Abstract

Coverage-preserving and energy-saving solutions have been reported in the literature and are generally based upon both quality coverage and off-duty scheme. Off-duty scheme based solutions present at least three challenging problems: (1) keeping coverage and connectivity of the network while optimizing the number of active sensor nodes; (2) resolving conflicts when determining which nodes should be turned off in order to save energy; and (3) finding optimal wake-up strategies that avoid waking up more nodes than necessary. This paper presents a novel distributed solution, the optimal coverage-preserving scheme (OCoPS), that extends the well-known Central Angle Method in order to identify fully sponsored nodes. OCoPS comprises an extended Central Angle Method, new decision algorithms devised to resolve the off-duty conflict problem under different network densities, and an energy-aware wake-up scheme that solves coverage hole problems in off-duty schemes. Compared to the widely used node scheduling scheme, our solution is based on local information exchange without the uncertainty of self-schedule algorithms. OCoPS is implemented as an extension of LEACH. A set of simulation experiments is carried out to evaluate its performance compared to other well-known schemes which are based on the Central Angle Method and self-scheduling. Our results indicate that on network lifetime OCoPS outperforms other schemes by over 20% and by over 25% when the coverage rate is higher than 80%. The experimental results also show that our coverage scheme effectively limits the number of on-duty node compared to the other schemes.

Keywords: Coverage; Wireless sensor network; Energy

Article Outline

1. Introduction

2. Related work

3. OCoPS: an optimal coverage-preserving scheme

3.1. Basic definitions for coverage

3.2. The extended Central Angle Method

3.3. The decision algorithms

3.3.1. The off-duty election algorithm

3.3.2. On-duty election algorithm

3.3.3. Alternate election algorithm

3.4. The wake-up strategy

3.4.1. The off-duty sensors should take over the sensing area of the dead sensor (a sensor that has run out of energy) as soon as possible in order to avoid coverage holes

3.4.2. The wake-up strategy should wake up as few necessary off-duty sensors as possible

3.4.3. The wake-up strategy should not be overly costly in terms of energy

4. Energy cost comparison of OCoPS and C-PNSS

5. Performance evaluation and simulation experiments

5.1. The simulation environment

5.2. Simulation results

6. Conclusion

Acknowledgements

References

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