PPM: Preamble and Postamble-Based Multi-Packet Reception for Green ZigBee Communication

Abstract

ZigBee, a low-power wireless communication technology, has been used in various applications, such as smart health/home/buildings. The proliferation of ZigBee-based applications (and thus devices), however, makes the concurrent transmissions—i.e., multiple transmitters send packets to the same receiver at the same time—common in practice, leading to inevitable collisions. Either retransmissions caused by collisions or the collision avoidance mechanism, e.g., CSMA/CA, introduces plenty of energy consumption. To facilitate the green and concurrent transmissions of ZigBee, we design pre/post-amble-based multi-packet reception (PPM), a method that recovers the collided ZigBee messages by exploiting their collision-free chips and the overlapped chips in their pre/post-ambles. We elaborately attach short postamble to standard ZigBee packet by manipulating the ZigBee payload, which can be compatible with standard ZigBee and only introduce negligible energy overhead. We further propose two design enhancements, cross-validation and reference chips calibration, to ensure the accuracy of PPM. Such a collision recovery of PPM reduces the retransmissions caused by collisions and eliminates the energy overhead of CSMA/CA simultaneously, facilitating the realization of green ZigBee. We have prototyped and evaluated PPM with USRP, showing PPM recovers the collided messages with bit-error-rates in the order of ${10}^{-6}$ , which is magnitudes lower than state-of-the-art methods. Experimental results show that PPM can achieve packet reception ratio more than 90% and less than 20 retransmissions in a concurrent transmission experiment with 400 packets resulting in negligible packet retransmission cost of energy.