Lower the frequency to trigger digital inclusion? A comparative study among different VHF/UHF/SHF solutions for the implementation of broadband wireless access

In the last decades the most advantageous opportunity to improve data rate and transport capacity over wireless connections has been made available by a progressive upper-shift of the frequency of the carrier. As a matter of fact, increasing the carrier frequency, channel allocation and modulation bandwidth can be increased. Unfortunately, in parallel, path losses augment, and obstacles, humidity and weather affect more negatively radio-transmissions. To face propagation losses, the number of installations is increased and the service area reduced, allowing the frequency reuse, but generating also an exponential raise of hardware costs. As a consequence, this strategy is unsuitable in developing countries. Inverting the trend, this paper presents a study carried out by means of several simulations, to evaluate coverage opportunities and cost impact by reducing the radiofrequency carrier, without varying any base-band characteristic of the communication platform. To this purpose, as an application example, low cost IP-based wireless cards implementing OFDM modulation were considered, at progressively lower frequencies, from 5.5 GHz down to 180 MHz. The comparison was run in real contexts, and applied to the region of El Carmen, Guayas, in Ecuador and the region, of Antsirabe Rural, Antananarivo, in Madagascar. In the first one, a proper network will be implemented by the end of 2009, in the framework of the ldquoInnovation for Development Programrdquo of the InterAmerican Development Bank.