Ultra low power protocol and algorithm for near distance wireless communication and RFID/USN systems

Some applications require that the communication link between the master and slave transceivers be maintained for a certain lifetime and be recovered as soon as possible whenever the link is broken. In these cases especially for mobile applications, it is most important to reduce the power consumption for both communication. While the master and slave are in linked status, neither of the receivers should have to wait for incoming packets without information on the arrival time, since the time elapsed before the reception of the packets wastes power in the receiver. One of the best strategies to save power is to let the master and slave communicate periodically with a given fixed period. Generally, this communication link is frequently broken, because of the mobile conditions, in which case it is important to recover the link as fast as possible to save reception power. When the link is broken, the receiver automatically tries to recover it and, in this case, the receiver opens up the receiving window all the time until the packet is received. This is a period when excessive receiving power is consumed. Moreover, even though a packet has been received successfully, it takes time to return to the minimal power condition and for this time duration the receiver consumes power. The main problem of the periodic setup of the communication link is the difficulty of synchronization between the timer of the master and that of the slave. Once synchronization is established, it is not possible to maintain it for long, due to the frequency drift of the transmitter clock caused by the variation of the temperature or power supply, which leads to the variation of the timer period. This shift of the time of arrival at the receiver provides the motivation for searching for a prediction algorithm for predicting the packet arrival time.