Multitier mobile ad hoc networks: architecture, protocols, and perfomance

While mobile ad-hoc networking (MANET) research has received a considerable attention in recent years, the majority of them have focused on single-tier (e.g., ground) and homogeneous (e.g., same radio for every node) MANET. Few have investigated the potential implications of multitier and heterogeneous natures of MANET on the design and performance of MANET protocols in a systematic manner. For example, one of the stark differences between single-tier and multitier MANET environments is that the multitier MANET naturally creates "coverage asymmetry" due to the much larger coverage area by airborne nodes compared to ground nodes. Consequently, the number of "neighbors" an airborne node sees can be potentially several orders of magnitude larger than that of a ground node. Treating this airborne node same as any ground node will adversely affect the performance of medium access control (MAC) and/or routing MANET protocols. In this paper, we present a detailed multitier MANET architecture, associated issues, and protocols developed. Our novel protocols and simulation tools designed for multitier MANET are described with preliminary performance results.