RADAR DETECTION IN A BROADBAND RADIO COMMUNICATION SYSTEM

• US 20140328286A1
• Filed: 07/18/2014
• Published: 11/06/2014
• Est. Priority Date: 01/19/2012
• Status: Active Grant

• Current Assignee: Cambium Networks Limited (Cambium Networks Corporation)
• Original Assignee: Cambium Networks Limited (Cambium Networks Corporation)
• Inventors: Crowle, Martin Richard, King, Nigel Jonathan Richard, Williams, Mark Howard
• Granted Patent: US 9,000,971 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: G01S 7/021 Auxiliary means for detecting or identifying radar signals or the like, e.g. radar jamming signals
• CPC Class Codes: H04B 1/1027 assessing signal quality or detecting noise/interference for the received signal
• CPC Class Codes: H04B 1/3805 with built-in auxiliary receivers
• CPC Class Codes: H04K 3/224 with countermeasures at transmission and/or reception of the jammed signal, e.g. stopping operation of transmitter or receiver, nulling or enhancing transmitted power in direction of or at frequency of jammer
• CPC Class Codes: H04K 3/226 Selection of non-jammed channel for communication spectrum sharing arrangements H04W16/14; selection of wireless resources by user or terminal H04W72/02
• CPC Class Codes: H04K 3/822 by detecting the presence of a surveillance, interception or detection
• CPC Class Codes: H04L 5/0062 Avoidance of ingress interference, e.g. ham radio channels
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks

Abstract

Potential radar pulses are detected in a received signal waveform at a terminal of a broadband radio communication system, and a reception time is ascertained for each of the potential radar pulses. A pair of pulses is selected having respective reception times separated by an allowed pulse repetition intervals. One or more further pulses is selected that is related to the selected pair by having a respective reception time separated from the respective reception time of at least one pulse of the pair of pulses by one or more pulse repetition intervals from the set of pulse repetition intervals. At least two other pulses are discounted, that have respective reception times separated by a pulse repetition interval in the set of allowed pulse repetition intervals on the basis of not being related to the selected pair by having a respective reception time separated from the respective reception time of at least one pulse of said pair of pulses by one or more pulse repetition intervals from the set of pulse repetition intervals. The transmission of data is inhibited at least in part in dependence on the selection of the further pulses related to the selected pair.

Claims

1. A method of transmission of data at a terminal of a broadband radio communication system, the terminal being arranged to inhibit the transmission of data dependent on detection of radar pulses, the radar pulses being transmitted with one or more pulse repetition intervals selected from a set of allowed pulse repetition intervals, the method comprising:

conducting transmission of data in a frequency channel;

receiving a signal waveform at the terminal;

detecting a plurality of potential radar pulses in the received signal waveform;

ascertaining a reception time for each of the plurality of potential radar pulses;

selecting a pair of pulses from the plurality of potential radar pulses, the pair of pulses having respective reception times separated by a selected pulse repetition interval selected from the set of allowed pulse repetition intervals;

selecting one or more further pulses, of the plurality of potential radar pulses, related to said selected pair by having a respective reception time separated from the respective reception time of at least one pulse of said pair of pulses by one or more pulse repetition intervals from the set of pulse repetition intervals;

discounting at least two other pulses from the plurality of potential radar pulses, the at least two other pulses having respective reception times separated by a pulse repetition interval in the set of allowed pulse repetition intervals, the at least two other pulses being discounted on the basis of not being related to said selected pair by having a respective reception time separated from the respective reception time of at least one pulse of said pair of pulses by one or more pulse repetition intervals from the set of pulse repetition intervals; and

inhibiting the transmission of data in said frequency channel at least in part in dependence on the selection of the further pulses related to said selected pair.

2. A method according to claim 1, wherein said inhibiting the transmission of data is not in dependence on the discounted at least two other pulses.

3. A method according to claim 1, the method comprising:

determining whether at least a pre-determined number of the further pulses have been selected; and

inhibiting transmission of data in said frequency channel at least in part in dependence on said determining.

4. A method according to claim 1, wherein said selecting comprises:

selecting the one or more further pulses, of the plurality of potential radar pulses, related to said selected pair by having a respective reception time separated from the respective reception time of at least one pulse of said pair of pulses by an integer multiple of a pulse repetition interval from the set of pulse repetition intervals.

5. A method according to claim 4, wherein said selecting comprises:

selecting the one or more further pulses of the plurality of potential radar pulses having respective reception times separated from the respective reception time of at least one of the said pair by a combination of an integer multiple of the selected pulse repetition interval and an integer multiple of at least a second pulse repetition interval selected from the set of allowed pulse repetition intervals.

6. A method according to claim 5, wherein said selecting comprises:

determining that the one or more further pulses have a sequence of reception times matching a pre-determined allowable sequence of reception times for a radar having pulse repetition intervals alternating between two values.

7. A method according to claim 5, wherein said selecting comprises:

determining that the one or more further pulses have a sequence of reception times matching a pre-determined allowable sequence of reception times for a radar having pulse repetition intervals having three or more values.

8. A method according to claim 1, wherein said detecting of the plurality of potential radar pulses in the received signal waveform comprises:

comparing a power of the received waveform with a threshold; and

detecting a detected pulse in dependence on the power of the received waveform being above the threshold.

9. A method according to claim 8, wherein said detecting of the plurality of potential radar pulses in the received signal waveform comprises:

determining a duration of a detected pulse; and

identifying the detected pulse as a potential radar pulse on a basis of the duration of the detected pulse.

10. A method according to claim 8, wherein said detecting the plurality of potential radar pulses in the received signal waveform comprises:

determining whether each detected pulse may be received as a wanted signal of the wireless communication system; and

identifying a detected pulse as a potential radar pulse on a basis of the determination as to whether each detected pulse may be received as a wanted signal of the wireless communication system.

11. A method according to claim 10, wherein determining whether each detected pulse may be received as a wanted signal of the wireless communication system comprises receiving a training sequence of a wanted signal.

12. A method according to claim 10, wherein determining whether each detected pulse may be received as a wanted signal of the wireless communication system comprises receiving a cyclic prefix of an orthogonal frequency division multiplexing (OFDM) signal.

13. A method according to claim 1, wherein said detecting of the plurality of potential radar pulses in the received signal waveform comprises detecting an error in the reception of a wanted signal of the wireless communication system.

14. A method according to claim 1, wherein the broadband radio communication system operates according to IEEE 802.11

15. A terminal for transmission of data in a broadband radio communication system, the terminal being arranged to inhibit the transmission of data dependent on detection of radar pulses, the radar pulses being transmitted with one or more pulse repetition intervals selected from a set of allowed pulse repetition intervals, the terminal comprising:

a transmitter arranged to conduct transmission of data in a frequency channel;

a receiver arranged to receive a signal waveform at the terminal;

a detector arranged to detect a plurality of potential radar pulses in the received signal waveform; and

a processor arranged to;

ascertain a reception time for each of the plurality of potential radar pulses;

select a pair of pulses from the plurality of potential radar pulses, the pair of pulses having respective reception times separated by a selected pulse repetition interval selected from the set of allowed pulse repetition intervals;

select one or more further pulses, of the plurality of potential radar pulses, related to said selected pair by having a respective reception time separated from the respective reception time of at least one pulse of said pair of pulses by one or more pulse repetition intervals from the set of pulse repetition intervals;

discount at least two other pulses from the plurality of potential radar pulses, the at least two other pulses having respective reception times separated by a pulse repetition interval in the set of allowed pulse repetition intervals, the at least two other pulses being discounted on the basis of not being related to said selected pair by having a respective reception time separated from the respective reception time of at least one pulse of said pair of pulses by one or more pulse repetition intervals from the set of pulse repetition intervals; and

inhibit the transmission of data in said frequency channel at least in part in dependence on the selection of the further pulses related to said selected pair, and not in dependence on pulses not selected as the further pulses.

16. A non-transitory computer readable medium having instructions to cause a processor to cause a terminal to perform a method of transmission of data at a terminal of a broadband radio communication system, the terminal being arranged to inhibit the transmission of data dependent on detection of radar pulses, the radar pulses being transmitted with one or more pulse repetition intervals selected from a set of allowed pulse repetition intervals, the method comprising:

conducting transmission of data in a frequency channel;

receiving a signal waveform at the terminal;

detecting a plurality of potential radar pulses in the received signal waveform;

ascertaining a reception time for each of the plurality of potential radar pulses;

selecting a pair of pulses from the plurality of potential radar pulses, the pair of pulses having respective reception times separated by a selected pulse repetition interval selected from the set of allowed pulse repetition intervals;

selecting one or more further pulses, of the plurality of potential radar pulses, related to said selected pair by having a respective reception time separated from the respective reception time of at least one pulse of said pair of pulses by one or more pulse repetition intervals from the set of pulse repetition intervals;

discounting at least two other pulses from the plurality of potential radar pulses, the at least two other pulses having respective reception times separated by a pulse repetition interval in the set of allowed pulse repetition intervals, the at least two other pulses being discounted on the basis of not being related to said selected pair by having a respective reception time separated from the respective reception time of at least one pulse of said pair of pulses by one or more pulse repetition intervals from the set of pulse repetition intervals; and

inhibiting the transmission of data in said frequency channel at least in part in dependence on the selection of the further pulses related to said selected pair.