Microsoft’s TV white spaces “Airband” initiative occasionally is difficult to understand. In principle, it makes sense that access to low-cost or free spectrum that can be used in fixed mode to support rural internet access is intriguing.
What has been less clear are the merits of doing so (the business case) in a marketplace that has burgeoning alternatives, ranging from constellations of low earth orbit satellites to fixed and mobile 5G, to say nothing of more-exotic techniques (unmanned aerial vehicles, balloons), and also has established suppliers of fixed wireless access systems.
Perhaps one clue is that Microsoft believes it can improve Airband capacity to reach levels now provided by other fixed wireless access systems that use licensed spectrum, but provide much better propagation and a lower cost platform.
The expectation might then be that Airband might provide a better solution, compared to existing fixed wireless platforms, if it can use free spectrum and perhaps lower transmission and customer premises gear.
The issue is whether the effort to scale capacity can keep pace with bandwidth growth over time.
Mobile network cell sites using millimeter wave will need backhaul in urban locations up to 1 Gbps, up to 350 Mbps in suburban areas and up to 150 Mbps in rural areas, Ericsson predicts.
By 2025, urban sites will require backhaul up to 20 Gbps, suburban sites will need capacity up to 5 Gbps, while rural sites might need 600 Mbps.
Airband, to remain viable, would have to scale to match those capacity requirements over time, as would all other fixed wireless suppliers.
The clear advantage Airband would have is propagation distance. Today, microwave backhaul most is useful for short links, based on the frequencies used for such purposes. Longer backhaul links beyond 1,000 meters (.6 miles) routinely use optical fiber, though microwave remains an option, as this graph of backhaul in Germany might suggest.
That further capacity improvements will be needed, for all suppliers of microwave access systems, is clear.
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