Method and apparatus for performing frequency hopping adaptation

• US 6,118,805 A
• Filed: 01/30/1998
• Issued: 09/12/2000
• Est. Priority Date: 01/30/1998
• Status: Expired due to Term

• Current Assignee: General Dynamics C4 Systems Incorporated (General Dynamics Corporation)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Chuprun, Jeffrey Scott, Kleider, John Eric, Bergstrom, Chad Scott
• Primary Examiner(s): Pham, Chi H.
• Assistant Examiner(s): WEBSTER, BRYAN E
• Application Number:
  US09/016,723
• Time in Patent Office: 956 Days
• Field of Search: 375/130, 375/132, 375/133, 375/134, 375/135, 375/136, 375/137, 370/208
• US Class Current: 375/132
• CPC Class Codes: H04B 1/713 using frequency hopping
• CPC Class Codes: H04B 2001/7152 with means for suppressing interference
• CPC Class Codes: H04K 3/228 Elimination in the received signal of jamming or of data corrupted by jamming interference suppression in receivers H04B1/10
• CPC Class Codes: H04L 1/0001 Systems modifying transmission characteristics according to link quality, e.g. power backoff adaptive data allocation for multicarrier modulation H04L5/0044; controlling transmission power for radio systems H04W52/04
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04L 25/0262 Arrangements for detecting the data rate of an incoming signal
• CPC Class Codes: H04L 27/0012 arrangements for identifying the type of modulation

Abstract

The invention relates to a communication system (300) having a receiver (304) that is capable of performing targeted interference suppression. An interference classifier (314) within the receiver (304) analyzes a signal received from a channel (306) and identifies and classifies interference components within the signal. An interference suppressor (316) then suppresses the interference components in the signal based on interference type. In one embodiment, the interference suppressor (316) includes a plurality of interference suppression modules that are each optimal for suppressing certain interference types. The interference suppressor (316) selects one of the interference suppression modules based on the type of interference present in the received signal. In another embodiment, a hybrid interference mitigation system (10) is provided by combining targeted interference suppression, frequency hopping adaptation, and processing gain adaptation.

Claims

1. A subsystem for use in mitigating interference effects in a spread spectrum communications system, comprising:

a signal receptor for receiving a signal from a communications channel;

an interference classifier for classifying a plurality of interference components within said signal to produce an interference type signal indicating a particular interference type;

a frequency hopping unit for performing frequency hopping in said spread spectrum communications system by varying a transmit signal between a plurality of frequency bands according to a predetermined frequency hopping sequence; and

an interference suppressor unit for modifying said predetermined frequency hopping sequence in response to said interference type signal.

2. The subsystem, as claimed in claim 1, wherein:

said interference suppressor unit includes means for removing a frequency band from said frequency hopping sequence.

3. The subsystem, as claimed in claim 2, wherein:

said means for removing removes a frequency band from said frequency hopping sequence based on the presence of an interference component within said frequency band.

4. The subsystem, as claimed in claim 2, wherein:

said means for removing removes a frequency band from said frequency hopping sequence based on the presence of an interference component meeting a predetermined criterion within said frequency band.

5. The subsystem, as claimed in claim 4, wherein:

said interference suppressor unit includes means for reintroducing a frequency band to said frequency hopping sequence when it has been determined that said frequency band no longer includes an interference component meeting said predetermined criterion.

6. The subsystem, as claimed in claim 2, wherein:

said means for removing removes a frequency band from said frequency hopping sequence based on the presence of an interference component having a particular interference type signal within said frequency band.

7. The subsystem, as claimed in claim 2, wherein:

said means for removing removes a frequency band from said frequency hopping sequence based the presence of an interference component that exceeds a predetermined mean amplitude value within said frequency band.

8. The subsystem, as claimed in claim 1, wherein:

said interference classifier includes means for determining parameters relating to said at least one interference component.

9. The subsystem, as claimed in claim 8, wherein:

said parameters include at least one of the following;

instantaneous frequency bandwidth, center frequency, amplitude excursion, mean amplitude, discriminator width, discrete phase modes, discrete amplitude modes, mean discriminate value, peak signal envelope to mean value, peak signal envelope to root mean square (RMS) value, signal baud rate, and adaptive filter class.

10. The subsystem, as claimed in claim 1, further comprising:

a processing gain adaptation unit for changing a transmit signal processing gain in said communications system in response to said interference classifier, said processing gain being related to the bandwidth of said transmit signal.

11. The subsystem, as claimed in claim 10, further comprising:

a chip sequence generator for generating a pseudo noise sequence for use in creating said transmit signal, said chip sequence generator receiving a control signal from said processing gain adaptation unit.

12. The subsystem, as claimed in claim 1, wherein:

said interference classifier includes a signal of interest memory for storing interference signal parameters for a plurality of interference types for use in classifying interference components.

13. The subsystem, as claimed in claim 12, wherein:

said signal of interest memory includes means for adding new interference signal parameters to said signal of interest memory, corresponding to new interference types.

14. The subsystem, as claimed in claim 12, wherein:

said signal of interest memory includes remote update and modification capability.

15. A method for use in mitigating interference effects in a spread spectrum communications system, comprising the steps of:

receiving a signal from a communications channel;

identifying at least one interference component within said signal;

first estimating a power of said at least one interference component within said signal;

second estimating a bandwidth of said at least one interference component within said signal;

third estimating a performance value using said estimated power and said estimated bandwidth; and

modifying a frequency hopping sequence based on a result of said third estimating step, said frequency hopping sequence comprising a predetermined pattern of frequency bands for use in generating a transmit signal for the spread spectrum communications system.

16. The method, as claimed in claim 15, wherein:

said step of identifying includes determining modal moment estimates for components within said signal, said modal moment estimates including at least a mean magnitude estimate and a standard deviation estimate.

17. The method, as claimed in claim 15, wherein:

said step of identifying includes classifying said at least one interference component according to interference type.

18. The method, as claimed in claim 16, wherein:

said step of first estimating includes using said modal moment estimates to estimate said power.

19. The method, as claimed in claim 16, wherein:

said step of second estimating includes using said modal moment estimates to estimate said bandwidth.

20. The method, as claimed in claim 15, wherein:

said step of third estimating includes estimating an error rate.

21. The method, as claimed in claim 15, wherein:

said step of modifying includes removing a frequency band from said frequency hopping sequence.

22. The method, as claimed in claim 15, wherein:

said step of modifying includes removing a plurality of frequency bands.

23. The method, as claimed in claim 15, wherein:

said step of modifying includes removing a frequency band from said frequency hopping sequence when said performance value fails to fall within a predetermined range.