| 1. |
- Byamukama, Maximus, et al.
(författare)
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Design Guidelines for Ultra-low Power Gateways in Environment Monitoring Wireless Sensor Networks
- 2017
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Ingår i: 2017 IEEE AFRICON. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781538627754 ; , s. 1472-1478
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Konferensbidrag (refereegranskat)abstract
- We explore techniques that can be used to reduce the power consumption of gateways in wireless sensor networks deployed in environment monitoring applications, such as Automatic Weather Stations (AWS). The challenge is the deployment of these networks in locations that are far from a consistent power source, such as a national grid. Such stations must be autonomous and power consumption must be minimized. We present test scenarios illustrating the impact of the suggested techniques. We explore hardware and software based methods of power reduction, assess the impact of each, the constraints to be expected and how to overcome them. We then provide a reference implementation of a gateway in which we integrate these techniques. We show that power consumption can be reduced by 48 - 85% when comparing best and worst case scenarios. The reference implementation we provide consumes 27mW at 3V.
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| 2. |
- Byamukama, Maximus, et al.
(författare)
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Energy Storage Options for Environment Monitoring Wireless Sensor Networks in Rural Africa
- 2018
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Ingår i: Proceedings - 2018 IEEE 12th International Conference on Compatibility, Power Electronics and Power Engineering, CPE-POWERENG 2018. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781538625088
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Konferensbidrag (refereegranskat)abstract
- This paper explores various traditional and emerging battery technologies available for deployments of automated environment monitoring devices using Wireless Sensor Networks (WSNs) in Africa and the considerations designers must take into account when implementing these systems. Environment-monitoring applications of WSNs are focusing more on reducing power consumption and optimizing data transmission and less on the constraints that their applications and deployment environments put on the energy storage device. We describe the various properties of energy storage devices and, for each, we highlight the requirements to be met for environment monitoring applications, especially in remote areas in Africa. We evaluate the performance of some of these energy storage options against the requirements using three use cases. We indicate the technologies that have shown reliability for each use case. We show that emerging battery technologies, such as Lithium Ion Capacitors are well suited for long-life low power deployments while the options for high-power deployments depend on the constraints faced by the designers, such as the power consumption of the sensor network components sand environment temperature range of the deployment environment.
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| 3. |
- Nungu, Amos, et al.
(författare)
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Design and Implementation of an Inclusive Ubiquitous Access
- 2012
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Ingår i: Wireless personal communications. - : Springer Science and Business Media LLC. - 0929-6212 .- 1572-834X. ; 67:1, s. 79-94
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Tidskriftsartikel (refereegranskat)abstract
- The development towards ubiquitous network access requires innovative solutions to get remote areas included, especially rural areas of developing regions. The challenges include robustness of network components, poor or non-existent power supply and sustainable business models. We argue that large scale user-driven community networks are becoming technically viable to deploy in areas that are short of supply of telecommunication services due to little or no commercial interest. To support this claim, we discuss the design of key network elements and careful power management based on alternative energy sources and storage. We also provide a status report from ongoing field-tests regarding provisioning of broadband network services in Serengeti, Tanzania, and outline briefly our strategy to achieve sustainability. On the technical side, we first discuss an affordable, high-performance, low-effect router based on open source software and standard off-the-shelf hardware offering both copper and fibre links. Our design is capable of forwarding more than 700 kpps at 22.3 W. The power consumption is considerably less than all alternatives in our comparison. Then we discuss power management and the use of batteries and super-capacitors as backup and storage solutions.
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| 4. |
- Nungu, Amos, et al.
(författare)
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Inclusive ubiquitous access - A status report
- 2015
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Ingår i: 6th International Conference on e-Infrastructure and e-Services for Developing Countries, AFRICOMM 2014. - Cham : Springer Publishing Company. - 9783319168852 ; , s. 13-22
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Konferensbidrag (refereegranskat)abstract
- The development towards ubiquitous network access requires innovative solutions to get remote areas included, especially rural areas of developing regions. We report on recent progress in the Serengeti Broadband Network, one of the first pilots established in the Tanzania ICT for Rural Development programme with the mission to design and validate a method to establish sustainable broadband markets in under-served areas. The challenges include ownership and leadership, sustainable business models, robustness of network components and poor or non-existent supply chains, including power supply.
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| 5. |
- Nungu, Amos, 1975-, et al.
(författare)
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On Powering Communication Networks in Developing Regions
- 2011
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Ingår i: Computers and Communications (ISCC), 2011 IEEE Symposium on. - Kerkyra, Greece : IEEE. - 9781457706806 - 9781457706783 ; , s. 383-390
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Konferensbidrag (refereegranskat)abstract
- The work behind this paper aims at demonstrat-ing innovative solutions for the establishment of sustainablecommunity broadband networks in areas where there is de-mand but no supply of broadband services. One of the majorchallenges turns out to be reliable power supply. To overcomethis challenge, we explore how to decrease the demand forpower as well as the feasibility of using alternative powersources, such as solar and wind, and alternative power storagetechnologies, such as batteries and ultra-capacitors.In this paper, we present data collected over 2 months fromthe Serengeti community network in rural Tanzania to discussthe quality of the existing power-grid and the feasibility ofusing solar and wind energy as alternative energy sources.The network backbone is based on 1Gbps Ethernet links overdark fibre while end-user connections are currently based onWiFi links.Our measurements regarding the quality of the power-gridshow up to 21 power-outages in one single day, with an averageof 2 outages per day. Some of the outages are due to plannedrationing schemes caused by insufficient power generationwhile some outages are due to poor wiring or installations.Our measurements and analysis of the feasibility of usingalternative power sources indicate wind speeds on the average2m/s and a persistent high-level insolation, making solar energythe prime candidate as an alternative source of electricity. Therelatively high cost of solar panels has to be mitigated byincreased energy efficiency of the network elements. We alsopropose power management to be included in the networkmanagement system to maximize the availability of the net-work services and decrease operational costs due to damagednetwork elements.
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| 6. |
- Nungu, Amos, 1975-, et al.
(författare)
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On the design of inclusive ubiquitous access
- 2011
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Ingår i: ICUFN 2011 - 3rd International Conference on Ubiquitous and Future Networks. - Dalian, China : IEEE. - 9781457711763 ; , s. 346-352
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Konferensbidrag (refereegranskat)abstract
- The development towards ubiquitous network access requires innovative solutions to get remote areas included, especially rural areas of developing regions. The challenges include robustness of network components, poor or non-existent power supply and sustainable business models. We argue that large scale user-driven community networks are becoming technically viable to deploy in areas that are short of supply of telecommunication services due to little or no commercial interest. To support this claim, we discuss the design of key network elements and careful power management based on alternative energy sources and storage. We also provide a status report from ongoing field-tests regarding provisioning of broadband network services in Serengeti, Tanzania, and outline briefly our strategy to achieve sustainability. On the technical side, we first discuss an affordable, high-performance, low-effect router based on open source software and standard off-the-shelf hardware offering both copper and fibre links. Our design is capable of forwarding more than 700kpps at 22.3W. The power consumption is considerably less than all alternatives in our comparison. Then we discuss power management and the use of batteries and super-capacitors as backup and storage solutions.
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| 7. |
- Nungu, Amos, et al.
(författare)
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Short paper - On the design of affordable and green high-performance routers for community networks
- 2010
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Ingår i: Proceedings of the 4th ACM Workshop on Networked Systems for Developing Regions, NSDR '10. - New York, NY, USA : ACM. - 9781450301930 ; , s. 11-
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Konferensbidrag (refereegranskat)abstract
- We argue that large scale user-driven community networks are becoming viable in areas without access to telecommunication services due to lack of commercial interest. We discuss the design of a key component supporting this claim: a high-performance, low-power-consuming and affordable router with fibre optic capable of forwarding 2 Gbps, 220kpps, powered by only 25W, which is between 7% and 17% of the alternatives in our comparison. The cost of the one-off prototype was below a third of the prices of comparable proprietary solutions and half of other open source alternatives. It can be reduced further in series production. Future work will include widening of bottlenecks without increasing cost and field tests in rural African settings.
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| 8. |
- Olsson, Robert, et al.
(författare)
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Powering devices using ultra-capacitor batteries
- 2015
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Ingår i: PROCEEDINGS OF THE 2015 12TH IEEE AFRICON INTERNATIONAL CONFERENCE - GREEN INNOVATION FOR AFRICAN RENAISSANCE (AFRICON). - : IEEE conference proceedings. - 9781479974986
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Konferensbidrag (refereegranskat)abstract
- We explore the use of ultra-capacitors as backup storage for solar powered electronic devices. We discuss two use cases: routers in off-grid broadband networks consuming a few Watt and wireless sensor network nodes using a few mW when operating and a few mu W in quiescent mode. We have been testing batteries with ultra-capacitor based cells, both EDLC and LIC, in the range from 40 to 3000F. We found them viable alternatives in some applications and started long term field tests to sort out some unclear aspects regarding maximum discharge levels. Besides the traditional function of a backup battery storage in low-power applications, the very low internal resistance of capacitors make them useful also in hybrid solutions to accommodate transient needs for high currents that traditional batteries cannot deliver. Due to the low resistance, charging/discharging can be very fast. We also show how a very simple design requiring only one LIC capacitor can power a WSN mote sending at 1 packet/minute for 6 weeks on a single charge.
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| 9. |
- Tanyingyong, Voravit, et al.
(författare)
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Design and Implementation of an IoT-controlled DC-DC Converter
- 2013
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Ingår i: 2013 Sustainable Internet and ICT for Sustainability, SustainIT 2013. - : IEEE. - 9783901882562 ; , s. 6685199-
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Konferensbidrag (refereegranskat)abstract
- In line with the shift towards renewable energy, small-scale solar panels have become commonly available. Solar panels are intermittent energy sources producing direct current, and DC-DC converters are needed to convert between different voltage levels, both for different power loads and for storing energy. DC-DC converters typically have a very limited functionality and are statically configured for specific voltage levels. In this paper, we propose a new generation of flexible DC-DC converters with software and communication support (through Contiki and CoAP) for remote power monitoring and control. We present a prototype design and implementation of a DC-DC converter including a microprocessor, a lean operating system, and networking support. With such a DC-DC converter, controlled over the Internet, we can address various types of power and energy related issues and advance the state-of-the-art of green networked applications.
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