Multi-antenna/multi-receiver array diversity system

• US 20030060178A1
• Filed: 09/25/2001
• Published: 03/27/2003
• Est. Priority Date: 09/25/2001
• Status: Active Grant

• Current Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Rice, Christopher W., Miller, Robert Raymond II, Erving, Richard Henry, Ghassemzadeh, Saeed S.
• Granted Patent: US 7,155,192 B2
• Time in Patent Office: Days
• US Class Current: 455/277.1
• CPC Class Codes: H04B 7/0808 comparing all antennas before reception
• CPC Class Codes: H04B 7/082 selecting best antenna path
• CPC Class Codes: H04B 7/0857 using maximum ratio combining techniques, e.g. signal-to- interference ratio [SIR], received signal strenght indication [RSS]
• CPC Class Codes: H04B 7/0874 using subgroups of receive antennas
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity

Abstract

The present invention is a system for increasing Signal-to-Noise Ratio (SNR) in a wireless communication system comprising a plurality of antennas each antenna providing a signal, a device for selecting a subset of signals provided by the plurality of antennas, a maximum ratio combiner for summing the selected subset of signals provided by the plurality of antennas, and a decision device for measuring the selected subset of signals against a predefined threshold. The device for selecting the subset of signals is coupled to the plurality of antennas. The maximum ratio combiner is coupled to the selected subset of signals and the decision device for measuring the selected subset of signals against a predefined threshold. The decision device is coupled to the selecting device such that one selected signal of the selected subset of signals is replaced by an unused signal provided by the plurality of antennas.

Claims

1. A system for increasing Signal-to-Noise Ratio (SNR) in a wireless communication system, comprising:

a plurality of antennas, each antenna providing a signal;

a device for selecting a subset of signals provided by said plurality of antennas, said device for selecting said subset of signals coupled to said plurality of antennas;

a maximum ratio combiner for summing said selected subset of signals provided by said plurality of antennas, said maximal ratio combiner coupled to said selected subset of signals; and

a decision device for measuring the selected subset of signals against a predefined threshold, said decision device coupled to said selecting device such that one selected signal of said selected subset of signals is replaced by an unused signal provided by said plurality of antennas.

2. The system according to claim 1, wherein said plurality of antennas further comprises four antennas.

3. The system according to claim 2, wherein said four antennas are arranged such that there are two antennas at each of two positions to accomplish spatial diversity and each of said two antennas at each of said two positions are in cross-polarization with each other in order to accomplish polarization diversity.

4. The system according to claim 1, wherein said selecting device selects the two largest signals from said signals provided by said plurality of antennas.

5. A method for replacing a signal of a selected set of signals when said selected signal falls below a predefined threshold, comprising the steps of:

ranking each antenna;

creating antenna states by making pairs of all ranked antennas;

determining next states for each created antenna state based on switching only one antenna of any antenna state pair in one time cycle, and further based on one of whether a highest rank of said antenna state pair is to be switched and a lowest rank of an antenna state pair is to be switched and no antennas in said antenna state pair are to be switched;

selecting a next state in said one time cycle;

switching to a next antenna state based on the results of said selecting step; and

repeating said selecting step and said switching step for each time cycle for which communication exists.

6. The method according to claim 5, wherein said determining step further comprises an adjustment of said antenna ranking when the highest rank antenna is to be switched, comprising the step of setting the rank of said highest ranking antenna to zero (0) before applying said determining step.

7. The method according to claim 5, wherein a set of available antenna states is the set of all created antenna states less an antenna state pair currently in use in said one time cycle.

8. A system for replacing a signal of a selected set of signals received by antennas when said selected signal falls below a predefined threshold, comprising:

means for ranking each antenna;

means for creating antenna states by making pairs of all ranked antennas;

means for determining next states for each created antenna state based on switching only one antenna of any antenna state pair in one time cycle, and further based on one of whether a highest rank of said antenna state pair is to be switched and a lowest rank of an antenna state pair is to be switched and no antennas in said antenna state pair are to be switched;

means for selecting a next state in said one time cycle;

means for switching to a next antenna state based on the results of said selecting step; and

means for invoking said means for selecting and said means for switching for each time cycle for which communication exists.

9. The system according to claim 8, wherein said means for determining further comprises an adjustment of said antenna ranking when the highest rank antenna is to be switched, comprising means for setting the rank of said highest ranking antenna to zero (0) before applying said means for determining.

10. The system according to claim 8, wherein a set of available antenna states is the set of all created antenna states less an antenna state pair currently in use in said one time cycle.

11. A method for increasing Signal-to-Noise Ratio (SNR) in a wireless communication system, comprising the steps of:

receiving a signal from each of a plurality of antennas;

selecting a subset of signals provided by said plurality of antennas;

summing said selected subset of signals provided by said plurality of antennas;

measuring each signal of said selected subset of signals against a predefined threshold; and

replacing one signal of said selected subset of signals provided by said plurality of antennas that has fallen below said threshold in a single time cycle.

12. The method according to claim 11, further comprising the step of optionally adjusting each of said selected subset of signals provided by said plurality of antennas by a coefficient.

13. The method according to claim 11, wherein said plurality of antennas further comprises four antennas.

14. The method according to claim 13, wherein said four antennas are arranged such that there are two antennas at each of two positions to accomplish spatial diversity and each of said two antennas at each of said two positions are in cross-polarization with each other in order to accomplish polarization diversity.

15. The method according to claim 11, wherein said selecting step selects the two largest signals from said signals provided by said plurality of antennas.

16. A system for increasing Signal-to-Noise Ratio (SNR) in a wireless communication system, comprising the steps of:

means for receiving a signal from each of a plurality of antennas;

means for selecting a subset of signals provided by said plurality of antennas;

means for summing said selected subset of signals provided by said plurality of antennas;

means for measuring each signal of said selected subset of signals against a predefined threshold; and

means for replacing one signal of said selected subset of signals provided by said plurality of antennas that has fallen below said threshold in a single time cycle.

17. The system according to claim 16, further comprising means for optionally adjusting each of said selected subset of signals provided by said plurality of antennas by a coefficient.

18. The system according to claim 16, wherein said plurality of antennas further comprises four antennas.

19. The system according to claim 18, wherein said four antennas are arranged such that there are two antennas at each of two positions to accomplish spatial diversity and each of said two antennas at each of said two positions are in cross-polarization with each other in order to accomplish polarization diversity.

20. The system according to claim 16, wherein said means for selecting selects the two largest signals from said signals provided by said plurality of antennas.