mSync: Physical Layer Frame Synchronization without Preamble Symbols

We present a novel physical layer frame format and a corresponding decoding strategy for energy-constraint single-carrier transceivers, often used in sensor networks and cyber-physical systems. The main advantage of our approach is that decoding does not rely on dedicated preamble symbols, which usually introduce considerable overhead in terms of energy consumption and utilization of the wireless channel. We show that omitting the preamble can be achieved by buffering the signal in the receiver and processing the samples twice; first to synchronize and in a second iteration to decode the actual data. To introduce our approach, we provide a theoretical description, including a discussion of the implications of synchronizing on data symbols instead of optimized preamble sequences. The practical feasibility of the algorithm is shown by simulations and experiments using prototype implementations based on software defined radio. We implemented our algorithm for two technologies, a custom ultra low-power BPSK transceiver and the O-QPSK physical layer of the IEEE 802.15.4 standard. Finally, we present an extension of the algorithm that allows us to reduce the buffered data to a small constant number of samples, making our algorithm applicable to physical layers independent from their maximum frame size.