Evaluation of scalability of Hybrid Wireless Mesh Protocol in IEEE 802.11

Mobile ad-hoc networks (MANETs) enable ubiquitous computing with wide availability of smart mobile devices and applications. However, robust and lightweight protocols are yet to be implemented for multihop communication. The latest IEEE 802.11 standard released in 2012 captures the concept of multihop MANETs under Wireless Mesh Networks and proposes Hybrid Wireless Mesh Protocol (HWMP) as the default multihop path selection protocol. Previous studies on the performance of HWMP have not addressed operating scenarios of mass mobility (to model human user mobility), non-availability of root nodes (to model absence of infrastructure support) and a wide span of node densities (to model different application scenarios). This paper analyses the scalability of HWMP in a MANET of IEEE 802.11 standard wireless mesh stations that move at human walking speeds. The end-to-end delay, data packet delivery ratio and path selection control overhead are evaluated in the presence of random waypoint and mass mobility models for increasing node densities. The simulation results show that there are no significant variations in any of the above important performance metrics among static, random waypoint mobility and mass mobility models. Furthermore, HWMP shows almost a linear path selection control overhead profile for increasing node densities while the packet delivery ratio and the end-to-end delay reaches a steady level as node density increases up to about 250 nodes.