Channel access mechanism
A method and system to improve backoff counter handling with relation to a clear channel assessment (CCA) process. The method and system improve a wireless medium availability by adjusting the backoff counter such that the processing of a preamble of a frame received during a backoff is taken into account. Received frames that fall between two CCA thresholds may require decoding of information in the preamble to assess whether the wireless medium is available. A portion of the preamble is decoded that identifies information utilized to determine whether the wireless medium may be considered to be busy. However, during this determination that requires the reading of the preamble of a received frame the backoff counter may be held or decremented even though the wireless medium status is unknown. The method and system provide a set of possible adjustments to the backoff counter to account for this uncertainty and the outcome of the CCA.
1. A method implemented by a network device, the method to improve efficiency for clear channel assessment (CCA) in a wireless local area network (WLAN) by adjusting a backoff counter to minimize delay caused by decoding a preamble of a received signal, the method comprising:
determining whether the received signal is above a first threshold;
starting a backoff counter adjustment in response to the received signal being above the first threshold, wherein starting the backoff counter adjustment holds the backoff counter upon detecting a start of the received signal and while decoding a COLOR value in a preamble of the received signal;
comparing the COLOR value identified in the preamble of the received signal with a COLOR value of the network device; and
completing the backoff counter adjustment based on the comparison of the COLOR value identified in the preamble of the received signal with the COLOR value of the network device, wherein completing the backoff counter adjustment includes decrementing the backoff counter after a duration of the entire received signal when the COLOR value identified in the preamble matches the COLOR value of the network device.
2. The method of claim 1 , wherein completing the backoff counter adjustment includes decrementing the backoff counter after decoding the COLOR value of the received signal when the COLOR value identified in the preamble is different from the COLOR value of the network device and the received signal is below a second threshold.
3. The method of claim 1 , wherein the backoff counter adjustment holds the backoff counter until after a duration of the entire received signal when the COLOR value identified in the preamble matches the COLOR value of the network device.
4. The method of claim 1 , wherein the backoff counter adjustment (1) stores the current value of the backoff counter upon initially detecting the start of the received signal and (2) when the COLOR value identified in the preamble matches the COLOR value of the network device, uses the stored current value to adjust the backoff counter and holds the backoff counter until after a duration of the entire received signal.
5. The method of claim 1 , wherein the backoff counter adjustment (1) stores the current value of the backoff counter upon initially detecting the start of the received signal, and (2) when the COLOR value identified in the preamble is different from the COLOR value of the network device, continues to decrement the backoff counter based on the stored current value.
6. The method of claim 1 , wherein the backoff counter adjustment (1) holds the backoff counter after detecting the start of the received signal, and (2) when the COLOR value identified in the preamble is different from the COLOR value of the network device, subtracts a value corresponding to a duration of the preamble from the backoff counter and continues decrementing the backoff counter after the COLOR value is decoded.
7. A wireless device operating in a wireless network, the wireless device comprising:
a hardware processor; and
one or more memories coupled to the hardware processor, wherein the one or more memories include one or more instructions, which when executed by the hardware processor cause the wireless device to adjust a backoff counter to minimize delay caused by decoding a preamble of a received signal by:
determining whether the received signal is above a first threshold;
starting a backoff counter adjustment in response to the received signal being above the first threshold, wherein starting the backoff counter adjustment holds the backoff counter upon detecting a start of the received signal and while decoding a COLOR value in a preamble of the received signal;
comparing the COLOR value identified in the preamble of the received signal with a COLOR value of the network device; and
completing the backoff counter adjustment based on the comparison of the COLOR value identified in the preamble of the received signal with the COLOR value of the network device, wherein completing the backoff counter adjustment includes decrementing the backoff counter after a duration of the entire received signal when the COLOR value identified in the preamble matches the COLOR value of the network device.
8. The wireless device of claim 7 , wherein completing the backoff counter adjustment includes decrementing the backoff counter after decoding the COLOR value of the received signal when the COLOR value identified in the preamble is different from the COLOR value of the network device and the received signal is below a second threshold.
9. The wireless device of claim 7 , wherein the backoff counter adjustment holds the backoff counter until after a duration of the entire received signal when the COLOR value identified in the preamble matches the COLOR value of the network device.
10. The wireless device of claim 7 , wherein the backoff counter adjustment (1) stores the current value of the backoff counter upon initially detecting the start of the received signal and (2) when the COLOR value identified in the preamble matches the COLOR value of the network device, uses the stored current value to adjust the backoff counter and holds the backoff counter until after a duration of the entire received signal.
11. The wireless device of claim 7 , wherein the backoff counter adjustment (1) stores the current value of the backoff counter upon initially detecting the start of the received signal and (2) when the COLOR value identified in the preamble is different from the COLOR value of the network device, continues to decrement the backoff counter based on the stored current value.
12. The wireless device of claim 7 , wherein the backoff counter adjustment (1) holds the backoff counter after detecting the start of the received signal, and (2) when the COLOR value identified in the preamble is different from the COLOR value of the network device, subtracts a value corresponding to a duration of the preamble from the backoff counter and continues decrementing the backoff counter after the COLOR value is decoded.
13. A non-transitory machine-readable storage medium having instructions stored therein, which when executed by a processor of a wireless device, cause the wireless device to adjust a backoff counter to minimize delay caused by decoding a preamble of a received signal by:
determining whether the received signal is above a first threshold;
starting a backoff counter adjustment in response to the received signal being above the first threshold-, wherein starting the backoff counter adjustment holds the backoff counter upon detecting a start of the received signal and while decoding a COLOR value in a preamble of the received signal;
comparing the COLOR value identified in the preamble of the received signal with a COLOR value of the network device; and
completing the backoff counter adjustment based on the comparison of the COLOR value identified in the preamble of the received signal with the COLOR value of the network device, wherein completing the backoff counter adjustment includes decrementing the backoff counter after a duration of the entire received signal when the COLOR value identified in the preamble matches the COLOR value of the network device.
14. The non-transitory machine-readable storage medium of claim 13 , wherein completing the backoff counter adjustment includes decrementing the backoff counter after decoding the COLOR value of the received signal when the COLOR value identified in the preamble is different from the COLOR value of the network device and the received signal is below a second threshold.
15. The non-transitory machine-readable storage medium of claim 13 , wherein the backoff counter adjustment holds the backoff counter until after a duration of the entire received signal when the COLOR value identified in the preamble matches the COLOR value of the network device.
16. The non-transitory machine-readable storage medium of claim 13 , wherein the backoff counter adjustment (1) stores the current value of the backoff counter upon initially detecting the start of the received signal and (2) when the COLOR value identified in the preamble matches the COLOR value of the network device, uses the stored current value to adjust the backoff counter and holds the backoff counter until after a duration of the entire received signal.