RU2315432C2 - Interleaving for multiplexed data - Google Patents

Abstract

FIELD: systems for communicating with moving objects.

SUBSTANCE: radio transmission device is claimed, made with possible communications in time division multi access standard, containing a circuit of radio transmitter and processing device for processing digital signals for generation of modulated signal for radio-transmitter circuit, where processing device is configured with possible realization of protocols stack having physical level and level for controlling access to transmission environment above physical level, where level for controlling access to transmission environment provides a set of transport channels, which are combined and then multiplied to create aforementioned modulated signal, where each transport channel is configured with possible processing of signal in accordance with a set of processing circuits, where configuration of transport channel is determined during call setup.

EFFECT: improved communication system.

5 cl, 11 dwg

Description

FIELD OF THE INVENTION

The present invention relates to a communication system with moving objects.

BACKGROUND

The concept of transport channels is known from UTRAN (universal access radio system radio access network). Each of these transport channels can carry a class of bits that has different quality of service (QoS) requirements. Multiple transport channels can be multiplexed and sent on the same physical channel.

SUMMARY OF THE INVENTION

The objective of the present invention is to improve communication systems using transport channels, relative to the prior art.

According to the present invention, there is provided a radio transmitting device comprising a radio transmitter circuit and processing means for processing digital signals to generate a modulating signal for a radio transmitter circuit, the processing means being configured to implement a protocol stack having a physical layer and a medium access control layer, according to the physical layer , provide many transport channels that combine and then interleave to form the specified modules signal.

Preferably, the device is configured to communicate a time division multiple access (TDMA) multi-access standard and said interleaving is performed with data blocks that consist of a plurality of TDMA packets.

Preferably, the processing means interleaves said transport channels before they are combined.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a mobile communication system according to the present invention;

FIG. 2 is a block diagram of a mobile station;

FIG. 3 is a structural diagram of a base transceiver station;

FIG. 4 shows a frame structure used in one embodiment of the present invention;

FIG. 5 shows a packet data channel in one embodiment of the present invention;

FIG. 6 shows the sharing of a radio channel with two half speed packet channels in one embodiment of the present invention;

FIG. 7 shows the lower layers of the protocol stack used in one embodiment of the present invention;

FIG. 8 shows radio signal generation using the first embodiment of the present invention;

FIG. 9 shows a data packet generated by a first embodiment of the present invention;

FIG. 10 shows radio signal generation using a second embodiment of the present invention; and

FIG. 11 shows a part of a reception process adapted to receive signals generated by a second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment of the present invention will now be described by way of example with reference to the accompanying drawings.

Turning to FIG. 1, a mobile telephone network 1 comprises a plurality of switching centers, which include first and second switching centers 2a, 2b. The first switching center 2a is connected to a plurality of base station controllers, which include first and second base station controllers 3a, 3b. The second switching center 2b is similarly connected to a plurality of base station controllers (not shown).

The first base station controller 3a is connected and controls the base transceiver station 4 and a plurality of other base transceiver stations. The second base station controller 3b is similarly connected and controls a plurality of base transceiver stations (not shown).

In the present example, each base transceiver station serves a corresponding cell (cell). Thus, the base transceiver station 4 serves cell 5. However, a plurality of cells can be served by one base transceiver station through directional antennas. Many mobile stations 6a, 6b are located in cell 5. It should be recognized that the number of mobile stations and their identifiers in any given cell change over time.

Mobile telephone network 1 is connected to a public switched telephone network 7 using a gateway switching center 8.

An aspect of packet data services in a given network includes a plurality of nodes 9 that support a packet data service (shown one) that are associated with a corresponding plurality of base station controllers 3a, 3b. At least one (gateway) (gateway) node 10 that supports the packet data service connects each node 10 supporting the packet data service to the Internet 11.

The switching centers 3a, 3b and nodes 9 supporting the packet data service have access to the home location register 12.

The communication between the mobile stations 6a, 6b and the base transceiver station 4 uses a time division multiple access (TDMA) scheme.

Turning to FIG. 2, the first mobile station 6a comprises an antenna 101, a radio frequency subsystem 102, a baseband digital signal processing subsystem (DSP) 103, an analog audio subsystem 104, a speaker 105, a microphone 106, a controller 107, a liquid crystal display 108, a keyboard 109, a memory 110 , a battery 111, and a power supply circuit 112.

The radio frequency subsystem 102 comprises intermediate frequency and radio frequency circuits of the transmitter and receiver of the mobile telephone and a frequency synthesizer for tuning the transmitter and receiver of the mobile station. An antenna 101 is attached to the radio frequency subsystem 102 for receiving and transmitting radio waves.

The baseband DSP subsystem 103 is coupled to the radio frequency subsystem 102 for receiving baseband signals from it and for sending baseband modulation signals to it. The baseband DSP subsystem 103 includes codec (encoder) functions that are known in the art.

The analog audio subsystem 104 is connected to the DSP subsystem 103 of the main frequency band and receives a demodulated audio signal from it. The analog audio subsystem 104 amplifies the demodulated audio signal and directs it to the loudspeaker 105. The acoustic signals detected by the microphone 106 are pre-amplified by the analog audio subsystem 104 and sent to the baseband DSP subsystem 103 for encoding.

The controller 107 controls the operation of the mobile phone. It is connected to the radio frequency subsystem 102 for delivering tuning commands to the frequency synthesizer and to the DSP subsystem 103 of the main frequency band for delivering control data for transmission. The controller 107 operates according to a program stored in the memory 110. The memory 110 is shown separately from the controller 107. However, it can be integrated with the controller 107.

The display device 108 is connected to the controller 107 for receiving control data, and the keyboard 109 is connected to the controller 107 for delivering signals input by the user to it.

Battery 111 is coupled to a power supply circuit 112 that provides adjustable power with various voltages used by the components of the mobile phone.

A controller 107 is programmed to control a mobile station for voice and data communications, and using application programs, for example, a WAP (Mobile Interactive Internet Protocol) browser, utilizes the mobile station's data capabilities.

The second mobile station 6b is configured in a similar manner.

Turning to FIG. 3 in a very simplified manner, the base transceiver station 4 comprises an antenna 201, an RF subsystem 202, a baseband DSP subsystem 203, a base station controller interface 204, and a controller 207.

The radio frequency subsystem 202 contains the intermediate frequency and radio frequency circuits of the transmitter and receiver of the base transceiver station and a frequency synthesizer for tuning the transmitter and receiver of the base transceiver station. An antenna 201 is connected to the radio frequency subsystem 202 for receiving and transmitting radio waves.

The baseband DSP subsystem 203 is connected to the radio frequency subsystem 202 for receiving baseband signals from it and for sending baseband modulation signals to it. The baseband DSP subsystem 203 includes codec (codec) functions that are known in the art.

The base station controller interface 204 connects the base transceiver station 4 to the base station control controller 3a.

The controller 207 controls the operation of the base transceiver station 4. It is connected to the radio frequency subsystem 202 to deliver tuning commands to the frequency synthesizer and to the DSP subsystem of the main frequency band to deliver control data for transmission. Controller 207 operates according to a program stored in memory 210.

Turning to FIG. 4, each TDMA frame used for communication between mobile stations 6a, 6b and base transceiver stations 4 contains eight 0.577 ms time slots (slots). One “multi-frame of 26 frames” contains 26 frames, and one “multi-frame of 51 frames” contains 51 frames. Fifty-one “multi-shots of 26 frames” or twenty-six “multi-shots of 51 frames” comprise one super-frame. Finally, the hyperframe contains 2048 superframes.

The data format within the time slots changes according to the function of the time slots. Standard package, i.e. time slot, contains three tail bits, followed by 58 encrypted data bits, a 26-bit training sequence, another sequence of 58 encrypted data bits and an additional three tail bits. A guard interval of eight and a quarter bit lengths is provided at the end of the packet. The frequency correction packet has the same tail bits and guard interval. However, its useful information contains a fixed 142-bit sequence. The synchronization packet is similar to the standard packet, except that the encrypted data is reduced to two clock pulses of 39 bits, and the training sequence is replaced by a 64-bit synchronization sequence. Finally, the packet available contains eight leading tail bits, followed by a 41-bit synchronization sequence, 36 encrypted data bits, and three more tail bits. In this case, the guard interval has a length of 68.25 bits.

When using circuit switched voice traffic, the channelization scheme is the same as that used in GSM (Global System for Communication with Mobile Objects).

Turning to FIG. 5, full-speed packet-switched channels use 12 radio blocks from 4 slots distributed over a “51-frame multi-frame”. Inactive slots follow the third, sixth, ninth, and twelfth radio blocks.

Turning to FIG. 6, for half-speed packet-switched channels, both dedicated and shared, the slots are allocated alternately to two subchannels.

The baseband DSP subsystems 103, 203 and the controllers 107, 207 of the mobile stations 6a, 6b and the base transceiver stations 4 are configured to implement two protocol stacks. The first protocol stack is for circuit-switched traffic, and it is essentially the same as that used in conventional GSM systems. The second protocol stack is for packet-switched traffic.

Turning to FIG. 7, the levels corresponding to the radio link between the mobile station 6a, 6b and the base station controller 4 are the radio link control layer 401, the medium access control layer 402, and the physical layer 403.

The radio link control level 401 has two modes: transparent and opaque. In transparent mode, data is simply passed up or down through the radio link control level without modification.

In opaque mode, the radio link control layer 401 provides line tuning and creates data blocks from data elements received from higher levels, segmenting or concatenating (linking) the data elements as necessary, and performs the reverse process for the data that is sent to the stack. He is also responsible for detecting lost data blocks or reordering data blocks for upstream transmission of their contents, depending on whether the acknowledgment mode is used. This level may also provide error correction by means of a repeated request in confirmation mode.

The medium access control layer 402 is responsible for distributing data blocks from the radio control layer 401 for tuning the transport channels and transmitting the received radio blocks from the transport channels to the radio control layer 403.

The physical layer 403 is responsible for creating the transmitted radio signals from the data passing through the transport channels, and transmitting the received data through the correct transport channel to the medium access control layer 402.

Turning to FIG. 8, data generated by applications 404a, 404b, 404c advances down the protocol stack to medium access control layer 402. Data from applications 404a, 404b, 404c may belong to any of a variety of classes that require different indicators of quality of service. Data belonging to many classes can be generated by one application. Media access control layer 402 directs data from applications 404a, 404b, 404c to various transport channels 405, 406, 407 in accordance with the class to which they belong.

Each transport channel 405, 406, 407 can be configured to process signals according to a variety of processing circuits 405a, 405b, 405c, 406a, 406b, 406c, 407a, 407b, 407c. The configuration of the transport channels 405, 406, 407 is set during call setup based on the capabilities of the mobile station 6a, 6b and the network, and the nature of the application or applications 404a, 404b, 404c that are running.

The processing circuits 405a, 405b, 405c, 406a, 406b, 406c, 407a, 407b, 407c are unique combinations of control using the cyclic redundancy code 405a, 406a, 407a, channel coding 405b, 406b, 407b and rate matching 405c, 406c, 407c. These unique processing schemes are called "transport formats." An interleaving circuit 405d, 406d, 407d can be selected for each transport channel 405, 406, 407. Thus, different transport channels can use different interleaving schemes and, in alternative embodiments, different interleaving schemes can be used at different times by the same transport channel.

The combined data rate obtained for the transport channels 405, 406, 407 should not exceed the speed of the physical channel or channels allocated to the mobile station 6a, 6b. This sets a limit on the combination of transport formats that may be allowed. For example, if there are three transport formats TF1, TF2, TF3 for each transport channel, then the following combinations may be valid:

TF1 TF1 TF2

TF1 TF3 TF3,

but not

TF1 TF2 TF2

TF1 TF1 TF3.

Data output by transport channel interleaving processes is multiplexed by multiplexing process 410 and then further interleaved 411.

Combination indicators of transport formats are generated by a process 412 for generating an indicator of a combination of transport formats from information from a medium access control layer and encoded using an encoding process 413. The indicator of the combination of transport formats is inserted into the data stream using the insertion process of the indicator of the combination of transport formats after additional interleaving 411. The indicator of the combination of transport formats is distributed over one radio block by placing its parts in fixed positions in each packet, in this example, on both sides of the training characters (Fig. 9). The complete indicator of the combination of transport formats therefore appears at fixed intervals, i.e. blocks with a length of 20 ms. This ensures that the indicator of the combination of transport formats is detected when various types of interleaving are used, for example, diagonal interleaving of 8 packets and rectangular interleaving of 4 packets. Since the indicator of the combination of transport formats is independent of the changing interleaving, it can be easily detected by the receiving station and used to control the processing of the received data.

The location of the data for each transport channel within the multiplexed bitstream can be determined by the receiving station from an indicator of the combination of transport formats and knowledge of the multiplexing process, which is deterministic.

Previously, a physical channel or subchannel was allocated to a specific mobile station for a particular call. When physical channels and subchannels are shared, mobile stations need to know when they have access to the uplink. For this purpose, when working with shared channels, each downlink radio block includes uplink status flags. This flag indicates for the receiving mobile station whether it can start sending data in the next uplink radio block. For compatibility with GPRS (General Packet Radio Service) and EGPRS (Advanced General Packet Radio Service) mobile stations, the uplink status flags preferably occupy the same bit positions as defined for the EGPRS standard, for example, data bits 150, 151, 168, 169, 171, 172, 174, 175, 177, 178, and 195 of each packet consisting of 348 data bits when 8PSK modulation (phase shift keying with octal phase signals) is used. When using GMSK modulation (Gaussian keying with minimal frequency shift), the situation becomes more complicated due to the fact that different bit positions are used in different packets, although in a completely circular manner. More specifically, in a cycle of four packets, bits 0, 51, 56, 57, 58 and 100 are used in the first packet, bits 35, 56, 57, 58, 84 and 98 are used in the second packet, bits 19, 56, 57, 58, 68, and 82 are used in the third packet, and bits 3, 52, 56, 57, 58, and 66 are used in the fourth packet.

Similarly, downlink radio packets include downlink status flags to indicate which mobile station the packet is intended for. These flags always have the same position within the packet so that the receiving mobile station can easily locate them. In a preferred embodiment, the uplink and downlink flags have the same mapping to the mobile stations 6a, 6b.

The mobile station 6a, 6b using the shared subchannel has its identifier, which is used for the uplink and downlink access control described above, in its own transmission. Again, this identifier is located at a given position within each packet. Although the network will generally know the identification of the transmitting mobile station 6a, 6b because it has scheduled this transmission, distortion of transmissions from the base transceiver station may result in incorrect transmission from the mobile station. The fact that the channel includes an identifier in this way enables the base transceiver station to identify the transmitting mobile station from the received signal and then decode the current block, starting from reading the indicator of the combination of transport formats and then choosing the correct decoding process of the transport channel depending on the identification of the transmitting mobile stations 6a, 6b and a decoded indicator of the combination of transport formats.

Turning to FIG. 10, in another embodiment, the media access control layer 402 may support multiple active transport format combination sets 501, 502. Each set of transport format combinations 501, 502 is applicable to transmission in accordance with a different modulation method, for example, GMSK and 8PSK. All active sets 501, 502 combinations of transport formats are set during call setup.

The signals in the control channel from the network to the mobile station 6a, 6b cause the mobile station 6a, 6b to switch modulation methods and, therefore, a set of transport format combinations 501, 502. Control signals may be generated in response to path quality or congestion levels. The mobile station 6a, 6b may also unilaterally decide which modulation method to use.

Turning to FIG. 11, at the receiving station, whether it will be a mobile station 6a, 6b or a base transceiver station 4, the received signal is used in demodulation processes 601, 602 for each type of modulation. The results of demodulation processes 601, 602 are analyzed 603, 604 to determine which modulation method is used, and then the transport format combination indicator is extracted 605 from the corresponding output demodulated signal and used to control additional signal processing.

It should be recognized that the above embodiments may vary in various ways without departing from the spirit and scope of the appended claims.

Claims (5)

1. A radio transmitting device configured to communicate a time division multiple access (TDMA) standard, comprising a radio transmitter circuit and processing means for processing digital signals to generate a modulated signal for a radio transmitter circuit, the processing means being configured to implement a protocol stack having a physical the level and level of control of access to the medium over the physical layer, characterized in that the level of access control to Food transmission provides a plurality of transport channels which are combined and then interleaved to form said modulated signal, each transport channel is configured to signal processing of a plurality of processing circuits, wherein the transport channel configuration is established during call setup. 2. The radio transmitting device according to claim 1, characterized in that the plurality of processing circuits includes cyclic redundancy check, channel coding and rate matching. 3. The radio transmitting device according to claim 1 or 2, characterized in that the processing means performs the interleaving of these transport channels before combining them. 4. The radio transmitting device according to claims 1, 2, or 3, characterized in that it comprises a multiplexer designed to multiplex the interleaved data provided by the transport channel before data is transmitted to the physical layer. 5. The radio transmitting device according to claim 4, characterized in that the physical layer contains an interleaver for additional interleaving of the signal issued from the level of access control to the transmission medium.

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