WO2002103925A1 - Diversite de transmission dans un systeme cellulaire de communication radio - Google Patents

Diversite de transmission dans un systeme cellulaire de communication radio Download PDF

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Publication number
WO2002103925A1
WO2002103925A1 PCT/EP2002/006064 EP0206064W WO02103925A1 WO 2002103925 A1 WO2002103925 A1 WO 2002103925A1 EP 0206064 W EP0206064 W EP 0206064W WO 02103925 A1 WO02103925 A1 WO 02103925A1
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WO
WIPO (PCT)
Prior art keywords
data
bursts
blocks
sub
analysing
Prior art date
Application number
PCT/EP2002/006064
Other languages
English (en)
Inventor
Luis Lopes
Rorie O'neil
Original Assignee
Motorola Inc
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 Motorola Inc filed Critical Motorola Inc
Publication of WO2002103925A1 publication Critical patent/WO2002103925A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission

Definitions

  • This invention relates to transmission and reception in time division multiplexed access cellular radio communication systems.
  • the invention is applicable to, but not limited to, Global System for Mobile Communications (GSM) and Enhanced Data Rate for Global Evaluation (EDGE) cellular radio communication systems.
  • GSM Global System for Mobile Communications
  • EDGE Enhanced Data Rate for Global Evaluation
  • TDMA time division multiplexed access
  • C/N carrier to noise
  • C/I carrier to interference
  • Antenna hopping only delivers useful gains if the receiving communication unit, e.g. a mobile station such as a mobile telephone, is stationary, which implicitly limits the usefulness of the method.
  • the receiving communication unit e.g. a mobile station such as a mobile telephone
  • the present invention provides an open-loop diversity method for a time division multiplexed access cellular radio communication system, as claimed in claim 1.
  • the present invention provides a method of transmitting with open-loop diversity in a time division multiplexed access cellular radio communication system, as claimed in claim 16.
  • the present invention provides a method of receiving an open-loop diversity transmission in a time division multiplexed access cellular radio communication system, as claimed in claim 23.
  • the present invention provides a storage medium storing processor-imple entable instructions, as claimed in claim 33.
  • the present invention provides an apparatus, as claimed in claim 34.
  • the present invention provides a communication unit, as claimed in claim 35.
  • diversity is achieved by performing transmission (at least substantially) simultaneously (e.g. within the timing control of a single timeslot of the TDMA scheme) from multiple antennas to a receiving communication unit such as a mobile terminal.
  • This is open-loop diversity, i.e. is performed without the need to provide a feedback route, for optimising signal levels or phases in the different antennas, from the receiving communication unit to the transmitting unit. Therefore the present invention does not need feedback channels to achieve diversity gain.
  • the gain is not highly sensitive to the characteristics of the radio channel.
  • a diversity procedure more attuned to a TDMA cellular radio communication system is provided.
  • a cellular communication system implements provision, transmission, reception and processing of substantially simultaneous diversity bursts .
  • training sequences are modified to enable data from different antennas to be distinguished.
  • FIG. 1 is a schematic illustration of part of a cellular radio communication system
  • FIG. 2 is an illustration in schematic block diagram form of certain parts of a communication unit
  • FIG. 3 illustrates a decoding process
  • FIGS. 4A and 4B schematically illustrate processing functions employed by the communication unit of FIG. 2;
  • FIG. 5 is a schematic illustration of part of a cellular radio communication system.
  • FIG. 1 is a schematic illustration of part of a cellular radio communication system 100 in which a first embodiment may be implemented.
  • the system 100 is a GSM system modified to perform the diversity method of this embodiment .
  • a communication unit which may be described as a receiving communication unit in the context of this embodiment, and in this example is a mobile station (MS) 102 (e.g. a mobile telephone), receives communication service from a base transceiver station (BTS) 104.
  • the BTS 104 also constitutes a communication unit, and may be described as a transmitting communication unit in the context of this embodiment.
  • the BTS 104 is coupled to a base station controller (BSC) 108.
  • the BSC 108 is coupled to a mobile services switching centre (MSC) 110, which is itself coupled to a public switched telephone network (PSTN) 112.
  • PSTN public switched telephone network
  • the BTS 104 contains a plurality of antennas, of which two are shown, namely antennas 120 and 122. When this embodiment is implemented, both antenna 120 and antenna 122 form respective radio links 124 and 126 with the MS 102, and transmit TDMA bursts containing a same information content simultaneously (i.e. substantially simultaneously, preferably in the same timeslots) to the MS 102.
  • the BTS 104 and the MS 102 have been adapted, to offer, and provide for, open loop transmission diversity, as will be described in more detail below. More particularly, in this embodiment the BTS 104 has been adapted to implement the present invention in a transmitting mode of operation, and the communication unit 102 has been adapted to implement the present invention in a receiving mode of operation.
  • the adaptations may be implemented in the respective communications units in any suitable manner. For example, new apparatus may be added to a conventional communications unit, or alternatively existing parts of a conventional communications unit may be adapted, for example by reprogramming of one or more processors therein. As such the required adaptation may be implemented in the form of processor- implementable instructions stored on a storage medium, such as a floppy disk, hard disk, PROM, RAM or any combination of these or other storage media.
  • adaptation of transmission characteristics may alternatively be controlled, implemented in full or implemented in part by adapting any other suitable part of the communications system 100.
  • conventional BTSs comprising plural antennas, but in which the antennas conventionally only transmit different information content from each other, may be controlled by a modified BSC 108 such as to implement the present embodiment .
  • implementation may be at any appropriate node such as any other appropriate type of base station, base station controller etc.
  • various steps involved in determining and carrying out such adaptation can be carried out by various components distributed at different locations or entities within any suitable network or system.
  • the MS 102 and the BTS 104 each constitute a communications unit. Details of MS 102 will now be described with reference to FIG. 2, which is an illustration in schematic block diagram form of certain parts of MS 102 that are useful for understanding the present embodiment .
  • MS 102 contains an antenna 202 coupled to a duplex filter or circulator 204 that provides isolation between receive and transmit chains within the MS 102.
  • the receiver chain includes scanning receiver front-end circuitry 206 (effectively providing reception, filtering and intermediate or baseband frequency conversion) .
  • the scanning front-end circuit is serially coupled to a signal processing function 208.
  • the output 210 includes a loudspeaker for audio output, a display and a data services output. (In the case of BTS 104,- the corresponding output comprises interface means for communicating with the BSC 108.)
  • the receiver chain also includes received signal strength indicator (RSSI) circuitry 212, which in turn is coupled to a controller 214 that operates to maintain overall control of the different functions and modules of the MS 102.
  • RSSI received signal strength indicator
  • the controller 214 is also coupled to the scanning receiver front-end circuitry 206 and the signal processing function 208 (generally realised by a digital signal processor, i.e. DSP).
  • the controller 214 includes a memory 216 that stores operating regimes, including those of interest with respect to this invention such as analysing received bursts of data to distinguish between the different bursts of data, and retrieving information content from the distinguished bursts of data, as will be described in more detail below.
  • a timer 218 is typically coupled to the controller 214 to control the timing of operations (transmission or reception of time-dependent signals) within the MS 102.
  • Input 220 includes a microphone for a user's voice input, and a keyboard.
  • input 220 comprises interface means for receiving communication from BSC 108.
  • the input device is coupled in series through transmitter/modulation circuitry 222 and a power amplifier 224 to the antenna 202.
  • the transmitter/modulation circuitry 222 and the power amplifier 224 are operationally responsive to the controller 214.
  • MS 102 applies equally to BTS 104, except that BTS 104 has plural antennas.
  • MS 102 and BTS 104 are realised in this embodiment in integrated component form. Of course, in other embodiments, they may be realised in discrete form, or a mixture of integrated components and discrete components, or indeed any other suitable form. Further, in this embodiment the controller 214 including memory 216 is implemented as a programmable processor, but in other embodiments can comprise dedicated circuitry or any other suitable form.
  • MS 102 and BTS 104 differ over conventional communication units by virtue that the controller 214, including memory 216, and where appropriate, the signal processing function 208 and the transmitter/modulation circuitry 222 is adapted with respect to provision (BTS 104) , transmission (BTS 104), reception (MS 102) and processing (MS 102) of substantially simultaneous diversity bursts, as will be described in more detail below.
  • the two sequences are theoretically orthogonal over a 16- symbol span, since essentially they are complex sinusoids modulated by the same pseudo-random sequence with a good auto correction. They will also remain orthogonal in spite of delays since the orthogonality between the complex sinusoids is maintained even with a phase shift. Hence it is possible to detect the mode by correlating with the two possible transmitted sequences. Mode detection errors will be caused by high relative noise levels or excessive multipath.
  • this concept is generalised by transmitting simultaneously (i.e. not selectively) from multiple antennas with the same sequence and different shifts.
  • the MS 102 analyses the received training sequence but splits it into multiple copies using the knowledge that the phase rotations are different. In this way the MS 102 can identify the channels from the multiple base station antennas to the mobile antenna. Negative shifts can also be used.
  • Example 1 for 2-antenna in GMSK mode (i.e. normal GSM) Use exp ( j n ⁇ / 2) and exp ( - j n ⁇ / 2)
  • the MS 102 has separate correlators 'tuned' into the orthogonal sequences, each one then obtains a channel estimate corresponding to the signal path from each antenna to the MS. It is noteworthy that as well as normal estimate corruption due to noise and multipath, some cross-correlation may also result in high multipath conditions.
  • the sequences are orthogonal only when assuming circular repetition, and thus as multipath effects appear some cross-correlation will also appear due to the effects of the data symbols on either side of the sequence .
  • PA Power Amplifier
  • sub-blocks A and B The data contained in sub-blocks A and B is repeated in the second burst type 320, transmitted from the second antenna 122, but with several differences:
  • one of the sub-blocks is inverted in amplitude. This is useful for the data manipulation detailed below.
  • the burst 320 from the second antenna 122 comprises a first sub-block B' (indicated by reference numeral ' 322) , a training sequence TS2 (indicated by reference numeral 326) and a second sub-block "inverted A' " (represented by the character " '" with a bar thereover) (indicated by reference numeral 324) .
  • the channel gain is hi for the first antenna link and h2 for the second.
  • the signal Si received in the first sub-block, and the signal S2 received in the second sub-block are respectively:
  • FIG. 4A shows the overall signal SI from the respective first sub-blocks 312 and 322 being passed through a matched filter 410 that is matched to channel 1 , and the overall signal S2 from the respective second sub-blocks 314 and 324 being passed through a further matched filter 415 which is matched to channel 2.
  • the outputs from the two matched filters are added in a combiner 420 and then forwarded to an equaliser 425, which equalises the outputs.
  • FIG. 4B shows the same arrangement, except that one of the inputs to the combiner 420 is inverted.
  • the equaliser consists of a maximum likelihood sequence estimator, using the knowledge of the two channels. It is clear that in the general case there is considerable interference from sequence A into B and vice-versa due to the channel dispersion and the matched filter. If either channel is much larger than the other, then there is no issue since this interference will be small. However, even in this case there may be significant cross-sequence interference if the symbols are not alternately real and imaginary as in some modes in EDGE. In this embodiment either of two ways may be used to carry out the 'unwrapping' of this interference:
  • the receiver now benefits from the channel gains from the two antennas, thereby reducing fading (diversity gain) .
  • two antennas are used to provide diversity
  • a larger number of antennas may be used.
  • the scheme is extended to more antennas by designing other burst mappings.
  • the plural antennas are located at the same BTS 104.
  • the different antennas may each be at different respective BTSs.
  • FIG. 5 shows the system 100 of FIG. 1 with such an arrangement. In FIG. 5, all the items are the same as in FIG. 1 (and indicated by the same reference numerals) , except that in this embodiment BTS 104 is replaced by BTS 105 and BTS 106, each carrying one of the antennas 120, 122.
  • MS 102 is a mobile telephone, but the receiving communication unit may include or consist of any other appropriate form of radio receiving apparatus, for example personal computers with radio modems, electronic organisers, video and/or audio players, etc.
  • the present invention finds particular application in wireless communication systems such as UMTS or EDGE systems.
  • inventive concepts contained herein are equally applicable to alternative wireless communications systems. Whilst the specific, and preferred, implementations of the present invention are described above, it is clear that variations and modifications of such inventive concepts could be readily applied by one skilled in the art.
  • the receiver benefits from the channel gains from the two antennas, thereby reducing fading (diversity gain) ;
  • the scheme may be readily extended to more antennas by designing other burst mappings.

Abstract

L'invention concerne un procédé de diversité en boucle ouverte pour un système (100) cellulaire de communication radio à accès multiples et division de temps, ce procédé comprenant les opérations suivantes : disposer d'une pluralité de rafales de données (310, 320), chacune ayant un contenu d'information commun avec les autres rafales, de sorte qu'elles peuvent être distinguées les unes des autres à la réception ; transmettre sensiblement simultanément ces rafales de données à partir de différentes antennes respectives (120, 122); recevoir les rafales de données des différentes antennes ; analyser les rafales de données reçues pour en faire la distinction ; extraire le contenu d'information des rafales de données ainsi identifiées. Le système cellulaire de communication comprend donc la fourniture, la transmission, la réception et le traitement de rafales de données de diversité sensiblement simultanée. Dans un mode de réalisation préféré, des séquences de formation (316, 326) sont modifiées pour permettre de distinguer les données provenant de différentes antennes.
PCT/EP2002/006064 2001-06-15 2002-06-03 Diversite de transmission dans un systeme cellulaire de communication radio WO2002103925A1 (fr)

Applications Claiming Priority (2)

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GB0114660.4 2001-06-15
GB0114660A GB2376601B (en) 2001-06-15 2001-06-15 Transmission diversity in a cellular radio communication system

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004059877A1 (fr) * 2002-12-30 2004-07-15 Koninklijke Philips Electronics N.V. Dispositif active pour l'optimisation du rendement spectral d'une liaison sans fil
DE102004035018A1 (de) * 2004-07-20 2006-02-16 Siemens Ag Verfahren zur Signalübertragung in einem Kommunikationssystem

Families Citing this family (1)

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Publication number Priority date Publication date Assignee Title
WO2006084625A1 (fr) 2005-02-08 2006-08-17 Alcatel Lucent Procede et dispositif de gestion de la transmission de liaisons radio dans un systeme de radiocommunication

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EP0674455A1 (fr) * 1993-10-12 1995-09-27 Ntt Mobile Communications Network Inc. Procede de transmission multistation et recepteur utilise a cet effet
EP1069707A1 (fr) * 1999-07-13 2001-01-17 Motorola, Inc. Emetteur et récepteur de diversité d'émision pour des systèmes de communications par radio
EP1128575A1 (fr) * 2000-02-22 2001-08-29 TELEFONAKTIEBOLAGET L M ERICSSON (publ) Evaluation de canal dans un récepteur en diversité utilisant des séquences d'apprentisssage simultanément transmises
WO2002043277A1 (fr) * 2000-11-23 2002-05-30 Nokia Corporation Procede de transmission d'informations dans un systeme de communication, systeme de communication et dispositif de communication sans fil
WO2002049236A2 (fr) * 2000-12-13 2002-06-20 Interdigital Technology Corporation Codeur en diversite d'emission a code spatio-temporel a bloc modifie

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EP0674455A1 (fr) * 1993-10-12 1995-09-27 Ntt Mobile Communications Network Inc. Procede de transmission multistation et recepteur utilise a cet effet
EP1069707A1 (fr) * 1999-07-13 2001-01-17 Motorola, Inc. Emetteur et récepteur de diversité d'émision pour des systèmes de communications par radio
EP1128575A1 (fr) * 2000-02-22 2001-08-29 TELEFONAKTIEBOLAGET L M ERICSSON (publ) Evaluation de canal dans un récepteur en diversité utilisant des séquences d'apprentisssage simultanément transmises
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WO2002049236A2 (fr) * 2000-12-13 2002-06-20 Interdigital Technology Corporation Codeur en diversite d'emission a code spatio-temporel a bloc modifie

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004059877A1 (fr) * 2002-12-30 2004-07-15 Koninklijke Philips Electronics N.V. Dispositif active pour l'optimisation du rendement spectral d'une liaison sans fil
DE102004035018A1 (de) * 2004-07-20 2006-02-16 Siemens Ag Verfahren zur Signalübertragung in einem Kommunikationssystem

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GB2376601B (en) 2004-02-25
GB0114660D0 (en) 2001-08-08
GB2376601A (en) 2002-12-18

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