We propose a novel multicast routing protocol, called adaptive multicast routing protocol for MANETs (Mobile ad hoc routing protocol). Multicast routing protocols can be classified two types according the structure used to establish route. Existing protocols are either tree-based or mesh-based. In mesh-based routing protocols, a reliable protocol ODMRP was proposed. In ODMRP, each sender has to broadcast control packet periodically in order to build mesh. But with an increase of number of senders, control overhead causes reliability reduced because of a large amount of overhead and collisions. Hence, ODMRP is not work well in this case. We proposed our scheme to aim at the drawback of ODMRP. We use packet delivery ratio (PDR) to determine if the load of network is congestion. When packet delivery ratio is high, it means that the network traffic load is low, and vice versa. We determine whether a sender broadcasts Join-Query control packet or not according to packet delivery ratio. As packet delivery ratio is decrease, a sender does not broadcast Join-Query as far as it can in order to avoid collisions. However the packet delivery ratio is increase, senders have strong probability to broadcast Join-Query to establish mesh nodes. We can improve reliability and reduce overhead is caused by control packets with this way.

Ad hoc wireless networks are increasingly being used to provide connectivity where a wired networking infrastructure is either unavailable or inaccessible. Many deployments utilize group communication, where several senders communicate with several receivers; multicasting has long been seen as an efficient way to provide this service. While there has been a great deal of research on multicast routing in ad hoc networks, relatively little attention has been paid to the design of multicast transport protocols, which provide reliability and congestion control. In this dissertation we design and implement a complete multicast transport architecture that includes both routing and transport protocols. Our multicast transport architecture has three modules: (a) a multicast routing and state setup protocol, (b) a mobility detection algorithm, and (c) a hop-by-hop transport protocol. The multicast routing and state setup protocol, called ASSM, is lightweight and receiver-oriented, making it both efficient and scalable. A key part of ASSM is its use of Source Specific Multicast semantics to avoid broadcasting when searching for sources. ASSM also uses routes provided by the unicast protocol to greatly reduce routing overhead. The second module, MDA, solves the problem of determining the cause of frame loss and reacting properly. Frame loss can occur due to contention, a collision, or mobility. Many routing protocols make the mistake of interpreting all loss as due to mobility, resulting in significant overhead when they initiate a repair that is not required. MDA enables routing protocols to react to frame loss only when necessary. The third module is a hop-by-hop multicast transport protocol, HCP. A hop-by-hop algorithm has a faster response time than that of an end-to-end algorithm, because it invokes congestion control at each hop instead of waiting for an end-to-end response. An important feature of HCP is that it can send data at different rates to receivers with different available bandwidth. We evaluate all three components of this architecture using simulations, demonstrating the improved performance, efficiency and scalability of our architecture as compared to other solutions.

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