Patent ID: 8825120

Claim:
A sensor for use in a wireless sensor network of devices, comprising: sensing means operable to detect values of a parameter; control means operable to determine a suitable sleep pattern of the sensor by comparing the detected values with thresholds and a transmitter operable to transmit an indication of the sleep pattern to a further device in the wireless sensor network; wherein there is a number of predefined sleep patterns determined by the number of thresholds, each threshold defining a boundary between a lower wake-up and a higher wake-up sleep pattern; and wherein the sensor further comprises a battery, the control means being operable to control the sleep pattern taking into account both the detected values and a current battery charge of the sensor by allowing or rejecting suitable sleep patterns according to predefined limits of acceptable battery charge and overriding any rejected suitable sleep pattern with a lower wake-up sleep pattern, the number of limits being equal to the number of thresholds and the control means allowing one fewer sleep pattern below each limit than above it.