Multicast Routing Protocols in Mobile Ad Hoc Networks: A Comparative Survey and Taxonomy <s> Broadcast Medium Window (BMW) <s> Traditional wireless ad hoc medium access control (MAC) protocols often utilize control frames such as request-to-send (RTS), clear-to-send (CTS) and acknowledgement (ACK) to reliably deliver unicast data. However, little effort has been given to improve the reliable delivery of broadcast data. Often, broadcast data are transmitted blindly without any consideration of hidden terminals. In this paper, we proposed a novel MAC protocol, broadcast medium window (BMW) that reliably delivers broadcast data. <s> BIB001 </s> Multicast Routing Protocols in Mobile Ad Hoc Networks: A Comparative Survey and Taxonomy <s> Broadcast Medium Window (BMW) <s> Multicast/broadcast is an important service primitive in networks. The IEEE 802.11 multicast/broadcast protocol is based on the basic access procedure of Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA). This protocol does not provide any media access control (MAC) layer recovery on multicast/broadcast frames. As a result, the reliability of the multicast/broadcast service is reduced due to the increased probability of lost frames resulting from interference or collisions. In this paper, we propose a reliable Batch Mode Multicast MAC protocol, BMMM, which substentially reduces the number of contention phases, thus considerably reduces the time required for a multicast/broadcast. We then propose a Location Aware Multicast MAC protocol, LAMM, that uses station location information to further improve upon BMMM. Extensive analysis and simulation results validate the reliability and efficiency of our multicast MAC protocols. <s> BIB002 </s> Multicast Routing Protocols in Mobile Ad Hoc Networks: A Comparative Survey and Taxonomy <s> Broadcast Medium Window (BMW) <s> In this paper, the interaction of the Medium Access Control (MAC) and routing layer is used to address the congestion control multicast routing problem in wireless ad hoc networks. We first introduce the Broadcast Medium Window (BMW) MAC protocol, which provides robust delivery to broadcast packets at the MAC layer. In doing so, we show that although BMW is able to provide high reliability under low to medium network load, reliability dramatically degrades under high network load. We then extend the wireless On-Demand Multicast Routing Protocol (ODMRP) to facilitate congestion control in ad hoc networks using BMW to combat the poor performance under highly congested network conditions. Through simulation, we show that ODMRP with congestion control adapts well to multicast sources that are aggressive in data transmissions. <s> BIB003 </s> Multicast Routing Protocols in Mobile Ad Hoc Networks: A Comparative Survey and Taxonomy <s> Broadcast Medium Window (BMW) <s> The basic carrier sense multiaccess control scheme for multicast communications in wireless ad hoc network suffers from the well know hidden terminal problem. The data packet collision probability is relatively high, and the packet delivery ratio is sensitive to the network topology, nodes distribution and traffic load. This paper generalizes the virtual earner sense collision avoidance approach to reduce packet collisions. The sender and receivers exchange RTS and CTS packets to reserve the channel. When more than one receivers reply with CTS packets, the sender will detect an "expected" collision which may be interpreted as a valid "clear-to-send" signal provided the collision satisfies the given timing requirements. Together with a receiver-initiated local recovery mechanism, the reliability of multicast communications can be improved to almost 100%. <s> BIB004
Protocol Description. A reliable multicast protocol based on round-robin polling is proposed in BIB001 BIB003 . Data packets are delivered in straight sequential order. A sending node exchanges RTS/CTS packets with its next-hop neighbors in round-robin order. The RTS packet will carry two additional fields (the multicast session ID and the sequence number of the current packet x). The polled receiving node will respond with the expected sequence number y. Upon receiving the CTS packet, the sending node transmits the packets numbered from y to x. Other receiving nodes that overhear the data packets will buffer the packets and update their expected sequence number. However, this protocol only guarantees that the polled receiving node is free from the interference of hidden terminals. Discussion. BMW requires that data packets be delivered in straight sequential order, which means that more buffer size is required at the intermediate nodes. In addition, BMW has the following drawbacks BIB004 . The length of the RTS packet is approximately doubled, which increases the probability of RTS packet collision and communication overhead. In addition, the traffic load is increased substantially if the sending node has a moderate-to-high fanout. Moreover, under high traffic load, the network will be jammed, because of the large amount of retransmission, and the system must fall back on the use of the basic blind broadcast scheme. However, this will defeat the purpose of the reliable multicast protocol, because it cannot be applied when it is most needed. It has been reported in BIB002 that BMW is inefficient, since it requires at least n contention phases for each multicast data frame. Not only is each contention phase lengthy in terms of time but also the sender must contend with other nodes for access to the medium. It is possible that some other nodes will successfully contend, which will interrupt and prolong the ongoing multicast process. In addition, in many applications (e.g., routing), multicast is time-sensitive. In other words, if the multicast request cannot be fulfilled within a certain amount of time, the multicast request will be considered unsuccessful by the higher layer. For such applications, the prolonged multicast process can easily lead to a time-out in that layer.