Throughput Optimal Switching in Multi-channel WLANs
For wireless network designers, this work provides a theoretical foundation for throughput-optimal channel switching in multi-channel WLANs, though it is incremental as it focuses on a specific class of schemes.
The paper identifies that opportunistic channel access based solely on SNR can lead to congestion, and derives the stability region for multi-user multi-channel WLANs to determine a throughput-optimal channel switching scheme that balances signal quality and congestion.
We observe that in a multi-channel wireless system, an opportunistic channel/spectrum access scheme that solely focuses on channel quality sensing measured by received SNR may induce users to use channels that, while providing better signals, are more congested. Ultimately the notion of channel quality should include both the signal quality and the level of congestion, and a good multi-channel access scheme should take both into account in deciding which channel to use and when. Motivated by this, we focus on the congestion aspect and examine what type of dynamic channel switching schemes may result in the best system throughput performance. Specifically we derive the stability region of a multi-user multi-channel WLAN system and determine the throughput optimal channel switching scheme within a certain class of schemes.