Research On Energy Efficient MAC And Routing Technologies In Mobile Ad Hoc Networks

A Mobile Ad hoc NETwork (MANET) is a wireless communication system with special structure. It is composed of a group of mobile, wireless nodes which cooperate in forwarding packets in a multi-hop fashion. It can be distributed and dynamicly self-orgnized without any centralized administration and can be deployed in many environments to support data communication. It becomes one of the current research hotspots. However, the wireless nodes in MANET are usually powered by batteries with limited energy, while the capability of the batteries cannot be greatly improved in a short term. Thus, energy efficiency has been the key problem in MANET's practical application. This thesis researches on the channel access, power control, energy efficient routing, energy efficient broadcasting algorithm, a series of energy efficient algorithms are proposed in this thesis to reduce the energy consumption. The main contributions of this thesis are listed as follows:Firstly, the MAC layer protocol techniques in MANET and insufficiency of spatial and time requirements reservation of IEEE802.11 DCF protocol carrier sensing technique were analyzed, and combined with MAC layer power control. A joint spatial and time reservation with power control MAC (STR_PC) protocol in mobile Ad Hoc networks was presented in this paper. It can efficiently utilize the available channel resource along with the spatial as well as time dimension, and improve channel spatial reuse through avoiding collision. The proposed protocol embeds the spatial and time reservation requirements in the PHY header, which is transmitted at the lowest data rate, so that a larger group of neighbors become aware of the ongoing communication and thus avoid collisions. By decreasing the transmission power of the data packet can decrease mobile nodes energy consumption. Simulation results indicate that comparing to the IEEE 802.11 MAC protocol, the proposed protocol can improve the throughput performance and decrease the power consumption greatly and improve the energy utilization of mobile terminals while avoiding collision.Secondly, energy efficient and load balanced routing protocols in mobile ad hoc network were analyzed. An energy efficient and load balanced (EE_LB) routing protocol in mobile ad hoc network based on AODV was presented. In this new protocol, the jitter delay of a node is calculated based on its current energy level and current load, so that the nodes with more remaining energy and less offered load can enter the route more quickly, energy consumption in the network can be fairer and offered load can be more balanced. The simulation results show that compared to AODV protocol the proposed protocol decrease the end-to-end delay, improve the network throughput ratio and the network performance.Thirdly, energy consumption is a crucial design concern in wireless ad hoc networks since wireless nodes are typically battery-limited. A multipath routing protocol for mobile ad hoc networks is proposed, called MMRE-AOMDV, which extends the Ad Hoc On-demand Multipath Distance Vector (AOMDV) routing protocol. The key idea of the protocol is to find the minimal nodal residual energy of each route in the process of selecting path and sort multi-route by descending nodal residual energy. Once a new route with greater nodal residual energy is emerging, it is reselected to forward rest data packets. It can balance individual node's battery power utilization and hence prolong the entire network's lifetime. Simulation results show that the proposed MMRE-AOMDV routing protocol performed better than AOMDV.Finally, due to flooding has broadcasting storm problem and inefficient to energy efficient routing protocol, in order to decrease broadcasting overhead, A broadcasting policy based on nodal power level was proposed,called energy efficient broadcasting algorithm (EE_BA), which does not need exchange neighborhood message periodically, implemented local optimal policy. It can decrease overhand of the control message, save the network bandwidth, decrease the nodal power consumption, prolong the lifetime of the wireless network. Simulation results show that the proposed protocol performs well.