Recently, wireless sensor networks have been used in many promising applications including military surveillance, wildlife tracking, habitat monitoring and so on. They are an indispensable requirement for a sensor node to be able to find its own location. Many range-free estimate approaches eliminate the need of high-cost specialised hardware, at the cost of a less accurate localisation. In addition, the radio propagation characteristics vary over time and are environment dependent, thus imposing high calibration costs for the range-free localisation schemes. In order to reconcile the need for...
