Wireless Communications Device Including a Joint Demodulation Filter for Co-Channel Interference Reduction and Related Methods

• US 20070195904A1
• Filed: 08/23/2006
• Published: 08/23/2007
• Est. Priority Date: 08/23/2005
• Status: Active Grant

• Current Assignee: Blackberry Limited
• Original Assignee: Blackberry Limited
• Inventors: Wu, Huan, Simmons, Sean, Kemenczy, Zoltan
• Granted Patent: US 7,639,763 B2
• Time in Patent Office: Days
• US Class Current: 375/262
• CPC Class Codes: H04L 25/0328 with interference cancellation circuitry adaptations for interference cancellation within a sequence estimator H04L25/03305; interference related aspects of direct sequence spread spectrum H04B1/7097; interference related aspects of frequency hopping spread spectrum H04B1/715; see also H04B1/10
• CPC Class Codes: H04L 25/03292 with channel estimation circuitry
• CPC Class Codes: H04L 25/03299 with noise-whitening circuitry

Abstract

A wireless communications device may include a housing and a wireless transmitter and a wireless receiver carried by the housing. The wireless receiver may include a joint demodulation filter for reducing co-channel interference between a desired signal and a co-channel interfering signal which may include an input receiving samples of the desired signal and the co-channel interfering signal, a Viterbi decoder, and a first signal path between the input and the Viterbi decoder comprising a first filter. The joint demodulation filter may further include a second signal path between the input and the Viterbi decoder and comprising a linear finite impulse response (FIR) modeler for generating a channel impulse response estimate for the co-channel interfering signal. Additionally, a third signal path may be between the input and the Viterbi decoder and include a whitened matched filter for generating a channel impulse response estimate for the desired signal.

Claims

1. A wireless communications device comprising:

a housing; and

a wireless transmitter and a wireless receiver carried by said housing;

said wireless receiver comprising a joint demodulation filter for reducing co-channel interference between a desired signal and a co-channel interfering signal, the filter comprising

an input receiving samples of the desired signal and the co-channel interfering signal,

a Viterbi decoder,

a first signal path between said input and said Viterbi decoder comprising a first filter,

a second signal path between said input and said Viterbi decoder and comprising a linear finite impulse response (FIR) modeler for generating a channel impulse response estimate for the co-channel interfering signal, and

a third signal path between said input and said Viterbi decoder and comprising a whitened matched filter for generating a channel impulse response estimate for the desired signal.

2. The wireless communications device of claim 1 wherein the desired signal and the co-channel interfering signal each includes a training sequence;

and wherein said joint demodulation filter further comprises a training-sequence locator upstream of said second and third paths and downstream from said input.

3. The wireless communications device of claim 1 wherein said third signal path comprises a desired-signal channel impulse response (CIR) estimator upstream of said whitened matched filter for generating a desired-signal CIR estimate.

4. The wireless communications device of claim 1 wherein said first filter comprises a first finite impulse response (FIR) filter.

5. The wireless communications device of claim 1 wherein said second signal path comprises a first summer and a second summer connected downstream therefrom.

6. The wireless communications device of claim 5 wherein said second signal path further comprises a remodulator between said desired-signal CIR estimator and said first summer and cooperating therewith for subtracting a remodulated desired-signal training sequence from samples of the desired signal and the co-channel interfering signal to thereby generate an interference signal estimate.

7. The wireless communications device of claim 1 wherein said linear FIR modeler comprises a blind interference and CIR estimator, and a second FIR filter downstream from said blind interference and CIR estimator.

8. The wireless communications device of claim 1 wherein said wireless receiver comprises a cellular receiver.

9. A wireless communications device comprising:

a housing; and

a wireless transmitter and a wireless receiver carried by said housing;

said wireless receiver comprising a joint demodulation filter for reducing co-channel interference between a desired signal and a co-channel interfering signal where the desired signal and the co-channel interfering signal each includes a training sequence, the filter comprising

an input receiving samples of the desired signal and the co-channel interfering signal,

a Viterbi decoder,

a first signal path between said input and said Viterbi decoder comprising a first finite impulse response (FIR) filter,

a second signal path between said input and said Viterbi decoder and comprising a linear finite impulse response (FIR) modeler for generating a channel impulse response estimate for the co-channel interfering signal,

a third signal path between said input and said Viterbi decoder and comprising a whitened matched filter for generating a channel impulse response estimate for the desired signal, and

a training-sequence locator upstream of said second and third paths and downstream from said input.

10. The wireless communications device of claim 9 wherein said third signal path comprises a desired-signal channel impulse response (CIR) estimator upstream of said whitened matched filter for generating a desired-signal CIR estimate.

11. The wireless communications device of claim 9 wherein said second signal path comprises a first summer and a second summer connected downstream therefrom.

12. The wireless communications device of claim 11 wherein said second signal path further comprises a remodulator between said desired-signal CIR estimator and said first summer and cooperating therewith for subtracting a remodulated desired-signal training sequence from samples of the desired signal and the co-channel interfering signal to thereby generate an interference signal estimate.

13. The wireless communications device of claim 9 wherein said linear FIR modeler comprises a blind interference and CIR estimator, and a second FIR filter downstream from said blind interference and CIR estimator.

14. A method for reducing co-channel interference between a desired signal and a co-channel interfering signal in a receiver of a wireless communications device, the method comprising:

filtering received samples of the desired signal and the co-channel interfering signal using a first signal path comprising a first filter;

generating a channel impulse response estimate for the co-channel interfering signal using a second signal path comprising a linear finite impulse response (FIR) modeler;

generating a channel impulse response estimate for the desired signal using a third signal path comprising a whitened matched filter; and

performing a decoding operation based upon the filtered received samples of the desired signal and the co-channel interfering signal, the channel impulse response estimate for the co-channel interfering signal, and the channel impulse response estimate for the desired signal using a Viterbi decoder.

15. The method of claim 14 wherein the desired signal and the co-channel interfering signal each includes a training sequence;

and further comprising performing a training-sequence location upstream of the second and third paths and downstream from the input.

16. The method of claim 14 wherein the third signal path comprises a desired-signal channel impulse response (CIR) estimator upstream of the whitened matched filter for generating a desired-signal CIR estimate.

17. The method of claim 14 wherein the first filter comprises a first finite impulse response (FIR) filter.

18. The method of claim 14 wherein the second signal path comprises a first summer and a second summer connected downstream therefrom.

19. The method of claim 18 wherein the second signal path further comprises a remodulator between the desired-signal CIR estimator and the first summer and cooperating therewith for subtracting a remodulated desired-signal training sequence from samples of the desired signal and the co-channel interfering signal to thereby generate an interference signal estimate.

20. The method of claim 14 wherein the linear FIR modeler comprises a blind interference and CIR estimator, and a second FIR filter downstream from the blind interference and CIR estimator.