Adaptive sectorization in a spread spectrum communication system

• US 5,621,752 A
• Filed: 06/23/1994
• Issued: 04/15/1997
• Est. Priority Date: 06/23/1994
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Gilhousen, Klein S., Zehavi, Ephraim, Wolf, Jack K., Antonio, Franklin P.
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): VO, DON NGUYEN
• Application Number:
  US08/265,664
• Time in Patent Office: 1,027 Days
• Field of Search: 375/200-208, 375/260, 375/264, 375/267, 375/316, 375/347, 375/349, 375/367, 375/205, 455/432-135, 455/277.1, 455/277.2, 455/278.1, 455/279.1, 455/140, 370/18, 370/95.1
• US Class Current: 375/144
• CPC Class Codes: H04B 1/7085 using a code tracking loop, e.g. a delay-locked loop
• CPC Class Codes: H04B 1/7117 Selection, re-selection, allocation or re-allocation of paths to fingers, e.g. timing offset control of allocated fingers
• CPC Class Codes: H04B 1/712 Weighting of fingers for combining, e.g. amplitude control or phase rotation using an inner loop
• CPC Class Codes: H04W 16/28 using beam steering

Abstract

A system and method for adaptively sectorizing channel resources within a digital cellular communication system is disclosed herein. The system includes an antenna arrangement for providing at least first and second electromagnetic beams for receiving a first information signal transmitted by a specific one of a plurality of users, thereby generating first and second received signals. A first set of beam-forming signals are then generated from the first and second received signals. A demodulating receiver is provided for demodulating at least first and second beam-forming signals included within the first set of beam-forming signals, thereby producing first and second demodulated signals. The system further includes a tracking network for tracking multipath information signals, received from various positions and angles of incidence, based on comparison of the first and second demodulated signals.

Claims

1. A digital communication system in which information signals are communicated among a plurality of users, said system comprising:

means for providing at least first and second electromagnetic beams for receiving components of said information signals transmitted by said users;

means for allocating said first electromagnetic beam to receive a first of said information signal components transmitted over a first transmission path so as to generate a first received signal, said first information signal component comprising at least a portion of a first information signal transmitted by a first of said users;

means for generating a first beam signal from said first received signal;

a first beam tracking network for generating a first beam tracking signal by demodulating said first beam signal; and

beam switching means for spatially tracking said first signal component by assigning said second electromagnetic beam to receive said first signal component based upon said first beam tracking signal.

2. The system of claim 1 further including means for generating a second beam signal from a second received signal derived from said second electromagnetic beam, said means for generating said first and second beam signals including means for sampling said first and second received signals in order to generate first and second sampled received signals.

3. The system of claim 2 wherein said means for demodulating includes means for adjusting timing at least of said first sampled received signal in accordance with said first beam tracking signal.

4. The system of claim 1 wherein said beam tracking network includes means for spatially tracking said first component of said information signal, said means for spatially tracking including an accumulator for generating a cumulative error signal by accumulating said beam tracking signal.

5. The system of claim 1 wherein said means for providing said first and second electromagnetic beams is disposed within a base station of said digital communication system, said means for providing said first and second beams including an antenna network.

6. The system of claim 1 further including means for providing third and fourth electromagnetic beams for receiving a second information signal component over a second transmission path so as to generate third and fourth received signals, said second information signal component comprising a second portion of said first information signal.

7. The system of claim 6 further including:

means for generating third and fourth beam signals from said third and fourth received signals;

means for demodulating said third and fourth beam signals in order to provide third and fourth estimates of said information signal; and

a second tracking network for generating a second tracking signal based on said third and fourth estimates of said information signal.

8. The system of claim 2 further including:

means for demodulating said second beam signal;

means for generating a set of symbol estimation signals by correlating said first beam signal with a corresponding set of information symbol sequences,

means for selecting one of said information symbol sequences by comparing said symbol estimation signals.

9. The system of claim 8 wherein said means for demodulating said first and second beam signals includes means for correlating said selected one of said information symbol sequences with said second beam signal.

10. A digital communication system in which information signals are communicated among a plurality of users, said system comprising;

means for providing a set of electromagnetic beams for receiving multipath signal components of a plurality of information signals transmitted by a corresponding plurality of users so as to generate a set of received signals;

switching means for spatially tracking said multipath signal components by altering allocation of subsets of said beam signals among a plurality of traffic channels, each of said traffic channels being associated with one of said plurality of users; and

receiver means for recovering a first of said information signals from a first of said subsets of beam signals allocated to a first of said traffic channels associated with a first of said users.

11. The communication system of claim 10 wherein said first receiver means includes first and second receiver fingers for processing first and second multipath signal components of said first information signal.

12. The communication system of claim 11 wherein said switching means includes means for assigning a first of said subsets of beam signals to said first receiver finger and a second of said subsets of beam signals to said second receiver finger.

13. The communication system of claim 10 wherein said first receiver finger includes a first demodulator for demodulating said beam signals included in said first set of beam signals in order to provide a corresponding first set of estimates of said first information signal;

and

a first tracking network for generating a first tracking signal based on said first set of estimates of said information signal.

14. The system of claim 13 wherein said first demodulator includes means for correlating said beam signals included within said first set of beam signals using a spread spectrum sequence.

15. The system of claim 10 wherein means for generating a set of beam signals includes:

means for sampling said set of received signals in order to generate quantized signals;

means for weighting said quantized signals; and

means for summing ones of said weighted quantized signals.

16. The system of claim 10 wherein said receiver means includes a plurality of receivers coupled to said switching means, each of said receivers including a receiver finger for processing one of said subsets of said beam signals.

17. A digital communication system in which information signals are communicated via at least one base station among a plurality of users, said system comprising:

an array of antenna elements, located at said base station, for providing a first set of electromagnetic beams for receiving information signals transmitted by said plurality of users to as to generate a first set of received signals;

a first beam-forming matrix, coupled to said array of antenna elements, for producing a first set of beam signals based on samples to said set of received signals, said beam-forming matrix including means for weighting and combining selected ones of said received signal samples;

switching means for spatially tracking said information signals received at said base station by altering allocation of subsets of said beam signals among a plurality of traffic channels wherein each of said traffic channels is associated with one of said plurality of users; and

a set of receivers coupled to said switching means, each of said receivers including means for extracting an information signal from the subset of beam signals allocated to one of said traffic channels.

18. The system of claim 17 further including a remote array of antenna elements, displaced from said base station and operatively connected to said beam matrix, for providing a second set of electromagnetic beams for receiving information signals transmitted by said plurality of users so as to generate a second set of received signals

a second beam-forming matrix, coupled to said remote array of antenna elements, for producing a second set of beam signals based on samples of said set of received signals, said second beam-forming matrix including means for weighting and combining selected ones of said samples of said signals included within said second set of received signals, said beam-forming matrix being operatively connected to a switch matrix included within said switching means.

19. A method for communicating information signals among a plurality of users within a digital communication system, said method comprising the steps of:

providing first and second electromagnetic beams for receiving a first information signal component over a first transmission path so as to generate first and second received signals, said first information signal component comprising at least a portion of a first information signal transmitted by a first of said users;

generating first and second beam signals from said first and second received signals;

demodulating said first and second beam signals in order to provide first and second estimates of said information signal; and

generating a first tracking signal based on said first and second estimates of said information signal, said first tracking signal being useable to spatially track said first transmission path.

20. The method of claim 19 wherein said step of generating said first and second beam signals includes the step of sampling said first and second received signals in order to produce first and second sampled received signals.

21. The method of claim 20 wherein said step of demodulating includes the step of adjusting timing of said first and second sampled received signals in accordance with said first tracking signal.

22. The method of claim 19 wherein said step of tracking includes the step of spatially tracking said first component of said information signal, said step of spatially tracking including the step of generating a cumulative error signal by accumulating said tracking signal.

23. The method of claim 19 wherein said step of providing said first and second electromagnetic beams is performed within a base station of said digital communication system.

24. The method of claim 19 further including the step of providing third and fourth electromagnetic beams for receiving a second information signal component over a second transmission path so as to generate third and fourth received signals, said second information signal component comprising a second portion of said first information signal.

25. The method of claim 24 further including the steps of:

generating third and fourth beam signals from said third and fourth received signals;

demodulating said third and fourth beam signals in order to provide third and fourth estimates of said information signal; and

generating a second tracking signal based on said third and fourth estimates of said information signal.

26. The method of claim 19 further wherein said step of demodulating said first and second beam signals includes the steps of:

generating a set of symbol estimation signals by correlating said first beam signal with a corresponding set of information symbol sequences,

selecting one of said information symbol sequences by comparing said symbol estimation signals.

27. The method of claim 26 wherein said step of demodulating said first and second beam signals includes the step of correlating said selected one of said information symbol sequences with said second beam signal.

28. A method for communicating information signals among a plurality of users within a digital communication system, said method comprising the steps of:

providing a set of electromagnetic beams for receiving multipath signal components of a plurality of information signals transmitted by a corresponding plurality of users so as to generate a set of received signals;

generating a set of beam signals based on said set of received signals;

spatially tracking said multipath components by altering allocation (of subsets of said beam signals among a plurality of traffic channels, each of said traffic channels being associated with one of said plurality of users; and

recovering a first of said information signals from a first of said subsets of beam signals allocated to a first of said traffic channels associated with a first of said users.

29. The method of claim 28 wherein said step of recovering includes the step of processing first and second multipath signal components of said first information signal using first and second receiver fingers, respectively, of a first receiver.

30. The method of claim 29 wherein said step of allocating includes the step of assigning a first of said subsets of beam signals to said first receiver finger and a second of said subsets of beam signals to said second receiver finger.

31. The method of claim 28 further including the steps of:

demodulating said beam signals included in said first set of beam signals in order to provide a corresponding first set of estimates of said first information signal, and

generating a first tracking signal based on said first set of estimates of said information signal.

32. The method of claim 31 wherein said step of demodulating includes the step of correlating said beam signals included within said first set of beam signals using a spread spectrum sequence.

33. The method of claim 28 wherein said step of generating a set of beam signals includes the steps of:

sampling said set of received signals in order to generate quantized signals;

weighting said quantized signals; and

summing ones of said weighted quantized signals.