EP1023790A1 - Procede et station radio pour transmettre des donnees - Google Patents

Procede et station radio pour transmettre des donnees

Info

Publication number
EP1023790A1
EP1023790A1 EP98961001A EP98961001A EP1023790A1 EP 1023790 A1 EP1023790 A1 EP 1023790A1 EP 98961001 A EP98961001 A EP 98961001A EP 98961001 A EP98961001 A EP 98961001A EP 1023790 A1 EP1023790 A1 EP 1023790A1
Authority
EP
European Patent Office
Prior art keywords
data
midamble
data symbols
transmission power
radio
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Withdrawn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
EP98961001A
Other languages
German (de)
English (en)
Inventor
Stefan Bahrenburg
Paul Walter Baier
Dieter Emmer
Johannes Schlee
Tobias Weber
Jürgen Mayer
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 EP1023790A1 publication Critical patent/EP1023790A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/04—TPC
    • H04W52/38—TPC being performed in particular situations
    • H04W52/42—TPC being performed in particular situations in systems with time, space, frequency or polarisation diversity
    • 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]
    • 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
    • H04B7/2628—Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile using code-division multiple access [CDMA] or spread spectrum multiple access [SSMA]

Definitions

  • the invention relates to a method and a radio station for data transmission via a radio interface in a radio communication system, in particular a mobile radio network.
  • messages for example voice, image information or other data
  • the electromagnetic waves are emitted at carrier frequencies that lie in the frequency band provided for the respective system.
  • GSM Global System for Mobile Communication
  • the carrier frequencies are in the range of 900 MHz.
  • radio communication systems for example the UMTS (Universal Mobile Telecommunication System) or other 3rd generation systems, frequencies in the frequency band of approx. 2000 MHz are provided.
  • UMTS Universal Mobile Telecommunication System
  • 3rd generation systems frequencies in the frequency band of approx. 2000 MHz are provided.
  • the emitted electromagnetic waves are attenuated due to losses due to reflection, diffraction and radiation due to the curvature of the earth and the like. As a result, the reception power that is available at the receiving radio station decreases. This damping is location-dependent and also time-dependent for moving radio stations.
  • a radio interface between a transmitting and a receiving radio station, via which a data transmission takes place with the aid of the electromagnetic waves.
  • a radio communication system which uses CDMA subscriber separation (CDMA code division multiple access), the radio interface additionally having a time division multiplex subscriber separation (TDMA time division multiple access).
  • CDMA subscriber separation CDMA code division multiple access
  • TDMA time division multiple access time division multiplex subscriber separation
  • a JD (Joint Detection) process is used to improve detection by knowing the spreading codes of several participants to carry out the transmitted data. It is known that at least two data channels can be assigned to a connection via the radio interface, each data channel being distinguishable by an individual spreading code.
  • transmitted data are transmitted as radio blocks (bursts), middle messages with known symbols being transmitted within a radio block.
  • These midambles can be used in the sense of training sequences for tuning the radio station on the reception side.
  • the receiving radio station uses the midambles to estimate the channel impulse responses for different transmission channels.
  • estimation errors occur in the channel estimation in the presence of noise. These estimation errors propagate in the detection algorithms of the data estimation and cause the detection quality to deteriorate by at least 1 dB for a mobile station and at least 3 dB for a base station if 8 mobile stations are supplied in one time slot. If the signal / noise ratio is poor, the deterioration in the quality of detection is even more significant.
  • the invention is therefore based on the object of specifying a method and a radio station for data transmission in a radio communication system which counteract the deterioration in the quality of detection.
  • This object is achieved by the method with the features of claim 1 and the radio station with the features of claim 15.
  • Advantageous further developments can be found in the subclaims.
  • At least two data channels are transmitted via a radio interface.
  • Data channels can be distinguished by an individual spreading code.
  • a data channel in addition to data Symbols transmit a midamble with known symbols, the mean transmission power of the midamble being greater than the mean transmission power of the data symbols.
  • the channel estimation and data estimation are improved at the receiving end.
  • This solution can be easily implemented since a corresponding margin for a much greater peak power than the average transmission power must be provided for transmitting devices in the transmitting radio station.
  • only one midamble is used for several connections. This means that only a part of the midamble is evaluated at the receiving end for each connection. In this case, the transmission power for the midamble is not set individually for each connection, but for all connections. This measure also simplifies implementation.
  • the data symbols of the at least two data channels of a connection are already superimposed on the transmitter. This means that the midamble for the data channels is generated once in the transmitter and the data symbols of the data channels are added up before transmission by means of high-frequency waves, advantageously as digital signals. This eliminates the considerable effort that would otherwise be necessary to process and transmit the signals of the different data channels in parallel.
  • the data symbols are overlaid with the same weighting, whereby of course different performance classes can be taken into account for the connections.
  • all data channels of a connection or the entire radio interface and their data symbols are prioritized equally.
  • data symbols become a first Category with a higher weight than data symbols superimposed on a second category.
  • the data symbols of the first category are emitted with a higher signal energy per data symbol and are thus better received by the receiver, ie they can also be detected with greater accuracy.
  • the data symbols of the first category could be signaling information, for example, which is better protected against speech information.
  • the necessary signal energy per connection is advantageously taken into account.
  • Mobile stations in the vicinity of the base station for example, require less signal energy than the connections to the other mobile stations.
  • Such a weighting of the data symbols reduces interference for neighboring radio cells.
  • the average transmission power of the midamble is approximately greater in relation to the number of data channels than the average transmission power of the data symbols. If every data channel is sent with a constant envelope, inexpensive amplifiers can be used. The sum of the peak transmission power of the data parts should correspond to the peak transmission power of the midamble. There are therefore no additional requirements between data parts and midamble due to a larger dynamic range.
  • the dynamic range indicates the power range for signals that can be amplified undistorted by signal amplification.
  • the ratio of the average power per symbol between the midamble and the data symbols is adjustable.
  • the ratio can therefore be adapted to the specific transmission conditions. If the channel estimate deteriorates at a receiving radio station, the transmission power for the mid-range is further increased. It is also advantageous to carry out an evaluation of the midamble for channel estimation on the receiving end, the length of an estimated impulse response being adjustable. If only a short channel impulse response is estimated, then a larger number of channel impulse responses, ie a larger number of connections, can be transmitted via the radio interface.
  • the specific terrain conditions for example, fjords or high mountains require long channel impulse responses due to strongly scattered signal propagation times
  • an evaluation of the midamble for channel estimation is carried out at the receiving end, the length of the midamble being adjustable.
  • the length of the midamble With simple terrain conditions (direct propagation path), only short channel impulse responses can be estimated, whereby the data parts can be extended accordingly. This increases the transferable data rate. If the channel conditions are particularly difficult, the length of the midamble can be increased at the expense of the data rate. If the midamble is shortened, the average transmission power of the midamble becomes greater in relation to the midamble lengths than the average transmission power of the data symbols. This counteracts the increase in the noise power of the channel impulse response caused by the shortened midamble.
  • the setting of the power ratio between the midamble and data symbols is based on a constant dynamic range.
  • An existing dynamic range can be used to set the power ratio between the midamble and data symbols in such a way that the transmission power for the midamble is increased. This further improves the channel estimate.
  • the radio interface additionally contains a TDMA component, so that a finite radio block consisting of middle messages and data symbols is transmitted in a time slot.
  • a shorter midamble length is advantageously used in the downward direction than in the upward direction. This means that the data rate can be increased in the downward direction without any loss of quality, since the channel estimation effort is lower with only one connection to be broken down. In this case in particular, an increase in output for the midamble is advantageous.
  • FIG. 1 shows a block diagram of a mobile radio network
  • IG 4 is a block diagram of the transmitter of a radio station
  • FIG. 5 shows a block diagram of the receiver of a radio station
  • FIG. 6 shows a schematic representation of the power ratios within a radio block.
  • the structure of the radio communication system shown in FIG. 1 corresponds to a known GSM mobile radio network which 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 base station controller BSC. Each base station controller BSC in turn enables a connection to at least one base station BS.
  • a base station BS is a radio station which can establish a radio connection to mobile stations MS via a radio interface.
  • An operation and maintenance center OMC implements control and maintenance functions for the mobile radio network or for parts thereof.
  • the functionality of this structure is used by the radio communication system according to the invention; however, it can also be transferred to other radio communication systems in which the invention can be used.
  • the base station BS is connected to an antenna device which, for example, consists of three individual radiators. Each of the individual radiators radiates in a sector of the radio cell supplied by the base station BS. However, it can alternatively, a larger number of individual steelworkers (according to adaptive antennas) can also be used, so that spatial subscriber separation using an SDMA method (space division multiple access) can also be used.
  • the base station BS provides the mobile stations MS with organizational information about all the individual members of the antenna device.
  • connections with the useful information ni and signaling information si between the base station BS and the mobile stations MS are subject to multipath propagation, which is caused by reflections, for example, on buildings in addition to the direct propagation path.
  • the multipath propagation together with further interference leads to the signal components of the different propagation paths of a subscriber signal being superimposed on one another in the receiving mobile station MS. Furthermore, it is assumed that the subscriber signals from different base stations BS overlap at the receiving location to form a receiving signal rx in a frequency channel.
  • the task of a receiving mobile station MS is to detect data d of the useful information ni transmitted in the subscriber signals, signaling information si and data of the organizational information.
  • the frame structure of the radio interface is shown in FIG 2.
  • Each time slot ts within the frequency range B forms a frequency channel.
  • Information from a number of connections is transmitted in radio blocks within the frequency channels provided for the transmission of user data.
  • FDMA Frequency Division Multiple Access
  • the Radio communication system assigned several frequency ranges B.
  • these radio blocks for the transmission of user data consist of data parts with data symbols d, in which sections with middle names m known on the reception side are embedded.
  • the data d are spread individually for each connection with a fine structure, a feed code, so that, for example, K data channels DK1, DK2, DK3,... DKK can be separated at the receiving end by this CDMA component.
  • Each of these data channels DK1, DK2, DK3, .. DKK is assigned a specific energy E per symbol on the transmission side (power setting).
  • the spreading of individual symbols of the data d with Q chips has the effect that Q sub-sections of the duration Tc are transmitted within the symbol duration Ts.
  • the Q chips form the individual spreading code.
  • the midamble m consists of L chips, also of the duration Tc.
  • a protection time guard of the duration Tg is provided within the time slot ts to compensate for different signal propagation times of the connections of successive time slots ts.
  • the successive time slots ts are structured according to a frame structure. Eight time slots ts are thus combined to form a frame, a specific time slot of the frame forming a frequency channel for the transmission of useful data and being used repeatedly by a group of connections. Additional frequency channels, for example for frequency or time synchronization of the mobile stations MS, are not inserted in every frame, but at a predetermined point in time within a multi-frame.
  • the parameters of the radio interface are e.g. as follows: duration of a radio block 577 ⁇ s
  • the parameters can also be set differently in the upward (MS -> BS) and downward direction (BS -> MS).
  • the transmitters and receivers according to FIG. 4 and FIG. 5 relate to radio stations, which can be both a base station BS or a mobile station MS. However, only signal processing for one connection is shown.
  • the scrambled data is then modulated in a MOD 4-PSK modulator, converted into 4-PSK symbols and then spread out in spreading means SPR in accordance with individual spreading codes.
  • This processing is carried out in parallel in a data processing means DSP for all data channels DK1, DK2 of a connection. Not shown is that in the case of a base station BS, the other connections are also processed in parallel.
  • the data processing means DSP can be carried out by a digital signal processor, which is controlled by a control device SE.
  • the spread data of the data channels DK1 and DK2 are superimposed in a summing element S, the data channels DK1 and DK2 having the same weighting in this superimposition experienced and the midamble m is weighted such that the peak power of the midamble m corresponds to the total peak power of the data parts.
  • the different transmission conditions of the individual connections can be met by an appropriately set weighting.
  • the discrete-time representation of the transmission signal s for the m th subscriber can be carried out according to the following equation:
  • K (m) is the number of the data channels of the mth subscriber and N is the number of data symbols d per data part.
  • the superimposed subscriber signal is fed to a radio block generator BG, which compiles the radio block taking into account the connection-specific central am m.
  • the output signal of a chip pulse filter CIF which connects to the radio block generator BG, is modulated by GMSK and has an approximately constant envelope if the connection only uses a data channel.
  • the chip pulse filter CIF performs a convolution with a GMSK main pulse. However, a constant envelope is also achieved for the entire radio block.
  • a digital / analog conversion, a transmission into the transmission frequency band and an amplification of the signal are carried out in a transmitting device TX. 'Then the transmission signal is emitted via the antenna device and possibly reached.
  • the receiving radio station for example a mobile station MS, via different transmission channels.
  • An individual midamble consisting of L complex chips is used for each connection.
  • the necessary M Different middle names are derived from a basic middle code of length M * W, where M represents the maximum number of subscribers (connections) and W the expected maximum number of values of the channel impulse response h.
  • the connection-specific Mitambel m is derived by a rotation to the right of the Grundmitta belcode by W * m chips and periodic expansion to L> (M + 1) * W - 1 chips. Since the complex basic midamble code is derived from a binary midamble ql code by modulation with], the transmission signal of the midamble m is also GMSK modulated.
  • the power ratios of a radio block are shown in FIG. 6 a.
  • the summing device weights the data symbols d in the data part and midamble m such that the peak power in the radio block is constant. This means that the middle one
  • Power of the midamble m is greater than the average power of the data parts. This usually occurs because several data channels DK1, DK2 are transmitted simultaneously in the frequency channel and both have a constant envelope.
  • the increase in the average transmission power of the midamble m corresponds to the number of data channels (for example 4 or 8). However, in order to further improve the channel estimate on the receiving side, it is possible to increase the ratio beyond this ratio (see FIG. 6 b). This is particularly advantageous if shortened middle amps m are used in a transmission direction (in the downward direction).
  • the performance ratio also takes into account the extent to which the mid-length is shortened.
  • the channel estimation of all M channel impulse responses h is carried out in accordance with DE 197 34 936, however, the channel impulse responses h are normalized in accordance with the increase in power of the midamble m.
  • the data estimation in the joint detection data estimator DS is carried out jointly for all connections. After the detection of the data symbols d of the data channels DK1 and DK2, demodulation takes place in a demodulator DMO, a design in a deinterleaver DI and a channel decoding in the convolutional decoder FD.
  • the digital signal processing is controlled by a control device SE on the transmitting side and on the receiving side.
  • the control device SE controls, in particular, the number of data channels DK1, DK2 per connection, the spread codes of the data channels DK1, DK2, the current radio block structure, the setting of the transmission powers of the data part and the central part m and the requirements for the channel estimation.
  • the superimposition of the data symbols d in the summing element S is influenced by the control device SE.
  • the weighting of the data symbols of different data channels DK1, DK2 can thus be set.
  • data symbols d of a first category e.g. signaling information
  • the radio block generator BG is also controlled by the control device SE and thus the energy per symbol is set.
  • FIG. 6 shows the power ratios within a radio block for the peak and average transmission power.
  • the aim here is that the dynamic range offered by the amplifier arrangements within the transmitting device TX is used, but at the same time no additional dynamics are necessary between data parts and midamble. If there is a dynamic reserve in the amplifier arrangements, it can be used to increase the transmission power of the midamble m.
  • the channel estimate is improved at the receiving end by increasing the power of the midamble m, so that the subsequent data detection also delivers a more reliable result. If an estimated value postprocessing is carried out in the channel estimation, ie channel coefficients are set with a power less than a predefinable threshold value equal to zero, additional profits can be achieved.
  • a further influence on the data rate is that it is not assumed that the radio block structure is constant, but that the control device SE changes the radio block structure.
  • the length of the midamble m can be adapted to the terrain conditions. In the case of complicated terrain conditions, e.g. in the high mountains or in fjords, the length of the midamble m is extended at the expense of the data parts. For simple terrain, e.g. flat land, the midamble m can be shortened.
  • the mobile radio network presented in the exemplary embodiments with a combination of FDMA, TDMA and CDMA is suitable for requirements on 3rd generation systems.
  • it is suitable for an implementation in existing GSM mobile radio networks, for which only a small amount of change is required.

Abstract

Dans un système de radiotélécommunications, au moins deux canaux de données sont transmis par l'intermédiaire d'une interface radio. Les canaux de données peuvent être différenciés par un code d'écartement individuel. Dans un canal de données, outres des symboles de données, il est prévu de transmettre un mi-ambule avec des symboles connus, la puissance d'émission moyenne du mi-ambule étant supérieure à celle des symboles de données. Ce procédé se caractérise en ce qu'il s'utilise notamment dans des réseaux radio mobiles TD/AMCR de la troisième génération.
EP98961001A 1997-10-16 1998-10-09 Procede et station radio pour transmettre des donnees Withdrawn EP1023790A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19745789 1997-10-16
DE19745789 1997-10-16
PCT/DE1998/002997 WO1999020011A1 (fr) 1997-10-16 1998-10-09 Procede et station radio pour transmettre des donnees

Publications (1)

Publication Number Publication Date
EP1023790A1 true EP1023790A1 (fr) 2000-08-02

Family

ID=7845758

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98961001A Withdrawn EP1023790A1 (fr) 1997-10-16 1998-10-09 Procede et station radio pour transmettre des donnees

Country Status (4)

Country Link
EP (1) EP1023790A1 (fr)
CN (1) CN1282471A (fr)
AU (1) AU1660099A (fr)
WO (1) WO1999020011A1 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3960373B2 (ja) * 1999-12-15 2007-08-15 ローク マナー リサーチ リミテッド 電気通信システムの送信電力制御方法及び装置
EP1598989A1 (fr) * 2004-04-30 2005-11-23 Siemens Aktiengesellschaft Procede, station d'abonne et dispositif de reseau pour la communication radio, en particulier dans le contexte de services HSDPA
WO2017026399A1 (fr) * 2015-08-13 2017-02-16 株式会社Ｎｔｔドコモ Terminal utilisateur, station de base sans fil et procédé de communication sans fil
NO20172061A1 (en) * 2017-12-29 2019-07-01 Elkem Materials Cast iron inoculant and method for production of cast iron inoculant

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07297776A (ja) * 1994-04-22 1995-11-10 Oki Electric Ind Co Ltd 通信システム
FI99182C (fi) * 1994-05-26 1997-10-10 Nokia Telecommunications Oy Menetelmä tukiaseman yleislähetyskanavan kuuluvuuden parantamiseksi, sekä solukkoradiojärjestelmä
DE19549148A1 (de) * 1995-12-29 1997-07-03 Siemens Ag Verfahren und Anordnung zur Funkübertragung von digitalen Signalen

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9920011A1 *

Also Published As

Publication number Publication date
CN1282471A (zh) 2001-01-31
AU1660099A (en) 1999-05-03
WO1999020011A1 (fr) 1999-04-22

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