A Distributed TDMA Slot Scheduling Algorithm for Spatially Correlated Contention in WSNs

Abstract

In WSNs the communication traffic is often time and space correlated, where multiple nodes in a proximity start transmitting simultaneously. Such a situation is known asspatially correlated contention. The random access method to resolve such contention suffers from high collision rate, whereas the traditional distributed TDMA scheduling techniques primarily try to improve the network capacity by reducing the schedule length. Usually, the situation ofspatially correlated contentionpersists only for a short duration, and therefore generating an optimal or suboptimal schedule is not very useful. Additionally, if an algorithm takes very long time to schedule, it will not only introduce additional delay in the data transfer but also consume more energy. In this paper, we present a distributed TDMA slot scheduling (DTSS) algorithm, which considerably reduces the time required to perform scheduling, while restricting the schedule length to the maximum degree of interference graph. The DTSS algorithm supports unicast, multicast, and broadcast scheduling, simultaneously without any modification in the protocol. We have analyzed the protocol for average case performance and also simulated it using Castalia simulator to evaluate its runtime performance. Both analytical and simulation results show that our protocol is able to considerably reduce the time required for scheduling.

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“…Nodes in IoT healthcare and WSNs are overcrowded, so the probability of collision is high, because of spatially correlated contention (SCC) [11], in which many nodes closely located sense the same event and concurrently start sending data. For solving the problem, we need to design and control SCC due to the fact that collisions can occur by reducing throughput and energy efficiency.…”

A New Intra-Cluster Scheduling Scheme for Real-Time Flows in Wireless Sensor Networks

“…At the same time, for inter-cluster controls, delay-bound data were routed using a minimum number of hops consisting of a combination of cluster heads and member nodes. The real-time query scheduling algorithm [3] assumes a pre-given routing tree for different scheduling strategies by considering the trade-offs between prioritization and throughput. The problem with TDMA scheduling for flat wireless sensor networks (WSNs) is that they are not scalable to the large networks, and have less slot reuse due to global view of the network [4] or large message exchanges.…”