DESIGN ISSUES AND EXPERIMENTAL STUDIES OF WIRELESS LAN MESH

Abstract

Wireless mesh networking, as a low-cost and reliable technology for rapid network deployment, has attracted considerable attention from academia and standardization in the industry. The IEEE 802.11s standard defines a wireless LAN mesh using the IEEE 802.11 medium access control and physical layers, and is one of the most active standards with increasing commercial opportunities. This study presents the design and development of a WLAN mesh system conforming to the latest IEEE 802.11s draft amendment. Without costly hardware modifications, the proposed solution is a pure software extension for commercial off-the-shelf WLAN chipsets. This study constructs an experimental testbed, and evaluates issues such as the transmission reliability of mesh broadcast-type control messages and multichannel transmissions. Experimental results demonstrate that the delivery of mesh broadcast-type control messages, such as routing construction frames, using the multiple acknowledged unicast scheme improves mesh stability from an 86 to a 98 percent success ratio in a 16-node grid. Transmitting packets using a single radio interface switching between multiple channels reduces inter-flow interference and doubles the throughput in our testbed.