Cross layer based MAC protocol for rate and power adjustment in multi hop Ad Hoc networks

Abstract

A Mobile Ad hoc Network has a set of mobile hosts which are operated without the support of established infrastructure of centralized administration such as base stations or access points In this network the nodes communicate via wireless links with other mobile hosts by their antennas Due to concerns such as radio power limitation and channel utilization a mobile host may not be able to communicate directly with other hosts in a single hop fashion In this case a multi hop scenario occurs where the packets sent by the source host must be relayed by several antermediate hosts before reaching the destination host This leads to excessive packet losses and re routing instability Unfairness may also arise when some flows experience higher contention than other flows The IEEE 802 11 Distributed Co ordination Function based on Carrier Sense Multiple Access with Collision Avoidance is the most popular Medium Access Control protocol used in wireless ad hoc networks In Mobile Ad hoc Network a MAC protocol has to contend with the hidden terminal and the exposed terminal problems To overcome these problems many protocols have been proposed in which protocols RTS and CTS packets are transmitted before the data transmission The sender will first transmit an RTS packet The receiver then consents to the communication by replying a CTS packet On hearing the CTS the sender can go on transmitting its data packet Such an approach has been accepted by the IEEE 80211 standard newline