WO2011075895A1 - Système et procédé de réception en liaison montante lte - Google Patents

Système et procédé de réception en liaison montante lte Download PDF

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Publication number
WO2011075895A1
WO2011075895A1 PCT/CN2009/075904 CN2009075904W WO2011075895A1 WO 2011075895 A1 WO2011075895 A1 WO 2011075895A1 CN 2009075904 W CN2009075904 W CN 2009075904W WO 2011075895 A1 WO2011075895 A1 WO 2011075895A1
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WO
WIPO (PCT)
Prior art keywords
frequency offset
fast fourier
fourier transform
compensators
arbitrary
Prior art date
Application number
PCT/CN2009/075904
Other languages
English (en)
Inventor
Johansson Jan
Aijun Cao
Yonghong Gao
Original Assignee
Zte Wistron Telecom Ab
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 Zte Wistron Telecom Ab filed Critical Zte Wistron Telecom Ab
Priority to PCT/CN2009/075904 priority Critical patent/WO2011075895A1/fr
Publication of WO2011075895A1 publication Critical patent/WO2011075895A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2657—Carrier synchronisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2668—Details of algorithms
    • H04L27/2669—Details of algorithms characterised by the domain of operation
    • H04L27/2671—Time domain
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2668—Details of algorithms
    • H04L27/2681—Details of algorithms characterised by constraints
    • H04L27/2684—Complexity

Definitions

  • the present invention relates to a communication technology, and especially to an uplink receiving system and method in LTE (Long Term Evolution) base-stations.
  • LTE Long Term Evolution
  • the multi-carrier with orthogonal frequencies is introduced into the next generation industry standard, such as OFDM (Orthogonal Frequency Division Multiplexing) for downlink or SC-FDMA (Single Carrier-Frequency Division Multiple Access) for uplink in LTE.
  • OFDM Orthogonal Frequency Division Multiplexing
  • SC-FDMA Single Carrier-Frequency Division Multiple Access
  • LTE is the name given to a project within the Third Generation Partnership Project to improve the UMTS (Universal Mobile Telecommunications System) mobile phone standard to cope with future technology evolutions.
  • UMTS Universal Mobile Telecommunications System
  • One of the goals of LTE is improving the spectral efficiency. Since the orthogonal frequency provides much more flexibility to allocate the radio resource than the current cellular standards, thus LTE improves the spectral efficiency.
  • the processing delay is much smaller compared to the former cellular communication systems such as WCDMA (Wideband Code Division Multiple Access) etc, from hundreds of ms down to 10ms.
  • WCDMA Wideband Code Division Multiple Access
  • the constraint on the processing delay by nature prohibits the complex techniques or algorithms in base-band which may possibly introduce too much processing delay.
  • the inventors found that actually for each individual UE, the best way to compensate the frequency offset is to do it before the system FFT, and after the system FFT, the corresponding RBs (Resource Blocks) assigned to the concerned UEs could be correctly adjusted in the frequency domain, which thus benefit the subsequent processing such as channel estimation etc.
  • the invention provides an uplink receiving system and method in LTE base-stations with a good trade-off between the performance and the complexity.
  • the present invention provides a method for uplink receiving in Long Term Evolution base-stations, comprising:
  • each compensator compensating the signal with both a fixed and an arbitrary frequency offset
  • This method of the present invention may further comprise the following step:
  • This method of the present invention may further comprise the following step:
  • a selected resource block for a concerned user equipment could have the closest frequency offset to the estimated frequency offset of the concerned user equipment.
  • the fixed frequency offset can be 7.5Hz.
  • this method of the present invention may comprise the following step:
  • k-means algorithm can be used to calculate arbitrary frequency offsets of all frequency offset compensators.
  • the present invention also provides a system for uplink receiving in Long Term Evolution base-stations, comprising:
  • a frequency offset compensator bank including a plurality of frequency offset compensators; a system Fast Fourier Transform bank including a plurality of system Fast Fourier Transform blocks; and
  • each frequency offset compensator is followed by one system Fast Fourier Transform block and is configured to compensate an input signal with both a fixed and an arbitrary frequency offset;
  • each system Fast Fourier Transform block is configured to make system Fast Fourier Transform to a compensated signal of its preceding frequency offset compensator to yield a resource block;
  • each system Fast Fourier Transform selector has a concerned user equipment and is configured to select a resource block for the concerned user equipment.
  • the system of the present invention may further comprise:
  • each frequency offset estimator being associated with a user equipment and being configured to estimate frequency offset for its associated user equipment on the basis of resource blocks yielded by the system Fast Fourier Transform bank.
  • the system may further comprise:
  • an dynamic arbitrary frequency offset calculation block being configured to calculate and update arbitrary frequency offsets for all of the frequency offset compensators for next period.
  • the fixed frequency offset used by the frequency offset compensators can be 7.5Hz.
  • a resource block selected by a system Fast Fourier Transform selector has the closest frequency offset to the estimated frequency offset of the concerned user equipment of the system Fast Fourier Transform selector.
  • the dynamic arbitrary frequency offset calculation block can be configured to calculate arbitrary frequency offsets for all of the frequency offset compensators with a k-means algorithm.
  • the input signal is compensated with an arbitrary frequency offset plus the fixed frequency offset, such as 7.5kHz.
  • the RBs assigned for the concerned UE from the system FFT block with the closest arbitrary frequency offset are chosen for the further processing such as channel estimation, demodulation and decoding etc.
  • the present invention decreases the computational complexity of the system by compensating the input signal before system FFT, and improves performance of the system by using more than one FFT blocks with each FFT block preceded by a frequency offset compensator, each compensator compensating the input signal with both a fixed and an arbitrary frequency offset.
  • the corresponding RBs assigned to the concerned UEs can be correctly adjusted in the frequency domain, which thus benefits the subsequent processings such as channel estimation etc.
  • Figure 1 shows the LTE uplink receiver system of the present invention.
  • FIG. 2 shows the LTE uplink receive method of the present invention.
  • the LTE uplink receiver system of the invention is shown in Figure 1.
  • This system includes a frequency offset compensator bank composed of N (N>1) frequency offset compensators, a system FFT bank composed of N system FFT blocks, M (M>1) frequency offset estimators for M UEs, M system frequency offset selectors for the M UEs, and a dynamic arbitrary frequency offset calculation block.
  • Each frequency offset compensator is followed by one system FFT block and is configured to compensate an input signal with both a fixed and an arbitrary frequency offset.
  • the compensated result of a frequency offset compensator is input to its following system FFT block.
  • each system FFT block is configured to receive a compensated signal and make system FFT to it to result a resource block.
  • each frequency offset estimator is associated with a UE and is configured to estimate frequency offset of its associated UE.
  • Each system FFT selector is concerned with a UE and is configured to select a resource block from results of all system FFT blocks for its concerned UE.
  • the dynamic arbitrary frequency offset calculation block is configured to calculate and update arbitrary frequency offsets for all of the frequency offset compensators.
  • N arbitrary frequency offset values (o , ⁇ ,.,., ⁇ ) are initialized with zeroes, or some coarse estimates from the random access procedure. Then during the uplink receiving process, follow steps are performed:
  • the frequency offset compensator bank receives a base-band signal from an Analog-to-Digital converter (ADC) and compensates the received signal with its N frequency offset compensators, wherein each compensator compensate the signal with both a fixed and an arbitrary frequency offset, and the fixed frequency offset is predefined in the protocol, such as 7.5Hz.
  • ADC Analog-to-Digital converter
  • Compensated signals of the N frequency offset compensators are put into the N following system FFT blocks respectively, and system FFTs are made on these compensated signals to result resource blocks.
  • Resource blocks are selected for concerned UEs for subsequent processings such as channel estimation.
  • a criterion must be used to determine which resource block is to be selected for the concerned UE.
  • a resource block with closest frequency offset to frequency offset of the concerned UE will be best.
  • frequency offset of each UE can be jointly estimated based on the resource blocks of the system FFT bank. The method of this estimation can be a known method in the art.
  • arbitrary frequency offset of each frequency offset compensator could be updated.
  • dynamic categorization algorithm such as k-means algorithm is used to calculate and update arbitrary frequency offsets of all frequency offset compensators based on the estimated frequency offsets of all UEs.
  • the frequency offset compensator bank receives a base-band signal from an ADC and compensates the received signal with its N frequency offset compensators, wherein each compensator compensate the signal with both a fixed and an arbitrary frequency offset.
  • Compensated signals of the N frequency offset compensators are put into the N following system FFT blocks respectively, and system FFTs are made on these compensated signals to result resource blocks.
  • the method for estimating frequency offset of a UE is known to those skilled in this art.
  • resource blocks are chosen for concerned UEs.
  • a resource block chosen for a concerned UE has closest frequency offset to that of the concerned UE.
  • the frequency offset of a resource block means the frequency offset used by the frequency offset compensator that precedes the system FFT block which generate the resource block . For example, among all the frequency offset compensators, if the frequency offset used by the ith frequency offset compensator is closest to the estimated frequency offset of a concerned UE, then the resource block generated by the system FFT block following the ith frequency offset compensator is chosen for the concerned UE.
  • estimated frequency offsets of all UEs are put into the dynamic arbitrary frequency offset calculation block to calculate and update arbitrary frequency offsets of the frequency offset compensator bank.
  • k-means algorithm is used to calculate and update arbitrary frequency offsets of the frequency offset compensator bank based on the estimated frequency offsets of the UEs: • Step one: Using the N arbitrary frequency offsets of current time n-1 ) as the N cluster centers of the k-means algorithm.
  • Step two according to all M estimated frequency offsets (A l (n), A 2 (n),...,A M (n)) of the M UEs, categorize each estimated frequency offset by the minimum distance between the estimated frequency offset and the N cluster centers, thus all the M estimated frequency offsets are classified into N groups, n is corresponding to the moment of updating the arbitrary frequency offset values.
  • Step three for each group, replace the cluster center with the mean value of all
  • the present invention decreases the computational complexity of the system by compensating the input signal before system FFT, and improves performance of the system by using more than one FFT blocks with each FFT block preceded by a frequency offset compensator, each compensator compensating the input signal with both a fixed and an arbitrary frequency offset.

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

Abstract

La présente invention concerne un système et un procédé de réception en liaison montante dans des stations de base LTE (« Long Term Evolution », évolution à long terme). Le procédé consiste : à compenser un signal d'entrée en utilisant une pluralité de compensateurs de décalage de fréquence pour fournir des signaux compensés, chaque compensateur compensant le signal avec un décalage de fréquence fixe ainsi qu'un décalage de fréquence arbitraire ; à réaliser des transformées de Fourier rapides de système sur les signaux compensés pour produire des blocs de ressources ; et à sélectionner des blocs de ressources pour des équipements utilisateurs concernés. Par rapport aux techniques antérieures, la présente invention peut obtenir un compromis satisfaisant entre les performances et la complexité, et être avantageuse pour les traitements suivants tels que l'estimation de canal.
PCT/CN2009/075904 2009-12-23 2009-12-23 Système et procédé de réception en liaison montante lte WO2011075895A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/CN2009/075904 WO2011075895A1 (fr) 2009-12-23 2009-12-23 Système et procédé de réception en liaison montante lte

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PCT/CN2009/075904 WO2011075895A1 (fr) 2009-12-23 2009-12-23 Système et procédé de réception en liaison montante lte

Publications (1)

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WO2011075895A1 true WO2011075895A1 (fr) 2011-06-30

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1905547A (zh) * 2005-07-26 2007-01-31 北京中电华大电子设计有限责任公司 通过时域过采样分集接收ofdm信号的方法与装置
CN101184075A (zh) * 2007-12-13 2008-05-21 华为技术有限公司 频偏补偿方法及装置

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1905547A (zh) * 2005-07-26 2007-01-31 北京中电华大电子设计有限责任公司 通过时域过采样分集接收ofdm信号的方法与装置
CN101184075A (zh) * 2007-12-13 2008-05-21 华为技术有限公司 频偏补偿方法及装置

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