Analysis of smart antenna based scheduling algorithms for IoT networks

IETF 6TiSCH protocol stack aims to create reliable, deterministic, and low-power wireless networks by using time slot and frequency channel resources in a planned way. To achieve this goal; the 6TiSCH scheduling function must distribute radio resources effectively among the wireless nodes. Frequency channel resources may be limited when the same frequency band is shared with other wireless technologies (i.e., Wi-Fi, Bluetooth, and other IEEE 802.15.4 networks) used within the same coverage area of the antennas. Similarly, time slot resources are also limited in dense networks consisting of many nodes, or when they have high data traffic. In this case, the use of antennas which can change their coverage area to increase the performance of the network, adds a spatial dimension to the scheduling and provides more efficient use of limited resources. In this study; two of the low complexity smart and directional antenna types (Switchable beam antenna and Steerable directional antenna) are integrated with the IETF 6TiSCH protocol, with the aim of creating a solution with higher spatial reuse. As a contribution to the literature; a novel neighbor discovery mechanism that allows nodes to discover each other before synchronization to the network, a method that provides the best antenna direction with neighbor nodes to obtain maximum signal strength, and two hybrid scheduling algorithms (distributed and autonomous, centralized and autonomous) for healthy transmission of control and data packets are proposed. 6TiSCH nodes equipped with smart and directional antennas improved the network performance metrics by scheduling bandwidth resources not only in the time and frequency domain but also in the spatial domain compared to traditional methods in terms of packet delivery ratio, energy consumption and end-to-end latency.