CF-END Frame Response Indication for Channel Access
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Solution Overview
Problem
Current wireless communication systems, particularly in IEEE 802.11 networks, face issues with channel access fairness and power consumption due to the failure of NAV counter resetting in cases of erroneous MAC header reception, leading to unnecessary energy consumption and unfair channel access.
Innovation Solution
Introducing a RESPONSE_INDICATION subfield in the Frame Control field of CF-END frames to determine whether a second CF-END frame is necessary, allowing stations to reset their RID counter and access the channel regardless of the NAV counter value, thereby facilitating channel access and power saving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stations wait for NAV counter to reset before accessing the channel, then channel access fairness is maintained, but power consumption increases and access delays occur when the medium is actually idle
Solution Approach 1:
The patent segments the channel access control mechanism into two independent counters: NAV (Network Allocation Vector) for virtual carrier sensing and RID (Response Indication Deferral) for tracking the actual medium occupancy duration. This segmentation allows stations to independently manage their channel access decisions based on actual medium status rather than being constrained by a single coupled counter, thereby reducing unnecessary power consumption while maintaining fairness.
Solution Approach 2:
The patent introduces an intermediary mechanism (the RESPONSE_INDICATION subfield and RID counter) that mediates between the NAV counter and actual channel access decisions. This intermediary allows stations to determine whether the medium is truly idle without being strictly bound by the NAV counter value, enabling power-saving early channel access when the medium is actually free while preserving overall access fairness.
2Reliability
If stations use virtual carrier sensing with NAV counter, then channel access fairness is improved, but access deadlocks occur when MAC header reception is erroneous
Solution Approach 1:
The patent prepares for potential MAC header reception errors by introducing the RID counter as a backup mechanism before such errors can cause deadlocks. The RID counter is initialized based on the actual medium occupancy duration announced in the MAC header, providing a cushion that allows stations to access the channel even when NAV counter resetting fails due to erroneous header reception, thus preventing access deadlocks while maintaining fairness.
Solution Approach 2:
The patent implements a feedback mechanism where the RESPONSE_INDICATION subfield in the Frame Control field provides information about whether the transmitter intends to send another CF-END frame. This feedback allows receiving stations to adjust their RID counter values and channel access timing accordingly, preventing deadlocks caused by erroneous MAC header reception while preserving channel access fairness through coordinated adjustments.
3Reliability
If CF-END frames are transmitted to release TxOP, then channel access fairness is maintained, but unnecessary power consumption occurs due to failed NAV counter resetting
Solution Approach 1:
The patent changes the parameters used for channel access control by introducing the RID counter with a different initialization and decrement behavior compared to the traditional NAV counter. The RID counter is initialized based on actual medium occupancy duration and decremented independently, allowing stations to make channel access decisions based on actual medium status rather than relying solely on NAV counter resetting, thereby reducing energy consumption while maintaining fairness.
Solution Approach 2:
The patent performs preliminary action by having the transmitter set the RESPONSE_INDICATION subfield in advance to indicate whether another CF-END frame will be sent. This allows receiving stations to pre-calculate appropriate RID counter values and prepare for channel access before potential NAV counter resetting failures occur, reducing unnecessary energy consumption from repeated CF-END frame transmissions and failed access attempts while preserving fairness.
Data Source
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AI summary
A method including determining by an apparatus if the apparatus intends to receive a notification from an access node regarding a completion of data transmission by the access node to the apparatus. Based upon the determining, a value is selected by the apparatus for a subfield of a frame control field or for a field within a Media Access Control (MAC) header. The method then includes transmitting by the apparatus an indication of completion of data transmission by the apparatus, where the indication of completion of data transmission by the apparatus includes the value.