Method and Device for Transmitting a Signal in a Multi-Antenna System, Signal, and Method for Estimating the Corresponding Transmission Channels

• US 20070238420A1
• Filed: 04/19/2005
• Published: 10/11/2007
• Est. Priority Date: 04/23/2004
• Status: Active Grant

• Current Assignee: ARKRAY, Inc, 3G Licensing S.A. (Fineur International S.A.)
• Original Assignee: Orange S.A.
• Inventors: Helard, Maryline, Legouable, Rodolphe, Helard, Jean-Francois, Auffray, Jean-Michel, Nir, Vincent
• Granted Patent: US 7,725,091 B2
• Time in Patent Office: Days
• US Class Current: 455/101
• CPC Class Codes: H04L 1/0625 Transmitter arrangements
• CPC Class Codes: H04L 1/0631 Receiver arrangements
• CPC Class Codes: H04L 1/0668 Orthogonal systems, e.g. using Alamouti codes
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 25/0242 using matrix methods

Abstract

A method for transmitting a digital signal via n transmit antennas, wherein n is strictly greater than 2, comprising the steps of combining with a source data vector n vectors to be transmitted respectively by each of the transmit antennas by a coding matrix <I>M</I> with a yield equal to 1, using reference symbols known to at least one receiver whereby it is able to estimate at least three transmission channels corresponding respectively to each of said transmit antennas. Said coding matrix <I>M</I> applied a mathematical transformation to the reference symbols prior to the transmission thereof.

Claims

1. Method of transmission comprising:

transmitting a digital signal via n transmit antennas, n being strictly greater than 2, in which n vectors to be transmitted respectively by each of said transmit antennas are associated with a source data vector by an encoding matrix M of rate equal to 1, using reference symbols known to at least one receiver and enabling this receiver to estimate n transmission channels respectively corresponding to each of said transmit antennas; and

mathematically transforming said reference symbols by said encoding matrix M before they are transmitted.

2. Method of transmission according to claim 1, wherein said reference symbols are distributed in space and in time.

3. Method of transmission according to claim 1, wherein said reference symbols are distributed in space and in frequency.

4. Method of transmission according to claim 1, wherein said encoding matrix includes at least two blocks, each of said blocks being orthogonal.

5. Method of transmission according to claim 4, wherein each of said blocks of reference symbols is transmitted separately, each of said blocks being transmitted on certain of said transmit antennas, the other transmit antennas being powered off.

6. Method of transmission according to claim 1, and further comprising a step of selection between a frequency distribution and a time distribution.

7. Method of transmission according to claim 6, wherein said selection step takes account of the characteristics of a transmission channel.

8. Method of transmission according to claim 1, wherein said reference symbols are transmitted on all the transmit antennas after mathematical transformation by said encoding matrix M.

9. Method of transmission according to claim 8, wherein said encoding matrix is a matrix obtained by a Jafarkhani type encoding and has the form:

10. Digital signal formed by n vectors respectively transmitted by n transmit antennas, n being strictly greater than 2, wherein the signal comprises encoded reference symbols, obtained after mathematical transformation of reference symbols by an encoding matrix M of rate equal to 1, so as to enable the estimation, in a receiver, of said n transmit channels respectively corresponding to each of said transmit antennas.

11. Method of estimation of the transmit channels in a multi-antenna system implementing n transmit antennas, where n is strictly greater than 2, and at least one reception antenna, according to which n vectors to be transmitted respectively by each of said transmit antennas are associated with a vector of source data, by an encoding matrix M, implementing reference symbols known to at least one receiver and enabling this receiver to estimate n transmit channels corresponding respectively to each of said transmit antennas, wherein the method comprises:

receiving a received reference vector, corresponding to a transmitted reference vector obtained by the multiplication of reference symbols by said encoding matrix M, and modified by at least one transmission channel for each of said transmit antennas; and

for each of said reception antennas, mathematically transforming said received reference vector by a decoding matrix, which is the inverse of said encoding matrix and takes account of the effect of a transmission channel associated with said reception antenna, to give an estimation of the effects of said transmit channels on said reference symbols.

12. Method of estimation according to claim 11, wherein said decoding matrix is an inverse matrix integrating an equalization in the sense of the MMSE or ZF criterion.

13. Method of estimation according to claim 12, wherein said criterion implemented is the MMSE criterion and said decoding matrix is formed by the elements:

14. Method of estimation according to claim 12, wherein said criterion implemented is the ZF criterion and in that said decoding matrix is formed by the elements:

15. Method of estimation according to claim 11, and further comprising an interpolation step delivering an estimation of said transmission channels, for each of the source data, from the estimation of the reference symbols.

16. Method of estimation according to claim 15, wherein said interpolation step implements a temporal interpolation and/or a frequency interpolation.

17. Method of estimation according to claim 15 wherein said interpolation step belongs to the group comprising:

linear interpolations;

Wiener interpolations.

18. Device for transmitting a digital signal feeding n transmit antennas, n being strictly greater than 2, comprising:

an encoding matrix M of rate equal to 1, which associates n vectors to be transmitted respectively by each of said transmit antennas with a source data vector, using reference symbols known to at least one receiver and enabling this receiver to estimate n transmission channels respectively corresponding to each of said transmit antennas, and

an encoder, which applies a mathematical conversion to said reference symbols by said encoding matrix M.

19. Device for transmitting according to claim 18, wherein the device forms or is integrated into at least one of the installations belonging to the group comprising:

a base station;

a terminal.

20. Reception device in a multi-antenna system, implementing n transmit antennas, where n is strictly greater than 2, and at least one reception antenna in which n vectors to be transmitted respectively by each of said transmit antennas are associated with a vector of source data, an encoding matrix M, implementing reference symbols known to said receiver and enabling this receiver to estimate n transmit channels corresponding respectively to each of said transmit antennas, wherein the reception device comprises:

a receiver, which receives a received reference vector, corresponding to a transmitted reference vector obtained by the multiplication of reference symbols by said encoding matrix M, and modified by at least one transmission channel for each of said transmit antennas, and

a decoder which, for each of said reception antennas, mathematically transforms said received reference vector by a decoding matrix, which is the inverse of the encoding matrix and takes account of the effect of a transmission channel associated with said reception antenna, to give an estimation of the effects of said transmit channels on said reference symbols.

21. Reception device according to claim 20, wherein the device forms or is integrated into at least one of the installations belonging to the group comprising:

a base station;

a terminal.