Most rural areas in developing countries are isolated due to the lack of appropriate low-cost communication technologies. Previous experiences have shown that IEEE 802.11 can be used for the deployment of large static mesh networks with only minor changes to the MAC layer that enable WiFi transceivers to work properly even for very long distances (up to 100 km in point to point links, and almost 40 km in point to multipoint setups). However, the impact of distance on performance of such long links has not been deeply analyzed. In addition, previous analytical models of IEEE 802.11 DCF cannot be applied because they implicitly assume that the propagation time can be neglected. This paper formally studies the impact of the distance on the behavior of IEEE 802.11 DCF and presents an analytical model of IEEE 802.11 DCF that accounts for distances correctly. The model is validated with simulations and within a controlled experimental framework, based on wireless channel emulation. Finally, we propose adjustments for ACKT imeout, CT ST imeout, SlotT ime, and CW min parameters that improve significantly the performance of DCF over long distances.
The computing for development community knows that technology interventions involve consideration of social, technical and environmental factors. Research into WiFi solutions has fallen off as ubiquitous mobile solutions penetrate even the deepest rural communities worldwide. This paper argues that the latest wave of WiFi mesh networks offers benefits that traditional top-down WiFi and mobile networks do not. In addition, we propose ethnographic and participatory methods to aid the effective rollout of mesh inverse infrastructure with and for a given community. This paper describes and then analyzes a mesh for voice rollout within a situated context. We explain how to conduct informed community co-design and how to factor in local socio-political concerns that can impact on the design, rollout and subsequent maintenance of community-based wireless mesh networks. While we have not yet analyzed baseline and initial usage data, we do have new lessons to offer.
A systematic review of telemedicine projects in Colombia was conducted. We searched electronic databases, and also searched for relevant Internet websites. Each project manager was contacted by telephone to identify projects which had not actually been carried out. They were interviewed to request information about the projects they were managing, and whether they knew of other projects in Colombia. The search process identified 43 different projects, which were classified into two groups: telemedicine research initiatives and projects for providing health-care services via telemedicine. There were 32 projects which provided telemedicine services, of which 14 had been finished, 11 remained active, 4 were being implemented and no data were available about the state of the other 3. Health-care services had been provided using telemedicine to at least 550,000 patients. The projects had connected more than 650 health-care institutions, mainly in deprived areas of the country. Unfortunately, although many projects seem to have had a positive effect, none of them had been rigorously evaluated, and therefore in the absence of scientific evidence no general recommendations can be made. However, the methodology of the present study appears suitable for similar reviews of telemedicine in other developing countries.
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