Minimization of the Total Cost of Wireless Sensor Networks for Railway Structural Monitoring

Abstract

We study a method to design wireless sensor networks (WSNs) for condition monitoring of railway structures so as to minimize the total cost of the investment and operation of WSNs. For the continuing long-term operation of WSNs, batteries in the network must be replaced before their depletion. However, large maintenance expense might be required if maintenance workers go to the site and replace batteries whenever a battery depletion occurs. On the other hand, a periodic inspection for railway structures shall be usually conducted once during a period of several years. Therefore it is practical for WSNs used for a condition monitoring of railway structures to replace batteries at the timing of a periodic inspection. This can make the continuing long-term operation of WSNs more effective. In this paper, we propose a mathematical model, that is to simultaneously determine the number of relays and gateways and their deployment locations, the transmission power level for each sensor and relay, and the routes for transferring sensor data to a gateway so as to minimize the total cost of the investment and operation of WSNs. Then we verify its effectiveness through computational experiments using real data acquired at the London underground.