Implementation of Dynamic Channel Switching on IEEE 802.11-Based Wireless Mesh Networks

Interference makes it difficult for a wireless network to provide robust performance and could sometimes lead to transient failures. Dynamic channel switching (DCS) allows a wireless network interface (NIC) to operate in different frequency channels during different time periods without disrupting network connections that traverse the NIC. DCS enables a wireless mesh network to avoid frequency channels with serious interference in certain parts of its coverage area by switching to more idle channels. Although DCS provides additional radio agility, it significantly increases the complexity of the wireless mesh network’s routing protocol. This paper describes the design, implementation and evaluation of a wireless mesh network system called Carlsbad, which supports both DCS and load-balancing/fault-tolerant routing, and successfully runs on low-cost commodity IEEE 802.11-based access points. Performance experiments on the first Carlsbad prototype show that despite the additional overhead it introduces, DCS can indeed improve the overall throughput of an IEEE 802.11-based wireless mesh network, sometimes by a factor of more than 2, for both TCP and UDP connections.