A generic wake-up radio based MAC protocol for energy efficient short range communication

To avoid idle listening and to improve energy efficiency in short range communication networks, a generic wake-up radio (WUR) based medium access control (GWR-MAC) protocol is proposed. GWR-MAC is not restricted to a specific WUR technology or data radio technology, and therefore it is suitable for a variety of scenarios in wireless sensor and body area networks. GWR-MAC includes a bidirectional wake-up procedure and a transmission period for data communication. Two different options for the wake-up procedure are defined: source-initiated and sink-initiated. The data transmission period can be implemented by using different type of channel access methods, which enables scalability. This paper describes the GWR-MAC protocol and an analytical model which is used to explore the energy efficiency of the proposed GWR-MAC based network and conventional duty cycle MAC based network. The comparison is done as a function of number of events to enable the selection of a correct radio technology for different application scenarios. The results clearly illustrate the usefulness and energy efficiency of the proposed protocol especially in applications that have low event frequency and require a low delay wake-up procedure.

I. Introduction

In wireless sensor and body area networks (WSN and WBAN) the sleep periods are typically controlled by using a duty cycle based medium access control (MAC) protocol. In duty cycle based MAC (DCM) protocols, the radios listen to the channel for part of the time, according to a schedule (or randomly), and they go to a sleep mode if incoming transmissions are not detected [1]. DCM protocols work well in many applications but not in scenarios where the frequency of events, and consequently communications, occur rarely. An important drawback of the DCM approach is the idle listening, which increases energy consumption and should be then minimized if possible. Idle listening can be decreased by setting the duty cycle very low when the traffic load is known to be low. Adaptive duty cycle protocols have also been proposed for these cases [2]. However, a low duty cycle will increase the communication delay and may not be able to satisfy the application requirements if the detected event must trigger immediate communication and actions.