System for wireless transmission of frame synchronized signals between a fixed station and a mobile terminal

The invention relates to a system for line transmission unbound a frame synchronized signal between a base station and at least a mobile terminal, before the transmission of data of a synchronous service for determining the intermittent, each to be used framework and a constant Number of synchronous channels is provided during the duration of the connection.

Such a system is for example a radio transmission system according to the GSM standard and working to the versions of the GSM system in the Publication "data transmission with GSM" radio show, no. 3, 1997, pages 68 are included to 70th In this article, in particular the data exchange between data networks (eg Internet, X.25) and mobile terminals described. Here, in order to achieve higher transmission rates, for example, Time slots or channels for a service summarized.

The invention has the object of providing a system for circuit-unbound Transmitting a frame synchronized signal between a base station and to provide at least one mobile terminal that greater flexibility having.

The invention is achieved by a system of the type mentioned in that the base station and at least one mobile terminal for transmitting Packets containing the data of an asynchronous service, in the frame-synchronized Signal are provided and that the base station for each frame for re-establishment of a number of for the transmission of the packets is serving asynchronous channels provided.

Such line unbound system as a radio transmission system, be an infrared or ultrasound system. A base station is usually made at least one base station, for example, radio communication with the mobile terminals controls, and may also contain as switching devices. Between the Base station and mobile terminals transmit data services. There shall be data of a synchronous and an asynchronous service to differ. Data of a synchronous service include voice data, ie data a call between at least two subscribers, wherein a continuous Data flow without long delay times is required. data of asynchronous service are provided by a packet transmission system packages. This can, for example, cells in the asynchronous transfer mode (ATM) be. Data may also in the base station or in a mobile terminal in be integrated packets and then transmitted.

The base station sets the synchronous channels for the duration of a connection, which are provided for the reception of synchronous data. It must be a Such a synchronous channel not for each successive frame for Available will be provided, but may also periodically, for example every third Frames are used. Thus, if a connection for a synchronous service is constructed, it is necessary to foresee synchronous channels throughout the Connection time ready. However, this does not rule out that for this Connection also uses different channels at different time frames will. For example, during a first frame is a synchronous service with 4, 6 and 7 and designated channels during a second frame with the 5, 6 and use 8 channels designated.

The area of ​​the frame that is not needed by the synchronous service, is used for the reception of packets or data of an asynchronous service. The assignment of the asynchronous channels of the base station for each frame set again. For example, an asynchronous service during a the first frame asynchronous channels 4, 8, 9 and 11, while a second Frame, the asynchronous channels 4 and 7, during a third frame no asynchronous channel and during a fourth frame, the asynchronous channels 1, 2 and 4 use. The system can by these measures according to the invention very much more flexible than the known systems respond to load changes.

A mobile terminal is divided by at least one control channel of the frame synchronized Signal of the base station the particular requirements of services With. The base station is establishing channels for communication between Fixed station and at least one mobile terminal and to indicate by means of a Control channel of the frame synchronized signal to at least one mobile terminal is provided on the assigned channels. Besides the synchronous and asynchronous Channel contains the frame-synchronized signal and control channels through which Radio links are established and terminated, by which control data between Base station and mobile terminal to be replaced. It is also possible that Number of control channels and the number of bits of a control channel is varied. The control channels, the synchronous and asynchronous channels may be anywhere in the Framework be distributed. The simplest realization arises when the Control channels, synchronous channels, and the asynchronous channels each are summarized.

A mobile terminal and a base station include an insertion and removal device, under the control of a MAC control circuit for inserting or Extraction of data of a synchronous service to or from at least one synchronous channel and packages to or from at least one asynchronous channel is provided. The Festtstation is t depending on the number of in an Buffer device of the base station or a mobile terminal located Number and priority packages for the award of the available asynchronous Channels per frame provided.

The base station or a mobile terminal add a word in a synchronous Channel and a packet in an asynchronous channel. sets the base station to in addition the number of synchronous and asynchronous channels per frame firmly.

Furthermore, the invention also relates to a base station and a mobile Terminal.

Embodiments of the invention will be described below with reference to the figures explained. Show it:<sl><li>Fig. 1, a radio transmission system,</li><li>mobile Fig. 2 is a block diagram of the base station shown in Fig. 1 or terminals,</li><li>Fig. 3 shows the frame structure of the radio transmission system according to Fig. 1 used frame-structured signal and</li><li>Fig. 4 shows a layer model of the functions of the base station and with her over the radio circuit coupled mobile terminals.</li></sl>

In Fig. 1 an embodiment of a spark-over conference system is shown, containing at least one base station 1 and a plurality of mobile terminals 2, respectively via the base station 1 with other mobile terminals 2 or directly with other terminals or via a network 3 with other participants can exchange messages. The radio transmission between a mobile Terminal 2 and the base station 1, for example, according to a TDMA, FDMA or CDMA techniques or by a combination of these or other methods done. The network 3 may be a wired network, with other networks and / or other base stations coupled. An example for such a wired network is the integrated services digital News Network (ISDN) and broadband ISDN, asynchronous after which Transfer mode (ATM) operates.

In a network which operates according to the asynchronous transfer mode, Information and messages by means of cells are transferred. A cell contains a header field of 5 bytes and an information field of 48 bytes. The in Information contained header field of the cell are used in particular for addressing and performing Vermittlungsfanktionen.

A mobile terminal includes in addition to the radio communication apparatus for necessary devices such as a device for voice communication, a personal computer, a workstation, etc.

A block diagram of the Basisisstation 1 or a mobile terminal 2 in FIG. 2 shown in more detail. This includes a service matching circuit 4, a radio management arrangement 5, a MAC control circuit 6 (MAC = Medium Access control), a converter device 7, a buffer device 8, an insert and Removal device 9 and a radio device 10 with connected antenna 10. The service adapter assembly 4 is replaced by the network 3, if the arrangement is shown in FIG. 2 part of the base station 1, or to certain arrays (Personal Computer, apparatus for speech communication, etc.) if the An arrangement according to FIG. 2, part of a mobile terminal 2, various Data streams. Such data streams can eg plesiochronous data from different Hierarchical levels, data of the synchronous digital hierarchy, multiplexed data with different bit rates (eg 64 kbit / s, 2 Mbit / s), data according to the Internet Protocol (IP), facsimile data, data according to the X.25 protocol, data according to the frame Relay Protocol, an ATM cell stream to be etc. The service matching arrangement 4 for example, can be configured as a multiplexer, and the various Data streams to a total of three basic data streams 12 to 14 summarize. Of the Data stream 12 contains all the synchronous data, ie, for example, data of a Call (voice data) between at least two subscribers, in which a is continuous data flow without long delay times required. Of further generates the service customization assembly 4 an asynchronous data stream contains 13, the data of a service in which no continuous data flow (Eg Internet, X.25, fax, etc.) is required. The third data stream 14 represents an ATM cell stream.

The radio management arrangement 5, which formed as a microprocessor system can be processed-associated data (signaling data). To the exchange connection is established between the base station and a mobile terminal the respective radio management arrangement 5 of the base station 1 and a mobile Terminal data via the respective MAC control circuit 6, the insert and Removal device 9 and the radio device 10 from. Further, the radio management arrangement 5 among other things provided for channel measurements eg using test data perform, with poor radio transmission carrier frequencies, if necessary change.

The MAC control circuit 6, which realizes, for example, as a microprocessor system and is the basis for controlling the circuit elements 7, 8 and 9 of call associated Data is provided which comes from the radio management arrangement 5 will. The asynchronous data 13 by means of the converter device 7 in a converted ATM cell stream and to the buffer for the intermediate storage device 8 Posted. The MAC control circuit 6 supplies this case the converter device 7 control data for the header of a for forming cell. Furthermore forms the converter device 7 from the data received from the buffer device 8 ATM cell stream asynchronous data 13 that the service matching arrangement 4 to be delivered. In addition to the asynchronous data converted into ATM cells stores the buffer device 8 cells of the ATM cell stream 14, from the the service adapter assembly 4 have been received. The buffer device 8 also receives data from an insert and removal device. 9

The output from the buffer device 8 and the cells of the service adaptation device 4 supplied synchronous voice data 12 by means of the insert and removal device 9 inserted in a frame-structured signal. This frame-structured signal is supplied to the radio device 10, the a codec, a modem and a high frequency part contains. This radio device 10 transmits and receives RF signals via the antenna 11. From the in the radio device 10 is formed from the received high-frequency signal frame-structured signal are in the insertion and extraction apparatus 9 synchronous data and 12 ATM cells removed and the synchronous data for 12 Service customization arrangement 4 and the ATM cells to the buffer device 8 delivered.

The MAC control circuit 6 receives from the radio management arrangement 5, as above mentioned, associated data. Each data stream 12, 13 and 14 are associated signaling data, the signaling interface, not shown here from a received. The synchronous data 12 are the corresponding associated data associated with corresponding time. The connection-relevant information of the ATM cells are contained in the header field. By storing a cell in the buffer device 8, the taken associated data from the header field of the cell and in the MAC control circuit 6 is provided. Other associated data receives MAC-control circuit 6 of the insertion and extraction apparatus 9 of the above Radio apparatus 10 received frame-structured signal. To build Radio links exchanges the MAC control circuit 6 of the radio management arrangement 5-obtained control data with the insertion and removal device. 9

The frame structure of the frame-structured signal is shown in Fig. 3. Of the Frame includes at least one control channel or control time slot CC, at least a synchronous channel or synchronous time slot and at least one SC asynchronous channel or asynchronous time slot AC. A synchronous channel SC contains a word of the synchronous data associated with connection and optionally associated control information for error protection (eg CRC data, CRC = cyclic redundancy check), for synchronization, etc. A word may one or more bytes are. It is assumed that a word k = 8 has bits and that the time duration of one frame L = 10 ms. a synchronous channel SC then has a bit rate of R = K / L = 0.8 kbit / s. If in each successive frame in a synchronous data channel of a synchronous service to be transmitted, is the minimum bit rate R_min = 0.8 kbit / s. This minimum bit rate can be reduced even further, if not in each frame in a synchronous channel, but perioisch data a synchronous service are transmitted. If data only in every fourth frame are transmitted, resulting in a bit rate of R_min = 0.2 kbit / s.

An asynchronous channel AC contains exactly one ATM cell of 53 bytes and optionally associated control information. As mentioned above, the asynchronous channels AC provided substantially for data from asynchronous Services (eg fax, Internet, etc.) in ATM cells over the radio path transfer.

The number of synchronous and asynchronous channels SC and AC is not set. Depending on the traffic load are from the MAC control circuit 6 in the base station 1, the synchronous and asynchronous channels SC and AC awarded. In extreme cases, only synchronous channels or asynchronous channels used will.

The control channels CC are used to control data between the base station 1 and replace the mobile terminals. 2 Which control data may contain control channels, for example, the publication "WATMnet: A Prototype Wireless ATM System for Multimedia Personal Communication ", Raychaudhuri et al., IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, Vol. 15, NO. 1, January 1977, pages 83 to 95. About these control channels CC gets the MAC-control circuit 6 of the base station 1, the Information from the mobile terminal 2, number of synchronous and asynchronous Channels are required in each case. Using the information from the mobile Terminals 2 and further information on existing and to be established Compounds from the radio management arrangement 5 of the base station 1 sets the MAC-control circuit 6 of the base station, the distribution of synchronous and asynchronous channels SC and AC fixed. A once allocated for a connection synchronous channel SC must remain unchanged throughout the entire compound stay. For example, for the transmission of synchronous data or the Using a synchronous service three synchronous channels SC required. The can for example be denoted by 1, 3 and 10 synchronous channels SC. These synchronous channels by the end of this compound synchronous service assigned. Before they can transfer to other synchronous data be used again. It is also possible that a synchronous service during the transmission as the first designated 10 synchronous channel SC and after more frames to 8 designated synchronous channel SC used. The MAC control circuit 6 must therefore examine each, the number of channels of the currently existing synchronous services are needed and appropriate for provide synchronous channels in one frame.

The assignment of the asynchronous channels AC is over the allocation of synchronous channels SC more flexible. Thus, in a first frame a Service using the ATM cells for transmission of its data (asynchronous Service), for example, four asynchronous channels AC and in a second subsequent frame an asynchronous channel AC are provided. The assignment of the asynchronous channels is fully dynamic. A mobile Terminal 2 sends a control channel CC a message that it has a certain has to transmit number of cells. The base station 1 shall inform the mobile terminal 2 then a control channel with which asynchronous Time slots are provided for the transfer of cells available. in this connection Also check out the individual cells assigned priorities are taken into account. For example, the base station 1 to a mobile terminal 2 for a frame i the designated 2 and 3 asynchronous channels and i for one frame + 1, assign 2, 4 and 6 referred to asynchronous channels. Such Allocation strategy is also used for the reverse direction from the base station 1 used to a mobile terminal the second

The synchronous and asynchronous channels are for transmission of data from the base station 1 to a mobile terminal 2 (forward link, downlink) and for a transmission of data from a mobile terminal 2 to the base station 1 (Reverse link, uplink) provided. The channels do not have it evenly be distributed to the return connections.

The insertion and removal device 9 is of the MAC control circuit 6 controlled such that these synchronous and asynchronous data in the corresponding Channels SC and AC and the control data in the respective control channels CC can insert or remove it. Because of delays in the Einfügeund Extraction circuit 9, the synchronous data 4 are not in a Waiting memory shown cached. Such a buffering of ATM cells is necessary in the insertion and removal of circuit no longer 9, since the Cells to the respective allotted time points of the buffer device 8 be read after it for inclusion in the MAC control circuit 6 an asynchronous channel have been released.

The various functions of the base station 1 and a mobile terminal 2 can be explained in addition to the layer model shown in FIG. 4. The lowermost layer RS ​​(radio subsystem), for example, in the OSI reference model is referred to as the physical layer refers to the radio transmission and , the radio device 10 and antenna 11 are assigned. The second Layer MAC (Medium Access Control) controls the channel allocation and the concerns Circuit elements 6 to 9. Since the circuit element 6 the MAC layer is assigned, it is also referred to as a MAC-control circuit 6th The third Layer SE (service adaptation) is used to adapt the incoming and outbound data to the network 3 (base station 1) or further Circuit elements, such as personal computers, fax, etc. (mobile terminal 2). The top or fourth layer AP (multimedia applications) refers to the various communications services, the radio transmission system using the can be handled. Parallel to the third and fourth layer is another Function is available, as layer RM (radio management and control) designated is, and the radio management arrangement 5 is assigned.