This letter proposes a simple k-hop flooding scheme for the temporarily lost child node of a multicast tree in a mobile ad hoc network where a group of nodes move together within a bound. Through simulation, we show that our scheme improves the packet delivery ratio of MAODV to be comparable to the epidemic routing with only small additional duplicate packets.

The IEEE 802.11 distributed coordination function (DCF) provides a contention-based distribution channel access mechanism for stations to share the wireless medium. However, performance of the DCF drops dramatically in terms of throughput, delay and jitter as the number of active stations becomes large. In this paper, we propose a simple and effective scheme, called distributed coordination function with virtual group (DCF/VG), for improving the performance of the IEEE 802.11 DCF mechanism. In this scheme, each station independently decides a virtual group cycle taking into account the current contention level. The virtual group cycle consists of one or more virtual groups and a virtual group includes an idle and a busy period. Each station chooses one virtual group and operates only in the chosen group of the cycle. In other words, each station decreases its backoff counter and tries to transmit its packet during the period of the chosen virtual group like in the IEEE 802.11 DCF. Performance of the proposed scheme is investigated by numerical analysis and simulation. Our results show that the proposed scheme is very effective and has high throughput and low delay and jitter behaviors under a wide range of contention levels.

Wireless multimedia sensor networks tend to generate a large number of sensing data packets within a short period. A multi-channel TDMA scheme can avoid the hidden terminal problem and and has been shown to achieve higher performance than the CSMA scheme. In order to deliver large volumes of sensing data within a time limit, our scheme for minigroup multicast can improve the performance gain of the multi-channel TDMA by incorporating deflection routing which constrains any intermediate nodes from serving multiple sessions and establishes a new path detour the nodes on the existing path of multicast sessions. Through simulations, we show that, even though the deflection routing builds non-optimal paths, our scheme supports 95% packet delivery ratio and higher throughput than the legacy multicast routing protocol with CSMA-based media access control.