Research On A Few Issues In The Ad Hoc Network

There are two kinds of ad hoc networks. One kind is Mobile Ad Hoc Network(MANET), which is self-organized by mobile nodes communicating with distributedprotocols. The second one is Sensor Ad Hoc Network, which is self-organized byfixed nodes. They all can function in absence of fixed routing infrastructures, such asbase stations. As the wireline network is not available, mobile ad hoc networksprovide a feasible means for ground communications and information access. Sensornetworks consist of sensor, MEMS and networking technology. It can monitor targetobject real timely and sensor all kinds of environments by cooperating with each other.Then the information is process, and is sent to the user. The topology of a MANET can change frequently since all communicatingnodes can move with unlimited mobility. The class routing techniques are designedwith implicit assumption of a comparatively stable network topology, and theirperformances degrade in mobile environments. New routing techniques are demandedfor mobile ad hoc network. Routing is a challenging problem in multi-hop wirelessnetworks. The nodes in sensor network seldom move, so it is not necessary to updatethe routing information. The exiting routing protocol in MANET can not be used forsensor networks. Building the effective routing is also a challenging problemespecially in large wireless sensor network. Routing is the core operation in both MANET and sensor network. By analyzingthe existing routing protocol, this dissertation focuses the problems routing protocoland joincast. The major contributions of this thesis include: 1) Research on routing problems in MANET and its improvement. Maintaining the routing information is time-effective in networks with dynamictopology. As the topology of a MANET can change frequently, efficient routemaintenance operations are required. In order to reduce the routing overhead, thetechnique of redundant routing is proposed to localize the influence of the changing ofnetwork topology. Meanwhile, it provides backup routes when a route is broken andimproves the routing reliability. AODV is widely used in MANET. Based on AODV, 第 III 页博士学位论文·无线自组网络若干技术的研究we design an enhanced routing information protocol utilizing the redundant routingtechnique. The enhanced AODV protocol can achieve better performance while thenetwork topology changes faster through simulation with ns-2. 2) Research on large scale sensor network The existing routing protocol in MANET can not be used in sensor network forthe different characters and requirements. Most nodes in sensor network are fixed.Because the noise is high in wireless channel, and the sensor node may not work. So itis required that the routing algorithm is robust, distribution and scalability. Weproposed a heuristic routing algorithm. Theory analysis and experience show thatthis algorithm can be used in large scale wireless sensor network. 3) Research on joincast The networking traffic in wireline network has the characteristic of self-similarand heavy tail distributed. The length of packet in sensor network is short for itslimited power. When many flows are translated, we can join them together. A joincastalgorithm is put forward, and the simulation results show that the algorithm canachieve better performance while there is heavy load.