Antenna diversity techniques

• US 6,522,642 B1
• Filed: 07/02/1998
• Issued: 02/18/2003
• Est. Priority Date: 11/03/1994
• Status: Expired due to Term

• Current Assignee: Inverness Medical Switzerland GmbH (Abbott Laboratories)
• Original Assignee: Intel Corporation
• Inventors: Scott, Logan
• Primary Examiner(s): TON, DANG T
• Application Number:
  US09/109,502
• Time in Patent Office: 1,692 Days
• Field of Search: 370/441,320,324,335,336,342,479,273,272,275,561,562,313,334,339,340,327,209 455/273,272,275,271.1,561,562,6.1,525,524,3.02,3.05,3.06,67.3 375/130,133,134,137,138,139,140,149,148,273,275,279,280,284,285,283 380/20 342/537.1,537.15,537.16
• US Class Current: 370/342
• CPC Class Codes: H04B 7/0837 using pre-detection combining H04B7/0868 takes precedence
• CPC Class Codes: H04B 7/12 Frequency diversity
• CPC Class Codes: H04W 88/085 Access point devices with remote components

Abstract

A receiver system for antenna diversity employing a single backhaul cable. A single backhaul cable couples a receiver to a plurality of antennas. The signals from the antennas are combined onto the single backhaul cable using frequency offsets, spread spectrum code division, time division, or a combination thereof. At the receiver, the signals from the antennas are decoupled. In the case of the frequency offsets, the antenna signals are decoupled by splitting the backhaul signal into a plurality of duplicate signals, frequency shifting selected ones of the duplicate signals, and correlating said frequency shifted signals. In the case of spread spectrum code division, the antenna signals are decoupled by splitting the backhaul signal into a plurality of duplicate signals and demultiplexing each of the duplicate signals with a different spread spectrum code. One or more antennas may be selected for communication in response decoupling the antenna signals.

Claims

1. A communication system, comprising:

a plurality of antennas generating a plurality of antenna signals in response to said plurality of antennas receiving a radio frequency signal;

a combining circuit having a plurality of inputs coupled to said plurality of antennas and an output from which a backhaul signal incorporating antenna signals from said plurality of antennas is output, said combining circuit including (a) a plurality of modulators having a plurality of inputs coupled to said plurality of antennas and a plurality of outputs, and (b) a summer circuit having a plurality of inputs coupled to said plurality of outputs of said plurality of modulators and an output;

a backhaul cable connected to said output of the summer circuit to conduct said backhaul signal from said output of said combining circuit to a second end thereof;

a decoupling circuit having an input coupled to said second end of said backhaul cable to separate said backhaul signal so as to generate a plurality of recovered antenna signals correlating to said plurality of antenna signals; and

a receiver having a plurality of ports coupled to receive said plurality of recovered antenna signals from said decoupling circuit;

the backhaul signal having a bandwidth substantially less than a sum of bandwidths of the plurality of antenna signals.

2. The communication system of claim 1 wherein:

said decoupling circuit includes (a) a splitter having an input coupled to said second end of said backhaul cable and a plurality of outputs, and (b) a plurality of correlators having a plurality of inputs coupled to said plurality of outputs of said splitter and a plurality of outputs coupled to said plurality of ports of said receiver;

said plurality of modulators modulate the plurality of antenna signals with respective Walsh function codes each selected from a set of orthogonal Walsh functions.

3. The communication system of claim 1 wherein:

said receiver selects at least one of said plurality of recovered signals in response to a plurality of reception qualities of said plurality of recovered antenna signals.

4. The communication system of claim 3 wherein said receiver uses selection diversity for selecting said at least one of said plurality of recovered signals.

5. The communication system of claim 3 wherein said receiver uses combining diversity for selecting said at least one of said plurality of recovered signals.

6. A communication system, comprising:

at least two antennas for receiving signals from a remote device;

a combining circuit capable of receiving an input from each of said at least two antennas and generating an output having a combined signal that includes said signals received from said at least two antennas, said combining circuit including (a) modulators having inputs coupled to said antennas and outputs, and (b) a summer circuit having inputs coupled to said outputs of said modulators and an output;

said combined signal having a bandwidth that is substantially less than the sum of the bandwidths of said input from each of said at least two antennas;

a backhaul cable, coupled to the output of the summer circuit, capable of transmitting said generated output of said combining circuit;

a decoupling circuit capable of receiving said generated output of said combining circuit from said backhaul cable and capable of separating said generated output of said combining circuit to respective signals received from said at least two antennas.

7. The communication system of claim 6 wherein said input from each of said at least two antennas is spread spectrum encoded and combined to generate said combined signal.

8. The communication system of claim 7 wherein said input from each of said at least two antennas is code division multiplexed to generate said combined signal.

9. The communication system of claim 8 wherein:

an output of one of said plurality of antennas is modulated with a first chip code and an output of another said plurality of antennas is modulated with a second chip code, said first chip code and said second chip code being distinct.

10. The communication system of claim 6 wherein said receiver is capable of selecting at least one of said signals from said at least two antennas in response to a plurality of reception qualities of said signals from said at least two antennas.

11. The communication system of claim 6 wherein said receiver is capable of selecting at least one of said signals from said two antennas using selection diversity.

12. The communication system of claim 6 wherein said receiver is capable of selecting at least one of said signals from said two antennas using combining diversity.

13. A method of receiving a wireless signal comprising:

generating an antenna signal from each of at least a plurality antennas in response to the wireless signal;

combining each of said antenna signals into a backhaul signal having a bandwidth that is substantially less than the sum of each of said signals, wherein combining each of said antenna signals into a backhaul signal comprises;

modulating the antenna signals; and

adding the modulated antenna signals at summer circuits;

transmitting said backhaul signal through a backhaul cable;

separating said backhaul signal into recovered antenna signals correlating to each of said antenna signals

selecting at least one of said recovered antenna signal according for processing.

14. The method as claimed in claim 13 wherein combining each of said antenna signals into a backhaul signal includes incorporating each of said antenna signal into a backhaul signal using a spread spectrum encoding technique.

15. The method as claimed in claim 14 wherein combining each of said antenna signals into a backhaul signal includes code division multiplexing each of said antenna signal.

16. The method as claimed in claim 13 wherein combining each of said antenna signals into a backhaul signal includes modulating each of said antenna signals with a chip code, said chip code for each of said antenna signals being distinct.

17. The method as claimed in claim 13 wherein selecting at least one of said recovered antenna signal according for processing includes selecting at least one of said recovered antenna signal using selection diversity.

18. The method as claimed in claim 13 wherein selecting at least one of said recovered antenna signal according for processing includes selecting at least one of said recovered antenna signal using combining diversity.

19. The method as claimed in claim 13 further comprising downconverting said backhaul signal to a baseband frequency prior to transmitting said backhaul signal.

20. The method as claimed in claim 13 wherein separating said backhaul signal into recovered antenna signals correlating to each of said antenna signals includes splitting said backhaul signal into duplicate signals and recovering a respective antenna signals from each of said duplicate signals.

21. A communications system, comprising:

at least two antennas for receiving signals from a remote device;

a combining circuit capable of receiving an input from each of said at least two antennas and generating an output having a combined signal generated by code division multiplexing said signals received from said at least two antennas using a spread spectrum transmission technique;

said combining circuit including (a) modulators receiving the input from each of said at least two antennas and generating outputs, and (b) a summer circuit having inputs coupled to said outputs of said modulators and an output;

a backhaul cable capable of transmitting said generated output of said combining circuit;

a decoupling circuit capable of receiving said generated output of said combining circuit from said backhaul cable and capable of separating said generated output of said combining circuit to respective signals received from said at least two antennas.

22. The communication system claimed in claim 21 wherein an output of one of said plurality of antennas is modulated with a first chip code and an output of another said plurality of antennas is modulated with a second chip code, said first chip code and said second chip code being distinct.

23. The communication system of claim 21 wherein said receiver is capable of selecting at least one of said signals from said at least two antennas in response to a plurality of reception qualities of said signals from said at least two antennas.

24. The communication system of claim 21 wherein said receiver is capable of selecting at least one of said signals from said two antennas using selection diversity.

25. The communication system of claim 21 wherein said receiver is capable of selecting at least one of said signals from said two antennas using combining diversity.