Research On The Acquirement Of Localization Information And Routing Algorithms For Wireless Sensor Networks

The acquirement of location information in wireless sensor networks (WSNs) mainlyconsists of both the estimation of target location and acquisition of nodes' own locations innetworks. The dissertation mainly addresses the single target tracking problem inhierarchical network topology. Based on the prediction technology for time series data, thesensor nodes relevant to tracking are designed with scheduling strategy and awakeningscheme, and the corresponding recovery approach is also supplied when target tracking isfailed. As to the node localization problem, when mobile anchor is used, estimation ofunknown node's location is converted to an unconstrained optimization problem withobjective of finding the shortest distance to the hyperspheres or hyperplanes.In addition, routing design plays an important role in designing protocols for WSNs.According to different research objects, the data centric routing problems in WSNs can beclassified into route discovery, relay selection, and link rate allocation, etc. In recent years,cross-layer design is incorporated with wireless networks naturally, because cross-layerdesign is simple and flexible to the philosophy of routing design, and also as it isapplicable to wireless network structure and application environment. In the paper, routingprotocols applicable in WSNs are proposed in chapter4to chapter6. Particularly, inchapter6, joint design of resource reconfiguration and robust routing is studied throughcross-layer design, and the designing is also adapted to the spectrum agile wireless sensornetworks. The main results are summarized as follows:Firstly, in problem of target localization, node set relevant to tracking is defined atfirst. According to the historical trajectories of target, high order exponential smoothingforecasting model is applied to waken the detection nodes dynamically. The cluster headsare responsible for scheduling sensing tasks of their member nodes, while operations ofon-site cluster head can be transferred to its downstream cluster head.Secondly, the aforementioned approach of target localization assists us in obtainingsolution to the node localization problem. Similar to the stated target localization problem, herein the mobile target is regarded as mobile anchor, while member nodes arecorrespondingly deemed as unknown nodes. Under the described assumptions, interactivemode of communications between mobile anchor and unknown nodes are hencedeveloped. In the mean time, by setting the beacon threshold, speed of mobile anchor canbe automatically adjusted. Furthermore, according to the mobile anchor's randommovement behavior, it has been proved that the localizing algorithm can still be energyefficient. At last, the program algorithm flow and simulation results are used to verify thelocalization performances as parameters vary.Finally, as to the routing problems in WSNs, we study the heuristic routing problemunder guarantee of QoS to achieve the multi-objective routing design. The selectionprobability of potential relay in two-hop range is defined based on the extended energycost metric. Further, node set of one/(two)-hop neighbors is updated according to theminimum value of tolerable delivery velocity. As to transmission reliability, relationsbetween link quality indicator and transmission reliability predict the packet reception rateat the receiver on the available link.When routing is introduced into the programming methods, we study the joint designproblem of hierarchical topology control and link rate allocation in cluster. In theformulated problem, affiliation relationships are modeled as the discrete variables, whilethe link rates in cluster are represented by continuous variables, and both of which aresubject to the objective of network lifetime maximization. Sequential fixing approach isused to solve the formulated combinatorial optimization problem, by which sub-optimalaffiliation relationships are hence obtained. By compared with the simulation results, it isfurther confirmed that the sub-optimal solutions well approximate to the global optimalsolutions.As to the wireless cognitive radio networks, spectrum sharing can effectively raisethe utilization rate of resources, suppress interferences, and expand the network capacity.Considering the avoidance of self-interferences and co-channel interferences, the paperdesigns band occupancy scheme in both the space and frequency domains. In thealgorithm, session rates are defined as random variables. In order to decrease theprobability of link outage and improve quality of service, portfolio of financial instruments in economic mathematics is applied to regulate the uncertainty of link outage.The joint consideration of resource reconfiguration and robust routing can be formulatedas a mixed integer non-linear programming problem with uncertain constraint, andevolutionary process of CR network states is given in the simulation experiment.