Improving wireless sensor network reliability by topology control

In this study, we aim to enhance the reliability of a WSN by a new partial redundancy protocol while maximizing network lifetime. We consider a network composed of a base station and many identical sensors with limited energy. The proposed mixed IP model PRF is built gradually. Initally, we develop the NRF model which maximizes network lifetime without any reliability protocol. Then to improve network reliability by eliminating possible massive data loss risks arising from overuse of central nodes, constraints that provide balanced use of sensors are added to get the bNRF model. Later FRF model is developed which employs balanced usage strategy and also forces each sensor to send multicopy of the same data on two node disjoint paths. In this model the purpose in sending multicopy on multipaths is to be able to transmit the data to the base station if a problem occurs on the path of the other copy of the same data. However using multicopy on multipath routing and balanced usage strategy at the same time decreases network lifetime significantly. Therefore a new model PRF which uses these protocols more efficiently is proposed. In PRF balanced usage strategy is considered but if there is a sensor whose extensive use leads to a better network lifetime, then it is allowed to be the central node. Moreover in this model only the sensors who send their own data through central node replicate their data and send it on two node disjoint paths. The performances of the models are evaluated according to some performance criteria such as lifetime, leftover energy, and conserved data. The tradeoff between network lifetime and reliability is examined. Finally to decrease the solution time of the PRF model a heuristic method is proposed.