Method to increase the bit rate in a communication system

• US 7,664,195 B2
• Filed: 08/21/2006
• Issued: 02/16/2010
• Est. Priority Date: 08/10/2001
• Status: Active Grant

• Current Assignee: Thales SA
• Original Assignee: Thales SA
• Inventors: Chenu-Tournier, Marc, Morgand, Philippe
• Primary Examiner(s): Ghayour; Mohammad H
• Assistant Examiner(s): Malek; Leila
• Application Number:
  US11/507,001
• Publication Number:
  US 20070014387A1
• Time in Patent Office: 1,275 Days
• Field of Search: 375/267, 375/259, 375/347, 375/299, 375/316, 375/229, 375/233
• US Class Current: 375/267
• CPC Class Codes: H04B 7/04 using two or more spaced independent antennas
• CPC Class Codes: H04B 7/0851 using training sequences or error signal minimizing error signal H04B7/0854
• CPC Class Codes: H04B 7/0854 using error minimizing algorithms, e.g. minimum mean squared error [MMSE], "cross-correlation" or matrix inversion

Abstract

Disclosed is a method and a device to increase the bit rate in a communications system comprising N transmitters (2_N) and M receivers (3_M), with M greater than or equal to N. The method comprises the following steps.

• • a) simultaneously sending different messages on several of the N (2_N) transmitters,
  • b) simultaneously receiving the superimposition of the messages sent during the step a) on several of the M (3_M) receivers or reception sensors,
  • c) estimating the characteristics of the transmission channel for each pair constituted by a transmission sensor and a receiver sensor,
  • d) jointly estimating all or at least the majority of the messages received in taking account of the signals as well as the characteristics of the transmission channel.
    Application to GSM signals and to systems of unicast transmission and multicast transmission, namely multipoint-to-point and multipoint-to-multipoint transmission.

Claims

1. A receiver apparatus in a communication system including N transmitters and M receivers, with M greater than or equal to N, said receiver being one of said M receivers, said receiver comprising:

a reception agent configured to simultaneously receive a superimposition of different messages sent by the N transmitters, which are spatially delocalized;

a demodulating agent configured to decode a signal representing said superimposition of the different messages sent by the N transmitters received by the reception agent;

a channel estimating agent configured to estimate a characteristic of a transmission channel between one of said N transmitters and said receiver by combining information of all of the different messages, the information of all the different messages based on said decoded signal representing said superimposition of the different messages sent by the N transmitters; and

an equalizer filter, coupled to said reception agent, configured to minimize a mean squared error between an output of said equalizer filter and a corresponding real symbol, said equalizer filter having a feed forward filtering function and a feed back filtering function,

wherein said equalizer filter is configured to minimize mean squared error according to;

$E<br><br>\left[{<br><br>\left[G-B\right]<br><br>\left[\begin{array}{c}{y}_n\\ y_n^{*}\\ d_n\\ d_n^{*}\end{array}\right]-b_n<br><br>}^2\right]$

where,

G is the feed forward function,

B is the feed back function,

y_n is a symbol at input of G,

d_n is a symbol at input of B,

b_n is a real symbol.

2. The receiver apparatus according to claim 1, wherein the demodulating agent comprises a SGWN (Standard Gaussian White Noise) demodulator.

3. The receiver apparatus according to claim 2, wherein the SGWN demodulator is implemented by a Viterbi decoder.

4. The receiver apparatus according to claim 1, wherein the equalizer filter further comprises a MF (Matched Filter).

5. The receiver apparatus according to claim 1, wherein the equalizer filter further comprises a DFE ZF (Decision Feedback Equalizer-Zero Forcing Filter).

6. The receiver apparatus according to claim 1, wherein the equalizer filter further comprises a DFE MMSE (Decision Feedback Equalizer-Minimum Mean Squared Error Filter).

7. The receiver apparatus according to claim 1, wherein

the N transmitters which are spatially delocalized are spaced at a sufficient distance from the M receivers as compared to a spatial decorrelation distance.

8. The receiver apparatus of claim 1, wherein the equalizer filter is configured to minimize the mean squared error between the output of the equalizer filter and the corresponding real symbol to produce a bit-error-rate of less than 10⁻

3, when the signal-to-noise ratio of the signal is greater than 5 dB.

9. A receiver apparatus in a communication system including N transmitters and M receivers, with M greater than or equal to N, said receiver being one of said M receivers, said receiver comprising:

means for receiving simultaneously a superimposition of different messages sent by the N transmitters, which are spatially delocalized;

means for demodulating to decode a received signal representing said superimposition of the different messages sent by the N transmitters;

means for estimating a characteristic of a transmission channel between one of said N transmitters and said receiver by combining information of all of the different messages, the information of all the different messages based on said decoded signal representing said superimposition of the different messages sent by the N transmitters; and

means for equalizing, coupled to means for receiving, to minimize a mean squared error between an output of said means for equalizing and a corresponding real symbol, said means for equalizing having a feed forward filtering function and a feed back filtering function,

wherein said means for equalizing includes means for minimizing said mean squared error according to;

$E<br><br>\left[{<br><br>\left[G-B\right]<br><br>\left[\begin{array}{c}{y}_n\\ y_n^{*}\\ d_n\\ d_n^{*}\end{array}\right]-b_n<br><br>}^2\right]$

where

G is the feed forward function,

B is the feed back function,

y_n is a symbol at input of G,

d_n is a symbol at input of B,

b_n is a real symbol.

10. The receiver apparatus according to claim 9, wherein

the N transmitters which are spatially delocalized are spaced at a sufficient distance from the M receivers as compared to a spatial decorrelation distance.

11. The receiver apparatus of claim 9, wherein the means for minimizing minimizes the mean squared error between the output of the means for equalizing and the corresponding real symbol to produce a bit-error-rate of less than 10⁻

3, when the signal-to-noise ratio of the signal is greater than 5 dB.

12. A receiving method configured to operate in a communication system including N transmitters and M receivers, with M greater than or equal to N, said receiver being one of said M receivers, said receiving method comprising:

receiving, at said receiver, simultaneously a superimposition of different messages sent by the N transmitters, which are spatially delocalized;

demodulating, at a demodulator of said receiver, to decode a received signal representing said superimposition of the different messages sent by the N transmitters;

estimating a characteristic of a transmission channel between one of said N transmitters and said receiver by combining information of all of the different messages, the information of all the different messages based on said decoded signal representing said superimposition of the different messages sent by the N transmitters; and

minimizing at an equalizer filter coupled to the receiver a mean squared error between an output of an equalizing filter and a corresponding real symbol, said minimizing including filtering with a feed forward filtering function and a feed back filtering function,

wherein said minimizing said mean squared error is performed according to;

$E<br><br>\left[{<br><br>\left[G-B\right]<br><br>\left[\begin{array}{c}{y}_n\\ y_n^{*}\\ d_n\\ d_n^{*}\end{array}\right]-b_n<br><br>}^2\right]$

where

G is the feed forward function,

B is the feed back function,

y_n is a symbol at input of G,

d_n is a symbol at input of B,

b_n is a real symbol.

13. The method of claim 12, further comprising:

estimating the characteristics of the transmission channel using a training sequence included in a message.

14. The method of claim 12, further comprising:

demodulating the received signal with a SGWN (Standard Gaussian Wide Noise) demodulator.

15. The method of claim 12, wherein the SGWN demodulator is a Viterbi decoder.

16. The method of claim 12, further comprising:

equalizing at equalizer filter using a MF (Matched Filter).

17. The method of claim 12, further comprising:

equalizing at equalizer filter using a DFE ZFF (Decision Feedback Equalizer-Zero Forcing Filter).

18. The method of claim 12, further comprising:

equalizing at equalizer filter using a DFE MMSE (Decision Feedback Equalizer-Minimum Mean Squared Error Filter).

19. The method of claim 12, wherein

the N transmitters which are spatially delocalized are spaced at a sufficient distance from the M receivers as compared to a spatial decorrelation distance.

20. The receiver method of claim 12, further comprising:

minimizing the mean squared error between the output of the equalizing filter and the corresponding real symbol to produce a bit-error-rate of less than 10<sup>−

3</sup>, when the signal-to-noise ratio of the signal is greater than 5 dB.