CHICAGO—When Sprint launches its Xohm network in the Windy City, it won’t be the first WiMAX carrier in Chicago. Towerstream has been offering fixed WiMAX services to businesses in downtown Chicago for some time and now has started offering mobile WiMAX.

Jeff Thompson, Towerstream’s CEO, said the overlay of mobile WiMAX on the carrier’s fixed network in Chicago doesn’t represent a change in strategy. Instead, it’s being done to take advantage of economies of scale.

Towerstream provides the customer premises equipment for its enterprise customers, which costs $400-to-$500 for the fixed equipment. Because mobile WiMAX, which is being launched globally by many carriers, will have a larger vendor ecosystem the costs will go down, he said.

Half of Towerstream’s capital spending is for devices, so when CPE costs decline below $100 it will have a major impact.

Using mobile WiMAX in the future also will make it possible to have roaming agreements and also will enable the use of 3.5 GHz spectrum in the future. Mobile WiMAX in the United States is now focused on 2.5 GHz with Xohm’s launch but will have the additional band in the future, he said. Mobile WiMAX technology also has better network performance, Thompson said, including non-line-of-site capabilities.

Towerstream doesn’t see Xohm as a competitor, Thompson said, because his business plan is to offer fixed service to enterprises and Xohm is aiming mainly at consumers. Towerstream has about 1,100 customers but ARPU is in the range of $1,000 a month.

Towerstream is using Alvarion’s BreezeMAX 3650 equipment for its mobile WiMAX overlay in Chicago.