Abstract
The discovery of neighbouring active nodes is one of the most challenging problems in asynchronous ad hoc networks. Since time synchronization is extremely costly in these networks, application of asynchronous methods like quorum-based protocols have attracted increased interest for their suitability. This is because Quorum-based protocols can guarantee that two nodes with differing clock times have an intersection within at least one timeslot. A higher neighbour discovery rate of active nodes is desired, but it also results in a higher active ratio and consequently and adversely more overall power consumption of the nodes and a shorter network lifetime. There must be a trade-off between extensive neighbour discovery and active ratio in order to design high-performance and efficient protocols. In this paper, two novel asynchronous quorum-based protocols to maximize the neighbour discovery and minimize the active ratio have been designed and presented. A new metric (Quorum Efficiency Ratio: QER) has also been designed to evaluate and compare the performance of quorum-based protocols in terms of their neighbour discovery (the Expected Quorum Overlap Size: EQOS) and the active ratio. The EQOS has been theoretically derived, along with the Active Ratio and the QER values for the proposed novel protocols and the other contemporary protocols. Finally, the proposed methods have been evaluated and compared against the other methods based on the current metrics and the new metric.
Highlights
Literally billions of remote and ambient standalone networked sensors are used to monitor our surrounding environment
A new metric to evaluate the performance of the quorum systems in terms of the active ratio and neighbour www.aetic.theiaer.org discovery is proposed which includes carrying out a comparison of all the mentioned methods based on this new metric
The results show that the Adaptive Stepped Grid (AS-Grid)(3 × w) and LPS-Grid(3 × w) have better Expected Quorum Overlap Size (EQOS) than other quorum-based protocols and have better neighbour discovery than the other methods
Summary
Literally billions of remote and ambient standalone networked sensors are used to monitor our surrounding environment. Given the challenging design and development of quorum time slots in quorum-based protocols, the available methods currently suffer from limitations such as: poor neighbour discovery; high Active Ratio; working only with fixed array size; using the same quorum size for all the different nodes (nonadaptive methods) and a high end-to-end latency. Two new quorum-based protocols are proposed, the ‘Adaptive Stepped-Grid’ (ASGrid), for minimising the delay and maximising the neighbour discovery and the ‘Low Power Stepped-Grid’ (LPS-Grid), for minimising the active ratio and maximising the network lifetime for asynchronous ad hoc networks and wireless sensor networks (WSNs). Two new quorum systems have been devised that have comparably high EQOS than the grid, cyclic, torus, etorus and FPP protocols Another merit of these two protocols is that unlike the existing quorum-based protocols, these two protocols are flexible in handling the system size and works with any array size.
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