Abstract-TV White Spaces (TVWS) technology allows wireless devices to opportunistically use locally-available TV channels enabled by a geolocation database. The UK regulator Ofcom has initiated a pilot of TVWS technology in the UK. This paper concerns a large-scale series of trials under that pilot. The purposes are to test aspects of white space technology, including the white space device and geolocation database interactions, the validity of the channel availability/powers calculations by the database and associated interference effects on primary services, and the performances of the white space devices, among others. An additional key purpose is to perform research investigations such as on aggregation of TVWS resources with conventional resources and also aggregation solely within TVWS, secondary coexistence issues and means to mitigate such issues, and primary coexistence issues under challenging deployment geometries, among others. This paper provides an update on the trials, giving an overview of their objectives and characteristics, some aspects that have been covered, and some early results and observations.
Receiver-based MAC (RB-MAC) is a preamblesampling MAC protocol for WSNs in which a receiver node is dynamically elected, among potential neighbors of the sender node, based on current channel conditions. In this paper, we evaluate the performance of RB-MAC and compare it with a senderbased preamble-sampling MAC protocol by using analytical methods, and implementation in real sensor nodes. We have used Configurable MAC (C-MAC), which is a framework to develop different MAC protocols in WSNs. This framework is realized as a component architecture that can produce application-specific communication protocols. The experimental results presented in the paper corroborate with the analytical and numerical results showing how RB-MAC outperforms sender-based MAC protocols in terms of transmission delay, and energy consumption.
In this study, the authors focus on utilising receiver-based MAC protocol (RB-MAC) and adaptive RB-MAC in routing protocol for low power and lossy wireless sensor networks routing protocol in low-power and lossy wireless channel. This results in a cross-layer approach in which routing decisions can be made based on MAC-layer functionalities. The authors study the effects of multiple receiver nodes, size of preamble and variable duty-cycle in number of retransmissions. Retransmissions increase energy consumptions and delay. Analytical and numerical results confirm that the RB-MAC and adaptive RB-MAC outperform the existing state-of-the art sender-based MAC protocols in terms of end-to-end energy-efficiency, reliability and delay. Simulation result demonstrates that using receiver-based MAC protocols in RPL-based lossy channel imply less retransmissions than sender-based MAC.
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