The Study Of Service Discovery Protocol For Manets

MANETs(Mobile Ad-Hoc Networks) are temporary infrastructure-less multi-hop wireless networks that consist of many autonomous wireless mobile nodes. Besides normal functions, each node should also act as a router. Service discovery is the operation of finding proper servers that provide services matching one's request. Service discovery technology tries to approach zero administration overhead and thus free users from tedious administrative and configuration work. Hence, service discovery protocol is critical to the success of high dynamic MANETs.Researching on analytical descriptions of properties of MANETs is helpful to research works on MANETs, e.g. facilitating the configuration of protocol parameters, optimization of protocol operations, and more exact estimation of protocol performance, etc. Basing on combinatorial theory and asymptotic method, we analyzed the properties of MANETs with nodes uniformly distributed in rectangular region. Mathematical formulas of some basic properties of MANETs are obtained, such as the expected number of wireless links, mean node degree, the relation between network connectivity and radio range.GSD(Group-based Service Discovery protocol) is typical service discovery protocols for MANETs. GSD selectively forwards service requests to some candidate nodes, which have seen some services belonging to the same group as the requested service. Requests will be matched at those nodes with higher probability. In this way, flooding of service requests is avoided. However, GSD causes much packet redundancy since that one unicast request packet is sent to each candidate node.Two technologies, FNC(Forward Node Combination) and BSU(Broadcast Simulated Unicast), are proposed to improve GSD. FNC sends service request packets to so called relay nodes of the founded candidate nodes instead of to the candidate nodes themselves. BSU replaces several unicast request packets sent by one node with a broadcasted request packet enclosing the receivers of those unicast packets. Mathematical analysis proves the effectiveness of BSU on saving request packets. Simulation results show that FaBGSD obtains lower request packet overhead, higher efficiency, and more prompt responce.FaBGSD still has defects for invalid candidate nodes and less-efficient...