# A Decision Framework for Choosing Telecommunication Technologies in Limited-Resource Settings
## 3 A Decision Framework
### Background on Telecommunication Technologies  
It is important to keep in mind that different telecommunication technologies could be divided into two groups, commercial and non-commercial technologies, and then within each case, the technology could be operating in regulated or unregulated frequency spectrum, as shown in Figure 3.  
To be more precise regulated and unregulated frequencies will be defined. Industrial, Scientific, and Medical radio bands (ISM) are unregulated in accordance to the United Nations agreement almost everywhere in the world. ISM operates in two frequencies: 2.4 and 5.8 GHz. On the other hand, TV White Spaces (TVWS) are defined (slightly differently in different places) to range from 54 MHz to 798 MHz (depending on the country). TVWS is almost completely regulated in most places around the world, and only ISM is unregulated everywhere by the UN agreement. TVWS does not overlap with ISM anywhere. Some slices of TVWS in some places may be unregulated, but not because of the UN agreement. If a slice of TVWS band is unregulated in one country, there is no reason to expect that the slice will be unregulated anywhere else.  
Often Wi-Fi transmission has been chosen as a low-cost, long-distance access technology to bridge the digital divide. However, the important issue of planning such networks involves several sets of variables: the network topology, tower heights, antenna types to be used and the orientations, and radio transmit powers [29]. The original 802.11b standard gave rise to the now ubiquitous Wi-Fi router. Wi-Fi routers can be used inside or outside, but generally radiate and receive omni-directionally. Hence, high gain antennas applied to Wi-Fi transceivers give rise to Wi-Fi Long Distance technology. The idea of long-range Wi-Fi is simple. The power necessary for a 100 m broadcast translates to a 40 km station to station hop. A long-distance point-to-point link can then be affected by including two directional dish antennas per station in a chain of point-to-point stations spaced by less than 40 km.  
There are numerous applications of WiLD technology, for example, mobile water sending with WiLD [30; 31; 32]. In addition, sustainable and successful WiLD networks have been implemented in the mountain areas of Nepal by the Nepal Wireless Networking Project [33; 34], as well as the jungle areas of India [28; 35] for treatment of eye disorders in rural populations.  
TVWS uses bandwidth in the high-frequency spectrum (from 50 MHz to 700 MHz in the US and Canada, from 470 to 790 in Europe, while in other areas it varies according to national regulations [6]) that has previously been employed in analog television transmission. TVWS is a much lower information bandwidth than WiLDNet because of the lower frequency that also allows the waves to penetrate some amount of foliage. Microwaves above 1 GHz do not penetrate even individual leaves that are often of quarter-wavelength (resonant) dimension. There are commercial producers of white space solutions, although the cost is still quite high per bandwidth compared to other solutions. The regulatory situation for white space is complex. In most places, the spectrum is licensed, although the rules, fees, and power levels differ greatly from country to country. There are industry groups such as the Dynamic Spectrum Alliance (DSA) that promote regulatory changes on a country  
Figure 3: Telecommunications technologies.  
by country basis, as well as for international pronouncements by such groups by the International Telecommunications Union (ITU). In this respect, TVWS option has not yet been fully researched.  
In relations to the proposed model, WiLD is a good choice in low population densities with or without rugged terrains, as long as there is a line of sight. TVWS could be a good choice in case of high population densities without a carrier.