Capacity and Fairness Issues in Enterprise-class Wireless Mesh Networks

Опубликовано 6 сентября 2016, 6:26

Today's wireless LAN deployments are limited to providing communication between mobile clients and access points. A comprehensive wired backbone still needs to be deployed to inter-connect these access points and the enterprise computing resources. In this talk, I will discuss a multi-hop wireless mesh backbone architecture, called Hyacinth, that can be readily built using commodity IEEE 802.11 hardware. Specifically, I will focus our discussion on capacity and fairness issues that arise in such networks. Inter-path and intra-path interference severely limits the number of links that can be simultaneously active in a wireless mesh network. To improve capacity, Hyacinth employs multiple radio channels in each radio neighborhood by equipping each node with multiple network interfaces. To fully utilize the performance potential of this approach, Hyacinth provides two traffic load-aware channel assignment and routing algorithms, each of which tunes the network channel assignment and routing based on the network topology and the latest traffic patterns. Even with the use of just 2 NICs per node, the proposed algorithms improve the network cross-section goodput by factors of up to 6 when compared with single-channel wireless mesh networks. The MAC protocol of IEEE 802.11 introduces serious unfairness among competing nodes when used in multi-hop wireless mesh networks. Hyacinth improves network fairness by implementing a stateful transport protocol that performs explicit bandwidth allocation among competing flows to achieve max-min fairness despite weaknesses in the MAC layer. Again our experiments suggest that the proposed protocol can substantially improve the fairness across flows, eliminate starvation problem, and simultaneously maintain a high overall network throughput.