Method and system for optimal receive diversity combining

• US 20070268988A1
• Filed: 10/24/2006
• Published: 11/22/2007
• Est. Priority Date: 05/19/2006
• Status: Abandoned Application

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Navini Networks, Inc. (Cisco Systems, Inc.)
• Inventors: Grabner, John, Jin, Hang, Hedayat, Ahmadreza, Guo, Li
• Application Number:
  US11/585,581
• Publication Number:
  US 20070268988A1
• Time in Patent Office: Days
• US Class Current: 375/347
• 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
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04L 1/0059 Convolutional codes
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 1/18 Automatic repetition systems, e.g. Van Duuren systems
• CPC Class Codes: H04L 25/067 providing soft decisions, i.e. decisions together with an estimate of reliability H04L25/068 and H04L25/069 take precedence; sequence estimation techniques H04L25/03178

Abstract

The present invention discloses a method and system for receive signal diversity combining that achieves the high effective SNR and high coding gain. The receive signal diversity combining method combines two or more received diversified signals of a predetermined original message and employs a Maximum Likelihood (ML) detection method to process the diversified signals to generate Log-Likelihood Ratio (LLR) data to exploit the available signal diversity and coding gain of each bit and to help the channel decoder to correctly determine the predetermined original message.

Claims

1. A method for receive diversity combining, the method comprising:

receiving two or more diversified signals of a predetermined original message;

down-converting the diversified signals;

processing the down converted diversified signals by employing a maximum likelihood (ML) detection to generate a log-likelihood ratio (LLR) data; and

decoding the LLR data to determine the original message.

2. The method of claim 1, wherein the diversified signals are time diversity signals.

3. The method of claim 1, wherein the diversified signals are spatial diversity signals.

4. The method of claim 1, wherein the diversified signals are frequency diversity signals.

5. The method of claim 1, wherein the diversified signals includes at least two or more diversity signals of at least one type (i.e. time, spatial or frequency).

6. The method of claim 1, wherein the employing the Maximum Likelihood (ML) detection further includes obtaining a probability when a kth bit of the transmitted symbol s is equal to bε

{0, 1} wherein a mathematical representation is

7. The method of claim 5, wherein employing the Maximum Likelihood (ML) detection further includes generating a LLR data Γ

_k when the LLR of the kth bit of the transmitted symbol s is equal to the difference of λ

_k for the two choices of b wherein a mathematical representation is;

Γ

_k(y)=λ

_k(y₁, . . . , y_N,

     0)−

λ

_k(y₁, . . . , y_N,

     1)

9. The method of claim 7, wherein the diversified signals are time diversity signals.

10. The method of claim 7, wherein the diversified signals are spatial diversity signals.

11. The method of claim 7, wherein the diversified signals are frequency diversity signals.

12. The method of claim 7, wherein the diversified signals include at least two or more diversity signals of at least one type (i.e. time, spatial or frequency).

14. The system of claim 11, wherein the diversified signals are received with one or more antennas placed apart in space.

15. The system of claim 11, wherein the RF and pre-baseband processing modules down-convert the received diversified signals.

16. The system of claim 11, wherein the optimal receive diversity module employing the Maximum Likelihood (ML) detection further obtains a probability when a kth bit of the transmitted symbol s is equal to bε

{0, 1} wherein a mathematical representation is;

8. A method for receive signal diversity combining, the method comprising:

receiving two or more diversified signals of a predetermined original message;

down-converting the diversified signals;

processing the down converted diversified signals by employing a maximum likelihood (ML) detection to generate a log-likelihood ratio (LLR) data; and

decoding the LLR data to determine the original message,

wherein the employing the Maximum Likelihood (ML) detection further includes obtaining a probability when a kth bit of the transmitted symbol s is equal to bε

{0, 1} wherein a mathematical representation is;

13. A receive diversity combining system comprising:

one or more antennas for receiving two or more diversified signals based on an original message;

one or more RF and pre-baseband processing modules associated with the antennas for processing the received diversified signals;

at least one optimal receive diversity combining module for employing Maximum Likelihood (ML) detection to process the diversified signals to generate a Log-Likelihood Ratio (LLR) data; and

at least one decoder for decoding the LLR data to determine the original message.