Evaluation of the interest of an extra-slot for a grouped polling-selecting method

Switched beam antennas (SBA) have been shown to offer many advantages when used in confined and obstructed environments that represent a difficult radio propagation environment. However, when SBA are used in wireless network, the popular contention-based medium access control protocol such as IEEE 802.15.4 MAC is no longer effective. Furthermore, the contention based nature of IEEE 802.15.4 MAC makes it not suitable for deterministic transmissions. In order to have a good compromise between range, data rate and deterministic behavior, in this paper, we propose data collection schemes based on polling-selecting strategies for low latency deterministic networked (LLDN) systems where the sink is equipped with a SBA and sensor nodes with usual omnidirectional antennas. Our solution is based on IEEE 802.15.4 frame exchanges in star topology. We present an analytical model to evaluate the benefit of using an extra slot in a collection scheme based on polling strategy. Several simulations were conducted to validate the analytical model and show that using an extra slot in a collection scheme based on polling strategy improves the frame delivery rate.