Research On Algorithms For Topology Control In Heterogeneous Wireless Sensor Networks

Wireless sensor network is ad hoc network which consists of many cheap wireless sensor nodes deployed in unattended monitoring area. It can get physical information of monitoring area through wireless sensor nodes. So, it can be widely applied in many fields, such as national defense, disaster warning, environmental monitoring, precision agriculture and health care. Recently, it has become a common concern research focus of academia and industry.How to prolong life time of wireless sensor is a critical problem that directly affects its widely application. Topology control is an effective method to resolve this problem. However, due to the commonly used assumption of homogeneous wireless sensor networks with uniform maximal transmission power, most topology control algorithms suffer from performance degradations in practical applications where physical characteristics of each node may be different. Hence, it is valuable to take heterogeneous wireless sensor networks into consideration.Recently, the research on topology of wireless sensor network has moved from constructing static structure to dynamic structure. So,heterogeneous wireless sensor network is not an exception. Centering on this issue, we design two adjustable topology control algorithms which are constructed from the angle of node degree and planar respectively.Firstly, to address the problem that the node degree of topology derived by heterogeneous wireless sensor network topology control algorithm EYG is very high, we propose an adjustable topology control algorithm YGMST which has lower degree than EYG. The algorithm is essentially the combination of Yao Graph structure and the minimum spanning tree algorithm, which adjust topology structure through a parameter k. It is shown by analysis and proof that YGMST is connected and symmetrical, and the topology derived by it is much sparser than EYG, and adjusted gracefully. Hence, it is better than EYG. Secondly, to address the problem that the planar and adjustable topology control algorithm TAP is not connected when it is applied to heterogeneous wireless sensor network, I propose quasi-planar and adjustable topology algorithm ETAP, which is an extension of TAP. The algorithm considers asymmetry of communication between nodes, which adjust topology structure through a parameter t. It is shown by analysis and proof that ETAP is connected, symmetrical, sparse and quasi-planar; ETAP is guaranteed to contain the minimum energy consumption path between any pair of nodes when all nodes have t = 1.