Periodic Global Broadcast Time Synchronization (PGB-TS) for TDMA Based Sensor Networks

Wireless sensor networks become a new alternative for satellite systems to sense fine grained small size subjects. Time synchronization is an important aspect of distributed systems including wireless sensor networks (WSNs). Traditional time synchronization methods are mostly optimized for scalability and precision. We propose a Periodic Global Broadcast Time Synchronization (PGB-TS) mechanism for TDMA based WSNs to maximize energy efficiency. PGB-TS assumes that the sink can send periodic broadcast to all sensor nodes. Sensor nodes receive the global reference broadcast and synchronize themselves to the sink PGB-TS estimates clock drift with linear regression and accepts receive error. Energy consumption of radio circuit of a sensor network is modeled analytically. Simulation results show that PGB-TS consumes significantly less energy at the expense of somewhat lowered precision. Unfortunately, because of its lower precision, energy consumption of a sensor network with PGB-TS increases with the increased number of children. To avoid the dependency in the number of children, we also propose to employ a new Data Indication Slot Mechanism (DISM) into PGB-TS. Beneficially, DISM prevents redundant checks at the expense of possible overhearing situations. Analytical model for the proposed PGB-TS with DISM is supported by the simulation results.