OFDMA Access Point Sub-Channel Allocation via RTS Duplication
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Solution Overview
Problem
Current wireless local area networks (WLANs) face challenges in efficiently managing orthogonal frequency division multiple access (OFDMA) communications, particularly in coordinating clear-to-send (CTS) frames across multiple sub-channels to ensure optimal channel availability and minimize interference.
Innovation Solution
The method involves an access point (AP) determining and allocating frequency sub-channels for client stations, transmitting a request-to-send (RTS) frame duplicated across sub-channels, and receiving CTS frames to identify available sub-channels for simultaneous communication, using scramble seeds to decode CTS frames transmitted by multiple clients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CTS frames are transmitted simultaneously by multiple client stations on the same sub-channel, then channel allocation efficiency is improved, but interference between simultaneous transmissions increases
Solution Approach 1:
The patent segments the communication channel into multiple sub-channels and assigns different scramble seeds to different client stations. This allows simultaneous CTS frame transmissions on the same sub-channel to be distinguished and decoded separately, reducing interference while maintaining high channel allocation efficiency.
Solution Approach 2:
The patent applies local quality by assigning unique scramble seeds to individual client stations. This local differentiation enables the access point to distinguish between simultaneous transmissions from different clients on the same sub-channel, resolving interference through localized identification rather than global channel separation.
2Reliability
If RTS frames are duplicated across multiple sub-channels, then reliability of frequency allocation information is improved, but transmission overhead increases
Solution Approach 1:
The patent uses copying by duplicating RTS frames across multiple sub-channels to ensure reliable delivery of frequency allocation information. The duplication provides redundancy so that if one sub-channel is blocked or experiences errors, the information can still be received on another sub-channel, improving reliability without requiring additional unique information transmissions.
3Productivity
If multiple client stations are coordinated to transmit CTS frames simultaneously, then communication throughput is improved, but coordination complexity increases
Solution Approach 1:
The patent simplifies coordination complexity by changing the parameter of scramble seed assignment. Instead of complex timing and frequency coordination, the system uses different scramble seeds as a simple distinguishing parameter that allows simultaneous transmissions to be automatically differentiated and decoded, reducing coordination overhead while maintaining high throughput.
Data Source
AI summary
An access point (AP) transmits a request-to-send (RTS) frame to a plurality of client stations. The RTS frame indicates that the plurality of client stations are requested to simultaneously transmit respective clear-to-send (CTS) frames to the AP. The AP receives at least some of the respective CTS frames from at least some of the plurality of client stations, including receiving a first CTS frame from a first client station, and receiving a second CTS frame from a second client station. The first CTS frame and the second CTS frame both span a first sub-channel, and are received simultaneously by the AP. The AP determines that the first sub-channel is available for communication with one or more client stations based on the reception of the first CTS frame and the second CTS frame.