Method for detecting the hopping sequence of an interfering wireless system
AssigneeSharp Laboratories of America, Inc.
InventorDaryl J. Hlasny
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Abstract
Knowledge of the frequency hopping patterns in use by co-located frequency hopping radio systems is useful in reducing the likelihood of collisions between potentially interfering systems. Detection of the frequency hopping pattern is accomplished by determining the time interval between transmissions at a plurality of frequencies by the interfering system and by correlating the time interval to a frequency hopping pattern used by the interferer. The system type of the potentially interfering system can be determined by timing the interval between successive transmissions at a single frequency and correlating this interval or hop pattern duration to a system identifier. Many frequency hopping radio systems can carry out these methods without additional hardware.
Claims26
A method of detecting a frequency hopping pattern of a spread spectrum transmission, said spread spectrum transmission comprising a succession of signals, each transmitted for a period of time at a frequency included in a frequency slot, said frequency hopping pattern being one of a plurality of sequences of said frequency slots, said method comprising the steps of:
- (a) timing a detection interval between detection of a first signal at a first frequency and detection of a second signal at a second frequency;
- and
- (b) correlating said detection interval to a transmission interval for a frequency hopping pattern, said transmission interval being an interval between a transmission in a first frequency slot, said first frequency slot including said first frequency and another transmission in a second frequency slot, said second frequency slot including said second frequency.
A method of detecting a frequency hopping pattern of a spread spectrum transmission, said spread spectrum transmission comprising a succession of signals, each transmitted for a period of time at a frequency included in a frequency slot, said frequency hopping pattern being one of a plurality of sequences of said frequency slots, said method comprising the steps of:
- (a) timing a first detection interval between detection of a first signal at a first frequency and detection of a second signal at a second frequency;
- (b) timing a second detection interval between detection of said second signal and detection of a third signal at a third frequency;
- and
- (c) correlating said first detection interval to a first transmission interval of said frequency hopping pattern, said first transmission interval being an interval between a transmission in a first frequency slot including said first frequency and another transmission in a second frequency slot including said second frequency, and
- (d) correlating said second detection interval to a second transmission interval of said frequency hopping pattern, said second transmission interval being an interval between said another transmission and still another a transmission in a third frequency slot including said third frequency.
A method of detecting a frequency hopping pattern of a spread spectrum transmission, said spread spectrum transmission comprising a sequence of signals, each transmitted for a period of time at a frequency included in a frequency slot, said frequency hopping pattern being one of a plurality of sequences of said frequency slots, said method comprising the steps of:
- (a) timing a detection interval between detection of a first signal at a first predetermined frequency and detection of a second signal at a second predetermined frequency;
- (b) determining a detection interval modulus as a function of said detection interval and a number of frequency slots in said frequency hopping pattern;
- and
- (c) correlating said detection interval modulus to a transmission interval of said frequency hopping pattern, said transmission interval being an interval between a transmission at a first frequency slot, said first frequency slot including said first predetermined frequency, and another transmission at a second frequency slot, said second frequency slot including said second predetermined frequency.
A method of identifying a frequency hopping pattern of a spread spectrum transmission, said spread spectrum transmission comprising a plurality of signals each occurring at a signal frequency in one of a plurality of frequency slots, said frequency hopping pattern being a repeatable sequence of said frequency slots, said method comprising the steps of:
- (a) timing an interval between detection of a first occurrence and a second occurrence of a signal at a signal frequency;
- and
- (b) correlating said interval to a transmission interval for a frequency hopping pattern, said transmission interval being a time between a transmission in a frequency slot and a next transmission in said frequency slot for said frequency hopping pattern.
A method of detecting a frequency hopping pattern of a radio transmission, said radio transmission comprising a succession of periodic transmissions, each occurring at a frequency within a frequency slot, and said frequency hopping pattern comprises one of a plurality of sequences of said frequency slots, said method comprising the steps of:
- (a) monitoring a signal strength at a first predetermined frequency;
- (b) initiating timing of a first interval when said signal strength at said first predetermined frequency reaches at least a threshold strength;
- (c) monitoring said signal strength at a second predetermined frequency;
- (d) terminating said timing of said first interval and initiating timing of a second interval when said signal strength at said second predetermined frequency reaches at least said threshold strength;
- (e) monitoring said signal strength at a third predetermined frequency;
- (f) terminating said timing of said second interval when said signal strength at said third predetermined frequency reaches at least said threshold strength;
- (g) comparing said first interval to a first transmission interval specifying a time between a transmission at said first predetermined frequency and a transmission at said second predetermined frequency for a plurality of frequency hopping patterns;
- (h) comparing said second interval to a second transmission interval specifying a time between a transmission at said second predetermined frequency and a transmission at said third predetermined frequency for at least one of said plurality of frequency hopping patterns;
- and
- (i) identifying as said frequency hopping pattern of said radio transmission, said frequency hopping pattern having first and second transmission intervals substantially equaling, respectively, said first and second intervals.
Dependencies are inferred from the claim text.