Per-Channel Backoff Control for WLAN Secondary Channel Access
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Solution Overview
Problem
The existing WLAN standards, such as IEEE 802.11ac, reduce spatial efficiency by only performing Clear Channel Assessment (CCA) and Network Allocation Vector (NAV) control for the primary channel, leading to underutilization of secondary channels and reduced resource efficiency in high-density WLAN environments.
Innovation Solution
A method and apparatus that perform CCA for both primary and secondary channels, allowing backoff procedures to resume on idle channels and setting NAV for all channels, ensuring efficient frame transmission and preventing data transmission errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If CCA and NAV control are performed only for the primary channel, then operational simplicity is maintained, but spatial efficiency and resource utilization are reduced
Solution Approach 1:
The patent segments the channel assessment and backoff control into per-channel operations. Instead of treating the primary channel as the sole control point, the system performs CCA and manages backoff procedures independently for each channel (primary and secondary), enabling finer-grained resource utilization while maintaining manageable complexity through modular per-channel processing
Solution Approach 2:
The patent extends the backoff procedure from a single-dimension (primary channel only) control mechanism to a multi-dimensional approach where each channel has its own backoff counter and CCA state. This dimensional expansion allows simultaneous channel access opportunities across multiple frequencies, improving spatial efficiency without sacrificing operational clarity
2Device complexity
If backoff procedure is performed only on the primary channel, then device complexity is reduced, but channel access efficiency and resource utilization are degraded
Solution Approach 1:
The backoff procedure is segmented into independent per-channel operations. Each channel maintains its own backoff counter that can be decremented independently based on CCA results for that specific channel. This segmentation allows the device to efficiently utilize multiple channels without requiring complex cross-channel coordination mechanisms
Solution Approach 2:
Each channel's backoff counter operates autonomously, decrementing itself when the corresponding channel is idle according to CCA results. This self-service mechanism eliminates the need for centralized backoff management across all channels, reducing device complexity while improving channel access efficiency through parallel autonomous operation
3Device complexity
If secondary channels are not utilized for frame transmission, then operational complexity is minimized, but wireless resource efficiency and transmission capacity are reduced
Solution Approach 1:
The patent implements dynamic channel selection where the system adaptively determines which channels (primary or secondary) are suitable for frame transmission based on real-time CCA results and backoff counter states. This dynamic approach allows flexible utilization of secondary channels when available, maximizing wireless resource efficiency without requiring fixed complex operational procedures for all channels
4Loss of time
If CCA is performed only for the primary channel, then processing overhead is reduced, but data transmission reliability and error prevention are compromised
Solution Approach 1:
Clear Channel Assessment is segmented into per-channel operations where CCA is independently performed for each channel before attempting transmission. This segmentation ensures that transmission decisions are based on accurate, channel-specific channel condition information, improving reliability without requiring excessive processing overhead through comprehensive multi-channel assessment
Data Source
AI summary
The present document relates to a backoff procedure and apparatus for efficiently accessing a broadband channel in a wireless LAN system. To this end, a station performs a clear channel assessment (CCA) operation in each of a plurality of channels, and when one or more of the plurality of channels is/are not used and the one or more channels is/are not used for frame transmission in the basic service set (BSS) of its/their station, the station is characterized in that it performs or re-performs a backoff procedure in the one or more channels. When a backoff counter value becomes zero according to the backoff procedure, the station may transmit a frame through the one or more channels.