Design and Evaluation of an IEEE 802.11 Based Dual MAC for MANETs

Multihop ad-hoc wireless networks offer great challenges for protocol designers. Stations in such networks are constrained by factors like low power, limited bandwidth, link errors, and collisions. Changes are needed at various levels of the protocol stack, most importantly at the medium access layer (MAC). The medium access mechanism in multi hop wireless networks should minimize collisions, and take care of the hidden and exposed node problems. The IEEE 802.11 MAC with Distributed Coordination Function (DCF) does not scale well in such networks. We introduce Point Coordination Function (PCF) in the region of high traffic areas, and discuss its effect on network performance. To improve network scalability and throughput, we propose the design of a new MAC called Dual MAC. This work discusses architecture and working of the dual MAC in detail. Performance results of the network using dual MAC are presented, and compared with that of pure DCF operation Wireless ad-hoc network consists of wireless mobile terminals forming a temporary network without any deployed infrastructure or centralized administration. The demand for mixed data, audio, and video applications, that is, multimedia services has grown recently in wireless ad hoc networks. In this paper, we propose the multi-code MAC scheme considering multimedia packets in multi-hop wireless ad hoc networks with flat architecture.The multi-code MAC enhances the pervious multichannel MACs, which simultaneously allocates multiple codes to the sender after the exchange of RTS/CTS/ACK message through common code. We perform a simulation to evaluate ourmulti-code MAC in view of throughput and average access delay.