Multicast Routing Protocols in Mobile Ad Hoc Networks: A Comparative Survey and Taxonomy <s> Optimized Polymorphic Hybrid Multicast Routing Protocol (OPHMR) <s> This document describes the Multicast extension for the Optimized Link State Routing protocol (MOLSR). MOLSR is in charge of building a multicast structure in order to route multicast traffic in an ad-hoc network. MOLSR is designed for mobile multicast routers, and works in a heterogenous network composed of simple unicast OLSR routers, MOLSR routers and hosts. In the last part of this document we introduce also a Wireless Internet Group Management Protocol (WIGMP). It offers the possibility for OLSR nodes (without multicast capabilities) to join multicast groups and receive multicast data. <s> BIB001 </s> Multicast Routing Protocols in Mobile Ad Hoc Networks: A Comparative Survey and Taxonomy <s> Optimized Polymorphic Hybrid Multicast Routing Protocol (OPHMR) <s> An ad hoc network is a dynamically reconfigurable wireless network with no fixed infrastructure or central administration. Each host is mobile and must act as a router. Routing and multicasting protocols in ad hoc networks are faced with the challenge of delivering data to destinations through multihop routes in the presence of node movements and topology changes. This paper presents the On-Demand Multicast Routing Protocol (ODMRP) for wireless mobile and hoc networks. ODMRP is a mesh-based, rather than a conventional tree-based, multicast scheme and uses a forwarding group concept; only a subset of nodes forwards the multicast packets via scoped flooding. It applies on-demand procedures to dynamically build routes and maintain multicast group membership. ODMRP is well suited for ad hoc wireless networks with mobile hosts where bandwidth is limited, topology changes frequently, and power is constrained. We evaluate ODMRP performance with other multicast protocols proposed for ad hoc networks via extensive and detailed simulation. <s> BIB002 </s> Multicast Routing Protocols in Mobile Ad Hoc Networks: A Comparative Survey and Taxonomy <s> Optimized Polymorphic Hybrid Multicast Routing Protocol (OPHMR) <s> In recent years, a variety of unicast and multicast routing protocols for Mobile Ad hoc wireless NETworks (MANETs) have been developed. The Zone Routing Protocol (ZRP) is a hybrid unicast protocol that proactively maintains routing information for a local neighborhood (routing zone), while reactively acquiring routes to destinations beyond the routing zone. In this paper, we extend ZRP for application to multicast routing and call it the Multicast Zone Routing Protocol (MZRP). MZRP is a shared tree multicast routing protocol that proactively maintains the multicast tree membership for nodes’ local routing zones at each node while establishing multicast trees on-demand. It is scalable to a large number of multicast senders and groups. IP tunnel mechanism is used to improve the data packet delivery ratio during transmission. Detailed simulations were performed on the NS-2 simulator. Its performance was also compared with that of ODMRP. <s> BIB003 </s> Multicast Routing Protocols in Mobile Ad Hoc Networks: A Comparative Survey and Taxonomy <s> Optimized Polymorphic Hybrid Multicast Routing Protocol (OPHMR) <s> We propose in this paper an optimized, polymorphic, hybrid multicast routing protocol for MANET. This new polymorphic protocol attempts to benefit from the high efficiency of proactive behavior (in terms of quicker response to transmission requests) and the limited network traffic overhead of the reactive behavior, while being power, mobility, and vicinity-density (in terms of number of neighbor nodes per specified area around a mobile node) aware. The proposed protocol is based on the principle of adaptability and multibehavioral modes of operations. It is able to change behavior in different situations in order to improve certain metrics like maximizing battery life, reducing communication delays, improving deliverability, etc. The protocol is augmented by an optimization scheme, adapted from the one proposed for the optimized link state routing protocol (OLSR) in which only selected neighbor nodes propagate control packets to reduce the amount of control overhead. Extensive simulations and comparison to peer protocols demonstrated the effectiveness of the proposed protocol in improving performance and in extending battery power longevity <s> BIB004
Protocol Description. OPHMR BIB004 is built using the reactive behavior of ODMRP BIB002 and the proactive behavior of the MZRP BIB003 protocol. In addition, the Multipoint Relay-(MPR-) based mechanism of the OLSR BIB001 protocol is used to perform an optimization forwarding mechanism. OPHMR attempts to combine the three desired routing characteristics, namely, hybridization (the ability of mobile nodes (MNs) to behave either proactively or reactively, depending on the conditions), adaptability (the ability of the protocol to adapt its behavior for the best performance when mobility and vicinity density levels are changed), and power efficiency. To enable hybridization and adaptability, that is, polymorphism, OPHMR introduces different threshold values, namely, power, mobility, and vicinity density. OPHMR is empowered with various operational modes which are either proactive or reactive, based on an MN's power residue, mobility level, and/or vicinity density level. In a route, each MN tries to determine the destination node according to its own strategy (proactive or reactive). Thus, the MNs try to find the next forwarding nodes by using their own routing tables, which are established in the background for proactive stations, or by using broadcasting for reactive stations. This feature ensures that any hysterical behavior is avoided. Each MN determines its mode of operation based on the threshold values mentioned earlier. When a node wants to join a multicast group or wants to send data to that group, it begins the route discovery procedure. If it is in reactive mode, it sends out a JREQ message and waits for replies. This is done as in ODMRP. If the node is in proactive mode or proactive ready mode, it first looks in its neighborhood table to see whether or not there are nodes that belong to the destination multicast group. If there are, it unicasts JREQ messages to all these nodes and waits for replies. Otherwise, the node will broadcast a JREQ message. When a node receives such a message and it is a member of the multicast group, it sends back a reply to the source of that message and updates its multicast routing tables to record the route. If the node could not send a reply, it checks its own behavior. If it is in reactive mode, it just propagates the JREQ message and records it in the route cache. If the node is in proactive mode or in proactive ready mode, it looks in its own neighborhood table to find the destination multicast group member. If there are members in its zone, it unicasts the JREQ message to all of them. If not, it just propagates the message. When the source node receives a reply, it updates its multicast routing tables to record the route and begins data transmission. Discussion. OPHMR is, in the long run, able to extend battery life and enhance the survivability of the mobile ad hoc nodes. As a result, it decreases the end-to-end delay and increases the packet delivery ratio, in comparison with other protocols, such as ODMRP BIB002 , while keeping the control packet overhead at an acceptable rate. OPHMR follows the proactive Hard-State approach to maintain the multicast topology. Hence, the packet delivery ratio decreases as the mobility of the nodes increases. Table 2 summarizes the common pros and cons of the IPLM that are in the same subcategory. We have chosen the following subcategories: routing scheme, multicast topology, and maintenance approach, because they have a significant effect on the performance of the multicast routing protocol, on control overhead and packet delivery ratio, for example.