September 12, 2014 · Wireless · Jeff C. Adams
Wireless Data Demand Predictions
"The wireless capacity has doubled every 30 months over the last 104 years1. This translates into an approximately million-fold capacity increase since 1957. Analyzing these gains shows a 25× improvement from wider spectrum, a 5× improvement by dividing the spectrum into smaller slices, a 5× improvement by designing better modulation schemes, and a whopping 1600× gain through reduced cell sizes and transmit distance. The enormous gains reaped as a result of smaller cell sizes arise from efficient spatial reuse of spectrum, or alternatively, a higher area spectral efficiency measured in bits per second per hertz per unit area"2.
Take-away
The vast majority of historical gains in data capacity have come from reducing or confining coverage size and transmit distance. This is driven by physics — there is a limit to how many bits/Hz can be squeezed out of a single wireless stream (Shannon's Law). The best way to increase capacity is to increase the density of access points. Combined with the fact that 70% of all cell-phone sessions begin and end in a building3, and that the greatest capacity gains have been demonstrated for indoor cellular deployments overlaid within conventional macro cells, this supports the strategic use of in-building DAS and heterogeneous networks to meet exponentially increasing data demands.