EP1104637A2 - Transmission de donnees a commutation par paquets dans un systeme radio - Google Patents

Transmission de donnees a commutation par paquets dans un systeme radio

Info

Publication number
EP1104637A2
EP1104637A2 EP99938418A EP99938418A EP1104637A2 EP 1104637 A2 EP1104637 A2 EP 1104637A2 EP 99938418 A EP99938418 A EP 99938418A EP 99938418 A EP99938418 A EP 99938418A EP 1104637 A2 EP1104637 A2 EP 1104637A2
Authority
EP
European Patent Office
Prior art keywords
transmission
delay
transmission unit
critical information
receiver
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.)
Withdrawn
Application number
EP99938418A
Other languages
German (de)
English (en)
Inventor
Mika Raitola
Harri Holma
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nokia Oyj
Original Assignee
Nokia Networks Oy
Nokia Oyj
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Nokia Networks Oy, Nokia Oyj filed Critical Nokia Networks Oy
Publication of EP1104637A2 publication Critical patent/EP1104637A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
    • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
    • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
    • H04L1/1812—Hybrid protocols; Hybrid automatic repeat request [HARQ]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0056—Systems characterized by the type of code used
    • H04L1/007—Unequal error protection
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
    • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
    • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
    • H04L1/1829—Arrangements specially adapted for the receiver end
    • H04L1/1835—Buffer management
    • H04L1/1845—Combining techniques, e.g. code combining

Definitions

  • the invention relates to a radio system and a method of transmitting packet-switched data between a transmitter and a receiver in the radio system.
  • the invention relates particularly to a system and a method, in which the connection between the transmitter and the receiver comprises at least two logical channels, and one logical channel is used for transmitting delay- critical information.
  • Circuit switching is a method in which a connection is established between users by providing the connection with a predetermined amount of transmission capacity.
  • the transmission capacity is used exclusively by said connection during the whole connection.
  • Known mobile communication systems e.g. GSM-based GSM 900/DCS 1800/PCS 1900 systems and the American IS-95 radio system applying the CDMA technique, are circuit- switched systems.
  • Packet switching for its part is a method in which a connection is established between users by transmitting data as packets which include the actual information and also address and control information.
  • Various connec- tions may simultaneously use the same transmission link.
  • the use of packet-switched radio systems especially in data transmission has been examined, because the method of packet switching can be applied to e.g. data transmission required when using interactive computer programs, whereby the data to be transmitted is produced in bursts. In such a case, the data transmission connection need not be allocated for the whole time, but only for the packet transmission. This way, the costs and capacity are saved considerably both when establishing and operating the network.
  • GPRS General Packet Radio Service
  • FEC Forward Error Correction
  • ARQ Automatic Repeat Request
  • the combination of these is called a hybrid ARQ.
  • the GPRS employs the following ARQ protocol, either in its basic form or a more advanced form.
  • the ARQ protocol (Automatic Repeat Request) refers to a proceedu- re which improves the reliability of the data to be transmitted by retransmitting the information to be transmitted.
  • the receiver transmits a request to the sender to retransmit the transmitted data, if the receiver considers the received data unreliable.
  • the unreliability of the data is detected by checking a check sum from the received packet, for example.
  • the protocol has mainly been used in fixed networks.
  • a big problem of radio networks is that the transmitting channels in radio connections have a fading character. Rayleigh fading means that multipath-propagated signal components arrive in opposite phases at a receiver and thus partly cancel each other. Then the power and also the quality of the received signal de- crease considerably.
  • a more advanced form of the ARQ protocol is the hybrid ARQ, which uses the combination of the ARQ and the FEC (Forward Error Correction).
  • the FEC means that the information to be transmitted is coded by a coding correcting errors.
  • an unsuccessful transmission is combined with a retransmission in the receiver. This combination can be performed by retransmitting the data coded in the same way and combining the soft decisions in the receiver. In the retransmission, additional coding can be used instead of transmitting the same data.
  • This method provides the advantage that the number of retransmissions can be decreased, whereby the transmission capacity increases considerably.
  • a disadvantage of the method is, however, that it works best when there are a lot of transmission errors, i.e. when the frame error rate (FER) is about 20 %.
  • the acknowledgement messages (ACK NACK) of the transmission units are, however, also subject to errors, which makes the sys- tern less functional. For example, if the transmission error equals 10 % in each transmission, there are 10 % of errors after the first transmission, 1 % after the second, 0.1 % after the third transmission etc.
  • the combining of the transmissions reduces the amount of errors, but only after the second transmission.
  • the operation point i.e. the frame error rate of each transmission, should be higher, e.g. 20 %. This harms, however, the delay-critical information, which cannot withstand the delay caused by the combining.
  • Figure 3 illustrates the structure of the receiver according to the in- vention
  • Figures 4a and 4b show flow charts illustrating the employment of the method of the invention for data information.
  • the present invention can be applied to radio systems using packet-switched connections.
  • the invention can preferably be applied to broadband CDMA-based cellular radio systems, such as WCDMA and
  • CDMA2000 but the multiple access method employed in the system is not as such substantially relevant to the invention.
  • the term 'transmission unit' refers to a transmission unit used in a bidirectional radio connection, which transmission unit is the protocol data unit of layer 1 , i.e. the physical layer, in the seven-layer OSI model of the ISO.
  • a transmission unit may comprise one or more TDMA time slots.
  • a transmission unit may be a limited period of time with one or more spreading codes.
  • a transmission unit may be a limited period of time with one or more frequencies.
  • a transmission unit may be any combination of the examples described above. Generally it can be stated that a transmission unit is any resource on the transmission path, i.e.
  • FIG. 1 shows an example of a radio system, to which the invention can be applied.
  • the radio system comprises a network part 110 and a set of subscriber terminals 112, 114.
  • the network part refers to the fixed part of the network, e.g. a base station 116, a base station controller 118, a mobile services switching centre 120 or various combinations of said parts.
  • a subscriber terminal is e.g. a mobile phone, a phone positioned in a car or a WLL terminal (Wireless Local Loop).
  • FIG. 2 includes only the blocks that are substantial for describing the invention, but it is obvious for a person skilled in the art that a common transmitter also comprises other functions and structures, which need not be described herein in greater detail.
  • the transmitter can basi- cally be e.g. a normal transmitter in the GPRS system, to which transmitter the modifications required by the invention are made.
  • the transmitter uses two services, i.e. logical channels.
  • data is transmitted and in the second channel 202 delay-critical information is transmitted.
  • Delay-critical information can be any data transmission which does not allow great delays, e.g. retransmissions, on the transmission path.
  • Such connections are e.g. power regulating messages, transmission rate information relating to a data channel, acknowledgement messages (ACK/NACK) of packets or e.g. speech information.
  • Data information 200 comprising transmission units is first taken to the first channel coder 204, after which the transmission unit is stored in a memory 206 for a potential retransmission. Thereafter, data is taken to the first transmission rate adapter 208, in which the data transmission rate is balanced as desired.
  • Delay-critical information 202 is taken to the second channel coder 212, from which the coded signal is taken to the second transmission rate adapter 214, in which the transmission rate is balanced.
  • the transmission units are taken from the first and the second transmission rate adapters 208, 214 to a multiplexer 210, in which the units are multiplexed with each other for the transmission.
  • the combined signal is taken from the multiplexer to the third transmission rate adapter 216, in which the common transmission rate is changed, if necessary.
  • the signal to be transmitted is taken to an interleaver 218, in which the interleaving is performed to improve the transmission quality.
  • the signal is taken from the interleaver further to radio frequency parts of the transmitter (not shown) in order to be transmitted to the transmission channel.
  • the memory 206 can also be located before the first channel coder
  • Figure 3 includes only the blocks that are substantial for describing the invention, but it is obvious for a person skilled in the art that a common receiver also comprises other functions and structures, which need not be described herein in greater detail.
  • the receiver can basically be e.g. a normal receiver in the GPRS system, to which receiver the modifications required by the invention are made.
  • a signal is received by an antenna 300, from which the signal is taken to radio frequency parts 302.
  • the signal is converted to an intermediate or baseband frequency, and it is taken to a demodulator 306, in which the demodulated signal is taken to a deinterieaver 308.
  • Said components can be implemented in ways that are obvious to a person skilled in the art.
  • the deinterleaved signal is taken to the first transmission rate adapter 310 and a demultiplexer 312.
  • the signal is divided into two channels used in the transmission, in the first of which channels 314 data was transmitted and in the second of which channels 316 delay-critical information, such as control information or speech, was transmitted.
  • Data information is taken to the second transmission rate adapter 318, from which it is taken to a combiner 320.
  • a transmission unit that may have been transmitted earlier and which is stored in a memory 322 in the reception is combined with the transmission unit.
  • the combined transmission unit is again stored in the memory for a potential retransmission.
  • the transmission unit is taken to the first channel decoder 324, in which errors are corrected as well.
  • the transmission unit is taken further to the other parts of the receiver. If the error correction indicates that the transmission unit is erro- neous, a retransmission has to be requested of the transmitter. This can be implemented e.g. by informing a control unit 326 of the receiver of the need for a retransmission, which control unit controls the operation of different receiver parts and conveys the information on the need for a retransmission to the transmitter by using the control channel of the opposite direction of transmis- sion.
  • the combiner 320 and the memory 322 can also be located before the second transmission rate adapter 318, but in any case after the demultiplexer.
  • the memory 322 can also be located after the channel decoder 324, which provides the advantage that only those transmission units are stored that need to be retransmitted. On the other hand, soft combining cannot then be used.
  • the delay-critical information 316 is taken from the demultiplexer
  • the number of transmission rate adapters both in the transmitter and in the receiver can differ from what is described above.
  • a different error correction procedure is applied to data information and to delay-critical information. If required, a stronger channel coding can be used for delay-critical information, whereby it is less subject to errors than data information.
  • Step 400 A receiver receives and demodulates a transmission unit.
  • Step 408 It is checked whether it deals with a retransmission, i.e. whether the previously transmitted transmission unit is found in the memory. If it is found, the transmission units are combined at step 410.
  • Step 412 The quality of the transmission unit is checked. If the quality of the transmission unit reaches a predetermined quality level, the algorithm is exited and it is moved to receive the next transmission unit.
  • Step 414 If the quality was not good, the transmission unit is stored. If the quality is very bad, the unit can be completely abandoned.
  • Step 418 A retransmission request formed on the basis of the quality of the transmission units is transmitted.
  • the sender is now requested to retransmit the same transmission unit whose quality level did not reach the required quality level. It is moved to step 400 to receive the transmission unit.
  • Figure 4b illustrates the optional handling of data information.
  • the quality of the transmission unit is immediately checked at step 402. If the quality is good, it is proceeded to step 408 and continued as described above. Otherwise the transmission unit is stored at step 404. If the quality is very poor, the unit may be completely abandoned.
  • a retransmission request formed on the basis of the quality of the transmission units is transmitted. Now the sender is requested to retransmit the same transmission unit whose quality level did not reach the required quality level. It is moved to step 400 to receive the transmission unit.
  • the described method is basically a more advanced form of the classic ARQ protocol in such a manner that the same transmission unit is cumulated before the detection so long that the quality of the cumulated transmission unit is good enough. It is to be noted herein that this is only one example of data error correction. In the solution of the invention, other ARQ- based solutions can be applied as well, as it is obvious for a person skilled in the art.
  • a CRC error check sum can be formed for both the transmission unit and the packet separately, on the basis of which sum the erroneousness of the transmission unit and/or the packet is checked in the reception. Other methods of forming the error check sum can be employed as well.
  • Quality may also be defined by forming a bit error rate for the transmission unit.
  • the quality of the received transmission unit can also be defined by forming a C/l ratio (Carrier/Interference) for the transmission unit by means of a training sequence.
  • C/l ratio Carrier/Interference
  • the quality level of a combined transmission unit is determined by comparing the average quality level of transmission units with the adaptive quality threshold.
  • the average quality level is formed e.g. by counting the mean value or by defining a numerical limit for the amount of packets of the transmission units that has to reach the required quality level.
  • the adaptiveness means that the system may be self-learning, whereby the system optimizes its operation by changing quality limits to conform to the conditions and to maximize the efficient use of the transmission capacity.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Detection And Prevention Of Errors In Transmission (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Data Exchanges In Wide-Area Networks (AREA)
  • Small-Scale Networks (AREA)
  • Communication Control (AREA)

Abstract

L'invention concerne un procédé de transmission de données à commutation par paquets et un système radio comprenant un émetteur (112, 114) et un récepteur (116) conçus pour émettre des données commutées par paquets. Dans le système, la connexion (122, 124) entre l'émetteur et le récepteur fait appel à au moins deux canaux logiques. L'émetteur et le récepteur, qui utilisent un seul canal logique pour transmettre les informations sensibles au retard, transmettent les informations en les localisant dans certaines unités de transmission et emploient pour ladite transmission la technique de protection contre les erreurs. Selon l'invention, l'émetteur (112, 114) et le récepteur (116) sont conçus de façon à utiliser une technique de protection différente selon qu'ils transmettent des données ou des données sensibles au retard. L'invention permet de transmettre simultanément, en les multiplexant, des services nécessitant une transmission rapide de grande qualité, tels que les données vocales et les données en paquets.
EP99938418A 1998-08-14 1999-08-12 Transmission de donnees a commutation par paquets dans un systeme radio Withdrawn EP1104637A2 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FI981757A FI981757A (fi) 1998-08-14 1998-08-14 Pakettikytkentäinen tiedonsiirto radiojärjestelmässä
FI981757 1998-08-14
PCT/FI1999/000670 WO2000010348A2 (fr) 1998-08-14 1999-08-12 Transmission de donnees a commutation par paquets dans un systeme radio

Publications (1)

Publication Number Publication Date
EP1104637A2 true EP1104637A2 (fr) 2001-06-06

Family

ID=8552310

Family Applications (1)

Application Number Title Priority Date Filing Date
EP99938418A Withdrawn EP1104637A2 (fr) 1998-08-14 1999-08-12 Transmission de donnees a commutation par paquets dans un systeme radio

Country Status (7)

Country Link
EP (1) EP1104637A2 (fr)
JP (1) JP3416118B2 (fr)
CN (1) CN1127866C (fr)
AU (1) AU755295B2 (fr)
FI (1) FI981757A (fr)
NO (1) NO20010732D0 (fr)
WO (1) WO2000010348A2 (fr)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB0107746D0 (en) 2001-03-28 2001-05-16 Nokia Networks Oy Transmissions in a communication system
FI991092A (fi) * 1999-05-12 2000-11-13 Nokia Networks Oy Menetelmä tietoliikenneyhteyden laadun parantamiseksi ja verkkoelement ti
GB2361850B (en) * 2000-04-25 2003-12-24 Ubinetics Ltd Multiplexing and de-multiplexing
JP4330767B2 (ja) 2000-06-26 2009-09-16 株式会社エヌ・ティ・ティ・ドコモ 自動再送要求を行う通信方法及び基地局装置
FI20001975A (fi) * 2000-09-07 2002-03-08 Nokia Corp Ohjaustietojen signalointimenetelmä
AU2002237170A1 (en) * 2002-02-21 2003-09-09 Linkair Communications, Inc. A method and apparatus for error controlling in high speed wireless packet data service
KR100512943B1 (ko) * 2003-10-14 2005-09-07 삼성전자주식회사 위성 방송 수신기 및 그의 위성 방송 수신 방법
KR100765317B1 (ko) * 2005-07-12 2007-10-09 삼성전자주식회사 디지털 방송 시스템에서의 채널 전환 장치 및 방법
JP2008131601A (ja) 2006-11-24 2008-06-05 Matsushita Electric Ind Co Ltd 通信端末装置、通信システム、通信方法及びプログラム

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19605223A1 (de) * 1996-02-13 1997-08-14 Sel Alcatel Ag Verfahren zum Betreiben einer Breitband-Verbindung zwischen einem Mobilfunk-Endgerät und einer netzseitigen Mobilfunkeinrichtung sowie Mobilfunk-Endgerät, netzseitige Mobilfunkeinrichtung und Mobilfunksystem
FI980293A (fi) * 1998-02-09 1999-08-10 Nokia Networks Oy Multimedia- ja monipalvelupuhelut matkaviestinverkossa

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0010348A2 *

Also Published As

Publication number Publication date
NO20010732L (no) 2001-02-13
CN1313013A (zh) 2001-09-12
NO20010732D0 (no) 2001-02-13
JP3416118B2 (ja) 2003-06-16
JP2002523934A (ja) 2002-07-30
WO2000010348A2 (fr) 2000-02-24
AU5292699A (en) 2000-03-06
FI981757A0 (fi) 1998-08-14
CN1127866C (zh) 2003-11-12
AU755295B2 (en) 2002-12-12
FI981757A (fi) 2000-02-15
WO2000010348A3 (fr) 2001-02-15

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