Time slot assignment for convergecast in wireless sensor networks

• Convergecast with minimum delay and minimum energy consumption is addressed.
• A theoretical lower bound on the number of TDMA time slots required is presented.
• Proposed time slot assignment algorithm performs close to the theoretical bound.

Convergecast, which is essentially the inverse of broadcast, can be used for data collection in a wireless sensor network. This paper addresses the problem of convergecast in a wireless sensor network that uses time division multiplexing in order to schedule its node-to-node communication in a time-bounded manner. A realistic system model and problem for convergecast with minimum delay and minimum energy consumption is formulated for wireless sensor networks. Then, based on a detailed analysis of this problem, a heuristic solution based on time slot assignments is proposed. Simulation results are used to show that the proposed algorithm performs significantly better than alternative methods for this problem. The simulation results also show that the data delivery time of the proposed algorithm is close to the theoretical bound. Furthermore, total energy consumption is significantly reduced, when compared to the alternatives, due to the time slot assignment method used in the proposed algorithm.