US Patent 7103344 Device with passive receiver

A wireless communications apparatus includes a wake-up receiver adapted to receive a wake-up signal and an initially powered-off, sleeping wireless communications transceiver. When the wake-up receiver receives the wake-up signal, it can in turn power on the wireless communications transceiver. In another aspect, the invention includes an apparatus for sending a wake-up signal to the wake-up receiver. The wake-up transmitter and the wake-up receiver can communicate via a variety of wireless communications protocols, including the BLUETOOTH™ standard.