Method and apparatus for cancelling interference jamming in digital radio transmission

• US 5,982,825 A
• Filed: 12/26/1996
• Issued: 11/09/1999
• Est. Priority Date: 12/28/1995
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Tsujimoto, Ichiro
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Maddox, Michael W.
• Application Number:
  US08/780,176
• Time in Patent Office: 1,048 Days
• Field of Search: 375/347, 375/267, 375/299, 375/260, 375/346, 375/349, 375/200, 375/201, 375/202, 375/203, 375/204, 375/206, 375/207, 375/208, 375/209, 375/210, 375/345, 375/232, 375/233 , 375/229, 370/342, 370/320, 370/335, 370/479, 455/101, 455/63, 455/65
• US Class Current: 375/347
• CPC Class Codes: H04B 7/0671 using different delays between antennas
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence

Abstract

At a transmitter side, signals are provided with a delay difference with a plurality of branches, coded multiplexed by spectrum spreaders and a combination unit, and transmitted by a single antenna. At a receiver side, the signals are received by a single antenna, and diversity branches are extracted and separated by first and second spectrum de-spreaders. They are subject to linear combination so that the mean square of the decision error signals is minimized. The output passes through an adaptive matched filter and an adaptive equalizer so as to provide an output from which interference waves are eliminated. Thus, interference is eliminated and diversity gain for a signal is ensured, while reducing the scale and cost of a system without using a plurality of antennae.

Claims

1. An apparatus for cancelling interference in a signal, comprising:

means for diversity-combining signals having a delay difference from a plurality of branches to provide branched data;

a single transmitting antenna for transmitting said branched data with said delay difference and having been diversity-combined, as transmitted signals;

means for receiving said transmitted signals, and for diversity-combining said transmitted signals to provide an output signal, said receiving means including;

a single receiving antenna;

an adaptive matched filter receiving said output signal; and

an adaptive equalizer coupled to said adaptive matched filter.

2. An apparatus according to claim 1, further comprising:

means for branching transmitting data into said plurality of branches and providing said delay difference to each of said branches for code-division-multiplexing.

3. An apparatus according to claim 2, wherein said branching means comprises means for performing a coded multiplexing by using an independent spreading code.

4. An apparatus as set forth in claim 1, wherein said means for diversity-combining said transmitted signals performs a diversity combination in a time region by using a minimum mean-square-error algorithm.

5. An apparatus as set forth in claim 1, wherein said adaptive equalizer comprises a decision feedback equalizer.

6. An apparatus as set forth in claim 2, wherein said adaptive equalizer comprises a decision feedback equalizer.

7. An apparatus as set forth in claim 1, wherein said plurality of branches includes N branches, wherein N is an integer no less than 2.

8. An apparatus for cancelling interference in a signal, comprising:

a divider for branching transmitting data into a plurality of branches and providing a delay difference to each of said branches for code-division-multiplexing;

means for diversity-combining signals from said branches;

a single transmitting antenna for transmitting said branched data with said delay difference and having been diversity-combined, as transmitted signals;

a receiver for receiving said transmitted signals, and for diversity-combining said transmitted signals to provide an output signal, said receiver including;

a single receiving antenna.

9. An apparatus according to claim 8, said receiver further comprising:

an adaptive matched filter for receiving said output signal; and

an adaptive equalizer coupled to said adaptive matched filter.

10. An apparatus according to claim 9, wherein said divider comprises means for performing a coded multiplexing by using an independent spreading code.

11. An apparatus as set forth in claim 9, wherein said means for diversity-combining said transmitted signals performs a diversity combination in a time region by using a minimum mean-square-error algorithm.

12. An apparatus as set forth in claim 9 wherein said adaptive equalizer comprises a decision feedback equalizer.

13. An apparatus as set forth in claim 9, wherein said plurality of branches includes N branches, wherein N is an integer no less than 2.

14. A diversity reception system, comprising:

a transmitter and a receiver for receiving signals from said transmitter, said transmitter including;

means for providing a different delay time for each of a plurality of transmitting signals which comprise a transmitting signal divided into N branches at a transmitter side, wherein N is an integer no less than 2;

means for individually spectrum spreading said N-branched transmitting signals;

means for combining said spectrum-spread signals; and

a single antenna for transmitting said combined signals;

wherein said receiver includes;

a single antenna for receiving the combined signals transmitted;

means for dividing said received signals into N branches, and decoding the divided signals through spectrum de-spreading corresponding to a transmitter side, respectively.

15. A diversity reception system according to claim 14, further comprising:

means for demodulating a spectrum de-spread output;

a plurality of multipliers for respectively receiving a demodulated signals for combination to provide combined signals; and

an adaptive matched filter for receiving said combined signals and providing an output.

16. A diversity reception system according to claim 15, further comprising:

an adaptive equalizer for receiving said output of the adaptive matched filter; and

means for correlating a decision error signal of said adaptive equalizer with said demodulated signals.

17. A diversity reception system as set forth in claim 16, wherein the time constant for a correlation is smaller than that of said adaptive equalizer.

18. A diversity reception system according to claim 17, wherein said adaptive equalizer comprises a decision feedback equalizer.

19. A diversity reception system according to claim 14, said receiver further comprising:

a Power Inversion Adaptive Array (PIAA), said PIAA including;

means for demodulating a spectrum de-spread output;

a plurality of multipliers for respectively receiving a demodulated signals for combination to provide combined signals;

a subtraction unit for subtracting outputs of said plurality of multipliers from one another; and

a summing unit for adding outputs of said plurality of multipliers to one another.

20. A diversity reception system according to claim 19, said PIAA further including:

an automatic gain control (AGC) circuit for receiving an output of said summing unit and providing a gain thereto; and

a selector for selectively outputting one of an output from said AGC circuit and an output of said subtraction unit.

21. A diversity reception system according to claim 20, further comprising:

an adaptive matched filter for receiving an output from said selector and providing an output.

22. A diversity reception system according to claim 21, further comprising:

an adaptive equalizer for receiving said output of the adaptive matched filter; and

means for correlating a decision error signal of said adaptive equalizer with said demodulated signals.

23. A diversity reception system as set forth in claim 22, wherein a time constant for a correlation is smaller than that of said adaptive equalizer.

24. A diversity reception system according to claim 23, wherein said adaptive equalizer comprises a decision feedback equalizer.

25. A method for cancelling interference in a signal, comprising steps of:

branching transmitting data into a plurality of branches and providing a delay difference to each of said branches for coded multiplexing;

diversity-combining said data having said delay difference to provide branched data;

transmitting, by a single transmitting antenna, said branched data with said delay difference as transmitted signals;

receiving, by a single receiving antenna, said transmitted signals;

demodulating, separating, and diversity-combining said transmitted signals, to provide a decision data output.