TerreStar pursues a satellite/3G hybrid.

The latest UMTS entrant in North America isn't your typical operator. Satellite broadband provider TerreStar Networks has contracted with Nokia Siemens to build a terrestrial 3G network using its Internet high-speed packet access technology. The result will be a network that covers every inch of Canada and the U.S., relying on the pervasive S-band satellite connection to provide blanket coverage and the HSPA network to fill in downtown zones and add capacity in high-demand areas.

“We don't have to deal with all of the highways and byways that cellular carriers have to build because we have the satellite component,” said Dennis Matheson, chief technology officer for TerreStar. “But satellites can't get to the mass consumer because they disappear into urban canyons. So we need the HSPA network to fill in the gaps.”

Nokia Siemens's all-IP I-HSPA architecture cuts out the legacy core and edge elements of a typical UMTS deployment, creating a flat-IP access network linked directly to the Internet. Linking the terrestrial and the orbital components will be an IP multimedia subsystem architecture built over an IP core. The I-HSPA platform discards traditional voice services, but TerreStar plans to offer voice-over-IP services that traverse both satellite and cellular networks. While there will be some issue with latency over the satellite component, Matheson said TerreStar is counting on the universal coverage benefits of the network to offset any concern about the network's natural delay. And if a customer is using voice or any other data service heavily in a particular location, TerreStar can meet its needs with strategic base station deployments, Matheson said.

“If there's a lot of traffic, we can always just drop a UMTS base station in to relieve the satellite in specific locations,” he said.

The network goes live next year, when TerreStar plans to launch its satellite into orbit and Nokia Siemens begins construction of the terrestrial component. Where that terrestrial component will be still hasn't been determined. Matheson said the HSPA rollout will be shaped by where its customers need coverage. Enterprise customers might dictate HSPA coverage throughout corporate headquarters and branch offices, while a government customer might need an entire downtown area augmented by 3G, Matheson said.

For Nokia Siemens, the TerreStar win is its first contract for the technology unveiled two years ago at CTIA Wireless' spring show. Nokia Siemens has marketed the technology concurrently with its WiMAX platform, which also is built on a flat, data-centric IP framework. While the two technologies may seem at odds, Mark Slater, vice president of sales and marketing for Nokia Siemens North America, said that both actually fall into very distinct business cases, depending on the assets and spectral holdings of a carrier.

“If you hold 2.5 GHz spectrum, that's an extremely good starting point to get into the broadband wireless business using market,” Slater said. “If you have UMTS spectrum or are a UMTS operator, it makes sense to stick with the 3GPP standards. If you're a virgin operator with new spectrum, well, your choice depends on what kind of operator you'd like to be.”

TerreStar falls into the virgin operator with virgin spectrum (2 GHz) category. So what kind of operator does TerreStar want to be? “We decided it was best to go with the next-generation UMTS architecture and upgrade later to [long term evolution],” Matheson said. “We're a start-up company that can't sway the big R&D budgets of the big players. So we have to ride the coattails of others' R&D budgets. UMTS simply has more dollars behind it now.”