WLAN Channel Access via RTS-CTS Bandwidth Adaptation
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Solution Overview
Problem
In wireless local area networks (WLANs), unlicensed devices face challenges in efficiently accessing channels in TV White Space (TVWS) while minimizing interference with licensed users, and existing methods lack effective mechanisms for bandwidth adaptation and power management to ensure reliable communication.
Innovation Solution
The method involves exchanging Request to Send (RTS) and Clear to Send (CTS) frames to adapt bandwidth and regulate transmission power, allowing devices to select channels with minimal interference and adjust bandwidth and power based on channel availability and occupancy, using RTS frames to request channels and CTS frames to confirm availability, and managing bandwidth and power to ensure efficient communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If unlicensed devices use spectrum sensing mechanism to detect incumbent user occupancy, then protection for licensed users is improved, but channel access efficiency deteriorates due to additional sensing overhead and time
Solution Approach 1:
The patent applies preliminary action by having the unlicensed device perform spectrum sensing in advance before actual data transmission. The sensing result is stored and used during the RTS-CTS exchange process, allowing the device to determine channel availability beforehand and make informed decisions about bandwidth adaptation without delaying the actual communication process
Solution Approach 2:
The patent implements dynamics by adapting the transmission bandwidth dynamically based on the sensed channel conditions and incumbent user occupancy. When spectrum sensing detects incumbent users on adjacent channels, the system dynamically reduces the transmission bandwidth to avoid interference, creating a flexible adaptation mechanism that responds to real-time spectral environment changes
2Reliability
If unlicensed devices transmit at high power to ensure reliable communication, then transmission reliability is improved, but interference with licensed users increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the transmission power level based on spectrum sensing results and the detected presence of incumbent users. When adjacent channels show incumbent user activity, the system reduces transmission power to protect licensed users while maintaining adequate power for reliable communication in cleared spectral environments
Solution Approach 2:
The patent implements feedback mechanisms where spectrum sensing continuously monitors the spectral environment and provides feedback to the transmission system. This feedback loop enables real-time adjustment of transmission parameters (power and bandwidth) based on actual channel conditions and incumbent user occupancy, creating a closed-loop control system that balances reliability and interference protection
3Device complexity
If unlicensed devices use fixed bandwidth for transmission, then system simplicity is improved, but adaptability to channel conditions deteriorates
Solution Approach 1:
The patent transforms the fixed bandwidth approach into a dynamic one by implementing bandwidth adaptation based on spectrum sensing results. The system automatically adjusts transmission bandwidth according to detected incumbent user occupancy and channel conditions, enabling flexible adaptation without requiring complex manual configuration or overly sophisticated control algorithms
Data Source
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AI summary
A method and apparatus of requesting a channel access in a wireless local area network is provided. A transmitter transmits a plurality of Request To Send (RTS) frames over a plurality of requesting channels and receives at least one Clear To Send (CTS) frame over at least one responding channel as a response for the plurality of RTS frames. Each of the plurality of RTS frames indicates a bandwidth for the plurality of requesting channels, and the at least one CTS frame indicates a bandwidth for the at least one responding channel.