WO2008028408A1

WO2008028408A1 - A communication method and system in the mimo system

Info

Publication number: WO2008028408A1
Application number: PCT/CN2007/002607
Authority: WO
Inventors: Bin Li; Hufei Zhu
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2006-08-31
Filing date: 2007-08-30
Publication date: 2008-03-13
Also published as: CN100499396C; CN101114862A

Abstract

A communication method in MIMO system is disclosed, which comprises the following steps: the receiver selects the transmitting antenna assemble according to the channel state; the receiver transmits the transmitting antenna assemble information to the transmitter; the transmitter transmits the signal to the receiver with the selected transmitting antenna assemble according to the received transmitting antenna assemble information. Moreover, a communication system in MIMO system is also disclosed, which includes the following elements: the transmitter and the receiver. According to the embodiments, because the receiver selects the transmitting antenna with the channel capacity maximization principle and transmits the selected transmitting antenna to the transmitter, the signal transmitted to the receiver by the transmitter can have a higher transmitting efficiency or have the lower packet error rate with the selected transmitting antenna.

Description

Communication method and system in multiple input multiple output system

TECHNICAL FIELD The present invention relates to communication technologies, and more particularly to a communication method and system in a multiple input multiple output system. BACKGROUND OF THE INVENTION According to information theory, the use of a multi-antenna array at both the transmitting end and the receiving end of a communication system, or both ends, can greatly increase the transmission bit rate of the system.

Figure 1 shows a wireless communication system with a space-time architecture using multiple antenna arrays at both the transmitting and receiving ends. This system, also known as MIMO (Multiple Input Multiple Output) system, operates in a Rayleigh scattering environment, and the elements of the channel matrix can be approximated as statistically independent. In the system shown in Figure 1, a data sequence can be divided into M uncorrelated symbol subsequences, each subsequence being transmitted by one of the M transmit antennas. The M subsequences are received by the N receiving antennas at the receiving end after being influenced by a channel whose channel matrix is H. The transmit signals may be transmitted by M different antenna elements a-1, aM, respectively, and the corresponding received signals ^x i , . . . , ^x w are received from N different antenna elements bl, . . . , bN, respectively. In the communication system, the number M of transmitting antenna units is at least 2, and the number N of receiving antenna units is at least M. The channel matrix H is a matrix of NxM, and the elements of the i-th row and the j-column in the matrix represent the coupling of the i-th receiving antenna and the j-th transmitting antenna through the transmission channel. The received signal, . . . , ^x w is processed in the digital signal processor to produce a recovered transmitted signal ^. The figure also shows the summation components c-1, c-2, cN, which represent the unavoidable noise signals ¹ \ ^w 2 , . . . , ^w ^ , which are added to the receiving antenna unit bl. , b-2, ..., bN received in the signal.

In the MIMO system shown in Fig. 1, a single code word (SCW: Single Code Word) mode can be used. The above single codeword mode is described in the IEEE 802.20 standard. In the single codeword mode, the transmitting end uses M virtual antenna ports to transmit signals to the receiving end, and the M is greater than or equal to 2 and less than At 4. On a plurality of virtual transmitting antennas, only one encoded data stream is transmitted at each moment, and multiple symbol strings in the data stream are converted and then distributed to each virtual transmitting antenna. At each TTI, the receiving end only feeds back one CQI information and one ACK/NACK information, wherein the CQI information tells the transmitting end what kind of MCS (the modulation and channel coding scheme) is used in the corresponding one TTI transmission of the encoded data. And the channel coding scheme), and the ACK/NACK information tells the transmitting end whether the encoded data in the corresponding one TTI transmission has been correctly decoded by the receiving end. The virtual antenna is used to transmit each element of the result vector by each different transmitting antenna of the transmitting end and to reach the receiving end through one channel. The resulting vector is a vector obtained by multiplying a vector of transmitted signals by one or more matrices. In the Virtual Antenna technique proposed in 3GPP TR 25.876 V1.7.1, the transmitted signal vector is sequentially multiplied by a matrix T and a matrix U, and the matrix T and the matrix U are defined as orthogonal matrices. In practice, it can be a non-orthogonal matrix.

For the above transmission method, the receiver may be a linear receiver of a single unit, such as a known MMSE (Least Mean Square Error) equalizer (spacer), or a complex space-to-channel transmission. A receiver that performs nonlinear joint demodulation of data, such as a nonlinear receiver using interference cancellation techniques.

In the SC mode specified in the IEEE 802.20 standard, the receiving end feeds back the dimension of the spatial multiplexing ( Rank ) K. According to this dimension K, the transmitting end must use all available M transmissions at each time in a TTI. K of the antennas are spatially multiplexed; the transmitting end alternately uses all M transmitting antennas at various times within one TTI, that is, using each transmitting antenna in turn, instead of using only K fixed in M. For example, there are 4 transmitting antennas at the transmitting end, 1, 2, 3, and 4. If two transmitting antennas are determined when the signal is transmitted, two transmitting antennas are used at each moment, but which two transmitting antennas are used Time varies, several times with the transmitting antenna 1, 2, several times with the transmitting antenna 3, 4, several times with the transmitting antenna 2, 3..., so that the transmitting antenna used in turn alternates until the traversal of all Possible combinations (here there are C ₄ ² = 6 combinations, ie antenna 12, antenna 34, antenna 13, antenna 24, antenna 14, antenna 23 are used. The receiving end feeds back the control word CQICHSCW to the transmitting end through the CQICHSCW (CQI: Channel Quality Indicator: CQI: Channel Quality Indicator: C) channel to control the MCS used by the transmitting end and transmit several signals in parallel. The word includes a total of 10 bits, where: the FormatType field occupies 1 bit, the CQIValueSCW field occupies 5 bits, the Rank field occupies 2 bits, and the Reserved (ie, reserved unused) field occupies 2 bits.

The above control word CQICHSCW is further described below. The CQIValueSCW is used to notify the transmitting end of the MCS (modulation and channel coding scheme), and the Rank is used to notify the transmitting end of the transmitting antenna usage information, indicating that a certain TTI (transmission time slot) can be spatially multiplexed. At the same time, the number of transmitted signals of the respective channels transmitted in parallel is K, and the K is less than or equal to ^. After the transmitting end obtains K, the K transmitting signals are transmitted in parallel by spatial multiplexing using K transmitting antennas at each moment of the chirp; and from the M transmitting antennas in several symbol periods of one TTI Selecting K transmit antennas, transmitting signals using the selected K transmit antennas, then selecting another K transmit antennas from the M transmit antennas for another number of symbol periods of the TTI, using the selected additional K The transmitting antenna transmits a signal until all C _M ^K transmitting antennas are combined to transmit signals, and the C _M ^K takes K antennas from the M antennas, and all possible combinations.

The concept of TTI and symbol period described above is introduced here. In order to combat channel fading, as well as channel interference and noise transmission errors, the transmitting end divides the data to be transmitted into multiple data packets (Block), channel coding and interleaving the information bits in the same data packet, and then modulating Multiple symbols are transmitted over the channel, and the length of time required to transmit such a packet determines the length of one TTI. The receiving end first receives all the symbols contained in the same data packet, and then deinterleaves and decodes. In this document, a TTI refers to the time interval at which such a packet is transmitted.

And each symbol in a data packet transmitted in a TTI may be distributed in different intervals in the time domain, or in different intervals in the frequency domain, or in different two-dimensional planes in the time domain and the frequency domain. Interval. A symbol period described herein refers to an interval occupied by a symbol transmitted through a channel in the time domain, or an interval occupied in the frequency domain, or an interval occupied in a two-dimensional plane in the time domain and the frequency domain. For example, the MIMO OFDM pass described in the document "MBFDD and MBTDD: Proposed Draft Air Interface Specification" of the IEEE 802.20 standard 2006-01-06 W

In the scheme, one packet uses 8 OFDM symbols in the time domain, and each OFDM symbol occupies 16 subcarriers in the frequency domain, then one symbol period refers to an interval on the two-dimensional plane of the time domain and the frequency domain. That is, 1 subcarrier on 1 OFDM symbol in the time domain, and this packet has 8 x 16=128 symbol periods.

In this way, since the channel conditions of the M transmitting antennas are different, in a TTI, the channel corresponding to the transmitting antennas of the M transmitting antennas is better, so that the receiving signal-to-noise ratio at the receiving end is better, and some The channel corresponding to the transmitting antenna is relatively poor, so that the received signal-to-noise ratio at the receiving end is relatively poor. Therefore, using a combination of all C _M ^K transmit antennas of ^K transmit antennas in one TTI to transmit signals in a TTI cannot fully utilize a combination of transmit antennas with better channel conditions to achieve higher transmission efficiency. Or achieve a lower packet error rate at the receiving end. Summary of the invention

Embodiments of the present invention provide a communication method and system in a multiple input multiple output system. The transmitting end can use the optimal transmitting antenna combination to transmit signals to the receiving end, from a transmitting antenna that can fully utilize the channel condition to achieve a higher transmission rate, or achieve a lower packet error rate at the receiving end.

The embodiment of the invention discloses a communication method in a multiple input multiple output system, comprising: receiving, by a receiving end, a transmit antenna combination according to a channel condition;

The receiving end sends the selected transmit antenna combination information to the transmitting end;

The transmitting end transmits a signal to the receiving end using the selected combination of transmitting antennas according to the selected transmitting antenna combination information.

The embodiment of the invention further discloses a communication system in a multiple input multiple output system, comprising: a transmitting end, configured to transmit a signal to a receiving end by using a transmitting antenna combination selected by a receiving end; and a receiving end, configured to select according to a channel condition The transmit antenna combination is combined and the selected transmit antenna combination information is fed back to the transmitting end, so that the transmitting end transmits the signal to the transmitting end by using the selected transmit antenna combination.

The embodiment of the invention further discloses a receiving end, comprising:

a receiving unit, configured to receive a transmit signal of each transmit antenna of the transmitting end; Selecting a unit, selecting a transmit antenna combination according to a channel condition;

The setting unit sets the selected transmit antenna combination information in the transmit antenna combination information field, and the sending unit is configured to send the transmit antenna combined information field to the transmitting end.

The embodiment of the invention further discloses a transmitting end, comprising:

a receiving unit, configured to receive, by the receiving end, the selected transmit antenna combination information;

The determining unit determines the transmit antenna combination according to the transmit antenna information fed back by the receiving end, and the transmitting unit is configured to transmit a signal to the receiving end by using the transmit antenna combination determined by the determining unit. Therefore, according to the embodiment of the present invention, since the transmitting antenna is selected by using the channel capacity maximization principle at the receiving end, and the selected transmitting antenna is sent to the transmitting end, the transmitting end transmits the signal to the receiving end by using the selected transmitting antenna. Higher transmission efficiency, or lower packet error rate at the receiving end. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing a MIMO wireless communication system;

2 shows a communication flow chart of an embodiment of the present invention;

FIG. 3 shows a schematic diagram of a communication system in accordance with an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to facilitate the understanding and implementation of the present invention, the embodiments of the present invention are described in conjunction with the drawings.

According to the embodiment of the present invention, the transmitting antenna combination information is fed back to the transmitting end by using the CQICHSCW channel at the receiving end, so that the transmitting end uses the feedback transmitting antenna combination to transmit signals to the receiving end, and can fully utilize the transmitting antenna with good channel condition to achieve better A high transmission rate, or a lower packet error rate at the receiving end, the transmitting antenna includes a physical antenna and/or a virtual antenna. In the embodiment of the present invention, the virtual antenna is configured to multiply a vector composed of the transmitted signal by a matrix or more than one matrix to obtain a result vector, and then transmit, by each of the transmitting antennas, each of the result vectors, where The matrix can be an orthogonal matrix or a non-orthogonal matrix. Therefore, the virtual in the embodiment of the present invention The pseudo antenna has a slightly larger range than the virtual antenna proposed in 3GPP TR 25.876 Vl.7.1.

The embodiment of the present invention provides a communication method in a multiple input multiple output system. The communication method of the embodiment of the present invention will be described in detail below with reference to FIG.

Step 1. The transmitting end uses each transmitting antenna to transmit a signal to the receiving end.

Step 2. The receiving end obtains the received signal to noise ratio value of each transmitting antenna and the selected transmitting antenna combination according to the transmitting signal of each transmitting antenna. The receiving end selects the transmitting antenna combination according to the transmission rate maximization principle, that is, which transmitting antennas are used. More specifically, the receiving end selects and uses several transmitting antennas having a large received signal to noise ratio.

Step 3: The receiving end obtains a CQI value, and sends the obtained CQI value and the selected transmitting antenna combination information to the transmitting end. The CQI value tells the transmitting end what MCS to use for the encoded data in a corresponding TTI transmission.

The receiving end sets the selected transmit antenna combination information in the control word CQICHSCW, and the structure of the control word CQICHSCW is as shown in Table 1.

Control word structure of CQICHSCW

As shown in Table 1, the CQICHSCW includes a RANK bit field, a CQIValue bit field, and a reserved bit field.

According to an embodiment of the present invention, taking four transmit antennas as an example, each bit of the RANK bit field and the reserved bit field may be associated with a predetermined transmit antenna. The selected transmit antenna combination information is set in the RANK bit field and the reserved bit field, so that whether or not the transmit antenna is selected can be determined according to the value of each bit in the RANK bit field and the reserved bit field. For example, when a certain bit value is taken as 1, the transmitting antenna corresponding to the bit is used in the current TTI, and when a certain bit value is 0, it indicates that The transmit antenna corresponding to each bit is not used in the current TTI. Of course, the opposite representation method can also be used, that is, when a certain bit value is taken as 1, the transmitting antenna corresponding to the bit is not used at the current time, and when a bit value is 0, the transmitting antenna corresponding to the bit is indicated. The current ΤΤΙ is used. Thus, the RANK bit field and the transmit bit corresponding to the bit value of 1 in the reserved bit field are selected transmit antennas. Since the transmitting antenna is selected by using the channel capacity maximization principle when selecting the transmitting antenna, the transmission of the signal to the receiving end by using the selected transmitting antenna can achieve higher transmission efficiency, or achieve a lower packet error rate at the receiving end.

Therefore, the embodiment of the present invention utilizes 2 bits of the reserved bit field and combines with 2 bits of the Rank field to form a 4-bit field. Each of the 4 bits controls each of the 4 transmit antennas. switch status. According to an embodiment of the present invention, the RANK bit field and the reserved bit field are also referred to as a transmit antenna combined information field.

Step 4. The transmitting end transmits a signal to the receiving end by using the selected combination of transmitting antennas.

After receiving the transmit antenna combination information through the CQICHSCW channel, the transmitting end obtains the transmit day combination information, and transmits the signal to the receiving end by using the selected transmit antenna combination.

As shown in FIG. 3, an embodiment of the present invention further discloses a communication system in a multiple input multiple output system, including: a transmitting end, configured to transmit a signal to a receiving end by using each transmitting antenna, or a selected combination of transmitting antennas. The receiving end is configured to select a transmitting antenna combination according to a transmitting signal of each transmitting antenna, and feed back the selected transmitting antenna combination information to the transmitting end, so that the transmitting end transmits the signal to the transmitting end by using the selected transmitting antenna combination.

The receiving end includes: a receiving unit, configured to receive a transmitting signal of each transmitting antenna of the transmitting end; a selecting unit, selecting a transmitting antenna combination according to a transmitting signal of each transmitting antenna; setting a unit, setting the selected transmitting antenna combination information In the transmit antenna combination information field, the sending unit is configured to send the transmit antenna combined information field to the transmitting end.

The transmitting end includes: a receiving unit, configured to receive selected transmit antenna combination information fed back by the receiving end; a determining unit, determining a transmit antenna combination according to the transmit antenna information fed back by the receiving end; and a transmitting unit, configured to use the determining unit to determine the transmitting The antenna combination transmits a signal to the receiving end.

Therefore, according to the embodiment of the present invention, the channel capacity maximization principle is adopted at the receiving end. The transmitting antenna transmits the selected transmitting antenna to the transmitting end. Therefore, the transmitting end transmits the signal to the receiving end by using the selected transmitting antenna to achieve higher transmission efficiency, or achieve a lower packet error rate at the receiving end.

While the invention has been described by the embodiments of the invention in the embodiments of the invention Request to limit.

Claims

Rights request

A communication method in a multiple input multiple output system, comprising: receiving, by a receiving end, a combination of transmitting antennas according to a channel condition;

The transmitting end transmits a signal to the receiving end using the selected combination of transmitting antennas according to the received transmitting antenna combination information.

The communication method according to claim 1, wherein the receiving end sends the selected transmit antenna combination information to the transmitting end, specifically: the receiving end sets the selected transmit antenna combination information in the transmit antenna combination information. In the domain, the transmit antenna combined information field is sent to the transmitting end.

The communication method according to claim 2, wherein the transmit antenna combined information field is used to replace the RANK bit field and the reserved bit field in the single codeword mode channel quality indication.

The communication method according to claim 2 or 3, wherein each bit in the transmit antenna combined information field corresponds to each transmit antenna of the transmitting end.

The communication method according to claim 4, wherein the transmitting end determines whether to select the respective ones of the transmitting antennas according to the values of the respective bits in the combined information of the transmitting antennas.

The communication method according to claim 1, wherein the selecting a combination of transmitting antennas specifically comprises: selecting a combination of transmitting antennas according to a principle of maximizing a transmission rate.

The communication method according to claim 2, wherein the receiving end sends the selected transmit antenna combined information field to the transmitting end, specifically: the receiving end transmits the antenna through a single codeword mode channel quality indicator channel. The combined information field is sent to the transmitting end.

The method according to any one of claims 1 to 3, characterized in that the transmitting antenna comprises a physical antenna and/or a virtual antenna.

A communication system in a multiple input multiple output system, comprising: a transmitting end, configured to transmit a signal to a receiving end by using a combination of transmitting antennas selected by a receiving end; and a receiving end, configured to select and transmit according to a channel condition Combining the antennas, and feeding back the selected combination of the transmitting antennas to the transmitting end, so that the transmitting end transmits the signal to the transmitting end by using the selected combination of transmitting antennas number.

The communication system according to claim 9, wherein the receiving end comprises: a receiving unit, configured to receive a transmitting signal of each transmitting antenna of the transmitting end;

Selecting a unit, selecting a transmit antenna combination according to a channel condition;

The setting unit sets the selected transmit antenna combination information in the transmit antenna combined information field, and the sending unit is configured to send the transmit antenna combined information field to the transmitting end.

The communication system according to claim 9, wherein the transmitting end comprises: a receiving unit, configured to receive selected transmit antenna combination information fed back by the receiving end;

The determining unit determines the transmit antenna combination according to the transmit antenna information fed back by the receiving end, and the transmitting unit is configured to transmit a signal to the receiving end by using the transmit antenna combination determined by the determining unit.

12. Communication system according to one of the claims 9 to 11, characterized in that the transmitting antenna comprises a physical antenna and / or a virtual antenna.

13. A receiving end, comprising:

a receiving unit, configured to receive a transmit signal of each transmit antenna of the transmitting end;

14. A transmitting end, comprising: