| Mobile Ad hoc networks composed of mobile nodes with wireless communication devices are typically characterized by their multi-hop, temporary and un-center. Each node in the network also acts as a router, forwarding data packets for other nodes. How to communicate with each other is one of the key problems in Ad hoc networks.The typical routing protocols presented by the MANET of IETF are all shortest routing, that is, the least hops routing, which do not consider the energy aware problem. However, the portable communication devices in Ad hoc networks are untethered, batteries operated and have limited energy, so the network is an energy-constrained system. How to preserve the nodes energy and prolong the lifetime of the system gradually plays an important role on evaluating the performance of Ad hoc network routing protocols. The energy conservation of the network system is a key problem especially in the situations such as military areas, disaster relief, classrooms and conferences, where the time and the devices is constrained. From the perspective of energy, the shortest path is not always the optimal path. On the contrary, using the shorter hops to replace the relatively longer hops may be a better choice to preserve the energy.While a variety of approaches to energy-aware routing protocols in Ad hoc networks have been proposed, depending on desired goals, they can be classified into two types. The goal of the first type is focusing on minimizing the total consumed energy when transmitting packets, which minimizes the energy consumption per packet or flow. However, these approaches may suffer the same problem as the above-mentioned routing protocols without consideration of energy conservation, if the same paths are being utilized repeatedly due to their minimal energy consumption, the nodes energy along these routes are consumed quickly and may cause the topology partitioned earlier as the classical routing protocols. The goal of the second type is to maximize the system lifetime which is defined as duration from the beginning of the service to the first time of some node's energy depletion by preserving the smaller energy left nodes to prolong the time of system split, which put more focus on load balancing among nodes to lengthen service time rather than minimization of energy for individual packet transmission. Based on the request delay mechanism and the nodes energy left, our algorithm is presented just by the second idea. On the one hand, the routing passes by the bigger energy left nodes, which prolong the system lifetime. On the other hand, the mechanism avoids the shortcoming of the longer delay time of RDRP.Firstly, this thesis describes the basic characteristic of Ad hoc networks and introduces the existing routing protocols in detail. Combined the mobile model and energy model, we evaluate the classical routing protocols in Ad hoc networks and study the problem of connectivity based on the simulation results. Used the request delay and the ideas of energy level, we implement and improve the classic routing protocols of AODV and MAODV, named the ELBRP and ECBMR respectively. Secondely, we compare the performance of existing protocols AODV, RDRP, MAODV and proposed ELBRP, ECBMR via simulation with NS2. The studies show that the improved routing protocols are implemented and available.This thesis has six chapters as below.Chapter 1 introduces the concept, the characteristic and research hotspot of Ad hoc networks and introduces the source and research meaning of this article, the working and innovation of which are given finally.Chapter 2 describes of the classic routing protocols in Ad hoc networks.Chapter 3 simulates the four routing protocols in different angels and put forward a simulation model for Ad hoc networks.Chapter 4 describes the ideas of ELBRP (energy level based routing protocol) in detail with the ideas of request delay and energy level. The simulation results show the ELBRP has a better effectiveness than AODV and RDRP.Chapter 5 intorduces the ECBMR (energy consumption balance multicast routing), which is implemented from the ideas of ELBRP, and describes the creat, the split and the combination of multicast tree. As same as chapter 4, we gave a compares of MAODV and ECBMR with simulation.Chapter 6 summarizes this paper and suggesting the future work.This thesis is supported by National Natural Science Foundation (Projects No. 90304018, 60672137) and the Ministry of Education P.h.D .Foundation (Projects No. 20060497105) of P.R .China. |
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