WO2002032040A1 - Augmentation de l'efficacite de la bande passante dans une transmission orientee paquets avec autocorrection des erreurs - Google Patents

Augmentation de l'efficacite de la bande passante dans une transmission orientee paquets avec autocorrection des erreurs Download PDF

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Publication number
WO2002032040A1
WO2002032040A1 PCT/DE2001/003831 DE0103831W WO0232040A1 WO 2002032040 A1 WO2002032040 A1 WO 2002032040A1 DE 0103831 W DE0103831 W DE 0103831W WO 0232040 A1 WO0232040 A1 WO 0232040A1
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WO
WIPO (PCT)
Prior art keywords
data
transmission
packet
cfl
error
Prior art date
Application number
PCT/DE2001/003831
Other languages
German (de)
English (en)
Inventor
Frank Burkert
Thi Min Ha Nguyen
Günther LIEBL
Original Assignee
Siemens Aktiengesellschaft
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
Priority claimed from DE10101092A external-priority patent/DE10101092B4/de
Application filed by Siemens Aktiengesellschaft filed Critical Siemens Aktiengesellschaft
Publication of WO2002032040A1 publication Critical patent/WO2002032040A1/fr

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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]
    • H04L1/1819—Hybrid protocols; Hybrid automatic repeat request [HARQ] with retransmission of additional or different redundancy
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H03M13/03—Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words
    • H03M13/05—Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words using block codes, i.e. a predetermined number of check bits joined to a predetermined number of information bits
    • H03M13/13—Linear codes
    • H03M13/15—Cyclic codes, i.e. cyclic shifts of codewords produce other codewords, e.g. codes defined by a generator polynomial, Bose-Chaudhuri-Hocquenghem [BCH] codes
    • H03M13/151—Cyclic codes, i.e. cyclic shifts of codewords produce other codewords, e.g. codes defined by a generator polynomial, Bose-Chaudhuri-Hocquenghem [BCH] codes using error location or error correction polynomials
    • H03M13/1515—Reed-Solomon codes

Definitions

  • the invention relates to a method for the packet-oriented transmission of data from a transmitting unit to a receiving unit via a transmission medium with a data channel and a response channel with the following method steps:
  • Redundancy generation by coding the data segments with an error-detecting code and / or an error-correcting code
  • Packet-oriented transmission of data generally results in packet loss for a variety of reasons.
  • packet losses are mainly caused by overload at network nodes. This happens, for example, as a result of buffer overflows and queue overflows in data packet switches or routers.
  • a router evaluates the addressing information contained in the data packets and uses routing tables to determine the cheapest further route. This information is used to decide what will continue to happen to the data packet.
  • the transmitted data is greatly reduced due to atmospheric interference and multipath propagation. disturbs. Due to the multipath propagation, a transmitted pulse generates several echoes. The superimposition of several such signal components or multi-way components with a respective phase shift compared to the direct propagation path leads to erasures which cause the so-called fast fading. These and other multipath fading phenomena lead to considerable fluctuations in the reception field strength. In addition to frequency-selective fading phenomena, there is also a temporal dispersion, with the result that individual symbols of the transmitted data “smear” over the part over several symbol durations and bit errors occur in digital transmission data.
  • frequency-selective fading phenomena there is also a temporal dispersion, with the result that individual symbols of the transmitted data “smear” over the part over several symbol durations and bit errors occur in digital transmission data.
  • the currently most widespread transmission protocols at the transport level namely the user datagram protocol UDP and the transmission control protocol TCP, react very critically to such bit errors in received data packets.
  • TCP is a connection-oriented transport protocol that enables a logical full-duplex point-to-point connection. It ensures that data is transmitted correctly and in the desired order over an underlying IP network. It extends the underlying IP (Internet Protocol) with functions for data backup and connection control.
  • IP Internet Protocol
  • Unreliable transport protocols such as e.g. UDP used. Compared to TCP, which is used much more frequently, UDP does not recognize and correct errors. However, UDP works faster and has a smaller header, which is why the ratio of the number of user data (in bits) to the data packet length (in bits) is better. UDP is more suitable for applications that send short messages and can repeat them completely if necessary, or for applications that must be carried out in real time (voice or video transmission).
  • the entire error correction is therefore carried out within the application. This affects not only bit errors, but also the total loss of data packets, since routers immediately discard UDP datagrams when there is a high network load.
  • the application can for special applications, for example in Ech 'Ttime area, higher in the error detection and error correction of further layers special protocols are supported, such as the RTP (Real-time Protocol).
  • RTP Real-time Protocol
  • the basic principle of RTP is the use of forward error control. This is made possible by an extended header that contains additional information. These are, for example, the type of user data transmitted (voice, image data, etc.) or the time of generation of the data, which makes it easier to put the data in a certain correct order or to discard them after a certain time.
  • UDP forward error correction
  • UDP packet-oriented transmission with unreliable transport protocols
  • the resulting methods should adapt to the properties of the transmission channel in order not to require more bandwidth than is absolutely necessary. This applies in particular to the transmission via mobile channels, since there the resource bandwidth is particularly valuable, i.e. is very expensive for the subscriber.
  • ARQ Automatic Repeat Request and represents a method for data transmission in which a transmitting unit sends data and waits for the correct acknowledgment by the receiving unit. If necessary, the sending unit sends the data again. This process is repeated until the data has been transferred correctly.
  • the return channel must guarantee secure transmission, i.e. ARQ processes must also be used there.
  • timers the number of repetitions and the Rpund trip delay (the time between the sending of information by the sending unit and the arrival of a response from the receiving unit via the return channel).
  • very high delays can be expected, especially in mobile transmission scenarios.
  • multimedia applications such as Streaming Videc, this means that there must be a very large buffer in the receiver. This also leads to increased complexity in the receiving terminal.
  • the object of the present invention application is therefore to simplify the transmission compared to the known prior art and still achieve an adaptation to the transmission channel.
  • this object is achieved in that the method described at the outset is developed further in that coded data segments with additional redundancy are transmitted incrementally by the transmission unit until the transmission unit either sends a message about the successful error-free via the response channel Decoding of the data packet to be transmitted is received by the receiving unit or until all redundancy of the coded data segments has been transmitted.
  • the coding is carried out in such a way that useful data of a data packet to be transmitted are in successive z H ⁇ ö C ⁇ ? df? tr P- rt _l. rt iQ for ⁇ P- tr ⁇ - • ⁇ ü O o 0 Hl
  • P- P- ⁇ d sQ 1 p 0 Pi ⁇ -i ⁇ d • ⁇ P- C ⁇ ⁇ 0 rt Hl P- P dddd P o P- ⁇ ; rt Q.
  • the error protection used is not sufficiently high. However, this can be largely avoided if the error-correcting code is selected in accordance with the long-term characteristics of the transmission channel, in particular the data channel, and the Bearer Services QoS parameter (Quality of Service, QoS).
  • the Bearer Services QoS parameter Quality of Service, QoS
  • the error-correcting code is selected on the basis of information of a long-term characteristic of the data channel such that there is adequate error protection even in the case of the poorest assumed transmission quality of the data channel.
  • RTCP real-time control protocol
  • a particularly advantageous embodiment of the invention uses a reed solo on code as the error-correcting code.
  • error-correcting codes can be found in the above-mentioned work by Lin, S./Costello, D.
  • a transmission unit or a reception unit can also be created to achieve the advantages mentioned, which have appropriate means for carrying out the method according to the invention for packet-oriented transmission of data.
  • Such transmitting units and receiving units can be used particularly advantageously in communication terminals or communication networks. The best results are achieved if transmission channels with the shortest possible round trip time are provided for a communication network.
  • a crucial distribution is that, in contrast to conventional ARQ methods, only a single reply (ACK) is required and not several. In addition, this response can be transmitted via a less complex reverse link or response channel. An additional ARQ procedure is therefore also not necessary for the response channel.
  • FIG. 1 shows a transmission and reception unit connected via a faulty transmission channel
  • FIG. 2 shows a block diagram of a transmission unit with the transmitter-side measures of the invention
  • FIG. 3 shows a block diagram of a receiving unit with the receiving measures of the invention.
  • FIG. 1 shows the scenario of a transmission between a transmitting unit S and a receiving unit E via a disturbed transmission channel (indicated by a lightning-shaped one)
  • the response channel AK can be technically simpler than the data channel DK, which is indicated by the arrow DK which is thicker than AK.
  • a streaming multimedia application via a mobile packet loss channel DK ie wi- CO co r KJ P- 1 P- 1 c- ⁇ ono Cn o Cn
  • this symbol can now be reconstructed separately in each code word CW1 to CW1 by means of the added redundancy R, and ultimately the content of the entire transmission block DS1 to DSn or DP. Due to the special property of RS codes, which are known to be ⁇ maximum-distance-separable ' ' , this type of reconstruction works as long as the number of lost data segments is less than or equal to the number of redundancy segments R or DSm + 1 to DSn ( in this case it is nm). This explanation may suffice to understand the following procedures.
  • redundancy R After redundancy R has been added by coding 2 or C as described above, data segments DS1 to DSn are transmitted 3 in accordance with their sequence via data channel DK (from the view of the illustration in FIG. 2 'from top to bottom ").
  • data channel DK from the view of the illustration in FIG. 2 'from top to bottom ".
  • This is advantageous in such a way that data segments DS1 to DSm, which contain user data N, and only then such data segments DSm + 1 to DSn are transmitted with redundancy R.
  • This can be done, for example, by means of a shift register SH into which a data segment is loaded and then sequentially output byte by byte over data channel DK until all 1 bytes of a data segment have been output, then the next data segment is loaded into the shift register and so on.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Detection And Prevention Of Errors In Transmission (AREA)

Abstract

Les données (D) présentes dans une pluralité de paquets de données (DP) à transmettre sont transmises paquet de données pour paquet de données. Chaque paquet de données est d'abord segmenté (1) en segments de données (DS) individuels et codés (2; C) à l'aide d'un code reconnaissant les erreurs et ensuite avec un code performant corrigeant les erreurs. La transmission commence alors par l'émission (3) incrémentielle des données codées segmentées (DS1...DSn) par l'intermédiaire du canal de transmission de données (DK). Dès que l'unité de réception (E) peut décoder (4; DC) sans erreur le paquet de données (DP) sur la base des segments de données déjà reçus, elle en fait part à l'unité d'émission (S), par l'intermédiaire du canal de réponse (AK), sous la forme d'un accusé de réception (ACK). Lorsque l'unité d'émission reçoit le message d'accusé de réception, elle arrête la transmission en cours et commence la transmission du paquet de données suivant.
PCT/DE2001/003831 2000-10-09 2001-10-05 Augmentation de l'efficacite de la bande passante dans une transmission orientee paquets avec autocorrection des erreurs WO2002032040A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE10049798.5 2000-10-09
DE10049798 2000-10-09
DE10101092.3 2001-01-11
DE10101092A DE10101092B4 (de) 2000-10-09 2001-01-11 Verbesserung der Bandweiteneffizienz bei einer paketorientierten Übertragung mit Vorwärtsfehlerkorrektur

Publications (1)

Publication Number Publication Date
WO2002032040A1 true WO2002032040A1 (fr) 2002-04-18

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2441164A (en) * 2006-08-22 2008-02-27 Iti Scotland Ltd Segmenting packets and providing error check portions for each segment

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0797327A2 (fr) * 1996-03-20 1997-09-24 Lucent Technologies Inc. Procédés de codage ARQ hybride du type adaptatif pour canaux à évanouissement dans des systèmes de radio mobile
WO2000027064A1 (fr) * 1998-11-03 2000-05-11 Lucent Technologies, Inc. Systeme et procede destines a la communication sans fil qui prend en charge l'adaptation de liaison et la redondance incrementale

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0797327A2 (fr) * 1996-03-20 1997-09-24 Lucent Technologies Inc. Procédés de codage ARQ hybride du type adaptatif pour canaux à évanouissement dans des systèmes de radio mobile
WO2000027064A1 (fr) * 1998-11-03 2000-05-11 Lucent Technologies, Inc. Systeme et procede destines a la communication sans fil qui prend en charge l'adaptation de liaison et la redondance incrementale

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2441164A (en) * 2006-08-22 2008-02-27 Iti Scotland Ltd Segmenting packets and providing error check portions for each segment

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