Research On AODV For Wireless Sensor Networks

With the development of sensors, computers and communications technology, the technology of wireless sensor networks which integrates the above three technologies has being paid much more attentions. Compared with traditional networks, wireless sensor networks which originated from the wireless network have many new features, such as low performance and less energy for single-node, high density of nodes, self-organizing structure, routing related to the applications. Thus, the efficiency and pertinence of routing protocols were demanded due to these characteristics.Firstly, the development of wireless sensor networks and the main types of Ad-Hoc routing protocols were introduced. And the typically Ad-Hoc routing protocols of OLSR, AODV, DSR and ZRP were compared in the functions of storage capacity, algorithm complexity, practicability and adaptability of topological changing. Finally, AODV was chosen as the basic protocol of this thesis. However, the data transmission mode of wireless sensor networks is multi-to-one, not one-to-one as usual. And wireless sensor networks have other characteristics such as low performance and less energy for single-node. So many problems which are peculiar to wireless sensor networks are caused and can not be effectively resolved by AODV such as "hot spot" and network partitioning. So EPMP-AODV routing protocol was presented, which was based on the AODV routing protocol and will be used in wireless sensor networks. Then programming and simulating of EPMP-AODV protocol was done in TinyOS platform. Finally, the performance of the EPMP-AODV protocol was tested in two ways that software simulation and practical wireless networks testing. The results verified the EPMP-AODV protocol can ease the effect on the lifetime of network by "hot spot" and network partitioning problems, and prolong the lifetime of the sensor network. And the network congestion also can be reduced by EPMP-AODV protocol, and packet delivery rate was improved which verified the feasible and validity of EPMP-AODV protocol.There are two aspects of the work in this thesis which are innovative and valuable as follows:1. The energy probability multi-path AODV protocol (EPMP-AODV Protocol) is presented. AODV protocol is extended to multi-path protocol, while the residual energy of the next hop node is inserted into the routing table. The using probabilities of paths are defined by the values of energy when data are transmitted. Therefore, EPMP-AODV Protocol avoids the problems that the single path easily leads to the premature death of nodes in static wireless sensor network. And packets are transferred by higher energy route in order to reduce the changes of network topology which are due to dead node. Although the protocol inevitably increases the routing overhead, but the capability of network energy balance which is more important for wireless sensor network is effectively enhanced and the lifetime of network is extended.2. EPMP-AODV protocol was programmed with NesC language in the TinyOS system. Then the performance of EPMP-AODV and the traditional AODV were compared by TOSSIM simulator in TinyOS system and practical network testing. The results showed that, the strategy of establishing multi-path, and using the path which had more energy can extend the lifetime of network, and it also can ease the congestion of network while high data transmission speed, so the validity of EPMP-AODV protocol was proved.