EP1159793A1 - Procede de transmission a debit binaire variable dans un canal d'acces aleatoire d'un systeme de radiocommunication - Google Patents

Procede de transmission a debit binaire variable dans un canal d'acces aleatoire d'un systeme de radiocommunication

Info

Publication number
EP1159793A1
EP1159793A1 EP00920355A EP00920355A EP1159793A1 EP 1159793 A1 EP1159793 A1 EP 1159793A1 EP 00920355 A EP00920355 A EP 00920355A EP 00920355 A EP00920355 A EP 00920355A EP 1159793 A1 EP1159793 A1 EP 1159793A1
Authority
EP
European Patent Office
Prior art keywords
spreading codes
fbi
radio blocks
radio
data rate
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.)
Pending
Application number
EP00920355A
Other languages
German (de)
English (en)
Inventor
Jean-Michel Traynard
Christoph MECKLENBRÄUKER
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.)
Siemens AG
Original Assignee
Siemens AG
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 Siemens AG filed Critical Siemens AG
Publication of EP1159793A1 publication Critical patent/EP1159793A1/fr
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/24—Radio transmission systems, i.e. using radiation field for communication between two or more posts
    • H04B7/26—Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile
    • H04B7/2618—Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile using hybrid code-time division multiple access [CDMA-TDMA]

Definitions

  • the invention relates to a method and a base station for transmission with variable data rate in a channel with random access of a radio communication system.
  • information for example voice, image information or other data
  • information is transmitted with the aid of electromagnetic waves via a radio interface between the transmitting and receiving radio station (base station or subscriber station).
  • the electromagnetic waves are emitted at carrier frequencies that lie in the frequency band provided for the respective system.
  • CDMA or TD / CDMA transmission methods CDMA Code Division Multiple Access, TD / CDMA Time Division CDMA
  • UMTS Universal Mobile Telecommunication Standard
  • a channel with the corresponding data rate can be reserved beforehand. This reservation requires a certain amount of signaling and thus ties up transmission capacity. For services with short data packets to be transmitted intermittently, this means an unfavorable relationship between useful data and signaling capacity.
  • the signaling effort is avoided in channels with arbitrary access, since the transmitting radio stations can access them without a prior reservation. Through the However, random access leads to collisions that make it difficult or even impossible to detect the transmitted data.
  • Solutions from DE 198 17 771 and DE 199 04 108 are known for the variability of the data rate and for collision detection. Collisions are avoided by temporal orthogonality and the data rate can be varied by single or double radio blocks. However, the variability of the data rate is very limited.
  • the object of the invention is to further increase the flexibility in increasing the data rate, taking into account the probability of a collision. This object is achieved by the method with the features of claim 1 and the base station with the features of claim 12. Advantageous developments of the invention can be found in the subclaims.
  • radio blocks with spreading codes are transmitted spread in a channel formed by a time slot with random access. Furthermore, several radio blocks per time slot can be transmitted at different times, if necessary. The probability of a collision is kept low by these measures.
  • the flexibility is further increased by the fact that within the connection to increase the data rate, two radio blocks with different spreading codes are transmitted simultaneously, which are in a comprehensible relationship to one another. Due to this ratio, which does not result from a previous assignment, a larger number of spreading codes can also be used in a channel with random access.
  • the receivers of radio stations are often limited in their ability to estimate channels, so that only a subset of the available spreading codes corresponding to the previously estimated channels can be used. If previously an assignment from spreading codes to connections, this disadvantage is insignificant since the other spreading codes can be assigned to the higher-rate connections.
  • the ratio of the spreading codes is specified such that the spreading codes are divided into at least two groups, a first group of spreading codes being provided for the use of different subscriber stations.
  • a subscriber station therefore does not use two spreading codes from the first group. This does not increase the probability of a collision.
  • a subscriber station can use at least one of the spreading codes from the first and one of the spreading codes from the second group at the same time.
  • the spreading codes of the second group serve to increase the data rate.
  • the assignment can be fixed and, for example, preset or updated using information from the organizational channel. This ensures high reliability.
  • An alternative variant provides that the simultaneous use of spreading codes from both groups is recognized on the basis of the same propagation paths. No assignment has to be signaled for this, but the propagation paths should differ sufficiently.
  • m it is possible for m to be the same as the spread codes of the first group. spread radio blocks, the assignment of the spreading codes is signaled. A few bits can be used to signal which other spreading codes belong to the connection. This means that only a little transmission capacity is lost, and yet full flexibility is given.
  • the data rate can thus be made more flexible in channels in which the spread codes are selected without prior allocation of resources.
  • the invention can be used particularly advantageously in the case of data transmission over a broadband radio interface between base stations and subscriber stations.
  • the capacity of the radio interface is large, a limitation of the actually used capacity would mean extensive unused resources.
  • the radio interface is advantageously organized according to a TDD partial separation method (Time Division Duplex), so that asymmetrical data services are also supported without wasting resources.
  • TDD partial separation method Time Division Duplex
  • Show 1 is a block diagram of a mobile radio system
  • Fig. 4- • 6 is a schematic representation of the inventive use of spreading codes to increase the data rate
  • Fig. 7 is a simplified block diagram of a base station.
  • the mobile radio system shown in FIG. 1 as an example of a radio communication system consists of a multiplicity of mobile switching centers MSC which are networked with one another or which provide access to a fixed network PSTN. Furthermore, these mobile switching centers MSC are each connected to at least one device RNM for allocating radio resources. Each of these devices RNM in turn enables a connection to at least one base station BS. Such a base station BS can connect via a radio interface to subscriber stations, e.g. Build mobile stations MS or other mobile and stationary devices. At least one radio cell Z is formed by each base station BS. In the case of sectorization or hierarchical cell structures, several radio cells Z are also supplied per base station BS.
  • connections VI, V2, V3 for the transmission of useful information and signaling information between mobile stations MS and a base station BS, the sending of organizational information in an organizational channel BCCH in the sense of a point-to-multipoint connection from the base station to the Mobile stations MS and an access channel R ⁇ CH (Random Access Channel) shown.
  • the access channel R ⁇ CH shown in the exemplary embodiment only in the upward direction, is a channel which the mobile stations MS can access arbitrarily without reservation.
  • An operations and maintenance center OMC implements control and maintenance functions for the mobile radio system or for parts thereof. The functionality of this structure can be transferred to other radio communication systems in which the invention can be used, in particular for subscriber access networks with a wireless subscriber line.
  • the frame structure of the radio transmission is shown in FIG. 2.
  • a frequency band extends over a frequency range B.
  • Some of the time slots ts0 to ts8 are used in the downward direction DL and some of the time slots ts9 to tsl5 are used in the upward direction UL.
  • the frequency band for the upward direction UL corresponds to the frequency band for the downward direction DL. The same is repeated for other carrier frequencies.
  • Information of several connections is transmitted in radio blocks within the time slots that can be used for the transmission of user data with previous allocation of resources. These radio blocks for.
  • User data transmission consist of sections with data d, in which training sequences tseql to tseqn known at the receiving end are embedded for channel estimation.
  • the data d are spread individually for each connection with a fine structure, a spreading code c, so that, for example, n connections can be separated at the receiving end by this CDMA component.
  • a channel is formed by a frequency band B, a time slot ts and a spread code c.
  • the spreading of individual symbols of the data d has the effect that within the symbol duration T S ym Q chips of the duration T ch i p will wear.
  • the Q chips form the connection-specific spreading code c.
  • the spreading code c can also result from a superimposition of several codes.
  • a protection time gp is provided within the time slot ts to compensate for different signal propagation times of the connections.
  • the successive time slots ts are structured according to a frame structure. So 16 time slots ts are combined into a frame for.
  • Chip rate 4096 Mcps
  • two radio blocks FBI, FB2 each filling only less than half of the time slot ts, are available for a transmitting mobile station MS.
  • the mobile station MS can also use both radio blocks FBI, FB2 and thus double the data rate.
  • 16 spreading codes c are still available per time slot and are divided into two groups.
  • a first group with the spreading codes cO to c7 corresponds to the eight channel estimates, which can be carried out simultaneously on the receiving side.
  • a transmitting mobile station MS arbitrarily selects one the spreading codes cO to c7 of the first group. This situation according to the prior art is shown in FIG. 3.
  • the mobile station MS can additionally select one or more further spreading codes c8 to cl5 which belong to a second group which does not overlap with the first group.
  • a mobile station MS therefore sends two or more radio blocks FBI at the same time, but these are spread with different spreading codes c.
  • the affiliation of the spreading codes cO to cl5 to the groups is predetermined or will be announced in the organizational channel BCCH.
  • the size of the group can also be smaller than eight. In the exemplary embodiment, eight is the maximum number of channel estimates that can be carried out simultaneously.
  • each spread code cO to c7 of the first group is assigned a spread code c8 to cl5 of the second group. This means that the data rate can be quadrupled to a maximum.
  • Other groupings, such as cO to c3 m of the first group, each with three assigned feed codes, e.g. c4 to c5 for cO are also possible.
  • FIGS. 4 and 5 shows a case in which two spreading codes c8 and c9 of the second group are assigned to a spreading code cO of the first group.
  • the solutions according to FIGS. 4 and 5 do not increase the likelihood of a collision as long as all mobile stations MS observe the assignment.
  • a mobile station MS which uses the spreading code cl, was unable to access the feed codes c8 or c9 assigned to the spreading code cO.
  • the data rate can also be increased beyond this limit if a mobile station MS uses several spreading codes cO and cl, see FIG. 6, from the first group. In this case, however, the probability of a collision also increases.
  • Remedial measures can, however, be provided by evaluation and collision detection according to DE 199 04 108.
  • the fixed assignment limits the flexibility somewhat, but can allow the connections in the channel with random access R ⁇ CH without a previous allocation of resources a corresponding variety of data rates.
  • the assignment rule can be optimized separately for the individual radio cells by signaling in the organization channel
  • Spreading codes c can be freely selected by the transmitting side. If MS rules are observed by the mobile stations, the probability of a collision increases only slightly. An assignment of spreading codes c to connections can be reconstructed by the receiving side without any signaling on the basis of the propagation paths.
  • a channel estimation for the spreading codes c of the first group is carried out in a first reception-side evaluation step, an assignment can be made for all 16 spreading codes based on the probability of individual metric paths of the Viterbi decoding in the detection according to the joint detection principle according to DE 41 21 356 to the channel estimation results and thus to the propagation paths and connections.
  • the reliability of the assignment can be checked on the basis of transmitted test bits, which each apply to several radio blocks FBI, FB2 and spreading codes c of the connection. This can also be used to check whether a correct assignment was made at the receiving end. Due to the variability of the data rate, a large number of different services (telemetry services, short message services, very time-variant but easily scalable data rate) can be supported in the R ⁇ CH channel with arbitrary access, and resource requests can also be sent with a low probability of collision. This makes this channel much more attractive.
  • the access blocks are evaluated in a base station BS according to FIG. 7. This consists of a broadcast /
  • Receiving device TX / RX which converts received signals from the frequency range of the data transmission into the baseband, converts them analog / digital, and amplifies the received signals. Digital signal processing takes place in a signal processing device DSP. A channel estimation is carried out and the transmitted data symbols are detected.
  • a signal evaluation device SA extracts the data components of the radio blocks FBI, FB2 on the basis of the temporal orthogonality and the spreading codes c.
  • the signal evaluation device SA takes the requirements for resource allocation and the data to be forwarded from the content of the data components.
  • the resource allocation itself is carried out in the facility RNM for allocating radio resources and signaled back to the base station BS.
  • a control device SE then assigns a channel for data transmission to the mobile stations MS by compiling a corresponding signaling block and transmitting this block by the transmitting / receiving device TX / RX.
  • the interaction of the components is also controlled by the control device SE.
  • the data and the assignment rules for the spreading codes c are stored in a memory device MEM.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

Selon l'invention, des blocs messages sont étalés au moyen de différents codes d'étalement dans un canal d'accès aléatoire, formé par un créneau temporel, et peuvent être transmis éventuellement de manière séparée dans le temps. Ce procédé permet de réduire la probabilité de collision. Pour faire varier le débit binaire, un ou deux blocs messages peuvent être envoyés par créneau temporel, à l'intérieur d'une liaison. La flexibilité de la transmission peut être accrue si, à l'intérieur d'une liaison, deux blocs messages, entre lesquels est établie une relation claire côté réception, sont transmis simultanément de manière étalée avec des codes d'étalement différents pour accroître le débit binaire. L'invention montre que, même dans des canaux d'accès aléatoire, la limitation de capacité par l'estimation de canaux n'entraîne pas une limitation de la capacité de transmission.
EP00920355A 1999-03-16 2000-03-01 Procede de transmission a debit binaire variable dans un canal d'acces aleatoire d'un systeme de radiocommunication Pending EP1159793A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19911712 1999-03-16
DE1999111712 DE19911712A1 (de) 1999-03-16 1999-03-16 Übertragungsverfahren mit variabler Datenrate in einem RACH-Kanal eines Funk-Kommunikationssystems
PCT/DE2000/000628 WO2000055990A1 (fr) 1999-03-16 2000-03-01 Procede de transmission a debit binaire variable dans un canal d'acces aleatoire d'un systeme de radiocommunication

Publications (1)

Publication Number Publication Date
EP1159793A1 true EP1159793A1 (fr) 2001-12-05

Family

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EP00920355A Pending EP1159793A1 (fr) 1999-03-16 2000-03-01 Procede de transmission a debit binaire variable dans un canal d'acces aleatoire d'un systeme de radiocommunication

Country Status (3)

Country Link
EP (1) EP1159793A1 (fr)
DE (1) DE19911712A1 (fr)
WO (1) WO2000055990A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8014359B2 (en) 2006-10-27 2011-09-06 Interdigital Technology Corporation Method and apparatus for assigning radio resources and controlling transmission parameters on a random access channel
CN101287286B (zh) * 2008-05-14 2012-10-03 中兴通讯股份有限公司 一种获得小区prach的时域位置的方法

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU8959191A (en) * 1990-10-23 1992-05-20 Omnipoint Corporation Method and apparatus for establishing spread spectrum communications
US5442625A (en) * 1994-05-13 1995-08-15 At&T Ipm Corp Code division multiple access system providing variable data rate access to a user
JP3215018B2 (ja) * 1994-09-09 2001-10-02 三菱電機株式会社 移動通信システム
DE69734190T2 (de) * 1997-05-02 2006-06-29 Siemens Ag TDMA/CDMA Nachrichtenübertragungssystem mit anpassbarer Datenrate
DE19733336A1 (de) * 1997-08-01 1999-02-18 Siemens Ag Verfahren und Funkstation zur Datenübertragung

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0055990A1 *

Also Published As

Publication number Publication date
DE19911712A1 (de) 2000-10-05
WO2000055990A1 (fr) 2000-09-21

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