can be carried out as a higher-rate bundled data transmission in more than one code channel. The establishment of such a connection is carried out by the base station in accordance with the method steps in claim 9.

FIG. 9 describes the mode of operation of the subscriber station in the case of an IP transmission using the state machine 47 (FIG. 5) for the downward direction. This state machine can assume the states "inactive" 90 and "reception" 97. The explanation is given in the case of the assignment of a code channel. If several code channels are assigned, the described data exchange takes place in parallel for the assigned code channels in the "Receive" state. An exception to this is the signal "repetition" 99, which is only transmitted in the first assigned code channel. The state machine sends to the base station in DCCH 29 of code channel_0 or after successful channel assignment in DCCH 29 of the assigned code channel, receives the BCCH 31 and UCCH 26 of code channel_0 or after successful channel assignment the UCCH 26 of the assigned code channel. The DCCH 29 includes the signals

- "Reception" 94. The signal "Reception" is an acknowledgment of receipt for the previous downward period 23 without a statement about freedom from errors.

- "Repetition" 99. The "Repetition" signal is a layer 2 signal and indicates which subpacket or from which subpacket, depending on the selected Layer 2 protocol, is to be repeated.

- "Rejection" 101. The "Rejection" signal means termination without proper completion of the transmission.

- "End" 103. The signal "End" means termination with the proper termination of the transmission, including the proper termination of the Layer 2 connection.

In the "inactive" state 90, the BCCH 31 is received and the call signal 91, comprising the subscriber number, service request and number of the assigned code channel, is transferred to the internal control as output signal 92. An input signal "receive" 93 from the internal control confirms that the call signal is correct for the subscriber station, it is sent in the DCCH of code channel_0 "receive" 94 and changes to the "receive" state 97. Subsequent signals "reception" 93 and "repetition" 98 coming from the internal control are sent in the DCCH of the assigned code channel as signals "reception" 94 and "repetition" 99 to the base station and returned to the state "reception" 97. Signals "rejection" 100th and "end" 102 coming from the internal control are sent in the DCCH of the assigned code channel as signals "rejection" 101 and "end" 103 and returned to the "inactive" 90 state.

REPLACEMENT LEAF The input signals "Versatz_1;Versatz_2" 60 and "Verh_K;Versatz_4" 61 are received in the UCCH 26. The reception takes place in the "inactive" state 90 in the code channel_0 or in the "reception" state 97 in the assigned code channel. The resulting output signals 62 or 63 are transferred to the internal control for further attention. For the sake of clarity, signals to be ignored have not been included in the illustration.

Access to establish an incoming POTS connection

The establishment of an incoming POTS connection is initiated by the base station by

- a code channel is selected for the downward transmission, - in the UCCH 26 "offset_1" 36 is increased by the amount 1, and

- The subscriber station is called in the BCCH 31 and the code channel and the service request are transmitted.

Access control for establishing an incoming POTS connection is also controlled by the state machine 47 (FIG. 5) already described above for controlling the downward direction in the subscriber station. The functions in the "inactive" state 90 (FIG. 9) are identical to the description above.

In the "reception" state 97 (FIG. 9), the signal "reception" 93 is transmitted by the internal control of the subscriber station only until the time slot pair in the assigned code channel is provided in the downlink and uplink direction by the base station, thereby signaling that in the UCCH 26 "Offset_2" 37 has reached the value zero. After the changed value of "offset_1" 36 is valid, the internal control reports "end" 102 and transmits it in DCCH 29 as "end" 103, which causes the state machine to return to the "inactive" 90 state. From this point in time, further signaling is transmitted in the signaling part of the assigned time slots in the up and down direction.

Synchronization of the subscriber stations

The access methods according to the invention assume that the subscriber stations are synchronized at all times in order to be able to transmit one of the code channels in a time slot or in the DCCH 29 of the upward direction without prior time-consuming synchronization procedures, without causing interfering interference in the base station.

Inactive subscriber stations are synchronized by a method that uses BCCH 31 and SCCH 33. The process involves that

- A subscriber call is transmitted from the base station in the BCCH 31, in which the service feature contains the information synchronization, - A synchronization signal is sent from the subscriber station in the subsequent SCCH 33, which can also be spread with a code sequence that is not the same as that for data transmission code sequences used in the downward and upward direction are identical,

the base station determines the length of time by which the synchronization signal received in the SCCH 33 deviates from the optimum reception time, the base station sends the deviation in the subsequent BCCH 31 as a signal "Sync_2", and

- The subscriber station corrects the start time and saves it for future transmissions.

REPLACEMENT LEAF All inactive subscriber stations are successively synchronized by the base station using this method.

Active subscriber stations are synchronized in that their transmissions in the upward direction are used by the base station to determine the length of time by which the received data signal deviates from the optimum reception time. For IP transmissions in the downlink, the signals sent by the subscriber station in the DCCH are used for this measurement. The base station transmits the correction values for the starting time of the subscriber station

with IP transmission in the upward direction by transmission of the correction value as "SyncJ" 44 in the UCCH 26,

in the case of IP transmission in the downward direction by embedding the correction value as a signaling packet in the downward data stream,

- With POTS connection by embedding the correction value as a signaling packet in the signaling part of the assigned time slot in the downward direction.

Reference literature list

[1] DE 4240249

[2] Vicente Quilez, Head of RCD Fixed Radio Systems Department, Alcatel, Telecom 99 lnter @ ctive "Effiient Provision of Internet in wireless access Systems" [3] US 6 131 012 [4] DE 100 56 087

REPLACEMENT LEAF Reference symbol I is

1 base station

2 Base station antenna 5 3 Air interface

4 subscriber station

5 Antenna of the subscriber station

6 PSTN subscriber interface of the subscriber station

7 Subscriber terminal 0 8 Ethernet interface of the subscriber station

9 Participant's computer or computer network

10 PCM interface of the base station

11 Optional controller boards

12 Central Office 5 5 PSTN (Pubiik Switched Telephone Network)

14 Base station Ethernet interface

15 routers

16 data line

17 ISP (Internet Service Provider) 0 18 Internet

19 OA&M Center

20 routers / proxy servers

21 Local OA&M facility

22 duplex period (duplex frame) 25 23 down period

24 up period

25 Protection time for runtime compensation

26 UCCH (up control channel)

27 time slots for downward data transmission

30 28 Protection time for the synchronization of subscriber stations

29 DCCH (down control channel)

30 time slots for upward data transmission

31 BCCH (call channel)

32 time slots for downward data transmission 35 33 SCCH (synchronization channel)

35 Occupancy, occupancy status of a code channel

36 "OffsetJ"

37 "offset_2"

38 "rejection" 40 39 "repetition"

40 "ADD K" 41 "offset_3"

42 "Verh_K"

43 "offset_4"

44 "SyncJ"

5 46 State machine for controlling the upward direction in the subscriber station

47 State machine for controlling the downward direction in the subscriber station

48 Internal control of the subscriber station

50 "Inactive" state of the state machine 46

51 Occupancy signal "free" 10 52 query "N = O?"

53 Return to the current status

54 Block for channel selection

55 occupancy signal "acceptance"

56 Setting "N: = RND"

15 57 Increase the number of the code channel to be received by the amount 1

58 reduction of N by 1 "N: = N-1"

59 input signal "ADD_K; Versatz_3"

60 input signal "offset_1; offset_2"

61 input signal "Verh_K; Versatz_4"

20 62 Output signal "Offset_1; Offset_2" to internal control

63 Output signal "Verh_K; Versatz_4" to internal control

64 "Access" input signal from the internal control

65 Query "Search?"

66 Set "Search"

25 67 Reset "L_Search"

70 State "Access of the state machine 46

71 "Access' output signal to internal control

72 Set "Brand_A"

73 Query "Brand_A?"

30 74 "Send" output signal to internal control

75 Reset "L_Marke_A"

76 Output signal "ADD_K; Offet_3" to internal control

77 Output signal "Sync_1" to internal control 80 State "Send" of state machine 46

35 81 Input signal "Send" from the internal control

82 "Repetition" output signal to internal control

83 "Abort" output signal to internal control

84 "End" output signal to internal controller 90 "Inactive" state of state machine 47

40 91 subscriber call in BCCH 31

92 Output signal subscriber call to internal control 93 Acknowledgment of receipt from the internal control

94 Acknowledgment of receipt "receipt" to the base station in DCCH 29

97 "Receiving" state of the state machine 47

98 "Repeat" input signal from the internal controller 99 "Repeat" output signal to the base station in the DCCH 29

100 "Reject" input signal from the internal control

101 "Reject" output signal to the base station in the DCCH 29

102 "End" input signal from internal control

103 "End" output signal to the base station in the DCCH 29

Claims

Expectations

1. Method for a wireless point-to-multipoint communication system with a combination of

Access networks to the PSTN and to the Internet, the communication system comprising a base station (1), an air interface (3) and a plurality of subscriber stations (4) which

Subscriber stations both via a subscriber interface (6) for access to the PSTN and one

Have ethemet interface (8) for access to the Internet, which can be used independently and simultaneously, and the capacity distribution between the two access networks is adapted depending on the load and the Airinterface works with Direct Sequence CDM / CDMA and an embedded TDM / TDMA and TDD, in particular with regard to the access method, characterized in that each subscriber station

- constantly receives a special code channel_0 in which the UCCH (26) and the subscriber calls transmitted by the base station (1) in a BCCH (31) for IP transmissions in the downlink, incoming POTS connections or for synchronization are received, when assigning an IP transmission in the downward direction, additionally in one or for higher-rate transmissions in several code channels assigned by the base station for a downward data transmission, which can also include the special code channel_0, the UCCH (26) and the time slots for the IP transmission receives and transmits in the DCCH (29) of the assigned code channels, - when an incoming POTS connection is assigned, additionally receives and transmits in a code slot assigned by the base station in a time slot pair of the downlink and uplink direction and receives the UCCH of the assigned code channel,

constantly receives a randomly selected code channel which is free in the upward direction, which can also be the special code channel JD, as an access channel in which the information transmitted by the base station in the UCCH of this code channel is evaluated for the establishment, control and removal of upward data transmissions, and sends access requests for IP transmission in the uplink or outgoing POTS connections in the uplink of this code channel,

- With successful access for an IP transmission in the uplink in the access channel and for higher-rate transmissions in other code channels assigned by the base station in the

Sends time slots for IP transmission and the UCCH receives these channels,

- when access is successful for an outgoing POTS connection in the access channel in a time slot pair in the downward and upward direction, receives and transmits and receives the UCCH of the access channel, - receives a plurality of further code channels, which may also include the special code channel_0, in which the occupancy information transmitted by the base station in the UCCH of these code channels can be evaluated for a quick search of a code channel free in the upward direction.

2. The method according to claim 1, characterized in that with IP transmission between the base station and a subscriber station, the up and down data connections

REPLACEMENT LEAF - set up, operated and dismantled independently of one another,

can be set up in different code channels if they are present at the same time,

- after complete transmission of the available data, comprising at least only one IP packet, and completion of the Layer 2 connection are terminated, - each use all time slots of the up or down period, except time slots that are occupied by a POTS connection or during the connection.

3. The method according to claim 1 or 2, characterized in that the subscriber station with IP transmission in the upward direction - in a first step even before a transmission request a free in the upward direction f code channel, g e marked by in signal "free "in U CCH (26) d it selects the code channel, changes to an" inactive "state and receives the UCCH of this code channel continuously,

- in a second method step, if there is a transmission request in the upward direction of the selected code channel, transmits an access request,

- In a third step in the process of positive confirmation of the access request by the base station, characterized by a signal "acceptance" in the UCCH of the code channel, which carries out the user data transmission, provided that the transmission from the base station is confirmed with "acceptance" from duplex frame to duplex frame, - in one fourth method step after the end of the user data transmission sends dummy data,

- In a fifth procedural step after confirmation of the positive completion of the transmission by the base station, characterized by a signal "free" in the UCCH of the code channel, changes back to the "inactive" state.

4. The method according to claim 3, characterized in that the subscriber station with IP transmission in the upward direction

- During the "Inactive" state after a "Acceptance" signal in the UCCH (26) of the selected code channel, indicating that successful access was made by another subscriber station, or

- During the access attempt or data transmission after a signal "rejection" in the UCCH of the selected code channel, the search for a free code channel in the upward direction is carried out by generating a random number N and when checking the UCCH of the code channels in a continuous sequence the N. free Code channel is selected, the subscriber station constantly in parallel with a plurality of code channels in consecutive order, starting from the currently selected or used code channel, whose UCCH receives and the occupancy signals "ifrei", "acceptance" and / or "rejection" still within the current Includes duplex period (22) in the channel search procedure.

5. The method according to claim 3, characterized in that for the transmission in the air interface, the data packets to be transmitted are subsegmented and based on the subpackets a layer 2 -

REPLACEMENT LEAF Securing takes place, and repetition requests from the base station are transmitted as a signal "repetition" (39) in the UCCH (26) of the first assigned code channel, it being possible to request repetitions of a subpacket or repetitions from a specific subpacket in accordance with the selected Layer 2 protocol.

6. The method according to claim 3, characterized in that higher-rate bundled data transmission takes place in more than one code channel,

- by the subscriber station requesting a second code channel in the access request in a first code channel, - the base station selects a code channel free in the upward direction and identifies this code channel as occupied for other subscriber stations by an occupancy signal "acceptance" in the UCCH (26), and

- The base station in the UCCH of the first code channel transmits a signal "Add_K" (40) which assigns the selected second code channel to the requesting subscriber station, and the method for assigning further code channels is modified such that the subscriber station requests the request as a signaling packet in the uplink. Data stream transfers.

7. The method according to claim 1 or 2, characterized in that the base station for IP transmission in the downward direction - in a first step in the presence of data for a subscriber station selects a free code channel in the downward direction,

- transmits a subscriber call (91) in the BCCH (31) in a second method step,

- In a third step, if the subscriber call is confirmed positively by the subscriber station, characterized by an acknowledgment of receipt “reception” (94) in the DCCH (29) of the assigned code channel, which carries out the user data transmission, provided the frame from frame transmits from the subscriber station with “reception” "is confirmed

sends dummy data in a fourth method step after the user data transmission has ended,

- In a fifth step after confirmation of the positive completion of the transmission by the subscriber station, characterized by a signal "end" (103) in the DCCH of the

Code channel that clears the connection.

8. The method according to claim 7, characterized in that for the transmission in the air interface, the data packets to be transmitted are subsegmented and based on the subpackets, a layer 2 backup is carried out, and repeat requests from the subscriber station as a signal "repeat" (99) in the DCCH (29 ) of the first assigned code channel are transmitted, it being possible to request repetitions of a subpackage or repetitions from a specific subpackage in accordance with the layer 2 protocol selected.

9. The method according to claim 7, characterized in that higher-rate bundled data transmission takes place in more than one code channel,

REPLACEMENT LEAF in that the base station selects one or more code channels free in the downward direction in the case of downward data transmission to a suitable subscriber station after the connection has been established in a first code channel, and

transmits the assignment of the further code channels as signaling packets in the downward data stream,

in a third step of the method, if the assignment is confirmed positively by the subscriber station, characterized by an acknowledgment of receipt “reception” (94) in the DCCH (29) of the assigned code channels, the base station carries out the user data transmission in the assigned code channels, provided the transmission from the subscriber station is confirmed with "reception" from duplex frame to duplex frame.

10. The method according to claim 1, characterized in that a POTS connection between the base station and a subscriber station always time slots are assigned in the order starting with the first time slot of the up period (24) and the down period (23) in the same code channel and

the occupancy of the time slots is indicated by the base station in the above-mentioned manner in the UCCH (26) in that a signal "offset_1" (36) per POTS connection is increased by one,

- The base station is indicated by a signal "offset_2" (37) in the UCCH, after how many duplex periods the signal "offset_1" is valid, and the signal "offset_2" from frame to

Frame is counted down to zero,

Base station and subscriber stations, which carry out IP transmissions in the upward direction and / or in the downward direction in the same code channel, no longer use the time slot assigned to the POTS connection from the point in time specified by the signal "offset_2",

- After setting up an outgoing POTS connection, the base station sends the signal "free" in the UCCH of this code channel from the point in time defined by the signal "Versatz_2" and thus enables access to the unused time slots of the uplink.

11. The method according to claim 1, characterized in that for controlling the ratio of down period to up period with constant duration of a duplex period, the number of time slots in the down period to up period can be changed in opposite directions and the setting valid for all existing and new connections from the base station is specified by

- From the base station in the UCCH of all code channels identical a signal "Verh_K" (42), which indicates how many time slots are assigned to the down period, and a signal

"Offset_4" (61) = 0, which indicates that the value of "Verh_K" is valid, are transmitted,

- When the ratio in the UCCH of all code channels changes, the new value of the signal "Verh_K" and a signal "Versatz_4"> 0 are transmitted, which indicates after how many duplex periods (22) the new value of "Verh_K" becomes valid , which is reduced by the value 1 with each duplex period and which, when "Offset_4" = 0 is reached, indicates the validity of the new value of "Verh_K".

REPLACEMENT LEAF

12. The method according to claim 1, characterized in that inactive subscriber stations are sequentially synchronized by the base station by

a subscriber call is transmitted from the base station in the BCCH (31), in which the service feature contains the information synchronization,

a synchronization signal is sent by the subscriber station in the subsequent SCCH (33), which can also be spread with a code sequence that is not identical to the code sequences used for data transmission in the downward and upward direction,

the base station determines the length of time by which the synchronization signal received in the SCCH deviates from the optimum reception time,

- The base station sends the deviation in the following BCCH as signal "Sync_2", and

- The subscriber station corrects the start time and saves it for future transmissions, and active subscriber stations are synchronized by using their transmissions in the upward direction by the base station to determine the length of time the received data signal deviates from the optimal reception time. In the case of IP transmissions in the downward direction, the signals sent by the subscriber station in the DCCH (29) are used for this measurement. The base station transmits the correction values for the starting time of the subscriber station

with IP transmission in the upward direction by transmission of the correction value as "Sync_1" (44) in the UCCH (26),

in the case of IP transmission in the downward direction by embedding the correction value as a signaling packet in the downward data stream,

- With POTS connection by embedding the correction value as a signaling packet in the signaling part of the assigned time slot in the downward data stream.

REPLACEMENT LEAF