Thinking LTE? Think Distributed

If there's one message about Long Term Evolution (LTE) to understand from the rash of wireless events recently, it's that it will be the most distributed wide-area network technology yet to be deployed.

The reason for this is simple: A deployment using multiple smaller cells -- rather than large but isolated cell sites -- will put more radios closer to users and help keep data speeds fast and consistent.

Verizon Wireless is the first major carrier in the U.S. to come to grips with the distributed approach to LTE. Verizon Wireless CTO Tony Melone said at the PCIA Wireless Infrastructure show yesterday that Verizon wants to use distributed antennas in areas like airports and arenas, and Picocell units in high traffic spots in the network. (See Verizon: This Is How We'll Do It.) Talking to Unstrung at the 4G World show last week, Doug Wolff, VP of LTE product management for Alcatel-Lucent (NYSE: ALU), said his company is finalizing its 700MHz LTE base station for Verizon's networking and looking at picocells and femtocells.

"We’re probably one rev away from final product on the software side," Wolff said of the base station. The company is "currently mapping" smaller cell designs for the technology, he added.

Of course, Verizon hasn't yet said whether it will use existing suppliers or new vendors for pico or femtocells. It is clear, however, that all infrastructure vendors will have to think smaller as more LTE deployments happen in the next few years.

In fact, femtocell vendors are already thinking LTE, even though 3G home base stations are only just starting to get launched. Femto chip vendor Picochip 's VP of marketing, Rupert Baines, explains why this is so in a recent video interview with Unstrung.

A distributed approach is not just going to apply to the radio access edge of LTE, but will be also be applied much deeper in the network. One of the points of consensus on the LTE backhaul panel at Light Reading's Backhaul Strategies for Mobile Operators event yesterday was that operators will be looking at a much more distributed evolved packet core (EPC) architecture as LTE networks grow.

EPC hardware and software are central parts of the LTE core network. LTE is an all-IP network with all the packet data flowing through a big pipe. A carrier needs to use EPC technology in the back of the network to manage all the different types of data calls (be it VoIP, video, or Internet browsing) coming in from mobile devices.

"The EPC will be more distributed than it is today," said Rajesh Chundury, solutions manager for broadband networks at Ericsson AB (Nasdaq: ERIC). He expects carriers to move from 6-to-10 EPC-related boxes today to "hundreds" of boxes in the LTE networks of the future.

Heavy Reading senior analyst Patrick Donegan also anticipates a more distributed future in the LTE core. "Clearly that's where it is going... We're already seeing that in Clearwire." WiMax networks also use an EPC architecture, he notes.

It shouldn't be anticipated, however, that all carriers will move to an extremely distributed approach with the LTE core straight away, because they have to make the technology work with their existing network or networks.

"There's not a cookie-cutter approach," Donegan says.

— Dan Jones, Site Editor, Unstrung