A method of communicating among wireless devices includes providing a frequency hopping schedule to a target device. The frequency hopping schedule includes a sequence of frequencies. The method also includes, at the target device, alternately sleeping and listening on a frequency in the sequence of frequencies according to the frequency hopping schedule, exchanging time base information between the target device and the transmitting device, at the transmitting device, using the time base information to determine a current frequency of the target device, from the transmitting device, and transmitting a packet of information uniquely addressed to the target device.