Wireless Medium Access Control under Mobility and Bursty Traffic Assumptions in WSNs

Abstract

In Wireless Sensor Networks (WSNs) the nodes can be either static or mobile depending on the requirements of each application. During the design of Medium Access Control (MAC) protocols, mobility may pose many communication challenges. These difficulties require first a link establishment between mobile and static nodes, and then an energy efficient and low delay burst handling mechanism. In this study, we investigate preamble-sampling solutions that allow asynchronous operation. We first introduce anycast transmission to ContikiMAC where a mobile node emits an anycast data packet whose first acknowledging node will serve as responsible to forward it towards the sink. Once this link is established, burst transmission can start, according to the respective burst handling mechanism of ContikiMAC. Although it is considered as negligible in the literature, such an anycast-based on-the-fly operation Georgios Z. Papadopoulos actually results in high packet duplication at the sink. Hence, we demonstrate that even a basic anycast-based MContikiMAC would fail to handle bursty traffic from mobile nodes mainly due to increased unnecessary traffic and channel occupancy. We then propose Mobility-Enhanced ContikiMAC (ME-ContikiMAC), a protocol that reduces packet duplications in the network by more than 90 % comparing to M-ContikiMAC. Moreover, our results in a 48-node scenario show that ME-ContikiMAC outperforms a number of state-of-the-art solutions (including MoX-MAC and MOBINET), by terms of reducing both delay and energy consumption.

Low-power neighbor discovery for mobility-aware wireless sensor networks

“…In [2] , authors overcome the previously mentioned limitations by proposing ME-ContikiMAC. Mobile nodes expecting to transmit n data packets in burst, will transmit one additional control packet upfront, n + 1 packets.…”

“…• Proactive protocol • Inefficient under intermittent link connections ME-ContikiMAC [2] • Traffic independent • Independency from underlying protocol • Inefficient handover and recovery procedures • Overhead minimization RX1, RX2, RX3 and RX4 that are 1, 2, 3, and 2 hops away from the sink respectively. The mobile node may connect to any of those neighboring static nodes (e.g.,the first acknowledging its request).…”

“…The reconfigured timers must be compliant with Eqs. (2) and (3) . The new values are illustrated in Figs.…”

“…Recently, applications such as patient or animal monitoring emerged, with mobility and bulk transmission schemes very often appearing to be essential [2,3] . In such applications, sensor nodes are attached to persons, animals or objects, while under burst transmissions, nodes may transmit n packets in a row once they gain access to the wireless medium [4] .…”

“…• We perform a thorough performance evaluation on top of COOJA (a simulator for Contiki OS). In addition, we compare MobiDisc (by considering default and FAN modes) against state-of-the-art solutions such as ME-ContikiMAC [2] and MoX-MAC [9] .…”