A Deafness-Free MAC Protocol in Ad Hoc Networks Using Directional Antennas

Abstract

Directional antennas provide many benefits, such as higher gain and increased transmission range in both ad hoc networks and infrastructure networks. However, deafness problems occur only with directional antennas and can greatly decrease transmission efficiency. In the typical deafness problem, the source node fails to communicate with the intended destination node because the destination node is beam forming in another direction. This thesis proposes a deafness-free medium access control (DF-MAC) protocol with one channel based on a code division multiple access (CDMA) technique for ad hoc networks using directional antennas. In addition to transmission codes, in DF-MAC, two control codes are used for both handshakes and overcoming one type of deafness problem. Our proposed DF-MAC totally solves all types of deafness problem occurring in ad hoc networks using directional antennas. To the best of authors’ knowledge, it is the first deafness-free MAC that solves all types of deafness problem. Furthermore, unlike other deafness-aware MAC protocols, DF-MAC supports mobility. Simulation results show that the proposed DF-MAC not only successfully solves all four types of deafness problem but also out performs the existing deafness-aware MAC protocols in terms of network throughput and control overhead in both static and mobile environments. If deafness problems occur often, the effect of DF-MAC is dramatically maximized.