A big slot scheduling algorithm for the reliable delivery of real-time data packets in wireless sensor networks

Abstract

In wireless sensor networks (WSNs), guaranteeing a reliable data transmission over a time-varying wireless channel is a challenging task. The existing TDMA-based MAC protocols assign time slots to the nodes individually for the transmission of data packets safely. However, these protocols may not be suitable for the industrial WSNs in which the stability of wireless links is threatened by various obstacles. In this paper, we propose a new slot allocation and utilization method that allocates one big slot for all nodes at each depth of a tree, and allows the nodes to share it through contention. The big slot constrains the packet transmission delay of all nodes at the same depth, thereby limiting the packet transmission delay to a sink. We show by simulation that the proposed approach is very dependable against the time-varying channel in WSNs.