Scheduling transmission of sensor data

Scheduling wireless transmission of sensor data to minimise contention and also to reduce energy consumption, particularly for industrial, scientific and medical (ISM) applications where a large number of sensors may be taking measurements and forwarding data to a single access point (AP) on a regular basis. Each of N sensor stations takes measurements at set intervals (ti the traffic period for station i) and obtains a consistent amount of sensor data. Stations transmit their sensor data over time slots (of duration T); in a preferred embodiment this time slot is the same length for each station, but alternatively it could differ between stations. At the commencement of a first transmission round each station may have sensor data available for transmission, and each station may then transmit its data in consecutive time slots. For subsequent transmission rounds there will only be transmission from those stations having data available in their buffers for transmission. The length of the transmission rounds will thus vary, being different numbers of time slots, depending on how many stations have data to transmit in each round.