MAP WLAN Sounding Using Coordinated NDP Transmission
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Solution Overview
Problem
Interference between multiple access points in a wireless local area network (WLAN) system deteriorates overall performance due to increased interference between basic service sets, necessitating improved channel estimation methods.
Innovation Solution
A method and apparatus for efficient channel estimation in a multiple access point (MAP) network using null data packets (NDPs) with predefined transmission schemes, coordinated beamforming, and joint transmission operations to reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of access points is increased to provide WLAN to more stations, then network coverage and capacity are improved, but interference between APs increases causing performance deterioration
Solution Approach 1:
The patent performs channel sounding and collects channel state information before actual data transmission begins. By pre-acquiring channel characteristics through NDP exchange and feedback mechanisms, the system can proactively adjust beamforming weights and spatial filters to mitigate interference between APs before it degrades performance
Solution Approach 2:
The patent implements a feedback loop where STAs measure channel state information from NDPs transmitted by multiple APs, then feed back this information to the APs. This feedback enables the APs to adaptively adjust their transmission parameters including beamforming weights and spatial filtering to reduce mutual interference in real-time
2Measurement precision
If channel sounding is performed in MAP networks, then channel estimation accuracy is improved, but transmission overhead and complexity increase
Solution Approach 1:
The patent combines channel sounding procedures across multiple APs into a coordinated framework where APs transmit NDPs in a structured manner and STAs collect channel information from multiple APs simultaneously. This merging of sounding operations into a unified MAP-level procedure reduces overall complexity compared to separate per-AP sounding while maintaining accurate channel estimation
Solution Approach 2:
The patent segments the channel sounding process into distinct phases: NDP transmission phase where APs send reference signals, measurement phase where STAs collect channel state information, and feedback phase where measurement results are reported. This segmentation allows each phase to be optimized independently and simplifies the overall implementation complexity
Data Source
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AI summary
Provided is a method of operating a first apparatus in a wireless local area network (WLAN) system, the method including receiving a multiple access point (MAP) network frame from a second apparatus, identifying a null data packet (NDP) transmission method for MAP sounding from the MAP network frame, and transmitting a first NDP to a third apparatus in association with transmission of a second NDP from the second apparatus to the third apparatus within an NDP transmission period based on an identified NDP transmission scheme.