A reliability-aware medium access control for unidirectional time-constrained WSNs

Wireless sensor networks (WSNs) are gaining in importance with an increasing need for interconnectivity in the advent of Internet of Things. A WSN typically consists of bidirectional nodes that are able to transmit and receive data. However, in applications such as home automation and body area networks, data needs to be conveyed in one direction, i.e., from sensors to a sink, in a single-hop network. Hence, unidirectional nodes can be used instead reducing costs in a considerable manner. Since unidirectional nodes are unable to acknowledge or retransmit packets, the resulting networks are strongly unreliable. To overcome this problem, we propose a medium access control (MAC) technique that can be configured to meet desired reliability requirements while fulfilling a maximum delay constraint or deadline. Our technique is based on a probabilistic analysis of packet losses in the worst case and allows, in contrast to other approaches from the literature, a more energy-efficient design. In order to evaluate the proposed technique, we present a large set of experiments and detailed simulations based on OMNeT++.