Hidden nodes avoidance in wireless sensor networks

We propose a new access method for wireless multi-hop sensor networks. It reduces collisions due to hidden nodes, a source of significant energy dissipation. Our access method operates similarly to SMAC by alternating sleeping and active periods, but it does not use RTS/CTS. Instead, it adjusts the contention window so that the probability of collisions due to hidden nodes becomes negligible. We analyze the hidden node problem to derive expressions for the number of hidden nodes and the probability of collisions. We show the numerical results for different low power radios and validate our access method through simulation.