Half-duplex scheduling in distributed synchronization

Synchronization of carrier frequency and frame alignment guarantees the proper communication and coding. Half duplex constraint represents a limit in synchronization as each device can only transmit its synchronization frames, or receive (and update) the synchronization from the other nodes. In this paper we investigate duplex scheduling as the trade-off between the time allocated to transmit or receive in dense cooperative networks. The proposed method is based on the same synchronization frame transmitted from multiple nodes used as a compound reference signal in synchronization process. The frame structure is designed from the family of CAZAC sequence properly arranged to achieve jointly timing and frequency synchronization. A modified distributed-phase locked loop (D-PLL) algorithm is adapted for timing and frequency correction. The paper shows that to maximize the convergence of timing and frequency synchronization the duplex scheduling can be random and independent on each node, with probability of transmission p ≪ 0.5.