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Abstract:The authors propose three variants of distributed and stateless forwarding strategies for wireless sensor networks, namely greedy minimum energy consumption forwarding protocol (GMFP), lifetime maximising GMFP (LM-GMFP) and variance minimising GMFP (VAR-GMFP), which aim at maximising the network lifetime while achieving a high forwarding success rate. GMFP selects a forwarding node that minimises per-packet energy consumption while maximising the forwarding progress. LM-GMFP extends the GMFP algorithm by also taking into account the remaining energy at the prospective one-hop forwarding nodes. In VAR-GMFP, on the other hand, the packet is forwarded to the next node that ensures a locally high mean and low variance of nodal remaining energy. Through simple probabilistic analysis the authors prove the intuition behind the optimum forwarding node selection for network lifetime maximisation. They then model the lifetime maximisation of a sensor network as an optimisation problem and compare the practical protocol-dependent network lifetime with the theoretical upper bound. Through extensive simulations the author demonstrate that the proposed protocols outperform the existing energy-aware protocols in terms of network lifetime and end-to-end delay.

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Energy Harvesting (EHV) circuits are developed as an alternative solution to supply energy to autonomous sensor nodes in Wireless Sensor Networks (WSN). In this context, this paper presents a micro-power management system for multi energy sources based on a novel design of charge pump circuit (CPC) to allow the total autonomy of self-powered sensors. This work proposes a low-voltage and high performance charge pump suitable for implementation in standard CMOS technologies. The charge pump (CP) design was implemented using Cadence Virtuoso with AMS 0.35μm CMOS technology parameters. Its active area is 0.112mm². Consistent results were obtained between the measured findings of the chip testing and the simulation results. The circuit can operate with an 800 mV supply and generate a boosted output voltage of 2.835V with 1MHz as frequency.Index terms-Wireless Sensor Networks (WSN); Energy harvesting (EHV); micro-power management system; charge pump circuit (CPC).