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As the 4G road forks, Clearwire chooses both paths

Clearwire commits to building a new LTE network rivaling any of its competitors, but plans to keep its WiMAX network running

No more hints. No more evasive answers. No more caveats. Clearwire is deploying long-term evolution (LTE) networks. Today on its earnings call, Clearwire said it would launch a Time Division-LTE network concurrent with WiMAX, using its vast reserves of 2.5 GHz spectrum and its current infrastructure to offer both 4G services simultaneously. The only question is when Clearwire starts its build-out as it still doesn’t have the cash to build any new networks, WiMax or LTE.

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Though Clearwire’s new commitment to LTE didn’t come as surprise, it was a bit of a shock when Clearwire revealed it would build the network itself—without the help of Sprint and its new Network Vision infrastructure. Sprint’s new technology-agnostic architecture will allow it to run multiple radio networks at different frequencies on the same equipment (CP: Sprint lays out vague path to LTE with $5B network modernization). Clearwire had been in discussions with Sprint about using Network Vision to host its future 4G networks (CP: Clearwire hints at LTE build with Sprint), but interim CEO John Stanton said that after investigating both scenarios Clearwire discovered it would be cheaper to overlay LTE on its own WiMAX infrastructure.

“It’s so inexpensive to add another technology to our equipment, it represents a significant economic advantage,” Stanton said. “Sprint is effectively buying new boxes. We’re using our existing boxes.”

Clearwire estimates adding LTE carriers to its Motorola (now Nokia Siemens Networks), Samsung and Huawei base stations in its most heavily trafficked markets will require a $600 million investment, a fraction of what it cost to deploy WiMAX. What’s more Clearwire can complete the upgrade within a year of its start.

Clearwire didn’t offer many details on how big its initial rollout will be, but it did say it would focus on the markets where it’s experiencing the biggest WiMAX demand, which would include 35 of the largest U.S. cities. Clearwire’s network today covers 132 million people in 71 markets, so even a complete LTE overlay would leave a substantial portion of the country uncovered. After Clearwire uses up its existing infrastructure, it would revisit a network hosting deal with Sprint, as any new market expansion would require Clearwire to build completely new networks.

Of course, these timelines are all hypothetical since Clearwire has no launch date yet for the new network. First, Clearwire needs to raise cash from investors. It has the funds to continue operating but it does not have the at-hand funds to expand or build a new network. The operator, however, has plenty of existing WiMAX capacity to offer its customers and resale partners, giving it several quarters of breathing room, Stanton said.

Clearwire is also breaking from other U.S. operators by deploying a time division duplexing (TDD) network, which blends the uplink and downlink into a single channel. Verizon, AT&T and MetroPCS all use frequency division duplexing, which splits the uplink and downlink into separate channels. Stanton said the configuration gives Clearwire a more efficient network allowing it allocated bandwidth between the uplink and downlink dynamically. It also matches the TDD configuration it uses for WiMAX. The question is whether Clearwire can get devices that run on such a configuration. Stanton said.

Clearwire is not worried. Operators and Asia and Europe are deploying TD-LTE networks creating a global ecosystem. “We would expect that LTE devices will be both TDD and FDD capable within a year or more,” he said.
The size of that TDD network could be considerable. Clearwire has as much as 100 MHz of spectrum in reserve in many of its markets, and it’s primarily contiguous spectrum. Using LTE-Advanced aggregation techniques, it could deploy carriers five to ten time the size of the 10 MHz WiMAX carriers it uses today. Clearwire has already done LTE-Advanced trials demonstrating speeds over 120 Mb/s.

Clearwire added 1.54 million new WiMAX subscribers in Q2, though all but 39,000 were wholesale subscribers—and given Sprint’s activation of 1.7 million WiMAX devices in Q2, all from its primary investor and wholesale partner.

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© 2014 Penton Media Inc.

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