Research On Neighbor Discovery Technology In Wireless Ad Hoc Networks

Since wireless ad hoc networks usually are not equipped e a fixed infrastructure and its network topology changes dynamically,each network node needs to regularly or irregularly perform the function of neighbor node discovery during the network initialization and communication stages,which updates its neighbor node list and network topology in real time.That can provide reliable guarantee for subsequent network basic functions such as route discovery and data transmission.Therefore,this paper focuses on the neighbor discovery technology of wireless ad hoc networks.On the one hand,for the energy-constrained wireless ad hoc networks equipped with omnidirectional antennas,we study the energy-saving neighbor discovery technology of the clock asynchronous network nodes in working and sleeping modes,and focused on the optimization of the following two energy-saving neighbor discovery problem.First,when the battery energy utilization of each network node is limited,how to shorten the maximum delay that any two neighbor network nodes needs to discover each other as much as possible.Second,when the delay that any two neighbor network nodes discovers each other is limited,how to save battery energy utilization of each network node as much as possible.For the two problems,based on the relaxed cyclic difference sets theory,we designed two kinds of working time slot generation methods for clock asynchronous network nodes,which are optimized by minimizing neighbor discovery delay and minimizing the proportion of node working time.As the numerical calculation results show,the two working time slot generation methods proposed in this paper can obtain better neighbor discovery maximum delay and better working time ratio than the existing methods of the same type.On the other hand,for the wireless ad hoc network with each network node equipped with directional antennas,we study the neighbor discovery technology based on directional antennas when any two neighboring nodes under the condition which they do not know each other's physical location,the way to numbering antenna sector and clock differences.At last,we design a sector switching sequence generation method suitable for network nodes equipped with directional antennas.The method can support any two nodes equipped with N-sector directional antenna to achieve all N~2 possible sector combinations within a limited time length under any clock difference,and can ensure that the two nodes realize neighbor discovery within a limited time period.The numerical calculation results show that the sector switching sequence generation method in this paper should have a smaller maximum and average sector alignment time interval compared with the existing sector switching sequence generation methods of the same type.The method can ensure that the directional antennas are aligned and neighbor discovery functions of any two network nodes can be achieved within a shorter time.