Radar detection method for radio local area networks
A method of radar detection in a channel for radio local area networks operating in a regulatory band. First, a quiet time and quiet period are set, in which the ratio of the quiet time to the quiet period equals 1:4. The channel is quieted for the quiet time periodically at a rate dictated by the quiet period in order to be tested for radar. During each quiet time, a received power is measured to determine whether it exceeds a predetermined threshold. Radar presence is declared when the received power on that channel exceeds the predetermined threshold.
1. A method of radar detection in a channel for radio local area networks operating in a regulatory band, comprising the steps of:
setting a quiet time and a quiet period;
periodically quieting the channel for the quiet time at a rate dictated by the quiet period;
testing the channel for radar and measuring a received power during each quiet time;
determining whether the received power exceeds a predetermined threshold; and
declaring that there is radar operating on the channel when the received power exceeds the predetermined threshold; wherein:
a ratio of at least 25% between the quiet time and the quiet period is designated first;
the quiet time is 1 TU and the quiet period is 4 TUs where TU represents a time unit equal to 2 10 μs; and
wherein the predetermined threshold is —(52+σ) dBm where σ is a predetermined value for measurement margin.
2. The method according to claim 1 , wherein the predetermined threshold is less than or equal to —52 dBm.
3. The method according to claim 1 , wherein the step of testing and measuring employs Received Signal Strength Indication (RSSI) as a measure of the received power on the channel.
4. The method according to claim 3 , wherein the determining step checks to see if the RSSI for the received power during each quiet time exceeds the predetermined threshold.
5. A method of determining the presence of radar in a channel, comprising the steps of:
setting a quiet time and a quiet period;
repeatedly quieting the channel for the quiet time at intervals of the quiet period;
measuring a received power on the channel during each quiet time;
determining whether the received power exceeds a predetermined threshold; and
declaring that there is radar operating on the channel when the received power exceeds the predetermined threshold; wherein the predetermined threshold is —(52+σ) dBm where σ is a predetermined value for measurement margin.
6. The method according to claim 5 , wherein the setting step specifies a ratio of at least 25% between the quiet time and the quiet period.
7. The method according to claim 6 , wherein the quiet time is 1 TU and the quiet period is 4 TUs where TU represents a time unit defined by the IEEE 802.11 standard.
8. The method according to claim 6 , wherein the quiet time is 1 TU and the quiet period is 3 TUs where TU represents a time unit defined by the IEEE 802.11 standard.
9. The method according to claim 6 , wherein the quiet time is 2 TU and the quiet period is 6 TUs where TU represents a time unit defined by the IEEE 802.11 standard.
10. The method according to claim 6 , wherein the quiet time is 2 TU and the quiet period is 5 TUs where TU represents a time unit defined by the IEEE 802.11 standard.
11. The method according to claim 5 , wherein the setting step specifies a ratio of at least 20% between the quiet time and the quiet period.
12. The method according to claim 11 , wherein the quiet time is 1 TU and the quiet period is 5 TUs where TU represents a time unit defined by the IEEE 802.11 standard.
13. The method according to claim 11 , wherein the quiet time is 2 TU and the quiet period is 10 TUs where TU represents a time unit defined by the IEEE 802.11 standard.
14. The method according to claim 11 , wherein the quiet time is 3 TU and the quiet period is 15 TUs where TU represents a time unit defined by the IEEE 802.11 standard.
15. The method according to claim 5 , wherein the measuring step employs Received Signal Strength Indication (RSSI) as a measure of the received power on the channel.
16. The method according to claim 15 , wherein the determining step checks to see if the RSSI for the received power during each quiet time exceeds the predetermined threshold.