RBP: Reliable Broadcasting Protocol in Large Scale Mobile Ad Hoc Networks Subrata Saha, Syed Rafiul Hussain and A. K. M. Ashikur Rahman Department of Computer Science and Engineering Bangladesh University of Engineering and Technology, Dhaka, Bangladesh Email: {subrata, rafiulhussain}@csebuet.org, ashikur@cse.buet.ac.bd Abstract—Conventional broadcasting protocols suffer from network congestion, frequent message losses and corruption of broadcast messages due to a vast number of duplicate packets transmitting in the network. In this paper, we propose an efficient, scalable and reliable broadcast protocol to send a message in the entire network where every node is guaranteed to receive the message with low overhead and minimal cost. The scalability and reliability of broadcast transmission is ensured by composing the entire network in a hierarchy of grids/squares. A higher order square is made up of four lower order squares forming a quad tree architecture. With this grid architecture a node does not need to flood the broadcast packet to the entire network. Rather a node exploits the Geographic Forwarding mechanism to send the packet to a particular square. The rest of the work is done by the very first node receiving the packet destined for that particular grid. This node has now the responsibility to update its own grid with the broadcast packet. The whole procedure is repeated iteratively in every grid. Simulation results show that our proposed algorithm is reliable, scalable, robust and also outperforms some other promising broadcasting protocols that exist in the current literature. Index Terms—Broadcast, Neighbor Allocation Table (NAT), Geographic Forwarding, Grid Formation Rule, Grid Forwarding, Reliable Broadcasting Protocol (RBP). I. I NTRODUCTION A Mobile Ad Hoc Network (MANET), sometimes called a mobile mesh network, is a self-configured network of mobile devices connected via wireless links. MANETs have several vital applications in real-world situations. It can be effectively used in the battle field or major disaster areas where the primary concern is to deploy an infrastructureless network for communicating to the rest of the world. Broadcasting in a Mobile Ad Hoc Network means to send a message to every node in the network. It is necessary for various reasons such as configuring a network automatically i.e., assigning unique IP address to every node, sending a special message in the entire network, paging a particular host, sending an alarm signal to all hosts, discovering a route to a particular host and so on. It can influence performance of many routing algorithms [5]. The task of broadcasting can be naively achieved by flood- ing the entire network with the message to be broadcast. In flooding, upon receiving a broadcast packet, a node simply retransmits the packet to all directions in its neighborhood. This approach causes a number of serious problems. For ex- ample, flooding produces a vast number of duplicate packets, in fact an infinite number, unless some precautions are taken. It effectively builds up heavy load i.e., network congestion in the entire MANET. As a result, some nodes may discard the broadcast packets from their queues due to finite capacity of memory and processing capability. Moreover, due to the fact that, flooding causes a large number of packets to be transmitted in the network, collisions and interferences occur frequently among neighboring nodes. Since message can be corrupted due to interference and collision, some nodes ob- viously may not receive the broadcast packet at all. These problems are collectively known as broadcast storm problem [1] in the networking literature. To ensure scalability and reliability to broadcast a message in entire network is a very difficult problem for any broad- casting protocol. A handful number of broadcast algorithm has been proposed to send messages to every node in the network. But almost all of them provide limited or no scalability as the number of node increases in the network. Flooding is a very well known and blind method to broadcast a packet in the whole network. As the number of node increases, the number of packet forward also increases proportionately. If the number of node in the network be n, then the timing complexity of flooding can be naively described as O(n). But our simulation result shows that the number of packet forward and latency is almost constant as the number of node increases in the network comparing two well known broadcasting protocols , i.e., Dominant Pruning [10] and Partial Dominant Pruning [11]. In our proposed protocol number of packet forward depends only on the number of Order-1 square of the network. If the number of Order-1 square is fixed, then the number of forward is also fixed. Hence our protocol does not depend on the increasing size of nodes which is indeed a characteristics of scalability. Again reliable broadcast is also a very challenging task. Sometimes the responsibility of making reliable data trans- mission (either a unicast or a broadcast) is handed over to a separate layer called medium access control (MAC) layer. For example, the IEEE 802.11 family of MAC schemes [14] is well equipped to handle point-to-point communication. When multiple parties try to talk at about the same time during unicast transmission, it avoids collisions with the help of a fourway handshake, RTS/CTS/DATA/ACK. The RTS/CTS part of the handshake removes the hidden terminal problem by including the recipient in the bandwidth reservation part 2010 24th IEEE International Conference on Advanced Information Networking and Applications 1550-445X/10 $26.00 © 2010 IEEE DOI 10.1109/AINA.2010.91 526