Mid-packet detection in wireless LAN
View Patent ↗A transmitting device may perform mid-packet detection (MPD) in a wireless channel by receiving a signal from the wireless channel, detecting first symbols having a first symbol duration in the signal during a first detection window, and detecting second symbols having a second symbol duration in the signal during a second detection window. The first and second symbol durations, excluding CPs, may be 3.2 and 12.8 microseconds respectively. A transmitting device may perform MPD in a wireless channel by receiving a signal from the channel, performing an MPD of symbols in the signal, producing first and second comparison result by comparing an output of the MDP to respective first and second thresholds, and determine whether to transmit a frame using the first comparison result and the second comparison result.
1. A method implemented by a transmitting device for performing mid-packet detection in a wireless channel, the method comprising:
receiving, by the transmitting device, a signal through the wireless channel;
detecting, using a first autocorrelation of the signal, one or more first symbols having a first symbol duration in the signal during a first detection window; and
detecting, using a second autocorrelation of the signal, one or more second symbols having a second symbol duration in the signal during a second detection window, determining whether the wireless channel is idle or busy during the first detection window using the results of detecting the one or more first symbols;
when the wireless channel is determined to be busy during the first detection window, preventing the transmitting device from transmitting using the wireless channel; and
when the wireless channel is determined to be idle during the first detection window: determining whether the wireless channel is idle or busy during the second detection window using the results of detecting the one or more second symbols,
when the wireless channel is determined to be idle during the second detection window, permitting the transmitting device to transmit either a High Efficiency (HE) frame or a Very High Throughput (VHT) frame, and
when the wireless channel is determined to be busy during the second detection window, permitting the transmitting device to transmit the VHT frame and preventing the transmitting device from transmitting the HE frame.
2. The method of claim 1 , wherein a duration of the first detection window is 25 microseconds, and a duration of the second detection window is greater than the duration of the first detection window.
3. The method of claim 2 , wherein the duration of the second detection window is less than a duration of a Distributed Coordination Function (DCF) InterFrame Space (DIFS).
4. The method of claim 3 , wherein the duration of the second detection window is in the range of 25 to 30 microseconds.
5. The method of claim 2 , wherein the first detection window occurs during the duration of the second detection window.
6. The method of claim 2 , wherein the second detection window occurs during the duration of a Distributed Coordination Function (DCF) InterFrame Space (DIFS).
7. The method of claim 1 , wherein the first symbol duration is 3.2 microseconds excluding a first Cyclic Prefix (CP), and the second symbol duration is 12.8 microseconds excluding a second CP.
8. The method of claim 1 , wherein permitting the transmitting device to transmit the VHT frame includes permitting the transmitting device to transmit either the VHT frame or a High Throughput (HT) frame.
9. The method of claim 1 , further comprising:
determining whether the wireless channel is idle or busy during the first detection window according to a first threshold; and
determining whether the wireless channel is idle or busy during the second detection window according to a second threshold, the second threshold being different from the first threshold.
10. The method of claim 1 , further comprising:
performing the first autocorrelation according to the first symbol duration; and
performing the second autocorrelation according to the second symbol duration.
11. A method implemented by a transmitting device for performing mid-packet detection in a wireless channel, the method comprising:
receiving, by the transmitting device, a signal through the wireless channel;
detecting, using a first autocorrelation of the signal, one or more first symbols having a first symbol duration in the signal during a first detection window; and
detecting, using a second autocorrelation of the signal, one or more second symbols having a second symbol duration in the signal during a second detection window;
determining whether the transmitting device is associated with a High Efficiency (HE) Access Point (AP);
when the transmitting device is associated with the HE AP:
determining whether the wireless channel is idle or busy during the second detection window using the results of detecting the one or more second symbols;
when the wireless channel is determined to be idle during the second detection window, permitting the transmitting device to transmit either a High Efficiency (HE) frame or a Very High Throughput (VHT) frame; and
when the wireless channel is determined to be busy during the second detection window, preventing the transmitting device from transmitting using the wireless channel; and
when the transmitting device is not associated with the HE AP:
determining whether the wireless channel is idle or busy during the first detection window using the results of detecting the one or more first symbols;
when the wireless channel is determined to be idle during the first detection window, permitting the transmitting device to transmit the VHT frame and preventing the transmitting device from transmitting the HE frame; and
when the wireless channel is determined to be busy during the first detection window, preventing the transmitting device from transmitting using the wireless channel.
12. The method of claim 11 , wherein a duration of the first detection window is 25 microseconds, and a duration of the second detection window is greater than the duration of the first detection window.
13. The method of claim 12 , wherein the duration of the second detection window is less than a duration of a Distributed Coordination Function (DCF) InterFrame Space (DIFS).
14. The method of claim 13 , wherein the duration of the second detection window is in the range of 25 to 30 microseconds.
15. The method of claim 12 , wherein the first detection window occurs during the duration of the second detection window.
16. The method of claim 12 , wherein the second detection window occurs during the duration of a Distributed Coordination Function (DCF) InterFrame Space (DIFS).
17. The method of claim 11 , wherein the first symbol duration is 3.2 microseconds excluding a first Cyclic Prefix (CP), and the second symbol duration is 12.8 microseconds excluding a second CP.
18. The method of claim 11 , further comprising:
determining whether the wireless channel is idle or busy during the first detection window according to a first threshold; and
determining whether the wireless channel is idle or busy during the second detection window according to a second threshold, the second threshold being different from the first threshold.
19. The method of claim 11 , further comprising:
performing the first autocorrelation according to the first symbol duration; and
performing the second autocorrelation according to the second symbol duration.