Abstract
Minimum latency scheduling has arisen as one of the most crucial problems for broadcasting in duty‐cycled Wireless Sensor Networks (WSNs). Typical solutions for the broadcast scheduling iteratively search for nodes able to transmit a message simultaneously. Other nodes are prevented from transmissions to ensure that there is no collision in a network. Such collision‐preventions result in extra delays for a broadcast and may increase overall latency if the delays occur along critical paths of the network. To facilitate the broadcast latency minimization, we propose a novel approach, critical‐path aware scheduling (CAS), which schedules transmissions with a preference of nodes in critical paths of a duty‐cycled WSN. This paper presents two schemes employing CAS which produce collision‐free and collision‐tolerant broadcast schedules, respectively. The collision‐free CAS scheme guarantees an approximation ratio of (Δ − 1)T in terms of latency, where Δ denotes the maximum node degree in a network. By allowing collision at noncritical nodes, the collision‐tolerant CAS scheme reduces up to 10.2 percent broadcast latency compared with the collision‐free ones while requiring additional transmissions for the noncritical nodes experiencing collisions. Simulation results show that broadcast latencies of the two proposed schemes are significantly shorter than those of the existing methods.
Highlights
Wireless Sensor Networks (WSNs) have become one of the most important technologies for the 21st century [1, 2] and have attracted a lot of attention from industrial and research perspectives [3,4,5,6,7,8,9,10,11]
Such periodic sleeping leads to a notable increase of communication latency between sensor nodes while reducing their energy consumption
CT-critical-path aware scheduling (CAS) further reduces the latency up to 9.3 percent more than CF-CAS by allowing collision at less critical nodes
Summary
Wireless Sensor Networks (WSNs) have become one of the most important technologies for the 21st century [1, 2] and have attracted a lot of attention from industrial and research perspectives [3,4,5,6,7,8,9,10,11]. In a low-duty-cycled WSN, a sensor node sleeps most of the time periodically waking up within a short time slot for possible data communication by either transmitting or receiving a message. Such periodic sleeping leads to a notable increase of communication latency between sensor nodes while reducing their energy consumption. We propose a novel approach, criticalpath aware scheduling (CAS) that offers an opportunity to reduce the latency by providing a preference for transmitting a message to nodes along critical paths of a duty-cycled WSN.
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