EP0760183A1 - Device for optimal distribution of data into data blocks in a time-division multiple access system - Google Patents
Device for optimal distribution of data into data blocks in a time-division multiple access systemInfo
- Publication number
- EP0760183A1 EP0760183A1 EP95920141A EP95920141A EP0760183A1 EP 0760183 A1 EP0760183 A1 EP 0760183A1 EP 95920141 A EP95920141 A EP 95920141A EP 95920141 A EP95920141 A EP 95920141A EP 0760183 A1 EP0760183 A1 EP 0760183A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- information
- dimensioning
- data
- unit
- block
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Ceased
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/005—Control of transmission; Equalising
Definitions
- the present invention relates to the optimization of error rates encountered in radiocommunication systems, and in particular a device for optimal distribution of information in the information blocks which are exchanged in a radiocommunication system.
- TDMA time division multiple access
- the transmitted sequence undergoes alterations in the transmission channel, the main of these alterations being the inter-symbol interference which is due to the fact that an emitted symbol can take several paths in the transmission channel. Indeed, if at least two paths have a difference greater than the distance separating two symbols transmitted successively, a symbol using one of these paths will come to interfere with a next symbol using another shorter path.
- an equalizer is used which, in order to operate correctly, must know the impulse response of the transmission channel.
- a training sequence is made up of known symbols, as opposed to the information symbols which are the subject of the transmission and which, by hypothesis, are not known to the receiver. It is thus common to provide that a block of symbols intended for a particular receiver successively comprises information symbols, a learning sequence and again information symbols, the learning sequence thus being placed in the center of the block.
- the probability of error increases as a function of the distance of the symbols from the training sequence. It is therefore necessary to avoid constructing blocks of information that are too large, but it is also necessary to optimize the distribution of information inside the block or of the frame insofar as some of them (for example signaling information) are more sensitive than others to the risk of error due to propagation conditions.
- the object of the invention is to provide a device allowing an optimal distribution of the payload of a block of information exchanged in a radiocommunication system as a function of the sensitivity of the different types of information to the risks of 'fault.
- the object of the invention is therefore a device for optimal distribution of the different types of information in an information block exchanged in a radiocommunication system of the type comprising a) a transmitter composed of an encoder of the digital information to be transmitted, a formatting and multiplexing unit and a modulator, and b) a receiver composed of a demodulator receiving the modulated information transmitted from the modulator, a deformatting and demultiplexing unit and a decoder restoring the digital information.
- the device includes a sizing and distribution unit located in the transmitter for sizing the information block and distributing the information in the areas of the block according to the types of information to be transmitted and the coding redundancy for each of the types , and a measurement unit located in the receiver for collecting the measurements relating to the quality of the transmission channel and transmitting them to the dimensioning and distribution unit located in the transmitter.
- FIG. 1 represents the general format of the blocks of information exchanged in a radiocommunication system
- FIG. 2 is a diagram representing the rate of errors as a function of the position in a block of information
- FIG. 3 represents a block of information in which the different types of information have been optimally distributed
- FIG. 4 is a schematic representation of the preferred embodiment of the device according to the invention.
- They comprise an SA learning sequence and a payload placed on either side of the SA learning sequence so as not to be too far from the latter, and finally the start and end symbols T block.
- the learning sequence SA can include 26 bits and each CU payload 57 bits. However, such a dimensioning is not fixed and depends mainly on the physical constraints of the transmission channel.
- Such a criterion may consist in not exceeding a certain error rate per symbol for the symbols placed at the ends of the block.
- the error rate per symbol or per bit depends on the position of the symbol in the block and in the general shape illustrated in FIG. 2. The further one moves away from the center of the curve, the higher the error rate. Consequently, the optimal length of the block, as a function of an error rate not to be exceeded, can be easily determined by taking into account the diagram illustrated in FIG. 1.
- • asymmetric coding (error control coding for speech in GSM): put the most important bits in the center, the others at the ends; • error control coding in a repeating mechanism: put the information bits in the center, the redundancy bits (for error detection) at the ends. The information bits will be less error-prone, and there will be less repetition. The radio channel will therefore be used more efficiently;
- signaling in the block Since the signaling bits are very sensitive to errors, they are placed as centrally as possible, for example just after the learning sequence; • mixed services: assuming we would have to mix two services in the same block (for example voice and data), the least sensitive service bits are placed at the ends (for example voice) and the most sensitive bits at the center (for example data);
- the signaling (1 and the) is placed on either side of the learning sequence SA, the most sensitive data symbols (2 and 2 ' ) on either side of the signs, and finally the least sensitive symbols (3 and 3 ') are placed at the ends.
- FIG. 4 schematically represents an optimal distribution device in an information block according to the preferred embodiment of the invention.
- the information to be transmitted in the block is of three types: voice (V), data (D) and signaling (S).
- the information is first coded in a channel coder 10 so as to determine redundancy bits for each type of information.
- the bits can be simple parity bits, or error detection and correction codes.
- the information is transferred to a formatting and multiplexing unit 12 responsible for defining the format of the block to be transmitted and for multiplexing the logical channels.
- a formatting and multiplexing unit is conventional and an adequate description can be found in the work "Teleinformatics: Transport and processing of information in networks" by C. Macchi, JP Guilbert, published in Dunod, 1987.
- the block of information is transmitted to a modulator 14 to be modulated and finally transmitted by the transmitting antenna 16.
- the device comprises a dimensioning and distribution unit responsible for dimensioning the block according to sensitivity criteria as we have just seen.
- the unit 18 also attaches information on the number of zones of the block and their size to allow correct demultiplexing on the reception side.
- the dimensioning and distribution unit 18 is connected to the information inputs V, D and S so as to draw therefrom information on the number of types of information present at the input, an indication of the priorities of the services relative to each other. to others, these priorities can be given by traffic conditions (for example promoting speech during peak hours), reception quality conditions (signaling more sensitive than data) and transmission delay conditions.
- the unit 18 is also connected at the input to the output of the encoder 10 from which it receives indications on the coding scheme adopted for each service or type of information, and on the quality desired for the data message itself and for the coding redundancy. Finally, the unit 18 also receives the result of measurements carried out in the receiver as will be seen.
- the set of indications received from the different modules of the transmitter and the measurements carried out in the receiver allow the unit 18 to size the information block and to distribute the information in the areas of the block in an optimal manner, as it has previously mentioned. This information is provided by the dimensioning and distribution unit directly to the formatting and multiplexing unit.
- the receiver receives the data modulated by an antenna 20 and demodulates it in a demodulator 22.
- the demodulated data is processed by a deformatting and demultiplexing unit 24 (a description of such a unit can also be found in the work cited above ) which separates the logical channels and supplies them to a channel decoder 26.
- the latter restores the digital information corresponding to voice (V), data (D) and signaling (S).
- a measurement unit 28 an integral part of the device according to the invention, is connected to the input and to the output of the demodulator to draw quality measurements from the transmission channel, and is connected to the output of the decoder 26 to derive quality measures from areas (corresponding to the different types of information).
- the measurement unit 28, once it has collected the required measurements, communicates said measurements to the dimensioning and distribution unit 18 by means of a return channel 30.
- This channel can be a channel directly linked to the band used to transmit useful information from the receiver to the transmitter, or else a channel outside this band, for example a channel used to transmit service information.
- the dimensioning and distribution unit can be implemented by means of a truth table using the input connections as many table inputs. Such a table can be pre-established by simulations or field tests. Software is required to update the outputs and input parameters of the table based on the measurement results provided by the receiver's measurement unit.
- the assembly can be effectively implemented in a data processing device such as a microcomputer.
- a person skilled in the art is able to implement the principles of the invention as set out above in different ways without departing from the scope of the invention.
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Mobile Radio Communication Systems (AREA)
- Detection And Prevention Of Errors In Transmission (AREA)
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR9406179 | 1994-05-20 | ||
FR9406179A FR2720207B1 (en) | 1994-05-20 | 1994-05-20 | Device for optimal distribution of information in the information blocks exchanged in a radiocommunication system. |
PCT/FR1995/000626 WO1995032557A1 (en) | 1994-05-20 | 1995-05-15 | Device for optimal division of data into data blocks in a time-division multiple access system |
Publications (1)
Publication Number | Publication Date |
---|---|
EP0760183A1 true EP0760183A1 (en) | 1997-03-05 |
Family
ID=9463385
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP95920141A Ceased EP0760183A1 (en) | 1994-05-20 | 1995-05-15 | Device for optimal distribution of data into data blocks in a time-division multiple access system |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP0760183A1 (en) |
CN (1) | CN1152378A (en) |
AU (1) | AU2571195A (en) |
FR (1) | FR2720207B1 (en) |
WO (1) | WO1995032557A1 (en) |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2271916B (en) * | 1992-10-23 | 1996-05-22 | Roke Manor Research | Improvements in or relating to digital radio communication systems |
-
1994
- 1994-05-20 FR FR9406179A patent/FR2720207B1/en not_active Expired - Fee Related
-
1995
- 1995-05-15 WO PCT/FR1995/000626 patent/WO1995032557A1/en not_active Application Discontinuation
- 1995-05-15 AU AU25711/95A patent/AU2571195A/en not_active Abandoned
- 1995-05-15 EP EP95920141A patent/EP0760183A1/en not_active Ceased
- 1995-05-15 CN CN 95193646 patent/CN1152378A/en active Pending
Non-Patent Citations (3)
Title |
---|
IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, vol. 41, no. 2, Mai 1992 NEW YORK * |
See also references of WO9532557A1 * |
US, pages 177-189, G.D'ARIA ET AL. 'SIMULATION AND PERFORMANCE OF THE PAN- EUROPEAN LAND MOBILE RADIO SYSTEM' * |
Also Published As
Publication number | Publication date |
---|---|
CN1152378A (en) | 1997-06-18 |
FR2720207B1 (en) | 1996-06-21 |
AU2571195A (en) | 1995-12-18 |
WO1995032557A1 (en) | 1995-11-30 |
FR2720207A1 (en) | 1995-11-24 |
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Legal Events
Date | Code | Title | Description |
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PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
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17P | Request for examination filed |
Effective date: 19961119 |
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RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: ALCATEL CIT |
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RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: ALCATEL ALSTHOM COMPAGNIE GENERALE D'ELECTRICITE |
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17Q | First examination report despatched |
Effective date: 19971006 |
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STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION HAS BEEN REFUSED |
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18R | Application refused |
Effective date: 19980328 |