Multicast Routing Protocols in Mobile Ad Hoc Networks: A Comparative Survey and Taxonomy <s> Multicast Evaluation Criteria <s> In this paper we investigate the performance of multicast routing protocols in wireless mobile ad hoc networks. An ad hoc network is composed of mobile nodes without the presence of a wired support infrastructure. In this environment, routing/multicasting protocols are faced with the challenge of producing multihop routes under host mobility and bandwidth constraints. In recent years, a number of new multicast protocols of different styles have been proposed for ad hoc networks. However, systematic performance evaluations and comparative analysis of these protocols in a common realistic environment has not yet been performed. In this study, we simulate a set of representative wireless ad hoc multicast protocols and evaluate them in various network scenarios. The relative strengths, weaknesses, and applicability of each multicast protocol to diverse situations are studied and discussed. <s> BIB001 </s> Multicast Routing Protocols in Mobile Ad Hoc Networks: A Comparative Survey and Taxonomy <s> Multicast Evaluation Criteria <s> Swarm intelligence refers to complex behaviors that arise from very simple individual behaviors and interactions, which is often observed in nature, especially among social insects such as ants. Although each individual (an ant) has little intelligence and simply follows basic rules using local information obtained from the environment, such as ant's pheromone trail laying and following behavior, globally optimized behaviors, such as finding a shortest path, emerge when they work collectively as a group. In this paper, we apply this biologically inspired metaphor to the multicast routing problem in mobile ad hoc networks. Our proposed multicast protocol adapts a core-based approach which establishes multicast connectivity among members through a designated node (core). An initial multicast connection can be rapidly setup by having the core flood the network with an announcement so that nodes on the reverse paths to the core will be requested by group members to serve as forwarding nodes. In addition, each member who is not the core periodically deploys a small packet that behaves like an ant to opportunistically explore different paths to the core. This exploration mechanism enables the protocol to discover new forwarding nodes that yield lower total forwarding costs, where cost is abstract and can be used to represent any metric to suit the application. Simulations have been conducted to demonstrate the performance of the proposed approach and to compare it with certain existing multicast protocols. <s> BIB002 </s> Multicast Routing Protocols in Mobile Ad Hoc Networks: A Comparative Survey and Taxonomy <s> Multicast Evaluation Criteria <s> A current trend in wireless communications is to enable wireless devices to transmit at different rates. That multirate capability has been defined in many standards such as 802.11a, 802.11b, 802.11g, and HiperLAN2. We propose a rate-adaptive multicast (RAM) protocol that is multirate-aware. During the process of path discovery, the quality of wireless links is estimated to suggest optimal transmission rates, which are then used to calculate the total transmission time incurred by the mobile nodes on a path. Among several considered paths from a source to a destination, RAM selects the path with the lowest total transmission time. Our work is the first that proposes the use of the multirate capability in multicast. The proposed RAM protocol works with any multirate standards, and does not require any modifications to the standards. Our simulation results show that RAM outperforms single-rate multicast in terms of packet delivery ratio, packet end-to-end delay, and throughput of the multicast group. <s> BIB003 </s> Multicast Routing Protocols in Mobile Ad Hoc Networks: A Comparative Survey and Taxonomy <s> Multicast Evaluation Criteria <s> Application layer multicasting has emerged as an appealing alternative to network layer multicasting in wireline networks. Here, we examine the suitability of application layer multicast in ad hoc networks. To this effect, we propose a flexible receiver-driven overlay multicast protocol which we call Application Layer Multicast Algorithm (ALMA). ALMA constructs an overlay multicast tree in a dynamic, decentralized and incremental way. First, ALMA is receiver-driven: the member nodes find their connections according to their needs. Second, it is flexible, and thus, it can satisfy the performance goals and the needs of a wide range of applications. Third, it is highly adaptive: it reconfigures the tree in response to mobility or congestion. In addition, our protocol has the advantages of an application layer protocol: (a) simplicity of deployment, (b) independence from lower layer protocols, and (c) capability of exploiting features such as reliability and security that may be provided by the lower layers. Through extensive simulations, we show that ALMA performs favorably against the currently best application layer and network layer protocols. In more detail, we find that ALMA performs significantly better than ODMRP, a network layer, for small group sizes. We conclude that the application layer approach and ALMA seem very promising for ad hoc multicasting. <s> BIB004
There are various criteria for evaluating multicast routing protocols, including, but not limited to, packet delivery ratio (PDR), delivery efficiency, protocol efficiency, average latency, number of total packets transmitted per data received, packet retransmission overhead, data forwarding overhead, and control overhead BIB002  BIB004 BIB003  BIB001  . (i) Packet delivery ratio (PDR): this expresses the number of non duplicate data packets successfully delivered to each destination versus the number of data packets supposed to be received at each destination. It is a metric which can be used as a measure of the effectiveness of the protocol. The higher the PDR, the more efficient and reliable the protocol. (ii) Total overhead: this represents the total number of control packets transmitted and the total number of data packets transmitted versus the total number of data packets delivered. Total overhead is a more important metric than control overhead because we are concerned about the number of packets transmitted to obtain the number of data packets delivered to the receivers, regardless of whether those packets were data or control. It is a measure which shows efficiency in terms of channel access, and is very important in ad hoc networks, since link layer protocols are typically contention-based. ( Control overhead represents the number of control packets transmitted (request, reply, acknowledgment) for each data packet that is successfully delivered to the destinations. Control packets are counted at each hop. This metric can be used as a measure of the effectiveness of a multicast protocol. An ineffective multicast protocol will generate a large number of control packets. It shows, relatively, the degree to which an extra wireless channel access is required for the protocol to exchange control information.), (iii) Average latency (average end-to-end latency): this represents the average time a data packet takes to travel from the transmitter to the receiver. It is a metric which can be used to evaluate the timeliness of the protocol. (iv) The data delivery delay between two nodes: this represents the average time it takes for a data packet to be transmitted from one forwarding node to another. (v) Delivery efficiency: this represents the number of data packets delivered per data packet transmitted. The term of "transmitted" includes "transmitted by sources" as well as "retransmitted by intermediate nodes." The larger its value, the smaller the number of retransmissions. (vi) Reachability (RE): this represents the number of all destination nodes receiving the data message divided by the total number of all destination nodes that are reachable, directly or indirectly, from the source nodes. (vii) Average throughput: receiver throughput is defined as the total amount of data a receiver R actually receives from all the senders of the multicast group divided by the time it takes for R to receive the last packet. The average over all the receivers is the average receiver throughput of the multicast group. The average throughput is the average receiver throughput divided by the number of senders. (viii) Stress: the stress of a physical link is the number of identical copies of a multicast packet that needs to traverse the link. This metric quantifies the efficiency of the overlay multicast scheme. Table 5 summarizes the major features of the multicast routing protocols described earlier. It provides a comparison of those protocols in terms of various characteristics: routing approach, dependency on unicast routing protocol, routing scheme, route acquisition latency, and multicast control overhead, and in terms of the presence or absence of the following characteristics: loop-free, control packet flooding periodic control message, QoS support. Concerning the qualitative evaluation in Table 5 , it should be noted that most of the values used have relative meaning (comparative evaluation), taking into account that no absolute values are used.