The Big Shift: Moving to LTE From WiMAX

If WiMAX is a fad — a short-term bridge on the path to LTE as the global fourth-generation wireless standard — how will operators move from one network technology to another? Russian WiMAX provider Yota said last week that it would stop deploying WiMAX networks and switch instead to LTE for the remainder of its buildout, and a few weeks before that Clearwire changed an agreement it had with its top investor, Intel, to make it easier for the U.S. operator to switch to an LTE network from WiMAX.

I’ve laid out the many similarities between WiMAX and LTE networks — for instance they both use the same underlying encoding scheme, while 3G rivals GSM and CDMA do not– and about 75 percent of the equipment they use is the same, meaning equipment vendors can offer dual-mode gear. As Susan Johnston, a Clearwire spokeswoman, explained to me via email:

Facilities such as core networks, wide-area network and backhaul are the same no matter which technology our network is using, WiMAX, LTE or both simultaneously. An LTE overlay of WiMAX would not require additional towers…The number of towers needed to support 4G services (be it WiMAX or LTE) is determined by capacity and not coverage. The CLEAR network is engineered to meet this criteria from Day 1 and coupled with our strong spectrum holdings, we are poised to deliver more 4G capacity than any other carrier in the U.S.

Clearwire has a lot of spectrum, so it could run two parallel networks, as some have suggested it should do — although such an endeavor would take dollars away from its marketing at a time when it’s racing to win customers in order to break even and beat Verizon’s LTE network. Plus, the LTE market is currently viewed by many is immature — among them Yota, which said that’s why it’s starting with WiMAX and then switching to LTE in the coming months.

Every Clearwire WiMAX device, be it a dongle, a personal hotspot, laptop, or simply a box that sits inside a customer’s home, would have to be replaced if Clearwire moved entirely to an LTE network because the radios inside them are tuned to WiMAX. However, Beceem, the chipmaker whose WiMAX radios are inside Clearwire’s current 4G devices, in February said it had designed a combo radio that will work with WiMAX and LTE networks. Having dual-mode devices and equipment means companies like Clearwire that do decide to make the transition have a bit more flexibility.

For Yota, Beceem’s chip will allow devices to run across the carrier’s mixed footprint. Lars Johnsson, VP of marketing and business development of Beceem, said he expects the chip to be in devices by the middle of next year. He added that it could also help a company that doesn’t have a lot of spectrum available for LTE to transition over the WiMAX network — T-Mobile is one candidate for such use.

However, as operators convene on LTE as the appropriate mobile broadband networking option, WiMAX may still have a place either as a fixed-wireless broadband product or even in networks in areas where LTE will be a long ways coming.

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