We propose here an extended linear feedback model, taking the binary exponential backo® mechanism adopted in IEEE 802.15.4 CSMA/CA and analyse the energy consumption issues of the one hop sensor nodes. Numerical results show that the energy consumption in Wireless Sensor Networks (WSNs) can be reduced by applying CSMA protocol with ¯xed contention window size. Besides, an optimal contention window size can achieve the reasonable successful probability of the packet transmission without extra wastage of the battery power
