Multicast Routing Protocols in Mobile Ad Hoc Networks: A Comparative Survey and Taxonomy <s> Batch Mode Multicast MAC/Location Aware Multicast MAC (BMMM/LAMM) <s> Wireless communications are becoming an important part of our everyday lifestyle. One major area that will have an enormous impact on the performance of wireless ad hoc networks is the medium access control (MAC) layer. Current random access MAC protocols for ad hoc networks support reliable unicast but not reliable broadcast. We propose a random access MAC protocol, broadcast support multiple access (BSMA), which improves the broadcast reliability in ad hoc networks. <s> BIB001 </s> Multicast Routing Protocols in Mobile Ad Hoc Networks: A Comparative Survey and Taxonomy <s> Batch Mode Multicast MAC/Location Aware Multicast MAC (BMMM/LAMM) <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> Batch Mode Multicast MAC/Location Aware Multicast MAC (BMMM/LAMM) <s> Efficient, scalable and robust multicasting support from the MAC layer is needed for meeting the demands of multicast based applications over WiFi and mesh networks. However, the IEEE 802.11 protocol has no specific mechanism for multicasting. It implements multicasting using broadcasting at the base transmission rate. We identify two fundamental reasons for performance limitations of this approach: (a) Channel-state Indifference: irrespective of the current quality of the channel to the receivers, the transmission always uses the base transmission rate; (b) Demand Ignorance: packets are transmitted by a node even if children in the multicast tree have received those packets by virtue of overhearing. We propose a solution for MAC layer multicasting called HIMAC that uses the following two mechanisms: Unary Channel Feedback (UCF) and Unary Negative Feedback (UNF) to respectively address the shortcomings of 802.11. Our study is supported by measurements in a testbed, and simulations. We observe that the end-to-end throughput of multicast sessions using MAODV can be increased by up to 74% while reducing the end-to-end latency by up to a factor of 56. <s> BIB003
Protocol Description. In BIB002 , two schemes were proposed to provide a reliable MAC layer multicast. The first scheme, known as Batch Mode Multicast MAC (BMMM), uses a similar mechanism of polling to the one used in BIB001 . However, to avoid the collision of CTS frames that occurred in BIB001 , the transmission of RTS/CTS is in strict sequential order to each of the destinations in BMMW. To prevent collisions among the ACK frames, the transmitter polls each of the neighbors by sending a new packet, called RAK (Request to ACK). This scheme adds considerable overhead to the transmission of a single DATA packet. The second scheme, known as Location Aware Multicast MAC (LAMM), attempts to avoid the control overhead of BMMW by assuming the location information of each of the nodes. It helps the sender to poll only a subset of nodes based on their location. Discussion. BMMM requires n RAK/ACK exchange pairs and n RTS/CTS exchange pairs for the transmission of a single data packet to n destinations, which means that BMMM is not scalable and is not practical, adding a great deal of control overhead, especially in high traffic networks BIB003 . In addition, BMMM does not fully utilize the broadcast nature of the broadcast medium, thereby wasting bandwidth. Compared with BMW, BMMM has many fewer contention phases involving the completion of the reliable multicast transmissions. Finally, BMMM will fail in a dense network, because there is contention among many nodes concurrently in the 2-hop neighborhood.