Cheng, XiuzhenDu, Ding-ZhuWang, LushengXu, Baogang2020-09-022020-09-022002-01-22https://hdl.handle.net/11299/215508In this paper, we propose a novel idea of maintaining connectivity by introducing relay sensors in a wireless sensor network. We restrict our consideration to a very important class of wireless sensor networks such as biomedical sensor networks, in which the locations of the sensors are fixed and the placement can be pre-determined. We formulate our problem to the NP-hard network optimization problem named Steiner Minimum Tree with Minimum number of Steiner Points (SMT-MSP) and present two approximate solutions. Meanwhile, we study the topology improvement in a wireless sensor network when relay sensors are introduced. In other words, we restrict transmission power of each sensor to a small value and use relay sensors to guarantee connectivity. The performance parameters under consideration are $P$, the total per node minimum power needed to maintain connectivity, and $D$, the maximum degree in the minimum power topology (maintained by $P$).Simulation study shows that with the introduction of relay sensors, we achieve better performance, especially for sparse topology.en-USReport