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Using sleep states to maximize the active time of transient computing systems

Using sleep states to maximize the active time of transient computing systems
Using sleep states to maximize the active time of transient computing systems
Energy harvesters are widely used to power wireless sensor systems, but the produced power is generally low, and can vary abruptly due to changes in the environment or the device's location. Energy buffers (batteries or supercapacitors) are normally incorporated into systems to smooth out these variations. However, they have a limited lifetime and increase system size and cost. Transient computing aims to address these issues by removing the energy buffer, and powering the system directly from the energy harvester. Approaches such as Hibernus++ deal with the resultant power intermittency by 'hibernating', i.e. saving a snapshot of the system state to non-volatile memory before a power failure, and restoring it after the power recovers. The overheads of this can be particularly costly with a low-current harvester, as the system may wake up and hibernate at a high frequency, doing little useful work in each power cycle.

This paper proposes an enhancement to these approaches, providing an efficient method to avoid repeated hibernation. The introduction of a 'sleep' state, which is entered when the power supply is detected to be failing, allows the system's supply voltage to recover without taking a snapshot. Thus, the application can spend more time on useful work rather than checkpointing. If the supply voltage continues to decline, a snapshot will then be taken. The approach has been simulated and experimentally validated, with results demonstrating that the proposed scheme provides up to a 65% improvement in system active run-time with low-current harvesters vs. conventional Hibernus++.
ACM
Lukosevicius, Giedrius
c1c564cc-4539-4f4e-a950-b33b45b483c1
Rodriguez Arreola, Alberto
e20f97e9-b616-47de-9f37-f4a445e0adac
Weddell, Alexander
3d8c4d63-19b1-4072-a779-84d487fd6f03
Lukosevicius, Giedrius
c1c564cc-4539-4f4e-a950-b33b45b483c1
Rodriguez Arreola, Alberto
e20f97e9-b616-47de-9f37-f4a445e0adac
Weddell, Alexander
3d8c4d63-19b1-4072-a779-84d487fd6f03

Lukosevicius, Giedrius, Rodriguez Arreola, Alberto and Weddell, Alexander (2017) Using sleep states to maximize the active time of transient computing systems. In Proceedings of ENSsys’17. ACM. 6 pp . (In Press) (doi:10.1145/3142992.3142998).

Record type: Conference or Workshop Item (Paper)

Abstract

Energy harvesters are widely used to power wireless sensor systems, but the produced power is generally low, and can vary abruptly due to changes in the environment or the device's location. Energy buffers (batteries or supercapacitors) are normally incorporated into systems to smooth out these variations. However, they have a limited lifetime and increase system size and cost. Transient computing aims to address these issues by removing the energy buffer, and powering the system directly from the energy harvester. Approaches such as Hibernus++ deal with the resultant power intermittency by 'hibernating', i.e. saving a snapshot of the system state to non-volatile memory before a power failure, and restoring it after the power recovers. The overheads of this can be particularly costly with a low-current harvester, as the system may wake up and hibernate at a high frequency, doing little useful work in each power cycle.

This paper proposes an enhancement to these approaches, providing an efficient method to avoid repeated hibernation. The introduction of a 'sleep' state, which is entered when the power supply is detected to be failing, allows the system's supply voltage to recover without taking a snapshot. Thus, the application can spend more time on useful work rather than checkpointing. If the supply voltage continues to decline, a snapshot will then be taken. The approach has been simulated and experimentally validated, with results demonstrating that the proposed scheme provides up to a 65% improvement in system active run-time with low-current harvesters vs. conventional Hibernus++.

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enssys-combined-15 - Accepted Manuscript
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More information

Accepted/In Press date: 15 September 2017
Venue - Dates: 5th International Workshop on Energy Harvesting & Energy-Neutral Sensing Systems: ENSsys 2017, Netherlands, 2017-11-05 - 2017-11-08

Identifiers

Local EPrints ID: 415332
URI: http://eprints.soton.ac.uk/id/eprint/415332
PURE UUID: 74499bf6-c08d-4add-ba7e-c609e9193d60
ORCID for Alexander Weddell: ORCID iD orcid.org/0000-0002-6763-5460

Catalogue record

Date deposited: 07 Nov 2017 17:30
Last modified: 30 Jan 2020 01:34

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