DE19533507C2 - Multiplex, access and duplex methods for a cellular radio system - Google Patents

Description

The invention relates to a multiplex, access and duplex method and devices for Realization of the method for a cellular radio system according to the preamble of the patent saying 1.

Multi-user systems for radio-based connection of telecommunications subscribers to the public Telecommunications networks are widely used. These are primarily cellular networks, Checker networks, networks based on the technology of cordless telephones (in particular also networks based on the DECT standard), networks of the category "Wireless Local Loop" ("Fixed Radio Access ") and Rural Networks. Existing systems are aimed at voice services provide and integrate such data services into one for voice services designed channel are transferable.

As a result, existing systems no longer meet the current trends in Communication needs. Basic requirements to be met according to these trends are that in a system voice services with low data rate, narrowband ISDN as well as components of broadband ISDN, general data services, video and Multimedia applications with data rates above that of narrowband ISDN dynamic capacity allocation to the different services have to.

The Multi is an essential criterion for the properties of radio communication networks plex, access and duplex processes that are used in the air interface. This determine alongside and partly in cooperation with other parameters such as Frequency range and modulation method such properties as bandwidth efficiency, Cell capacity, limit ranges, service flexibility and quality of service, to name but a few essential to name.

Known systems such as the C network existing in Germany or the Mobile radio system NMT (Nordic Mobile Telephone) work with FDM / FDMA (Frequency Division Multiplex / Frequency Division Multiple Access) in connection with FDD (Frequency Duplex Division). That means that radio connections over frequency separated and in channels arranged according to a defined channel grid and two for duplex connections frequency bands offset by the duplex spacing can be used. Such systems are relative easy to use, but only offer constant channel bandwidths. The requirement to provide services with offer different bandwidth requirements and dynamic capacity allocation cannot be implemented on this basis.  

Systems with digital transmission also use TDM / TDMA (Time Division Multiplex / Time Division Multiple Access) with FDD or TDD (Time Division Duplex). That means everyone Connection cyclically a certain time period within a data stream, which over a Radio channel is transmitted, is assigned. It must be for the transfer of n connections the data rate in the radio channel is at least n times the data rate of the individual Connections are if FDD is used, or 2 * n times if TDD is used. A typical representative of the TDM / TDMA / FDD combination is Example GSM (D or E networks) and for the combination TDM / TDMA / TDD networks on the Basis of the DECT standard. In both cases, combinations with FDM / FDMA used to increase the channel capacity of networks over size n (number of Connections per radio channel).

A disadvantage of TDMA is that there are guard times between the individual participants' transmissions must be inserted, the tolerances of access and different terms Due to different distances between a base station and radio users consider. (Wired systems can overlap from Process input signals without interference by placing the signals in Buffer memories are buffered and then classified correctly in the time slots will. With a radio system, the receiver of a base station can only transmit signals without Process mutual influence if there is no overlap.) This requires that the amount of data must be transferred in a shorter time and therefore the above mentioned factors n or 2 * n can in practice be up to 2 * n or 3 * n. The Bandwidth efficiency of the TDMA is reduced to the same extent. Measures to Reducing this disadvantage are:

• - Reduction / limitation of the range to small values, an example of this is DECT with a maximum of 500 m.
• - Limitation of the number of connections per radio channel (number of participants) An example of this is GSM with 8 connections per radio channel.
• - Reduction of the sampling rate, that is, enlargement of the transmitted per time slot Amount of data. The consequence is that the time difference between two samples increases and is included as a delay time in the parameters of the transmission path.

The requirement to offer services with different bandwidth requirements and one Carrying out dynamic capacity allocation is based on TDM / TDMA can be realized by providing the subscriber with multiple time slots for a connection if required be assigned to.  

The latest solutions are based on the application of CDM / CDMA (Code Division Multiplex / Code Division Multiple Access) in connection with FDD or TDD. These procedures are theoretically known for a long time, but their effective use has only been known for a few years Years possible after having required the necessary elaborate integration Circuit solutions can be produced with reasonable effort. The process is based on that each bit of the message to be transmitted spread with a code sequence and then as broadband signal is transmitted (DS-CDM / CDMA, Direct Sequence -...). On the The receiving side is checked with a correlator for the presence of the code sequence and the Data stream reconstructed. Condition for a detection of the signal in the receiver are corresponding properties of the autocorrelation function of the code sequence used, the means a pronounced maximum and high suppression of secondary maxima.

If several mutually orthogonal code sequences are used, that means that their Cross-correlation functions have no maxima, so several spread with it Data streams are additively overlaid and separated again on the receiving side. In principle, there is also the possibility to implement CDM / CDMA processes in such a way that instead of the orthogonal code sequences, very long and statistically independent PR sequences (Pseudo-random sequences) are used and the data streams thus spread in same additive superimposed and separated on the receiving side again.

The differences between the two methods are that

• - In the case of DS methods, the number of available orthogonal code sequences is limited and an arbitrary increase in the number means the inclusion of code sequences that deteriorated correlation conditions and thus deteriorated recognition reliability have. A disadvantage-free increase in the number is only possible if the length of the Code sequences possible, but what correspondingly higher gross data rates in the radio channel means.
• - Strictly strictly statistical independence for procedures based on PR consequences is only given in the case of correlation over the total length, but in the case of the real condition Correlation over shorter episodes of statistical independence may be violated and then the recognition reliability drops or is temporarily lost.

A problem to be considered with CDM / CDMA processes is the control of the Transmission powers (Power Control). The aim is that those overlapping each other in the receiver Receive signals arrive at ideally the same levels. One in relation to other channels too strong a signal would make an impermissible interference contribution in the other channels and thus negatively affect the bit error rate there. In (1) a power control system is included a radio system with CDM / CDMA described, which the transmission power of the transmitter  Mobile subscriber controls and which consists of two control loops. A first control loop, the is effective internally in the mobile device, measures the reception field strength and regulates it inversely the transmission power. A second control loop measures the reception field strength of the concerned mobile device and derives from it a control variable which is transmitted via the transmitter of the Base station is transmitted to the mobile device and there a position of the transmission power causes. There is no provision for regulating the transmission power in the base station. The selection This source is considered arbitrary because of the power control problem in literature and Patents occupies a wide space.

In (2) it is described that CDMA and ATM (Asynchous Transfer Mode) in combination have significant advantages, especially when a wide range of different Services and bit rates to use. As a first problem to be considered, that the delay times that occur when converting voice services into ATM plus further delays due to switching and transmission, up to 25 ms can. Attention is drawn to the resulting echo problems without any method for To avoid avoidance. The second problem to be considered here is that CDMA requires very precise power control of the transmitter in order for everyone to run in parallel working channels to ensure equal and minimized interference conditions. As Multiplex method for the downlink (from a base station to the radio subscribers) is a CDM method using a constant spreading factor and orthogonal Code sequences considered advantageous. For the opposite direction, the Use of a CDMA with variable spreading factors (depending on the transmitting bit rate) and the elimination of orthogonal code sequences.

(3) examines and demonstrates that the combined use of CDMA and ATM leads to advantageous solutions. As in other publications (see above Literature examples (1) and (2)) are the power control of the transmitter in CDMA systems as an important prerequisite for being able to take full advantage of the CDMA. It is also pointed out, without naming specific possible solutions, that In the case of voice services, the suppression of signal transmission during pauses in speech is a useful one It is possible to improve the transmission parameters and / or transmission capacity.

In (4), based on the results of the work on the CODIT project (Code Division Testbed) as part of the RACE program CDMA as future technology of mobile radio favors. To different services and bit rates in parallel in a uniform system To be able to offer, a solution is presented in which, depending on requirements, different Chip rates of 1 MHz, 5 MHz or 20 MHz are used, which are variably assigned and can be transmitted in parallel in the air interface.  

In (5) a radio communication system is described, which is suitable for different Manage services and bit rates on a uniform system basis. The basic approach is that Radio communication system works internally on the basis of the ATM and at the interfaces to Communication environment and to the participant, if necessary, an appropriate Implementation is made. That means that the transmission over the air interface also takes place in the ATM. The solution it contains is for various multiplex, access and The duplex process is designed to be open and allows in a particularly advantageous manner Application of the solution presented in this description.

The selection of references makes it clear that the use of ATM is a trend that is becoming increasingly popular in radio communication systems. ATM implies that digital Information of whatever kind is transmitted in packetized form (cells). These cells have a uniform length of 53 bytes, of which 5 bytes header and 48 bytes useful information (payload). Cells can also be partially filled. In this case it will Payload supplemented by empty bits to 48 bytes. Cells from multiple sources, even from different ones Data rates from these sources can be asynchronous in a transmission link or switch facility can be fed. Each cell contains VPI (Virtual Path Identifier) and VCI (Virtual Channel Identifier), which per transmission section or for several together hanging transmission sections characterize a connection. This will all cells a connection of ATM switches independently switched. On the other hand, ATM cells receive all cells of a transmission Analysis by VPI and VCI and the cells destined for this receiving device selected. Because of this, ATM has favorable properties for multiplexing and access method. The solution according to the invention assumes that in a radio communication system one or more VPIs are permanently assigned to a base station and the VCI or VPI / VCI (in the case of several VPIs) for addressing the subscriber devices that are connected to them Base station are connected. This is the without any additional effort Addressing for the purpose of establishing a connection and also during an ongoing transfer given in the air interface. If several VCIs are assigned to one subscriber device, so signaling and simultaneous connections for a subscriber device can be independent be handled by each other. In addition, the PTI contained in the header of each cell (Payload Type Identifier) used to identify data types within a connection and make it selectable. These requirements result in independence from multiplex, Access and duplex procedures from the procedures for building, holding and dismantling Connections, the type of services and associated signaling and controls.

Details of the invention are based on the relationships shown in the drawings described in more detail. Show it:

Fig. 1 TDD (Time Division Duplex) with runtime compensation

Fig. 2 segmentation of ATM cells

Fig. 3 HIB - Identification header bytes

Fig. 4 connection with standard transmission rate

Fig. 5 connection with multiples of the standard transmission rate

Fig. 6 ATM / CDM mapping for the transmission direction of the base station

Fig. 7 CDM / ATM mapping for the reception direction of the base station

Fig. 8 ATM / CDM mapping for the transmission direction of the subscriber radio station

Fig. 9 CDM / ATM mapping for the direction of reception of the subscriber radio station.

A CDM / CDMA procedure in connection with TDD (Time Division duplex), in which each code sequence is handled as one channel, over which a constant net bit rate is transmitted (physical channel), which of the Standard application with the lowest bit rate. Connections with higher bit rates are realized in that several such physical channels for these connections can be used in parallel. A connection as a logical channel / bearer can thus or use multiple physical channels. A base station has parallel ones CDM / CDMA receiving / transmitting devices according to the number of code sequences / physical Channels. The subscriber radios have at least one and for higher rate connections corresponding to the required multiplication factor number of parallel CDM / CDMA receiving / transmitting devices, which are optional each code sequence can be assigned from the pool of available code sequences.

In Fig. 1, the timing diagram of the TDD scheme is illustrated. In this illustration, 1.1 (see FIG. 1) contains the time diagram of the transmission phases and 1.2 the time diagram of the reception phases in the radio base station. The radio base station simultaneously sends bursts 1.7 in all channels, which are received by the subscriber radios after a distance-dependent signal propagation time. 1.4 and 1.6 contain the time diagrams of the reception phases and 1.3 and 1.5 the time diagram of the transmission phases of two such subscriber radios TS2 and TS1, which receive bursts 1.9 and 1.11 in accordance with channel assignment. The subscriber radio TS2 should have the maximum permissible distance from the radio base station, so that the signal _delay 1.13 has the maximum value t _Pmax . After a minimum _{switchover time} 1.14 of length t _Dmin , this device transmits burst 1.10 in its transmission phase 1.3 . This burst in turn arrives after the maximum signal runtime 1.15 in the radio base station, which is in the receiving phase. The bursts 1.12 emitted by other subscriber radios, for example TSI, during their transmission phases 1.5 are delayed in these subscriber radios in such a way that the bursts 1.8 arrive synchronously in the radio base station. After a minimum switchover time 1.16 of length t _Dmin , the radio base _station can _{carry out} a new transmission. The time t _v = 2 × t _Pmax + 2 × t _Dmin is a loss time that is not used for data transmission, whereby t _{Pmax is} dependent on the distance and therefore cannot be influenced _{if the} distance is _specified accordingly, while t _{Dmin is} due to technical / physical reasons and must be minimized .

The ratio of t _v to the duplex period 1.17 (see FIG. 1) with the length T _D is a measure of the losses in transmission capacity and can only be improved for a predetermined value of t _v by increasing the duplex period 1.17 . However, the duplex period 1.17 is included in the data transmission as a delay time, which must be taken into account in time-critical transmissions (voice transmission). For the duplex period 1.17 , for example, with a burst length based on the ATM cell length and a standard transmission rate of 32 kbit / s per transmission direction, an unacceptable value of approx. 12 ms results for T _D. For this reason, segmentation of the ATM cells as shown in FIG. 2 is carried out in an exemplary embodiment. The ATM cell consists of the header 2.1 (see FIG. 2) with a length of 5 bytes and the payload 2.2 with a length of 48 bytes. By prefixing 2 HIB (Header Identification Bytes) 2.3 , a total length of 55 bytes is added and then divided into 5 segments with 11 bytes each. A BPB (burst preamble bit) 2.6 , 2.10 , 2.12 is added to each segment. . . prepended. The first segment thus consists of BPB 2.6 , 2 HIB 2.7 , header 2.8 and 4 byte payload 2.9 . The four following segments are constructed identically and, like segment 2, consist of BPB 2.10 and 11 byte payload 2.11 . If these segments are used as bursts in the TDD method according to FIG. 1, the duplex period 1.17 (see FIG. 1) with T _D under 2.5 ms results in an acceptable size. Signal interference has a negative impact on the performance, capacity and applicability of CDMA processes. An essential source of such interference are runtime errors of different subscriber radio devices when they are received in the radio base station as so-called multiuser interference.

For this applies

To minimize this value, a runtime correction is provided such that the bursts emitted by the subscriber radio devices arrive in the radio base station as synchronous reception signals 1.8 (see FIG. 1). A burst-synchronous reception is shown here. In principle, however, it is sufficient for the minimization of I _MU if the synchronicity extends to the code sequences, which is used in another embodiment according to the invention. This variant of the method lowers the effort for controlling the time-delayed transmission in the subscriber radios, since only a relative control in a small window is required.

If four samples per chip are assumed and assumed that this accuracy also applies to the runtime compensation is achieved, and an additional time error due to jitter in the carrier and Clock recovery of 0.05 chip lengths is not exceeded, it follows (under Neglect of other sources of interference)

dt = (0.25 + 0.05) * T _chip
I _MU = 0.03
I _MU = -30.5 dB

According to the invention, HIB 2.7 (see FIG. 2) are used for the transmission of the control signals for the runtime compensation. In Fig. 3, the structure of HIB is illustrated. Corresponding to this representation, the 14th bit 3.4 (see FIG. 3) contains the information as to which control variable - power or runtime - should be corrected, the 15th bit 3.5 the information as to whether the control variable is to be changed by the amount 0 or 1 and the 16th bit 3.6 the information whether the sign of the manipulated variable change is positive or negative. Based on the above-mentioned values of the TDD method, approximately 90 manipulated variable changes per second can be transmitted even in the worst case. To implement the values of the runtime correction mentioned above, in an exemplary embodiment in the 15th bit 3.5 (see FIG. 3), the amount 1 of the manipulated variable change is equal to a quarter of the _chip length T _chip .

Another important source of signal interference are different power levels with which subscriber radios are received in the radio base station. The above considerations for multiuser interference therefore only apply if the signals of the subscriber radios 1.8 (see FIG. 1) are received with the same power in the radio base station. Constant control of the transmission power of the subscriber radios by the radio base station, which is able to compensate for fading even during an active connection, is therefore imperative for CDMA systems. According to the invention, HIB 2.7 (see FIG. 2) are used for the transmission of the control signals for the power control. In Fig. 3, the structure of HIB is illustrated. In accordance with the above statements, the 14th bit 3.4 (see FIG. 3) is used to alternatively determine whether the subsequent bits 3.5 and 3.6 are used to set the time of transmission (runtime correction) or transmission power. In order to realize optimal values of the interference contributions caused by power differences in the 15th bit 3.5 (see FIG. 3) the amount 1 of the manipulated variable change is set to 0.2 dB in an exemplary embodiment.

According to the invention, ATM cells are prepared for transmission in the air interface by segmentation as shown in FIG. 2. There are several different types of transmission in the air interface.

A first variant includes the case that fully filled ATM cells 4.1 (see FIG. 4a) are present. This is shown for data transmission at the standard transmission rate, in which only one physical channel is occupied. In this case, segments 1 , 2 . . . a fully present ATM cell 4.1 sequentially into bursts 4.2 , 4.3 . . . the transmission phases of the radio base station 1.1 (see FIG. 1) or of the subscriber radios 1.3 , 1.5 . . . classified.

A second variant includes the case that partially filled ATM cells 4.5 (see FIG. 4b) are present. This is shown for data transmission at the standard transmission rate, in which only one physical channel is occupied. The partial filling of ATM cells is a function of the ATM layer and is agreed on a connection-related basis between the ATM source and the ATM sink. It proves to be expedient that a partial fill is specified for a standard transmission rate of 32 kbit / s so that the last two segments 4.6 and 4.7 only contain fill bits in the ATM cell 4.5 . In this case, segments 1 , 2 and 3 of a fully present ATM cell 4.5 are sequentially divided into bursts 4.9 , 4.10 and 4.11 of the transmission phases of radio base station 1.1 (see FIG. 1) or of subscriber radios 1.3 , 1.5 . . . classified. The fill bits are not transmitted and are added again on the receiving side. A distinction between the aforementioned two variants is communicated to the receiver in HIB 2.7 (see FIG. 2) by correspondingly setting the 12th bit of HIB 3.2 (see FIG. 3). This second variant is important for voice transmissions with a reduced data rate of 32 kbit / s. The formation of fully filled ATM cells leads to an impermissible (or undesirably long) delay time of more than 12 ms. By using partially filled cells with the filling level mentioned above, this delay time is reduced to an acceptable 6.2 ms. A complete transmission of these partially filled ATM cells via the air interface, on the other hand, would almost double the transmission rate in the air interface, which is why the way was chosen not to transmit fill bits of the ATM cells in the air interface. This method also allows the use of partially filled cells even in cases where there is no prior agreement between the source and the sink. A practical application is to fill ATM cells for control and signaling variably as required and to transmit them with minimal load on the air interface.

A third variant includes the case that the payload 2.2 (see FIG. 2) of an ATM cell may only contain zero information during speech transmission during the speech pauses. Facilities known as "Voice Activity Circuits" allow this state to be determined. In this case, only the first segment of an ATM cell 4.12 (see FIG. 4c) is in the burst 4.13 of the transmission phases of the radio base station 1.1 (see FIG. 1) or of the subscriber radios 1.3 , 1.5 . . . classified. The subsequent empty segments of the ATM cell 4.12 are not transferred for transmission, so that there is no transmission during a corresponding number of transmission phases 4.14 until the next ATM cell is available for transmission. The missing segments are added again on the reception side. Recognition of this case is made possible for the receiver in HIB 2.7 (see FIG. 2) by setting the 13th bit of HIB 3.3 (see FIG. 3) accordingly. This third case is significant for voice transmissions that can contain up to 50% speech pauses. In a radio cell with a large number of channels operated in parallel, this can lead to a considerable relief of the air interface, which has the effect of a statistically relevant reduction in signal interference.

A fourth variant includes the case that a connection or several simultaneous connections to the same subscriber radio take up a (not necessarily an integral) multiple of the standard transmission rate. ATM cells 5.1 , 5.6 , 5.7 arriving sequentially for this subscriber radio . . . (see Fig. 5) are segmented and the segments are transmitted in several parallel channels. In the example of a connection with the multiple N with INT (N) = 4, the transmission takes place in four channels 5.2 , 5.3 , 5.4 and 5.5 . The segments are classified cyclically so that the first four segments 5.6 , 5.7 , 5.8 and 5.9 of the ATM cell 5.1 are transmitted simultaneously in a transmission phase. The fifth segment 5.10 is transmitted in channel 5.2 in the subsequent transmission phase, in parallel with the first segments of the subsequent ATM cell, provided that this is already completely present. The channels and their sequence are agreed when establishing or changing connections using signaling procedures, which are not the subject here. The signaling procedures use ATM cells, which are identified as cells with signaling content, and which are classified in the transmission without special regime requirements.

The procedure described above takes place on the respective reception side Reassembly, the separation of the HIB and the processing of the ATM cells and Execution of the control commands with regard to runtime or transmission power according to the in the HIB contained information. The procedures described above are followed by appropriate Facilities implemented in the radio base station and the subscriber radios.

The radio base station is for this purpose as an ATM cross-connect 6.1 (see Fig. 6) performed in the Fig. 6, not shown duplex transmission path with an ATM switching device is connected via a. The cross-connect function is implemented using a cell bus structure 6.2 . The interposition of a cross connect between the ATM switching device and the process-determining modules was preferred over the direct connection, since this enables several of the process devices described below to be connected and operated in parallel on the Cell-Bus 6.2 if this is necessary for capacity reasons, and to switch on a central control computer of the radio base station in such a way that it can communicate with the subscriber radios for control and monitoring purposes via the cell bus 6.2 and the devices according to the method.

Such a device according to the method is connected to the cell bus 6.2 via a cell bus connection 6.3 (see FIG. 6) and a cell bus interface module 6.4 . The cell bus interface module 6.4 is connected to an interface controller 6.6 via a processor interface 6.5 . The interface module 6.4 is able to select ATM cells for control purposes and to output them via the processor interface 6.5 . Insofar as this is connection-relevant information, it is transferred from the interface controller 6.6 to the central controller 6.8 via the processor interface 6.7 . These statements apply to both directions of transmission. The central controller 6.8 is connected via a processor interface 6.14 to the connection modules 6.10 and a processor interface 6.23 to the channel modules 6.19 . The following process-relevant processes are implemented by the Central Controller 6.8 :

• - Control of the sending and receiving processes of the TDD process.
• - Monitoring the runtime deviations of the received signals in the receive modules 7.4 (see FIG. 7) and from this deriving the manipulated variables for the runtime correction and transferring them to the controllers 6.12 for insertion in the HIB of the send direction.
• - Monitoring the power / interference quantities of the received signals in the reception modules 7.4 and deriving therefrom the manipulated variables for the power setting in the subscriber radios and transferring them to the controller 6.12 for insertion in the HIB of the transmission direction.
• - Power setting of the transmitter modules 6.22 of the channel assemblies 6.19 on the basis of the information in the HIB of the transmissions of the subscriber radios, which were transferred from the controllers 6.12 via the processor interface 6.14 .

The present invention includes only the method for transmitting the Control variables for the power setting in the subscriber radios as well as the radio base station, but not the measurement methods for received power / interference quantities and the Algorithm for optimizing the performance.

In the following, only the elements that are relevant for the transmission direction of the radio base station are shown and described accordingly in FIG. 6. ATM cells that are to be assigned connections are output by the interface module 6.4 via a data bus 6.9 . A large number of connection modules 6.10 are connected to this data bus, the number of which is equal to the number of subscriber radio devices which can be active at the same time. If these are predominantly subscriber radios with a standard transmission rate that occupy only one channel, this number is identical to that of the channel modules 6.19 . The connection modules 6.10 each contain a controller 6.12 and a RAM0 6.13 for the storage of connection-relevant data, and a RAM1 6.11 , which is organized as a FIFO memory (first in, first out). The controller 6.12 is connected to the central controller 6.8 via a processor bus 6.14 . The central controller 6.8 transfers the connection-relevant data relating to an active subscriber radio to the controller 6.12 via the processor bus 6.14 and stores it in a RAM0 6.13 . This data includes:

• - VPI and VCI of the ATM cells to be taken over by the data bus 6.9 .
• - VPI and VCI of partially filled ATM cells and the respective fill level.
• - VPI and VCI at which "Voice Activity Checking" should take place.
• - Variable parts of HIB 2.7 (see Fig. 2) for controlling the runtime or transmission power of the subscriber radios.
• - Number, numbers and cyclical order of the channels to be assigned.

Controllers 6.12 perform the following functions using the data stored in RAM0 6.13 :

• - Transfer of ATM cells from data bus 6.9 to RAM1 6.11 .
• - Address comparison for incoming ATM cells. If there is no match with the assigned VPI and VCI and stored in RAM0 6.13 , the ATM cell is deleted.
• - "Voice Activity Checking", if applicable, depending on the test result, if applicable Deletion of the payload of the ATM cell.
• - Removal of filler bits in partially filled cells, if applicable.
• - Formation of the HIB and its classification in front of the header of the ATM cell.
• - Enclosure of the processed ATM cell in the queue for output for the Transmission.
• - Segmentation of the processed ATM cells according to the aforementioned Procedural rules
• - Segmented transfer of the ATM cells in accordance with the aforementioned procedural instructions and the following description to the channel modules 6.19 .

For each physical channel there is a channel module 6.19 which contains a RAM2 6.20 , a channel controller 6.21 and a transmitter module 6.22 . The RAM2, which are organized as FIFO memories (First In, First Out), have a size of 11 bytes and are therefore suitable for the inclusion of a segment. The transfer of the segments intended for transmission to the channel modules 6.19 takes place sequentially in the reception phase in such a way that at the beginning of the transmission phase all the channel modules 6.19 can start transmitting synchronously.

For this purpose, the central controller 6.8 is connected to all controllers 6.12 of the connection modules 6.10 via an address bus 6.15 . Furthermore, each of the controllers 6.12 is connected to a line 6.16 which leads to the ready input of the central controller 6.8 . With this part of the device, the central controller 6.8 activates each of the active connection modules 6.10 sequentially in the receive phases via the address bus 6.15 . During the activation phase, the connection module 6.10 can transfer segments intended for transmission to the channel modules 6.19 . After completion of the transfer in accordance with the procedural instructions, the connection module 6.10 sends a ready signal via line 6.16 to the central controller 6.8 , which can then activate the next connection module 6.10 .

For the purpose of data transfer, the RAM1 6.11 of all connection modules 6.10 are connected to the RAM2 6.20 of all channel modules 6.19 via a data bus 6.17 . Furthermore, the controllers 6.12 of all connection modules 6.10 are connected to the channel controllers 6.21 of all channel modules 6.19 via an address bus 6.18 . During the activation phase of a controller 6.12 determined by the central controller 6.8 , the latter can activate one or several sequential channel controllers 6.21 and, in the respective activation phase of a channel controller 6.21, transmit a segment via the data bus 6.17 into the associated RAM2 6.20 .

The segments stored in RAM2 6.20 are transferred synchronously to the TX modules 6.22 at the start of the transmission phase. The burst preamble bits 2.6 , 2.10 ,. . . (see FIG. 2) are only placed in front of the segments in the TX module 6.22 .

The majority of existing memory areas and controllers with the same purpose as well as memory areas and controllers with the same purpose are shown only as logical structures. Depending on capacity and time criteria, these can be physically integrated into high-performance memories and controllers in a specific engineering implementation. This also applies to all facilities described below. In the following, only the elements that are relevant to the reception direction of the radio base station are shown and described accordingly in FIG. 7. The channel assemblies 19/06 (see Fig. 6 and Fig. 7) for reception purposes include a receiving module 7.4 and a 7.3 RAM3. The RAM3, which are organized as FIFO memories (First In, First Out), have a size of 11 bytes and are therefore suitable for the inclusion of a segment. The burst preamble bits 2.6 , 2.10 ,. . . (see FIG. 2) are split off from the segments in the reception module 7.4 . The transfer of the segments to the RAM4 7.2 (see FIG. 7), which are organized as FIFO memories (first in, first out), takes place sequentially in the connection modules 6.10 in the transmission phase. Since there is an alternating operation, the same devices and the same algorithm as in the transmission direction are used for this. The mode switching is performed by a not represented control signal of the central controller 14.6 (see FIG. 6 and FIG. 7).

Controllers 6.12 perform the following functions using the data stored in RAM0 6.13 :

• - Transfer of the segments from the data bus 6.17 into a RAM4 7.2 in accordance with the aforementioned procedural instructions and description
• - Reassembly of the ATM cells. This is done according to the information in the HIB Supplement to the payload of the cells if filler bits are removed from partially filled cells or no payload was generally transferred during speech pauses.
• - Removal of the HIB.
• - Address comparison for incoming ATM cells. If there is no match with the assigned VPI and VCI and stored in RAM0 6.13 , the ATM cell is deleted.
• - Enclosure of the processed ATM cells in the queue for output for transmission to the Cell-Bus interface module 6.4 .
• - Transmission of the ATM cells according to the description below to the Cell-Bus interface module 6.4 .

ATM cells that are to be assigned connections are transmitted from the connection modules 6.10 via a data bus 7.1 to the cell bus interface module 6.4 . The data bus 7.1 (see FIG. 7) is not identical to the data bus 6.9 (see FIG. 6), since the cell bus interface module 6.4 has separate data buses for both transmission directions and the transmission of ATM cells between cell bus interface modules 6.4 and Connection module 6.10 does not have to correlate with the send and receive phases. The access method for the transmission of a large number of connection modules 6.10 to the cell-bus interface module 6.4 is controlled by the cell-bus interface module 6.4 by cyclically querying the connection modules 6.10 .

The subscriber radios are designed in the telecommunications sense as NT (Network Termination in the general sense, not specifically ISDN-related). For this purpose, a subscriber radio device has at least one subscriber interface module 8.1 (see FIG. 8) which has a service-specific interface 8.2 on the subscriber side, which allows the connection of service-specific terminals or terminal combinations. If the subscriber side is not an ATM service, the subscriber interface module 8.1 is designed as an interworking unit, which carries out the implementation of STM-ATM and vice versa. Furthermore, a subscriber radio has at least one channel module 8.10 , which realizes a physical channel.

In the following, only those elements are shown in FIG. 8 and are described accordingly, which are relevant for the direction of transmission of the subscriber radio station. ATM cells that are to be assigned connections are transmitted from the subscriber interface module (s) 8.1 to a connection module 8.4 via a data bus 8.3 . The access method for the transmission from a large number of subscriber interface modules 8.1 to the connection module 8.4 is controlled by the connection module 8.4 by cyclically querying the user interface module 8.1 . The connection module 8.4 contains a controller 8.5 and a RAM0 8.7 for the storage of connection-relevant data, and a RAM1 8.6 , which is organized as a FIFO memory (first in, first out). Connection-relevant data can be transferred from subscriber interface modules 8.1 as well as from the radio base station. This data includes:

• - VPI and VCI of the ATM cells to be taken over by the data bus 8.3 .
• - VPI and VCI of partially filled ATM cells and the respective fill level.
• - VPI and VCI at which "Voice Activity Checking" should take place.
• - Variable parts of HIB 2.7 (see Fig. 2) for controlling the transmission power of the radio base station.
• - Number, numbers and cyclical order of the channels to be assigned. Controller 8.5 performs the following functions using the data stored in RAM0 8.7 :
• - Transfer of ATM cells from the data bus 8.3 into a RAM1 8.6 .
• - Address comparison for incoming ATM cells. If there is no match with the assigned VPI and VCI stored in RAM0 8.7 , the ATM cell is deleted.
• - "Voice Activity Checking", if applicable, depending on the test result, if applicable Deletion of the payload of the ATM cell.
• - Removal of filler bits in partially filled cells, if applicable.  
• - Formation of the HIB and its classification in front of the header of the ATM cell.
• - Enclosure of the processed ATM cell in the queue for output for the Transmission.
• - Segmentation of the processed ATM cells according to the aforementioned Procedural rules
• - Segmented transfer of the ATM cells to the channel modules 8.10 in accordance with the aforementioned procedural instructions and the following description.

The channel assembly (s) 8.10 each contain a RAM2 8.12 , a channel controller 8.11 and a transmitter module 8.13 . The RAM2, which are organized as FIFO memories (First In, First Out), have a size of 11 bytes and are therefore suitable for the inclusion of a segment.

The transfer of the segments intended for transmission to the channel assemblies 8.10 takes place sequentially in the reception phase in such a way that at the beginning of the transmission phase all the channel assemblies 8.10 can start transmitting synchronously. For the purpose of data transfer, RAM1 8.6 of connection module 8.4 is connected to RAM2 8.12 of all channel modules 8.10 via a data bus 8.8 . Furthermore, the controller 8.5 of the connection module 8.4 is connected to the channel controllers 8.11 of all the channel modules 8.10 via an address bus 8.9 . The number of channel modules 8.10 depends on the maximum number of physical channels a subscriber radio should use simultaneously. The segments stored in RAM2 8.12 are transferred synchronously to TX modules 8.13 at the start of the transmission phase . The burst preamble bits 2.6 , 2.10 ,. . . (see FIG. 2) are only placed in front of the segments in TX module 8.13 .

In the following, only the elements that are relevant to the reception direction of the subscriber radio station are shown and described accordingly in FIG. 9. The channel assemblies 08/10 (see Fig. 8 and Fig. 9) included for reception purposes a receiver module 9.4 and a 9.3 RAM3. The RAM3, which are organized as FIFO memories (First In, First Out), have a size of 11 bytes and are therefore suitable for the inclusion of a segment. The burst preamble bits 2.6 , 2.10 ,. . . (see FIG. 2) are split off from the segments in the RX module 7.4 . The transfer of the segments to the RAM4 9.2 (see FIG. 9) in the connection module 8.4 , which is organized as a FIFO memory (first in, first out), takes place sequentially in the transmission phase. Since there is an alternating operation, the same devices and the same algorithm as in the transmission direction are used for this. The mode switching is performed by a not represented control signal from the controller 8.5 (see Fig. 8 and Fig. 9).

Controller 8.5 performs the following functions using the data stored in RAM0 8.7 :

• - Transfer of the segments from the data bus 8.8 into the RAM4 9.2 in accordance with the aforementioned procedural instructions and description
• - Reassembly of the ATM cells. This is done according to the information in the HIB Supplement to the payload of the cells if filler bits are removed from partially filled cells or no payload was generally transferred during speech pauses.
• - Removal of the HIB.
• - Address comparison for incoming ATM cells. If there is no match with the assigned VPI and VCI stored in RAM0 8.7 , the ATM cell is deleted.
• - Enclosure of the processed ATM cells in the queue for output for transmission to the subscriber interface modules 8.1 .
• - Transmission of the ATM cells according to the following description to the subscriber interface modules 8.1 .

ATM cells, which are to be assigned connections, are transmitted from the connection module 8.4 via a data bus 9.1 to the subscriber interface modules 8.1 . The data bus 9.1 (see FIG. 9) is not identical to the data bus 8.3 (see FIG. 8) because the subscriber interface modules 8.1 have separate data buses for both transmission directions and the transmission of ATM cells between the subscriber interface modules 8.1 and the connection module 8.4 does not have to correlate with the transmission and reception phases. The access method for the transmission from the connection module 8.4 to the subscriber interface modules 8.1 is controlled by the controller 8.5 in that an address-dependent transmission takes place to the subscriber interface modules 8.1 corresponding to the respective address.

• (1) US Patent Number 52 65119
• (2) "Mobile Access to an ATM Network Using a CDMA Air Interface" an ATM network using a CDMA air interface) / M. J. Mc. Tiffin, A. P. Hulbert, T. J. Ketseoglou, W. Heimsch, G. Crisp / IEEE Journal on Selected Areas in Communications, Vol. 12, No. 5, June 1994
• (3) "Mobile Multimedia Scenario Using ATM and Microcellular Technologies" (Mobile multimedia [communication] scenario using ATM and small cells  technology) / Raghvendra R. Gejji, Member IEEE / IEEE Transaction on Vehicular Technology, Vol. 43, No. August 3, 1994
• (4) "Design Study for a CDMA-Based Third-Generation Mobile Radio System" Design of a third generation mobile radio system based on CDMA) / Alfred Baier, Uwe Carsten, Wolfgang Granzow, Wolfgang Koch, Paul Teder, Jörn Thielecke / IEEE Journal on Selected Areas in Communications, Vol. 12, No. 4, May 1994
• (5) DP 195 06 893.9-31, examination request dated February 20, 1995 "Radio communication system for multivalent services using ATM"

US Patent Number 51 79571 / US Patent Number 51 84347 / US Patent Number 51 85762 US Patent Number 51 95090 / US Patent Number 51 95091 / US Patent Number 52 06882 US Patent Number 52 28053 / US Patent Number 52 39557 / US Patent Number 52 78892 U.S. Patent Number 53,95308 / DE 30 36 707 / DE 30 36 739

Claims (10)

1. Multiplex, access and duplex methods for a cellular radio system which works with digital transmission and stationary radio subscribers allows access to different communication networks, electronic media and services (hereinafter referred to as "networks") with different transmission rates, and which from gateway to the communication networks, concentrator and / or switching device (s), central control device, transmission device (s) to one or more radio base stations, the radio base stations and service-specific and / or multivalent subscriber radios and in which the subscriber radios are designed as network termination and not as terminals are and accordingly have one or more subscriber interfaces to which the subscriber can connect service-specific or multimedia terminals, and with which for all concentrator, switching and transmission gsfunctions including control of the Air Interface and the system control ATM (Asynchronous Transfer Mode) is used, characterized in that a CDM / CDMA method is used for the Air Interface in connection with TDD (Time Division Duplex), in which each code sequence as one Channel is handled over which a constant net bit rate is transmitted (physical channel), which corresponds to the standard application with the lowest bit rate, and connections with higher bit rates are realized by using several such physical channels in parallel for these connections (logical channel, Bearer), and in which the subscriber radios have at least one and, for higher-rate connections, a corresponding number of parallel CDM / CDMA receiving / transmitting devices in accordance with the required multiplication factor, and the receiving / transmitting devices of the subscriber radios optionally any code sequence can be assigned from the pool of available code sequences. 2. A cellular radio system according to claim 1, characterized in that the ATM switch in a Radio base station serially arriving ATM cells for transmission over the air Interface are prepared in such a way that the cells according to logical channels (Connections) separately and regardless of the data rate of the connection in each case  an area of a first buffer memory (RAM) is written, which as FIFO (First In, First Out) memory is organized and that a control device is present that the data of each area of this first buffer memory in the Input buffer memory of the allocated for use for the respective connection transfers physical channel, and the data of the corresponding area of the first buffer memory in a quantization to be specified and order cyclically in the input buffer memory of several assigned physical channels. 3. A cellular radio system according to claim 1, characterized in that the processing of the subscriber radios received data for transmission to the ATM switching device in this way that the outputs of the receivers of the physical channels Output buffer memories are assigned and a control device the received Data from these memories in the buffer memory of the logical channels (connections) reciprocally to the method described in claim 2. 4. A cellular radio system according to claim 1, characterized in that the arrangement of buffer memories at the inputs of the physical channels is used to implement a synchronous CDM by Code sequences of the same length are used and the starting point and chip clock for the transmission of the code sequences is identical in all channels. 5. A cellular radio system according to claim 1, characterized in that for the Air Interface TDD (Time Division Duplex) Is used, in which the transmissions of the radio base station in Burst operation takes place and in the break between the bursts the subscriber radios transmit their data to the radio base station and for this purpose the pause between is two bursts longer than the burst duration by at least that Sum of the double running time between radio base station and Subscriber radio with the maximum configured distance and the switching times from reception to transmission in the radio base station and in the subscriber radio corresponds.   6. A cellular radio system according to claim 1, characterized in that the number of bytes that can be transmitted with a single burst is less than the number of bytes of an ATM data packet (53 bytes) and for that Transmission of a data packet multiple bursts are used and for this purpose Each data packet is preceded by one or more HIB (Header Identification Bytes) so that an integer division of the sum of HIB and packet length by the Number of bursts for the transmission of a packet is possible. 7. A cellular radio system according to claim 1 and 6, characterized in that the channel end for both directions of transmission services are set to a minimum level, which on the one hand meets the required level BER (Bit Error Rate) and minimized Interference contribution generated in the other channels, and for this purpose the HIB (Header identification byte) can be used in both transmission directions to in order to control the transmission power of the To be transmitted to the remote station and thus a fine adjustment of the transmission power to realize short response times. 8. A cellular radio system according to claim 1 and 6, characterized in that the starting time of the radio base station Broadcasts of the subscriber radio is controlled so that the broadcasts of all Subscriber radios arrive in the radio base station in code sequence synchronism and thereby a quasi-synchronous CDMA is realized, and for this purpose the HIB (Header Identification Byte) in the direction of transmission from the radio base station to the subscriber radio to be used during an active connection Data for controlling the start time of the transmissions of the subscriber radio to transfer and thus a fine adjustment for runtime compensation with low Realize response times. 9. A cellular radio system according to claim 1 and 6, characterized in that when only partially filled ATM data packets are transmitted the filler bits contained in the data packets before transmission can be removed and the HIB (Header Identification Byte) in both Data transfer directions are used during an active connection  to transmit, which state that with a only partially filled data packet Empty bits are not transferred and must be added again by the remote station. 10. A cellular radio system according to claim 1 and 6, characterized in that when ATM data packets are transmitted which are used for Example in speech pauses contain only zero information, there is the possibility only transmit the packet header and the HIB (Header Identification Bytes) can be used in both transmission directions during an active Connection to transmit data that state that only one packet header is transmitted and the missing user data from the remote station as zero information again are to be added.