WLAN Frame PHY Header Channel State Sharing for Hidden Node Collision Avoidance
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Solution Overview
Problem
In next-generation wireless local area networks (WLANs), the hidden node problem occurs during flexible downlink/uplink (DL/UL) transmission in multi-band aggregation, leading to data collisions between access points (APs) and stations (STAs) in a hidden node relationship, as they cannot recognize transmissions on other bands, resulting in inefficient data transmission and reduced throughput.
Innovation Solution
The method involves sharing channel state information across bands by including it in the physical (PHY) header of frames, allowing STAs to configure Network Allocation Vectors (NAV) based on the channel state of other bands, preventing collisions by indicating whether a band is idle or busy, and providing transmission duration information to synchronize transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If flexible DL/UL transmission is performed in multi-band aggregation, then spectrum efficiency and area throughput are improved, but data collisions occur between hidden nodes leading to reduced reliability
Solution Approach 1:
The patent introduces channel state information as an intermediary element that mediates between transmitting stations. This information acts as a messenger that allows hidden nodes to indirectly know about ongoing transmissions on other bands, preventing collisions without requiring direct communication between all nodes. The channel state information includes busy/idle status and duration, serving as a coordinating mechanism across multiple bands.
Solution Approach 2:
The patent implements preliminary action by having stations share channel state information before potential collisions can occur. By proactively transmitting information about current transmissions on other bands, the system prevents hidden node problems before they happen. The channel state information is shared in advance, allowing receiving stations to configure NAV values and avoid transmitting during busy periods.
2Productivity
If flexible DL/UL transmission is performed in multi-band aggregation, then area throughput is improved, but hidden nodes cannot recognize transmissions on other bands leading to data collisions
Solution Approach 1:
The patent uses channel state information as an intermediary to transfer transmission awareness between hidden nodes. Instead of requiring direct detection of transmissions on all bands (which is impossible for hidden nodes), the system introduces this information carrier that conveys the state of other bands. The channel state information includes details about transmission duration and band status, enabling stations to make informed transmission decisions.
Solution Approach 2:
The patent implements feedback by having transmitting stations send channel state information back to other stations about their current transmission status. This feedback loop allows the network to maintain awareness of ongoing transmissions across multiple bands. The receiving stations use this feedback to adjust their transmission behavior, configuring NAV values based on the received channel state information.
3Reliability
If channel state information is shared across bands, then data collision probability is reduced, but frame structure complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the channel state information into distinct components within the PHY header. Rather than adding a single complex field, the information is segmented into multiple structured fields that can be independently processed. This segmentation makes the overall system more manageable and easier to implement while maintaining the benefits of shared channel state information.
Solution Approach 2:
The patent uses local quality by adding channel state information specifically where it is most needed - in the PHY header of frames. This localized addition provides the necessary information exactly at the point where transmission decisions are made, without unnecessarily complicating other parts of the frame structure. The channel state information is embedded in the physical layer header, making it readily available for immediate use in collision avoidance.
Data Source
AI summary
Provided is a method and device for transceiving a frame in a wireless Local Area Network (LAN) system. Particularly, an Access Point (AP) transmits a first frame to a first station (STA) via a first band. The AP receives a second frame from a second STA via a second band while the first frame is being transmitted. The first band and the second band are combined with each other as a multi-band. The multi-band simultaneously supports a Downlink (DL) transmission and a Uplink (UL) transmission. The relationship between the first STA and the second STA is a hidden node. A Physical (PHY) header of the first frame includes channel status information of the second band. A Network Allocation Vector (NAV) of the first STA is set up on the basis of the channel status information.