Wireless communication system, wireless communication apparatus and wireless communication method

• US 8,194,720 B2
• Filed: 04/26/2007
• Issued: 06/05/2012
• Est. Priority Date: 04/27/2006
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Yamaura, Tomoya
• Primary Examiner(s): Bost, Dwayne
• Assistant Examiner(s): Wyche, Myron
• Application Number:
  US11/790,593
• Publication Number:
  US 20070253501A1
• Time in Patent Office: 1,867 Days
• Field of Search: 455/86.1, 455/67.7, 455/69, 455/101, 455/513, 455/67.11, 455/186.1, 375/262, 375/260, 375/267, 375/219, 375/347, 375/341, 370/208, 370/329
• US Class Current: 375/219
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0421 utilizing implicit feedback, e.g. steered pilot signals
• CPC Class Codes: H04B 7/043 using best eigenmode, e.g. beam forming or beam steering
• CPC Class Codes: H04B 7/0456 Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04B 7/0628 Diversity capabilities
• CPC Class Codes: H04B 7/0643 Feedback on request
• CPC Class Codes: H04L 1/0625 Transmitter arrangements
• CPC Class Codes: H04L 1/0681 adapting space time parameters, i.e. modifying the space time matrix
• CPC Class Codes: H04L 2025/03414 Multicarrier
• CPC Class Codes: H04L 2025/03426 transmission using multiple-input and multiple-output channels
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/022 of frequency response
• CPC Class Codes: H04L 25/0242 using matrix methods
• CPC Class Codes: H04L 25/03159 operating in the frequency domain H04L25/03165, H04L25/03178 take precedence
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems

Abstract

A wireless communication system which performs data transmission using spatially multiplexed streams from a first terminal including N antennas to a second terminal including M antennas (N is an integer of 2 or more and M is an integer of 1 or more) is disclosed. The system includes notifying means, training means, channel matrix estimation means, beamforming information feedback means, transmission weight matrix setting means, and beamforming means.

Claims

1. A wireless communication system which performs data transmission using spatially multiplexed streams from a first terminal including N antennas to a second terminal including M antennas, N being an integer of 2 or more and M being an integer of 1 or more, the system comprising:

notifying means for notifying the first terminal of a maximum dimension N_max at a time of estimating a channel matrix of the second terminal, wherein N_max is an integer of M or less;

training means for transmitting a sounding packet including training sequence for exciting a channel corresponding to the maximum dimension N_max from the first terminal to the second terminal, the sounding packet being transmitted in a staggered format including first and second sections, the first section having a first format corresponding to a format of one of the streams, and the second section having a second format, wherein the sounding packet is transmitted in the staggered format for temporally dividing;

a training signal part used for a space division process of a data part; and

a training signal part for exciting a channel of a spatial dimension larger than or equal to the number of streams of data;

channel matrix estimation means for dividing the training sequence received by the antennas of the second terminal into N_max or less streams and estimating the channel matrix having M rows and N_max or less columns, wherein the channel matrix is estimated based on a determination that a number of antennas N of the first terminal is greater than a number of antennas M of the second terminal;

beamforming information feedback means for preparing beamforming information necessary for calculating a transmission weight matrix for beamforming in the first terminal on the basis of the channel matrix estimated in the second terminal and feeding back the beamforming information from the second terminal to the first terminal;

transmission weight matrix setting means for setting the transmission weight matrix for beamforming at a time of transmitting data from the first terminal to the second terminal on the basis of the beamforming information fed back from the second terminal to the first terminal; and

beamforming means for performing beamforming in transmission signals of the antennas of the first terminal using the transmission weight matrix for beamforming when a data packet is transmitted from the first terminal to the second terminal.

2. The wireless communication system according to claim 1, wherein forward spatial multiplexing stream transmission from the first terminal to the second terminal is performed according to a protocol based on predetermined standard specification included in a predetermined management frame, and a capability description field for describing a possible maximum spatial dimension is defined when a beamformee of explicit feedback receives a packet including training sequence, and

wherein the notifying means notifies the first terminal of the maximum dimension N_max at the time of estimating the channel matrix of the second terminal using the management frame for describing the capability description field.

3. The wireless communication system according to claim 1, wherein the training means includes a request signal for requesting feedback of the beamforming information from the first terminal to the second terminal in the sounding packet for exciting a channel.

4. The wireless communication system according to claim 1, wherein the training means requests feedback of channel information from the first terminal to the second terminal in a packet including a data symbol which is transmitted prior to the sounding packet when a dedicated sounding packet for exciting a channel which does not include the data symbol is transmitted.

5. The wireless communication system according to claim 1, wherein the training means transmits the sounding packet in the staggered format from the first terminal to the second terminal.

6. The wireless communication system according to claim 5, wherein the training means transmits the sounding packet, in which a channel of N_max spatial dimensions is excited in the training signal part used for the space division process of the data part and the training signal for exciting a channel of remaining N-N_max spatial dimensions is not related to the space division of a signal, from the first terminal to the second terminal.

7. The wireless communication system according to claim 6, wherein the channel matrix preparing means excites the channel of N_max spatial dimensions in the training signal part used for the space division process of the data part to estimate a channel matrix having M rows and N_max or less columns, but the training signal for exciting the channel of the remaining N-N_max spatial dimensions is not processed, when the second terminal receives the sounding packet.

8. The wireless communication system according to claim 6, wherein the training means excites the channel of N_max spatial dimensions in the training signal part used for the space division process of the data part and transmits the sounding packet which does not include the training signal for exciting the channel of the remaining N-N_max spatial dimensions from the first terminal to the second terminal.

9. The wireless communication system according to claim 1, wherein the training means performs conversion for mapping N_max or less transmission streams to all N transmission antenna branches when a dimension number of the sounding packet of the first terminal is suppressed to the maximum dimension N_max or less.

10. The wireless communication system according to claim 9, wherein the training means performs the mapping to the N transmission antenna branches by multiplying transmission streams of N_max dimensions by a mapping matrix having N rows and N_max or less columns.

11. The wireless communication system according to claim 9, wherein the mapping to the transmission antenna branches which becomes equal to the training means is performed with respect to the transmission streams formed using the beamforming means.

12. The wireless communication system according to claim 10,

wherein orthogonal frequency division multiplexing (OFDM) modulation is used as a wireless communication signal, and

wherein the training means gives different cyclic shift delay amounts to the transmission antenna branches after the multiplication of the mapping matrix.

13. The wireless communication system according to claim 9, wherein OFDM modulation is used as a wireless communication signal, and

wherein the training means performs different mappings in a subcarrier unit when the conversion for mapping the transmission streams of the N_max dimensions to all the N transmission antenna branches is performed.

14. The wireless communication system according to claim 1,

wherein the beamforming information feedback means feeds back the channel matrix having M rows and N_max or less columns estimated in the channel matrix estimation means from the second terminal to the first terminal as CSI information, and

wherein the transmission weight matrix setting means calculates the transmission weight matrix for beamforming, on the basis of the CSI information received by the first terminal.

15. The wireless communication system according to claim 1,

wherein the beamforming information feedback means feeds back the transmission weight matrix for beamforming having M rows and N_max or less columns and calculated from the channel matrix estimated by the channel matrix estimation means from the second terminal to the first terminal in a compressed or uncompressed format, and

wherein the transmission weight matrix setting means uses the transmission weight matrix for beamforming received by the first terminal.

16. A wireless communication apparatus which includes N antennas and performs data transmission using spatially multiplexed streams to a receiver terminal including M antennas, N being an integer of 2 or more and M being an integer larger of 1 or more, the apparatus comprising:

notification receiving means for receiving notification of a maximum dimension N_max at a time of estimating a channel matrix of the receiver terminal, wherein N_max is an integer of M or less;

training means for transmitting a sounding packet including training sequence for exciting a channel corresponding to the maximum dimension N_max to the receiver terminal, the sounding packet being transmitted in a staggered format including first and second sections, the first section having a first format corresponding to a format of one of the streams, and the second section having a second format, wherein the sounding packet is transmitted in the staggered format for temporally dividing;

a training signal part used for a space division process of a data part; and

a training signal part for exciting a channel of a spatial dimension larger than or equal to the number of streams of data;

beamforming information receiving means for receiving beamforming information necessary for calculating a transmission weight matrix for beamforming composed of a channel matrix having M rows and N_max or less columns, wherein the channel matrix is estimated by the receiver terminal using the packet and based on a determination that a number of antennas N of the wireless communication apparatus is greater than a number of antennas M of the receiver terminal;

transmission weight matrix setting means for setting the transmission weight matrix for beamforming on the basis of the received beamforming information; and

data transmitting means for performing beamforming of the antennas using the set transmission weight matrix for beamforming and transmitting a data packet to the receiver terminal.

17. The wireless communication apparatus according to claim 16,

wherein forward spatial multiplexing stream transmission to the receiver terminal is performed according to a protocol based on a predetermined standard specification included in a predetermined management frame, and a capability description field for describing a possible maximum spatial dimension is defined when a beamformee of explicit feedback receives a packet including training sequence is defined, and

wherein the notification receiving means receives the notification of the maximum dimension N_max at the time of estimating the channel matrix by receiving the management frame for describing the capability description field from the receiver terminal.

18. The wireless communication apparatus according to claim 16, wherein the training means includes a request signal for requesting feedback of the beamforming information to the receiver terminal in the sounding packet for exciting a channel.

19. The wireless communication apparatus according to claim 16, wherein the training means requests feedback of channel information from the first terminal to the second terminal in a packet including a data symbol which is transmitted prior to the sounding packet when a dedicated sounding packet for exciting a channel which does not include the data symbol is transmitted.

20. The wireless communication apparatus according to claim 16, wherein the training means transmits the sounding packet in the staggered format to the receiver terminal.

21. The wireless communication apparatus according to claim 20, wherein the training means excites a channel of N_max spatial dimensions in the training signal part used for the space division process of the data part and transmits the sounding packet, in which the training signal for exciting a channel of remaining N-N_max spatial dimensions is not related to the space division of a signal, to the receiver terminal.

22. The wireless communication apparatus according to claim 21, wherein the training means transmits the sounding packet, in which the channel of N_max spatial dimensions is excited in the training signal part used for the space division process of the data part and the training signal for exciting the channel of the remaining N-N_max spatial dimensions is not included, to the receiver terminal.

23. The wireless communication apparatus according to claim 16, wherein the training means performs conversion for mapping N_max or less transmission streams to all N transmission antenna branches when a dimension number of the transmission streams is suppressed to the maximum dimension N_max or less.

24. The wireless communication apparatus according to claim 23, wherein the training means performs the mapping to the N transmission antenna branches by multiplying transmission streams of N_max dimensions by a mapping matrix having N rows and N_max or less columns.

25. The wireless communication apparatus according to claim 23, wherein the data transmission means performs mapping to the transmission antenna branches which becomes equal to the training means with respect to the transmission streams formed using the beamforming means.

26. The wireless communication apparatus according to claim 24,

wherein OFDM modulation is used as a wireless communication signal, and

wherein the training means gives different cyclic shift delay amounts to the transmission antenna branches after the multiplication of the mapping matrix.

27. The wireless communication apparatus according to claim 24, wherein OFDM modulation is used as a wireless communication signal, and

wherein the data transmission means performs different mappings in a subcarrier unit when the conversion for mapping the transmission streams of the N_max dimensions to all the N transmission antenna branches.

28. The wireless communication apparatus according to claim 16,

wherein the beamforming information receiving means receives the channel matrix having M rows and N_max or less columns estimated by the receiver terminal as CSI information, and

wherein the transmission weight matrix setting means calculates the transmission weight matrix for beamforming, on the basis of the received CSI information.

29. The wireless communication apparatus according to claim 16,

wherein the beamforming information receiving means receives the transmission weight matrix for beamforming having M rows and N_max or less columns and calculated from the channel matrix estimated by the transmission-destination terminal in a compressed or uncompressed format, and

wherein the transmission weight matrix setting means uses the received transmission weight matrix for beamforming.

30. A wireless communication method which performs data transmission using spatially multiplexed streams to a receiver terminal including M antennas in a wireless communication apparatus which includes N antennas N being an integer of 2 or more and M being an integer of 1 or more, the method comprising the steps of:

receiving notification of a maximum dimension N_max at a time of estimating a channel matrix of the receiver terminal, wherein N_max is an integer of M or less;

transmitting a sounding packet including training sequence for exciting a channel corresponding to the maximum dimension N_max to the receiver terminal, the sounding packet being transmitted in a staggered format including first and second sections, the first section having a first format corresponding to a format of one of the streams, and the second section having a second format, wherein the sounding packet is transmitted in the staggered format for temporally dividing;

a training signal part used for a space division process of a data part; and

a training signal part for exciting a channel of a spatial dimension larger than or equal to the number of streams of data;

receiving beamforming information necessary for calculating a transmission weight matrix for beamforming composed of a channel matrix having M rows and N_max or less columns, wherein the channel matrix is estimated by the receiver terminal using the packet and based on a determination that a number of antennas N of the wireless communication apparatus is greater than a number of antennas M of the receiver terminal;

setting the transmission weight matrix for beamforming on the basis of the received beamforming information; and

performing beamforming of the antennas using the set transmission weight matrix for beamforming and transmitting a data packet to the receiver terminal.

31. A wireless communication system which performs data transmission using spatially multiplexed streams from a first terminal including N antennas to a second terminal including M antennas, N being an integer of 2 or more and M being an integer of 1 or more, the system comprising:

a notifying unit which notifies the first terminal of a maximum dimension N_max at a time of estimating a channel matrix of the second terminal, wherein N_max is an integer of M or less;

a training unit which transmits a sounding packet including training sequence for exciting a channel corresponding to the maximum dimension N_max from the first terminal to the second terminal, the sounding packet being transmitted in a staggered format including first and second sections, the first section having a first format corresponding to a format of one of the streams, and the second section having a second format, wherein the sounding packet is transmitted in the staggered format for temporally dividing;

a training signal part used for a space division process of a data part; and

a training signal part for exciting a channel of a spatial dimension larger than or equal to the number of streams of data;

a channel matrix estimation unit which divides the training sequence received by the antennas of the second terminal into N_max or less streams and estimates the channel matrix having M rows and N_max or less columns, wherein the channel matrix is estimated based on a determination that a number of antennas N of the first terminal is greater than a number of antennas M of the second terminal;

a beamforming information feedback unit which prepares beamforming information necessary for calculating a transmission weight matrix for beamforming in the first terminal on the basis of the channel matrix estimated in the second terminal and feeds back the beamforming information from the second terminal to the first terminal;

a transmission weight matrix setting unit which sets the transmission weight matrix for beamforming at a time of transmitting data from the first terminal to the second terminal on the basis of the beamforming information fed back from the second terminal to the first terminal; and

a beamforming unit which performs beamforming in transmission signals of the antennas of the first terminal using the transmission weight matrix for beamforming when a data packet is transmitted from the first terminal to the second terminal.

32. A wireless communication apparatus which includes N antennas and performs data transmission using spatially multiplexed streams to a receiver terminal including M antennas, N being an integer of 2 or more and M being an integer of 1 or more, the apparatus comprising:

a notification receiving unit receives notification of a maximum dimension N_max at a time of estimating a channel matrix of the receiver terminal, wherein N_max is an integer of M or less;

a training unit which transmits a sounding packet including training sequence for exciting a channel corresponding to the maximum dimension N_max to the receiver terminal, the sounding packet being transmitted in a staggered format including first and second sections, the first section having a first format corresponding to a format of one of the streams, and the second section having a second format, wherein the sounding packet is transmitted in the staggered format for temporally dividing;

a training signal part used for a space division process of a data part; and

a training signal part for exciting a channel of a spatial dimension larger than or equal to the number of streams of data;

a beamforming information receiving unit which receives beamforming information necessary for calculating a transmission weight matrix for beamforming composed of a channel matrix having M rows and N_max or less columns, wherein the channel matrix is estimated by the receiver terminal using the packet and based on a determination that a number of antennas N of the wireless communication apparatus is greater than a number of antennas M of the receiver terminal;

a transmission weight matrix setting unit which sets the transmission weight matrix for beamforming on the basis of the received beamforming information; and

a data transmitting unit which performs beamforming of the antennas using the set transmission weight matrix for beamforming and transmits a data packet to the receiver terminal.