REDUCING BUFFER OVERHEAD IN A RELIABLE MULTICASTING PROTOCOL FOR MANETS

Abstract

As the technology of Mobile ad hoc networks (MANETs) develops, many kinds of new applications emerge demanding new and better services with each research being done. The major area of challenge for these ad hoc networks is the multicast service as it is difficult to adapt this in an environment where failures are frequent. The level of reliability differs with the framework of different applications. At its minimum, reliability is assurance of the final delivery of all the multicast data packets to the entire destinations. It also guarantees delivered data packets to be error free along with minimal use of bandwidth and power. The second level of the reliability is to retain the order (partial or total) between data packets. Maintaining the order is crucial for the real- time applications, which requires that all packets be received to every receiver in precisely that order. Various issues of the reliable multicasting include detection of loss of packet, starting the recovery process from such loss and managing the buffer overhead of nodes. However, depending upon the protocol, any of the sender or the receivers may be responsible for these processes. To perform a reliable multicast delivery of data packets, it is necessary to get a feedback from each multicast receiver which in turn indicates whether or not a retransmission is required. A reliable multicast delivery refers to receipt of multicast packet by each of the mentioned receivers. Thus, one or all members need to buffer data packet for possible error recovery. A number of multicast protocols support group communication in MANETs and the main purpose of these protocols is to deliver multicast packets in an efficient and reliable manner. In this project we have proposed an algorithm to improve the performance of Reliable Multicasting AODV Protocol by reducing the buffer overflow and managing the buffers of different nodes. Uniqueness of this algorithm is the selection of one hop set of neighbours of the sender as forwarding nodes (FNs). These forwarding nodes forward the data packets to all the receivers and keep the packets in their respective buffers so as to retransmit the packets whenever it gets a retransmission request. So this distributes the buffer usage from sender to FNs and hence reducing the buffer overhead of the sender. Finally, simulation results show that the modified protocol has low packet dropping as compared to original Reliable MAODV protocol.