As demand for mobile broadband services continues to explode, mobile wireless networks must expand greatly their capacities. This paper describes and quantifies the economic and technical challenges associated with deepening wireless networks to meet this growing demand. Methods of capacity expansion divide into three general categories: the deployment of more radio spectrum; more intensive geographic reuse of spectrum; and increasing the throughput capacity of each MHz of spectrum within a given geographic area. The paper describes these several basic methods to deepen mobile wireless capacity. It goes on to measure the contribution of each of these methods to historical capacity growth within U.S. networks. The paper then describes the capabilities of 4G LTE wireless technology, and further innovations off of it, to further improve network capacity. These capacity expansion capabilities of LTE-Advanced along with traditional spectrum reuse are quantified and compared to forecasts of future demand to evaluate the ability of U.S. networks to match future demand. Without significantly increasing current spectrum allocations by 560MHz over the 2014–2022 period, the presented model suggests that U.S. wireless capacity expansion will be inadequate to accommodate expected demand growth. This conclusion is in contrast to claims that the U.S. faces no spectrum shortage. 
Expanding mobile wireless capacity: The challenges presented by technology and economics