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Africa’s ICT Infrastructure
Backbone Network Infrastructure As the number of broadband subscribers increases, so does the amount of traffic being carried on the networks; operators therefore need to invest in the core infrastructure that carries the traffic. Operators have traditionally used fixed networks of copper and, more recently, fiber-optic cable for broadband. Mobile operators in Africa, however, typically use wireless technologies exclusively (Williams 2010). Although wireless backbone networks can be built quickly and relatively inexpensively, they are adequate for only low traffic volumes. Fiber-optic backbones can carry much greater volumes of traffic but are more expensive to build. Still, as traffic increases, the average cost of transporting that traffic falls quickly so that, once a certain volume is reached, fiber-optic networks become more cost efficient than wireless networks. On any route, the traffic volume and the geographic distance that communications traffic must travel are the most important determinants of which technology will be used. For example, fiber-optic links are installed on high-traffic routes, whereas links carrying lower volumes of traffic often remain wireless. A basic rule for guiding technology selection is given in table 2.1. Once a certain traffic level is reached, fiber-optic cable becomes the most cost-effective type of communications infrastructure. This is particularly important to keep in mind when considering the ability of Africa’s telecommunications infrastructure to provide broadband Internet services. Because these services generate much larger volumes of traffic than voice services (figure 2.24), the extent of a country’s fiber-optic infrastructure can become a limiting factor on its ability to deliver highbandwidth services to customers. The recent growth of broadband services in Africa has stimulated investment in fiber-optic backbone infrastructure, even by operators that previously had entirely wireless-based networks. Fiber-optic backbone
Table 2.1 Choice of Broadband Backbone Technology Based on Traffic Volume and Distance Traveled
Distance <100 km >100 km
<8 Mbps Satellite/microwave Satellite
Source: Williams 2010. Note: Mbps = megabits per second.
Capacity 8–450 Mbps Microwave Microwave/fiber optic
>450 Mbps Fiber optic Fiber optic