The adoption of Long Term Evolution (LTE) technology quickly eclipsed WiMAX's potential market hold. Yet WiMAX remained critical to the availability of wireless broadband service in many markets, ranging from emerging to developed countries and urban to rural environments. In the US, for example, Sprint recently confirmed that 20% of its network is running over WiMAX networks this year. Like the cellular carriers, however, most WiMAX operators plan to migrate to LTE. In a white paper titled, "A Smooth Transition from WiMAX to LTE with Dual-Mode Devices," Senza Fili Consulting offers suggestions on easing that transition for manufacturers of both infrastructure equipment and devices as well as network operators.

The 16-page paper highlights the fact that devices supporting both WiMAX and LTE provide many benefits. For instance, they offer increased flexibility in managing the timing of the operators' transition to LTE. They also lower funding requirements at the beginning of that transition, thanks to a more gradual deployment of LTE infrastructure. In addition, existing WiMAX network resources are used for a longer time and more efficiently. This approach also will ease the introduction of LTE devices, rather than creating an "LTE or nothing" situation. The firm estimates that this dual-mode approach will provide 4% cost savings over five years.

To ensure such a clean handover, however, operators need to develop a device migration strategy that complements the radio-access-network (RAN) transition. Several transition plans are examined: no overlay, fast transition, gradual transition, and long-term coexistence. Operators who choose no overlay, for example, most likely will be those with insufficient spectrum to support both WiMAX and LTE. The paper notes that this option is the most costly, disruptive, and prone to risk.

A total-cost-of-ownership (TCO) model is provided for single- and dual-mode devices, assuming a medium-sized WiMAX operator that has launched service over the past couple of years and plans to transition to LTE. Costs are then compared for the single- and dual-mode cases. The operator in a dual-mode case benefits from both a shift forward in cash flow and, overall, cumulative cost savings. The paper closes by exploring four additional scenarios for transition periods other than two years. The fast-switch scenario was found to be least affected by dual-mode devices. It also was concluded that shorter transition time necessitated a higher up-front investment.

Senza Fili Consulting, LLC, 602 216th Ave., NE, Sammamish, WA 98074; (425) 657-4991; FAX: (206) 350-5295; www.senzafiliconsulting.com.