Centralized channel assignment and routing algorithms for multi-channel wireless mesh networks

TLDR

IEEE 802.11 WLAN standards support multiple non‑overlapping frequency channels that can be used simultaneously to increase aggregate bandwidth, a capability routinely exploited in infrastructure mode but rarely applied to multi‑hop ad‑hoc LANs, especially since most prior multi‑channel research requires MAC‑level modifications incompatible with commodity hardware. The paper proposes and evaluates a multi‑channel multi‑hop wireless ad‑hoc network architecture built with commodity 802.11 hardware by equipping each node with multiple NICs on different channels. To realize this architecture, the authors develop centralized algorithms for channel assignment, bandwidth allocation, and routing in multi‑channel wireless mesh networks. Evaluation shows that with intelligent channel and bandwidth assignment, equipping each mesh node with just two NICs on different channels can increase total network goodput by up to eight‑fold compared to a conventional single‑channel ad‑hoc network.

Abstract

The IEEE 802.11 Wireless LAN standards allow multiple non-overlapping frequency channels to be used simultaneously to increase the aggregate bandwidth available to end-users. Such bandwidth aggregation capability is routinely used in infrastructure mode operation, where the traffic to and from wireless nodes is distributed among multiple interfaces of an access point or among multiple access points to balance the traffic load. However, bandwidth aggregation is rarely used in the context of multi-hop 802.11-based LANs that operate in the ad hoc mode. Most past research efforts that attempt to exploit multiple radio channels require modifications to the MAC protocol and therefore do not work with commodity 802.11 interface hardware. In this paper, we propose and evaluate one of the first multi-channel multi-hop wireless ad-hoc network architectures that can be built using standard 802.11 hardware by equipping each node with multiple network interface cards (NICs) operating on different channels. We focus our attention on wireless mesh networks that serve as the backbone for relaying end-user traffic from wireless access points to the wired network. The idea of exploiting multiple channels is particularly appealing in wireless mesh networks because of their high capacity requirements to support backbone traffic. To reap the full performance potential of this architecture, we develop a set of centralized channel assignment, bandwidth allocation, and routing algorithms for multi-channel wireless mesh networks. A detailed performance evaluation shows that with intelligent channel and bandwidth assignment, equipping every wireless mesh network node with just 2 NICs operating on different channels can increase the total network goodput by a factor of up to 8 compared with the conventional single-channel ad hoc network architecture.