Frame Preamble MAC for Multihop Wireless Sensor Networks: Design and Implementation

MAC protocols based on preamble sampling techniques offer significant energy savings for low data- rate multihop wireless sensor networks by efficiently reducing idle listening in lightly loaded networks. However, without any particular optimization, preamble sampling protocols still consume large amounts of energy due to the overhead induced by the long preamble transmitted prior data frames. To reduce the overhead induced by the use a full length preamble, many improvements have been proposed. These proposals targeted both the cost at the receiver and that at the transmitter. At the transmitter side, proposals tends to minimize the preamble size by means of explicit synchronization, whereas at the receiver, proposals aim at reducing the duration of listening by replacing the preamble with a series of frames.

In this paper, we focus on reducing the cost at the receiver side while showing that our solution is also compatible with solutions that reduce the cost at the transmitter side. We propose a new idea that reduces overhearing further on by avoiding reception of irrelevant frames. With our idea that is based on digest information, not only unicast frames can be filtered but also irrelevant (redundant) broadcast frames can be avoided a priori. We show that the use of the digest information together with the sequence number field substantially increases the energy savings of frame preamble MAC protocols. We propose two possible implementations, Micro Frame Preamble (MFP) and Zebra Frame Preamble (ZFP), in which avoiding reception of irrelevant broadcasts can be integrated. We provide an analytical framework, in which we model the lifetime of various frame preamble MAC protocols. We complete the theoretical analysis with ns2 simulation and experimental validation through implementation on the Chipcon CC 2500 evaluation kit. We analytically show that the solution based on micro frames yields better performance. We discuss implementation choices and effect of power consumption of the micro controller on the overall performance of the solution. We also discuss potential improvements from using new architectures in which hardware circuitry can be used for constructing and transmitting preamble frames.