A Low Latency Synchronous Duty Cycle Mac Protocol for Wireless Sensor Networks

Abstract

Recent advances in sensors, as well as wireless communication technologies have made it possible to build powerful wireless sensor networks. A Wireless Sensor Network (WSN) is composed of many low-cost and small wireless sensor nodes. These sensor nodes are distributed in a designated region. In WSN MAC protocols, there are multiple fields on which researchers often focus on for example end to end delivery latency, duty cycling, and delivery ratio. The basic factor in wireless sensor networks is energy efficiency because there is limited battery in WSNs. Low duty cycling can help to minimize energy consumption in WSNs. Duty cycle MAC protocols have been proposed to meet demanding energy requirements of WSNs. Although existing duty cycle MAC protocols such as S-MAC [1] and DW-MAC [6] are power efficient, they introduce significant end-to- end delivery latency. R-MAC [5] allows a node to transmit a data packet for multiple hops in a single duty cycle, which is made possible by exploiting a control frame named Pioneer (PION) for the path set up. PR-MAC is a MAC protocol that can schedule multi hop transmissions of data in a single duty cycle to reduce end-to-end delivery latency. In this thesis, we present a MAC protocol called Hop Extended Pipelined Routing MAC (HE-PRMAC) that enables a node to transmit a data packet for multiple hops in a single duty cycle like PR-MAC. Similar to RMAC, it employs PION frame to set up the path for multiple hop transmission, which contains the information about the maximum hop that a packet can travel through in a single duty cycle. The main role of HE-PRMAC is that it extends the relay of a packet beyond the termination of the data period by one or more hops compared to R-MAC and PR-MAC. Also along with this, our proposed protocol introduces RTR message with the help of which we can handle traffic overhead. This RTR message contains the information of how much packets sender is going to send and a receiver can receive. We evaluate the performance through ns-2 simulations. Compared to R-MAC and PR-MAC, HE-PRMAC shows 22.1% less power consumption and 13.6% less packet delay on average for 250 nodes in chain, cross and real scenario.