WO2007104203A1 - Procédé de transmission multi-antenne dans un système de multiplexage par répartition orthogonale de la fréquence et appareil associé - Google Patents

Procédé de transmission multi-antenne dans un système de multiplexage par répartition orthogonale de la fréquence et appareil associé Download PDF

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Publication number
WO2007104203A1
WO2007104203A1 PCT/CN2006/003720 CN2006003720W WO2007104203A1 WO 2007104203 A1 WO2007104203 A1 WO 2007104203A1 CN 2006003720 W CN2006003720 W CN 2006003720W WO 2007104203 A1 WO2007104203 A1 WO 2007104203A1
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WO
WIPO (PCT)
Prior art keywords
antenna
division multiplexing
frequency division
transmitting
orthogonal frequency
Prior art date
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Ceased
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PCT/CN2006/003720
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English (en)
Chinese (zh)
Inventor
Lina Chen
Peigang Jiang
Jianghua Liu
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Huawei Technologies Co Ltd
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Huawei Technologies Co Ltd
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Publication date
Application filed by Huawei Technologies Co Ltd filed Critical Huawei Technologies Co Ltd
Publication of WO2007104203A1 publication Critical patent/WO2007104203A1/fr
Anticipated expiration legal-status Critical
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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
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/022—Channel estimation of frequency response
    • 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
    • H04L27/2614—Peak power aspects
    • H04L27/2621—Reduction thereof using phase offsets between subcarriers
    • 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
    • H04L27/2626—Arrangements specific to the transmitter only

Definitions

  • Multi-antenna transmission method and device for orthogonal frequency division multiplexing system The present application claims to be submitted to the Chinese Patent Office on March 15, 2006, application number 200610067776.0, and the invention name is "multi-antenna transmission of orthogonal frequency division multiplexing system" The priority of the Chinese Patent Application, the entire disclosure of which is hereby incorporated by reference.
  • the present invention relates to the field of wireless communication technologies, and in particular, to radio frequency technology, and more particularly to a multi-antenna transmission method and apparatus for an orthogonal frequency division multiplexing system. Background technique
  • OFDM Orthogonal Frequency Division Multiplexing
  • MIMO multi-input multi-output
  • OFDM As a multi-carrier digital modulation technique, OFDM encodes data and transmits it in the frequency domain. OFDM simultaneously transmits multiple high speed signals over a specially calculated orthogonal frequency. OFDM, in turn, acts as a multiplexing technique that multiplexes multiple signals onto different orthogonal subcarriers. The required bandwidth is much less. Due to the use of interference-free orthogonal carrier technology, no guard bands are required between individual carriers. This makes the available spectrum more efficient to use. In addition, OFDM technology can dynamically allocate data on subchannels. For maximum data throughput, multi-carrier modulators can intelligently allocate more data to sub-channels with less noise.
  • OFDM encodes the data to be transmitted as frequency domain information, modulates it into a time domain signal, and transmits it on the channel, and performs inverse process demodulation at the receiving end.
  • Figure 1 shows the various components of an OFDM communication system.
  • the data is first encoded at the transmitting end, and then digitally modulated, where the digital modulation is a common modulation, such as Quadrature Amplitude Modulation (QAM), and then the data stream is segmented and converted in parallel,
  • IFFT Inverse Fast Fourier Transform
  • the domain information is then subjected to parallel and serial conversion, and the cyclic prefix CP is added, and then sent to the communication channel through the transmitting module; on the receiving end, the signal is received first by the receiving module, followed by de-CP, serial-to-parallel conversion, fast Fourier transform.
  • FFT Fast Fourier Transform
  • parallel-to-serial conversion digital demodulation, decoding.
  • Multiple Input Multiple Output MIMO technology is a multi-input multi-antenna multi-antenna technology, in which multiple antennas are placed at the transmitting end and the receiving end of the communication system.
  • SDM Space Division Multiplex
  • MIMO technology One of the key applications of MIMO technology is diversity, which can achieve spatial diversity gain to improve system performance.
  • Cyclic Shift Diversity is a multi-antenna transmit diversity method based on OFDM systems.
  • the frequency diversity gain is obtained by performing different cyclic shifts of the same OFDM symbols in the time domain and then transmitting them from a plurality of transmitting antennas, the specific transmitter system structure, as shown in FIG.
  • the OFDM symbols on each antenna need to be added with a cyclic prefix CP, and then simultaneously transmitted out from different antennas to implement space division multiplexing.
  • the length of the CP should be greater than the maximum multipath delay of the channel.
  • the signal of the OFDM symbol in the time domain is x( «), (o ⁇ « ⁇ N - 1),
  • the expression in the formula is the number of bits of the cyclic shift in the time domain. According to the above shift relationship, the signal of each antenna on each subcarrier in the frequency domain can be obtained as follows:
  • y W ⁇ 3 ⁇ 4r Is the received signal at the first subcarrier, indicating the frequency domain channel response between the first transmit antenna and the receive antenna on the first subcarrier. Indicates additive white Gaussian noise.
  • the multi-antenna system above 4 bar is equivalent to a single antenna system, which is expressed as:
  • the cyclic shift of different antennas in the time domain is equivalent to introducing multipath in the time domain, and the performance in the frequency domain is enhanced by frequency selectivity, so that the OFDM modulation is used.
  • the channel coding can obtain the frequency diversity gain.
  • this cyclic shift method can obtain more frequency diversity gain under the same channel coding and interleaving.
  • CSD CSD regardless of the number of antennas, its encoding rate is always 1.
  • implementation of CSD for different antenna numbers is simple, and its transmission and reception algorithms are similar for different antenna numbers.
  • the method is prone to frequency puncturing, resulting in a decrease in the reliability of the wireless channel.
  • the diversity channel is formed by superimposing a plurality of subchannels after a fixed phase shift. Due to the uncertainty or randomness of the transmission characteristics of the subchannels, once the subchannel transmission characteristics themselves satisfy a certain relationship, such as a common divisor relationship , it will cause some equally spaced frequency blind spots on the resulting diversity channel, and the signal can not be transmitted at these frequency points, which is called frequency puncturing effect. Obviously, the appearance of the frequency puncturing effect will greatly reduce the channel transmission performance. Especially when the coding method such as interleaving code is adopted, the transmission signal itself is regularly interleaved in the transmission code.
  • the diversity method has a reliability problem and may cause deterioration of channel transmission performance.
  • the method reduces the correlation bandwidth of the channel by speeding up the frequency domain channel transform speed.
  • the estimation accuracy is reduced.
  • the frequency selectivity is completely determined by one parameter of the delay, and the selectivity cannot be flexibly controlled.
  • the main object of the present invention is to provide a multi-antenna transmission method and apparatus for an orthogonal frequency division multiplexing system, so that an OFDM system realizes multi-antenna transmit diversity, obtains frequency diversity gain, improves transmission reliability, and effectively overcomes CSD. Disadvantages.
  • An embodiment of the present invention provides a multi-antenna transmission method for an orthogonal frequency division multiplexing system, where the orthogonal frequency division multiplexing system is provided with at least two transmitting antennas, and the method includes the following steps:
  • the transmitting end multiplies each frequency domain signal to be transmitted by a phase sequence corresponding to each transmitting antenna
  • the time domain signals are appended with cyclic prefixes and transmitted on respective corresponding transmit antennas.
  • the method further comprises the steps of:
  • the receiving end demodulates the received signal according to the received phase sequence information.
  • the multiplexed frequency domain signals multiplied by the phase sequence corresponding to the same transmitting antenna are added before the orthogonal frequency division multiplexing modulation is converted into the time domain signal.
  • An embodiment of the present invention further provides a multi-antenna transmitting apparatus for an Orthogonal Frequency Division Multiplexing system, including a phase multiplying module, an orthogonal frequency division multiplexing modulation module, a cyclic prefix module, and at least two transmitting antennas.
  • the phase multiplication module is configured to multiply each channel-coded and modulated frequency domain signal by a phase sequence corresponding to the transmit antenna;
  • the orthogonal frequency division multiplexing modulation module is configured to perform orthogonal frequency division multiplexing modulation on a signal from the phase multiplication module to obtain a time domain signal;
  • a cyclic prefix module configured to add a cyclic prefix to the time domain signal from the orthogonal frequency division multiplexing modulation module
  • the transmitting antenna is configured to send a signal from a cyclic prefix module.
  • the device further comprises:
  • An adding module configured to add phase-multiplied multiplex data corresponding to the same transmitting antenna
  • the orthogonal frequency division multiplexing modulation module performs orthogonal frequency division multiplexing modulation on the signal from the adding module to obtain a time domain signal, and then sends the cyclic prefix module to the cyclic prefix module.
  • the sub-channel is modulated by orthogonal frequency division multiplexing and is applied to each antenna.
  • the diversity transmission realizes the frequency diversity gain and obtains a high coding rate; wherein the phase sequence can be designed according to specific rules according to requirements, effectively avoiding the frequency puncturing effect and improving the channel transmission reliability; and, by setting the phase sequence every n (n is A positive integer) subcarrier changes once, which can ensure that the relevant bandwidth of the channel is constant within the range of n subcarriers, and the accuracy of the channel characteristic estimation by the receiving end is guaranteed to be unchanged.
  • the phase sequence can also be adaptively adjusted according to the transmission quality evaluation and feedback at the receiving end, thereby improving the system robustness; the free setting of the phase sequence greatly improves the flexibility of the multi-antenna diversity transmitting system.
  • the diversity gain of coding rate 1 is realized under any multiple antennas, and the transmission performance of the wireless channel is improved, which is achieved by directly multiplying the phase. More flexible control of the final channel response, increased system flexibility, and by avoiding frequency puncturing effects by setting the phase sequence as required, either time-varying or non-time-variant, random or ordered, adaptively adjusted, etc. , thereby improving the performance of the system decoder and improving the reliability of wireless communication.
  • 1 is a schematic structural diagram of an OFDM communication system
  • FIG. 2 is a schematic structural diagram of a transmitter system of cyclic shift diversity
  • 3 is a schematic structural diagram of a diversity transmitting apparatus according to an embodiment of the present invention
  • 4 is a schematic structural diagram of a diversity transmitting apparatus according to another embodiment of the present invention. detailed description
  • the present invention selects the OFDM modulated signal before the orthogonal frequency division multiplexing modulation transform, and separately performs phase multiplication, and then respectively modulates and adds the loop by orthogonal frequency division multiplexing.
  • the prefix CP is simultaneously transmitted on the antenna in diversity.
  • the selection or design of the phase sequence is a key factor in determining the diversity performance. It may be generated by the system using some kind of pseudo-random code or according to a fixed law, which may be changed with time or statically, and may be adaptively adjusted according to feedback. and many more.
  • the basic innovations are: Setting phase sequence multiplication prior to Orthogonal Frequency Division Multiplexing modulation makes these completely free and flexible configurations possible, and provides the basis for improving or optimizing the diversity channel.
  • the encoded data to be transmitted needs to be used as frequency domain information, and then modulated into a time domain signal.
  • the fast data to be transmitted is usually subjected to fast inverse Fourier transform IFFT, and other transforms may be adopted. In this way, get time domain information.
  • the frequency diversity gain is obtained by performing different cyclic shifts in the time domain and then transmitting them from multiple transmit antennas.
  • CSD can be equivalent to multiplying the data on the frequency i or each subcarrier by different phases on the antenna.
  • the CSD signal expression is as follows:
  • Embodiments of the present invention utilize this equivalent characteristic to replace the cyclic delay of the time domain by adding phase shifting in the frequency domain.
  • the multi-antenna transmit diversity device of the orthogonal frequency division multiplexing system of this configuration is multiplied by the phase sequence before the orthogonal frequency division multiplexing modulation, as shown in FIG.
  • the device includes a source-to-channel coding module and an OFDM modulation module.
  • the channel coding module is configured to encode and transmit the information to be transmitted to the OFDM modulation module, and the OFDM modulation module is used for future confidence.
  • the coded signal of the channel coding module is OFDM-modulated to obtain a frequency domain signal.
  • the single signal from the OFDM modulation module is split into signals corresponding to the respective antennas, and each of the signals passes through: a phase multiplication module, an orthogonal frequency division multiplexing modulation module, a CP module, and a transmitting antenna.
  • the phase multiplication module is configured to multiply the frequency domain OFDM modulated signal modulated by the OFDM modulation module by the phase sequence corresponding to the transmit antenna; the orthogonal frequency division multiplexing modulation module is configured to use the frequency from the phase multiplication module.
  • the domain signal is subjected to orthogonal frequency division multiplexing modulation to obtain a time domain signal; the cyclic prefix module is configured to add a cyclic prefix to the time domain signal from the orthogonal frequency division multiplexing modulation module, and finally send the respective transmit antennas, which is Implement frequency domain diversity transmission.
  • the data to be transmitted is channel-coded and modulated and then copied into M parts and mapped onto the M ⁇ antenna.
  • the frequency domain signal transmitted by the antenna m can be expressed as:
  • the equivalent channel frequency selectivity can be made stronger, thereby increasing the frequency diversity gain.
  • the transmitting end can also notify the receiving end of the phase sequence multiplied in the frequency domain on each antenna by broadcasting or other means, and the receiving end can demodulate the data.
  • the transmitting end multiplies the frequency domain modulated signals to be transmitted by the phase sequence corresponding to each transmitting antenna; and then performs orthogonal frequency division multiplexing modulation to obtain a time domain signal; finally, the time domain signal is added with a cyclic prefix, and Each is transmitted simultaneously on the corresponding transmit antenna.
  • the transmitting end also notifies the receiving end of the phase sequence information, so that the receiving end demodulates the received signal.
  • phase sequence multiplied by each antenna in the frequency domain may be varied or constant.
  • the phase sequence can be a pseudo-random sequence, and has a certain rule, when each element of the phase sequence takes a value
  • the present invention is equivalent to the effect of the CSD, T m CSD i.e. the cyclic delay.
  • the transmission characteristics of each subchannel corresponding to the transmitting antenna are random, so the phase sequence can be generated by the system through the pseudo random code, which can significantly reduce the probability of frequency domain puncturing in the finally synthesized channel. , improve reliability;
  • the system can set the transform period of the phase sequence to n (n is a positive integer) subcarriers; ensure that the relevant bandwidth of the channel is not affected in n subcarriers, and guarantee the performance of channel estimation and interference cancellation;
  • a feedback mechanism can be established to implement adaptive adjustment.
  • the receiving end evaluates and feeds back channel transmission performance information according to the received demodulation signal, and the transmitting end automatically adjusts the phase sequence according to the feedback information, so that the performance of the channel tends to be optimal, and the specific There are many ways to adjust.
  • FIG. 1 A diversity transmitting device architecture according to another embodiment of the present invention is shown in FIG. There are multiple sets of data sending units in the system, which can send multiple data streams at the same time.
  • multiple data streams can be simultaneously transmitted on different antennas, that is, spatial multiplexing.
  • the method described in the foregoing embodiment can be implemented for each data stream.
  • Each data stream is copied into the same data in the frequency domain.
  • Each branch is multiplied by a different phase sequence, and the same branches of different data streams are added to perform orthogonal frequency division multiplexing modulation and adding cycles. After the prefix CP is operated, it is sent on M antennas.
  • the plurality of data streams may be data streams generated from different sources and encoded and modulated by different channels, or may be generated by the same source through the same channel coding and modulation and then serial-to-parallel conversion.
  • Combining spatial multiplexing with the technical solutions described in the foregoing embodiments can be obtained simultaneously
  • the spatial multiplexing gain that is, the simultaneous transmission of multiple data streams increases the transmission rate, and simultaneously obtains the frequency diversity gain for each data stream, thereby improving the reliability of the transmission.
  • the cyclic delay diversity CSD is equivalent to multiplying the data on each subcarrier by a phase in the frequency domain, so that the equivalent channel change of the signal passes faster, that is, the correlation bandwidth of the channel becomes smaller, thereby obtaining Frequency diversity gain.
  • the estimated value needs to be averaged over the n subcarriers in the frequency domain.
  • the number of subcarriers n is proportional to the correlation bandwidth.
  • the phase sequence change period on each antenna is set to n, that is, on the adjacent n subcarriers, the multiplied phases are the same, and the phase is different every n subcarriers. This ensures that the accuracy of the n subcarriers with the same phase is not reduced when averaging the estimated values, and the channel variation can be accelerated every n subcarriers to obtain the frequency diversity gain.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Power Engineering (AREA)
  • Radio Transmission System (AREA)

Abstract

L'invention concerne un procédé de transmission multi-antenne dans un système de multiplexage par répartition orthogonale de la fréquence et un appareil associé. Selon l'invention, les signaux de domaine de fréquence sont multipliés par différentes séquences de phase avant modulation du multiplexage par répartition orthogonale de la fréquence, ils sont ensuite modulés dans chaque chemin et transmis avec une diversité d'antenne, la séquence de phase étant déterminée de manière aléatoire ou choisie sur demande. La configuration de la variation de la séquence de phase pour chaque n (n étant un entier positif) sous-porteuses, garantit la largeur de bande du canal associée et la précision de l'estimation des caractéristiques du canal de la réception dans une fourchette de n sous-porteuses.
PCT/CN2006/003720 2006-03-15 2006-12-30 Procédé de transmission multi-antenne dans un système de multiplexage par répartition orthogonale de la fréquence et appareil associé Ceased WO2007104203A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN200610067776 2006-03-15
CN200610067776.0 2006-03-15

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WO2007104203A1 true WO2007104203A1 (fr) 2007-09-20

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114785699A (zh) * 2022-05-27 2022-07-22 北京智芯微电子科技有限公司 低压配电台区物理拓扑识别方法以及高速电力线载波芯片
CN116436739A (zh) * 2023-06-08 2023-07-14 西南交通大学 一种信道估计方法、装置、设备及可读存储介质

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1401122A2 (fr) * 2002-09-17 2004-03-24 Alps Electric Co., Ltd. Récepteur à multiplexage fréquentiel orthogonal
WO2004025841A2 (fr) * 2002-09-10 2004-03-25 Cognio, Inc. Techniques de correction de decalages d'amplitude et de phase dans un dispositif radio mimo
WO2005114939A1 (fr) * 2004-05-07 2005-12-01 Qualcomm Incorporated Diversite d'orientation pour systeme de communication a antennes multiples a multiplexage par repartition orthogonale de la frequence (mrof)

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004025841A2 (fr) * 2002-09-10 2004-03-25 Cognio, Inc. Techniques de correction de decalages d'amplitude et de phase dans un dispositif radio mimo
EP1401122A2 (fr) * 2002-09-17 2004-03-24 Alps Electric Co., Ltd. Récepteur à multiplexage fréquentiel orthogonal
WO2005114939A1 (fr) * 2004-05-07 2005-12-01 Qualcomm Incorporated Diversite d'orientation pour systeme de communication a antennes multiples a multiplexage par repartition orthogonale de la frequence (mrof)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114785699A (zh) * 2022-05-27 2022-07-22 北京智芯微电子科技有限公司 低压配电台区物理拓扑识别方法以及高速电力线载波芯片
CN116436739A (zh) * 2023-06-08 2023-07-14 西南交通大学 一种信道估计方法、装置、设备及可读存储介质
CN116436739B (zh) * 2023-06-08 2023-09-05 西南交通大学 一种信道估计方法、装置、设备及可读存储介质

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