Opportunistic Channel Feedback for WLAN Uplink Resource Allocation
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Solution Overview
Problem
Existing wireless local area networks (WLANs) face inefficiencies in uplink resource allocation due to inaccurate channel information, leading to low system throughput as APs struggle to allocate bandwidth effectively among multiple STAs with varying radio channels.
Innovation Solution
The implementation of systems and techniques that opportunistically estimate wireless channel characteristics between an access point and multiple wireless stations, allowing for improved determination of uplink channel information and dynamic resource allocation based on observed downlink channel information, using a joint uplink channel matrix and flexible message types for channel feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional channel estimation methods are used, then downlink channel information can be obtained, but uplink channel information remains inaccurate
Solution Approach 1:
The patent implements a feedback mechanism where STAs measure downlink channel characteristics using NDPs and feed back their measurements to the AP. The AP then uses this feedback information to estimate uplink channel characteristics, resolving the asymmetry between downlink and uplink channel knowledge.
Solution Approach 2:
The patent introduces downlink channel measurements as an intermediary element. Instead of directly measuring uplink channels, the system uses downlink channel measurements (which are easier to obtain) as an intermediary to infer uplink channel characteristics through reciprocity relationships.
2Productivity
If an AP allocates bandwidth to STAs with weak uplink channels, then fairness is improved, but overall system throughput decreases
Solution Approach 1:
The patent replaces the mechanical/random resource allocation approach with an intelligent system that uses channel measurements and feedback to make informed allocation decisions. The AP uses estimated uplink channel characteristics to optimize resource allocation, substituting blind allocation with measurement-based allocation.
3Loss of information
If traditional sounding procedures are used, then channel information can be obtained, but the process is complex and resource-intensive
Solution Approach 1:
The patent makes the downlink NDP serve multiple functions: it acts as both a data transmission vehicle and a channel sounding signal. STAs use the same NDP to measure downlink channels and provide feedback for uplink estimation, eliminating the need for separate sounding procedures.
Solution Approach 2:
The patent extracts channel measurement functionality from the data transmission process. Instead of adding separate measurement procedures, the system extracts channel information from the existing NDP transmissions, separating the measurement function from dedicated sounding signals.
Data Source
AI summary
Uplink resource assignment in a wireless local area network (WLAN) by an access point (AP) to wireless stations (STAs) is herein provided using opportunistic feedback from the STAs. The AP sends a message to a first STA; the message is also observed by a second STA. Each STA can determine if it wishes to opportunistically send information concerning the message to the AP. The second STA can perform power measurements on the message and send subcarrier signal to noise ratio (SNR) or ranking information to the AP. Thus, the AP can receive, possibly without expectation, encoded or compressed information describing radio channels of the first STA and/or the second STA. Based on the received channel information the AP improves operation of a dynamic resource allocation algorithm which determines uplink grants of resource units (RUs) to the STAs.