WO2006064389A2 - Procede et dispositif permettant de realiser un traitement adapte a la voie - Google Patents

Procede et dispositif permettant de realiser un traitement adapte a la voie Download PDF

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Publication number
WO2006064389A2
WO2006064389A2 PCT/IB2005/054036 IB2005054036W WO2006064389A2 WO 2006064389 A2 WO2006064389 A2 WO 2006064389A2 IB 2005054036 W IB2005054036 W IB 2005054036W WO 2006064389 A2 WO2006064389 A2 WO 2006064389A2
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WO
WIPO (PCT)
Prior art keywords
radio signals
detection method
processing
received radio
channel estimation
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Application number
PCT/IB2005/054036
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English (en)
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WO2006064389A3 (fr
Inventor
Gang Wu
Yueheng Li
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Koninklijke Philips Electronics N.V.
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.)
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Application filed by Koninklijke Philips Electronics N.V. filed Critical Koninklijke Philips Electronics N.V.
Publication of WO2006064389A2 publication Critical patent/WO2006064389A2/fr
Publication of WO2006064389A3 publication Critical patent/WO2006064389A3/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69—Spread spectrum techniques
    • H04B1/707—Spread spectrum techniques using direct sequence modulation
    • H04B1/7097—Interference-related aspects
    • H04B1/7103—Interference-related aspects the interference being multiple access interference
    • H04B1/7105—Joint detection techniques, e.g. linear detectors
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69—Spread spectrum techniques
    • H04B1/707—Spread spectrum techniques using direct sequence modulation
    • H04B1/7097—Interference-related aspects
    • H04B1/7103—Interference-related aspects the interference being multiple access interference
    • H04B1/7107—Subtractive interference cancellation
    • H04B1/71075—Parallel interference cancellation

Definitions

  • the present invention relates generally to a communication method and apparatus, and more particularly, to a method and apparatus for processing received radio signals.
  • TD-SCDMA is one of 3G mobile communication standards, and it can allow different users to receive and transmit radio signals in the same frequency band (wireless channel) by allocating different timeslots and spreading codes to different users.
  • the radio signals received over the wireless channel are usually affected by two kinds of interferences: one is ISI (inter-symbol interference) between adjacent symbols (or chips) in the signals associated with a single user due to multipath fading and delay extension; another is MAI (multiple access interference) between different user signals caused by sharing of the same frequency band by different users and loss of orthogonality between different spreading codes allocated for different users.
  • ISI inter-symbol interference
  • MAI multiple access interference
  • Rake reception is an early proposed signal detection method, in which the receiving side separates the desired signal from the received signals by using a filter matched with the spreading code of the transmitting side, in combination with multi-path channel impulse response (CIR).
  • CIR channel impulse response
  • JD Joint Detection
  • radio signal transmission will also be affected by other factors, such as communication environment like weather or obstacles, moving speed and etc. While in an environment where the visibility is very low and there are many obstacles, if the communicating user happens to be in high-speed motion, the radio signal will lose some energy during propagation, thus it's very likely to get greatly faded signals at the receiver side. In this case, even JD can't meet the QoS requirement.
  • a modified multiuser detection method is proposed, combining JD technology with PIC (Parallel Interference Cancellation) technology.
  • This method also performs JD on the received signals based on taking full advantage of all user signals that caused the MAI, estimates the interference between user signals according to known information like the spreading code of each user, and subtracts the estimated interference from the received signals, thus to facilitate data decision of the received signals.
  • Multiuser detection method is, therefore, becoming a research hotspot in 3G mobile communication system based on CDMA. But in practical applications, multiuser detection technology increases the complexity of the system hardware, and increases the processing time delay in particular, which becomes a problem to be addressed.
  • An object of the present invention is to provide a method and apparatus for adaptively processing received radio signals, with which a suitable signal detection method can be chosen adaptively to process received signals according to different wireless channel quality, so as to shorten the processing time and decrease power consumption on the basis of meeting the system performance requirement.
  • a method for processing the received radio signals comprising the steps of: performing channel estimation on the wireless channel transferring the radio signals, according to the received radio signals; choosing a corresponding signal detection method to process the received radio signals according to the channel estimation result, to cancel the MAI corrupting the radio signals.
  • An apparatus for processing the received radio signals comprising: a channel estimation unit, for performing channel estimation on the wireless channel transferring the radio signals, according to the received radio signals; an adaptive processing unit, for choosing a corresponding signal detection method to process the received radio signals according to the channel estimation result, to cancel the MAI corrupting the radio signals.
  • a wireless terminal comprising: a receiving unit, for receiving radio signals; a channel estimation unit, for performing channel estimation on the wireless channel transferring the radio signals, according to the received radio signals; an adaptive processing unit, for choosing a corresponding signal detection method to process the received radio signals according to the channel estimation result, to cancel the MAI corrupting the radio signals.
  • Fig.l illustrates a block diagram of the receiver for performing channel adaptive processing on the received radio signals in accordance with an embodiment of the present invention
  • Fig.2 illustrates a flowchart of the method for performing channel adaptive processing on the received radio signals in accordance with an embodiment of the present invention
  • Fig.3 illustrates a flowchart on how to apply different detection methods on the received radio signals according to the channel estimation results in accordance with an embodiment of the present invention.
  • channel estimation is performed on the wireless channel transferring the radio signals, then a suitable signal detection method is chosen to process the radio signals according to the channel estimation result, to get the radio signals with MAI and ISI canceled, for subsequent baseband processing.
  • Fig.l is a block diagram illustrating the receiver for performing channel adaptive processing on the received radio signals for use in TD-SCDMA system in accordance with an embodiment of the present invention.
  • the proposed receiver Compared with a normal receiver for performing spreading code matching on each user signal respectively according to conventional DSSS (Direct Sequence Spreading Spectrum) theory, the proposed receiver adds two switches 50 and 60 and several functional blocks (such as decorrelator 70 and parallel interference canceller 80) performing different detection algorithms respectively and corresponding to the operational modes of the two switches.
  • the two switches can switch to different branches under the control of channel estimation unit 30, to perform the detection method corresponding to the channel estimation result.
  • antenna 10 first receives analog radio signals. After being filtered and over- sampled at match filter & over- sampler 20, the generated digital signals are sent to channel estimation unit 30.
  • Channel estimation unit 30 estimates the digital signals, to determine the channel condition of the radio signals.
  • the channel estimation result indicates the wireless channel transferring the wireless signals only includes one main propagation path or the wireless channel is AWGN (Additive White Gaussian Noise).
  • AWGN Additional White Gaussian Noise
  • Rake receiver can meet the system QoS requirement, thus switch 50 is switched on position 1 under the control of channel estimation unit 30.
  • switch 60 and functional blocks like decorrelator 70 and parallel interference canceller 80 are in non-operating status, and the receiver functions as a Rake receiver, wherein Rake receiving unit 40 performs signal separation on the digital signals from match filter and over- sampler 20 to get the desired signals.
  • the separated desired signals are inputted into demapping unit 100 via the branch of position 1, for subsequent baseband processing, i.e. to get the baseband digital signals via demapping at demapping unit 100, the first de-interleaving at first de-interleaving unit 110, radio frame combination at radio frame combining unit 120, the second de-interleaving at second de-interleaving unit 130 and decoding at channel decoding unit 140.
  • the channel estimation result by estimating the wireless channel transferring the radio signals shows that the wireless channel includes two main propagation paths, each with moving speed not more than 30km/h and different and not exponentially fading power for transferring signals, SIR (Signal-to-interference Ratio) will deteriorates seriously if only Rake signal separation method is used to take MAI as interference like thermal noise.
  • SIR Signal-to-interference Ratio
  • channel estimation unit 30 should control switch 50 to be switched to position 2 and switch 60 to position 1.
  • Rake processing unit is connected to decorrelator 70 via the branch of position 2, and thus a JD receiver is constructed.
  • the separated multipath signals are inputted into decorrelator 70.
  • decorrelator 70 according to the spreading codes and channel impulse responses of all users, ZF-BLE algorithm for example, is performed on the multipath signals, thus to separate multiple user signals overlaid in time domain and frequency domain into individual user signals.
  • Each separated user signal is inputted into demapping unit 100 via the branch of position 1 of switch 60, for subsequent baseband processing.
  • the spreading codes of all users needed for performing JD algorithm can be provided to decorrelator 70 after being detected by spreading code detection unit 90 according to the channel estimation result of channel estimation unit 30.
  • channel estimation unit 30 controls switches 50 and 60 to switch to their respective position 2.
  • Rake processing unit is connected with decorrelator 70 via the branch of position 2 of switch 50 and connected with parallel interference canceller 80 via the branch of position 2 of switch 60, thus to construct a receiver combining JD and PIC.
  • the digital signals from match filter & over- sampler 20 are processed at Rake processing unit and decorrelator 70, and then all resulting user signals are inputted to parallel interference canceller 80 via position 2 of switch 60.
  • Parallel interference canceller 80 has a multilevel architecture. According to the spreading codes of all users provided from spreading code detection unit 90, each level of the multilevel architecture estimates and cancels the MAI each user causes in parallel, and inputs the final desired user signals to demapping unit 100, for subsequent baseband processing.
  • JD is performed on the received signals before PIC, which improves the reliability of data inputted to the parallel interference canceller, hence this detection method combining
  • PIC algorithm can cancel MAI and ISI more precisely, compared with single JD.
  • the particular case can be one of the following three cases:
  • the wireless channel transferring the radio signals has three or more main propagation paths;
  • the wireless channel has two main propagation paths, each with movement speed more than 30km/h;
  • the wireless channel has two main propagation paths, transferring signals with almost the same or exponentially fading power.
  • step SlO After receiving the radio signals transferred over the wireless channel (step SlO), channel estimation is performed on the wireless channel transferring the radio signals according to the received radio signals (step S20). According to the channel estimation result, the corresponding signal detection method is executed to cancel the multipath interference corrupting the radio signals (step S30).
  • step S30 the specific implementation procedure of step S30 is shown in Fig.3.
  • step S301 determine whether the wireless channel transferring the radio signals only includes a main propagation path or the wireless channel is AWGN, according to the channel estimation result (step S301). If the channel estimation result shows that the wireless channel only includes a main propagation path or the wireless channel is AWGN, Rake reception method is chosen to process the received radio signals (step S306).
  • step S301 determines whether the wireless channel includes three or more main propagation paths (step S302). If the answer at step S302 is yes, the detection method combining JD and PIC is chosen to process the received radio signals (step S307). If the answer at step S302 is no, that is, the channel estimation result shows that the wireless channel includes two main propagation paths, determine whether the moving speed of the two propagation paths is above 30km/h (step S303). If the answer at step S303 is yes, the detection method combining JD and PIC is chosen to process the received radio signals (step S307).
  • step S304 determines whether the two propagation paths have basically the same power for transferring signals. If the answer at step S304 is yes, the detection method combining JD and PIC is chosen to process the received radio signals (step S307).
  • step S304 determines whether the two propagation paths transfer signals with power exponentially fading (step S305). If the answer at step S305 is yes, the detection method combining JD and PIC is chosen to process the received radio signals (step S307).
  • JD method is chosen to process the received radio signals (step S308).
  • Matrix n is the noise vector corrupting the received signal.
  • the structure of the generalized channel matrix A is shown as:
  • each shadowed rectangle represents one column vector
  • the CIR vector h ( "° or namely propagation channel parameters h*" 0 in equation (2) can usually be obtained by evaluating the midamble embedded in the timeslot.
  • Rake receiver According to the estimated propagation channel parameters h (TM ' , if the noise vector n in equation (1) is AWGN, Rake receiver should be adopted in accordance with the present invention.
  • the operation to be performed by Rake receiver can be expressed as:
  • JD JD is performed can be represented as:
  • [.] represents inverse operation of matrix.
  • the algorithm is in fact a maximum likelihood (ML) detection, which jointly processes the received signals of all the UEs.
  • a 2 is the (Mn - M + m) th column of A where bjf' stays.
  • (T - A 1 1 M) in equation (5) is the operation of MAI cancellation.
  • the receiver can employ the architecture shown in Fig.l, wherein switches 50 and 60 and channel estimation unit 30 construct a mode selection unit and chooses the corresponding signal detection method (e.g. Rake reception, JD, combining JD and PIC) according to the channel estimation result, so as to shorten processing time delay and save power consumption as much as possible on the basis of satisfying QoS requirement; or the channel estimation unit and a determining unit (not given here) construct a mode selection unit, the determining unit choosing the corresponding signal detection method according to the channel estimation result and controlling the receiver to correspondingly configure the component for performing the chosen signal detection method, thus to realize the receiver function shown in Fig.l and reduce the receiver size and decrease the hardware cost as well.
  • switches 50 and 60 and channel estimation unit 30 construct a mode selection unit and chooses the corresponding signal detection method (e.g. Rake reception, JD, combining JD and PIC) according to the channel estimation result, so as to shorten processing time delay and save power consumption as much as possible on the basis of satisfying QoS requirement
  • the receiver and the channel adaptive processing method it performs it's suitable for mobile terminals, and equally applicable to base stations as well.
  • the proposed receiver and the channel adaptive processing method it performs can choose any of Rake receiver, JD and detection method combining JD and PIC adaptively. Therefore, the present invention can realize synthesized optimization of combating MAI and ISI, shortening processing time delay and saving power, compared with conventional radio signal receiver and the single receiving and processing method it adopts.
  • the method and apparatus for performing adaptive processing on the received radio signals as disclosed in this invention is not only suitable for TD-SCDMA system, but also applicable to a lot of CDMA-based communication systems, like UMTS TDD system. It is to be understood by those skilled in the art that the method and apparatus for performing adaptive processing on the received radio signals as disclosed in this invention can be modified without departing from the scope of the invention as defined by the appended claims.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Noise Elimination (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)

Abstract

L'invention concerne un procédé destiné au traitement de signaux radio reçus, consistant à réaliser une estimation de voie sur la voie sans fil sur laquelle les signaux radio sont transmis, en fonction des signaux radio reçus, puis à sélectionner un procédé de détection de signal correspondant pour traiter les signaux radio reçus en fonction du résultat de l'estimation de voie et ainsi contrer les interférences à accès multiples (MAI) appliquées aux signaux radio.
PCT/IB2005/054036 2004-12-13 2005-12-05 Procede et dispositif permettant de realiser un traitement adapte a la voie WO2006064389A2 (fr)

Applications Claiming Priority (2)

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CN200410102122 2004-12-13
CN200410102122.8 2004-12-13

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WO2006064389A3 WO2006064389A3 (fr) 2006-09-14

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013040754A1 (fr) * 2011-09-20 2013-03-28 St-Ericsson Sa Procédé, appareil, récepteur, programme d'ordinateur et support de stockage pour une détection multiutilisateur

Citations (2)

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Publication number Priority date Publication date Assignee Title
DE19961594A1 (de) * 1999-12-21 2001-06-28 Bosch Gmbh Robert Verfahren für die Übertragung von Datensignalen zwischen einer Sendestation und mehreren Empfangsstationen, Sendestation und Empfangsstation
EP1233536A1 (fr) * 2000-09-29 2002-08-21 Matsushita Electric Industrial Co., Ltd. Demodulateur et procede de demodulation

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19961594A1 (de) * 1999-12-21 2001-06-28 Bosch Gmbh Robert Verfahren für die Übertragung von Datensignalen zwischen einer Sendestation und mehreren Empfangsstationen, Sendestation und Empfangsstation
EP1233536A1 (fr) * 2000-09-29 2002-08-21 Matsushita Electric Industrial Co., Ltd. Demodulateur et procede de demodulation

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Title
GANG WANG ET AL: "An efficient ZF-SIC detection algorithm in MIMO CDMA system" PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, 2003. PIMRC 2003. 14TH IEEE PROCEEDINGS ON SEPT. 7-10, 2003, PISCATAWAY, NJ, USA,IEEE, vol. 2, 7 September 2003 (2003-09-07), pages 1708-1711, XP010679421 ISBN: 0-7803-7822-9 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013040754A1 (fr) * 2011-09-20 2013-03-28 St-Ericsson Sa Procédé, appareil, récepteur, programme d'ordinateur et support de stockage pour une détection multiutilisateur
US9287924B2 (en) 2011-09-20 2016-03-15 St-Ericsson Sa Method, apparatus, receiver, computer program and storage medium for joint detection

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