Small cells are coming, but where is the backhaul?

Lynnette LunaSmall-cell architecture is gaining some significant momentum during this week's Mobile World Congress. Once seen as somewhat of an afterthought, whereby operators go back and fill in their macro coverage later with picocells, small-cell architectures may very well be in the forefront of new LTE networks because they are capable of providing higher capacity, greater data throughput and indoor coverage.

The idea is to use multiple network layers--macro- and small-cell--to improve user data rates and network spectral efficiency. It's a story about bringing users closer to a cell site. The bigger the cell site, the less capacity available per user. Hence, the heavy focus this week on carrier-grade Wi-Fi solutions that allow users to seamless move between Wi-Fi and the macro network. Femtocells and picocells are still envisioned and used to offload heavy data traffic and provide better in-building coverage.

One of the more radical approaches is Alcatel-Lucent's (NASDAQ: ALU) lightRadio concept that breaks down a base station into its component elements and then distributes them into both the antenna and throughout a cloud-like network. In addition, antennas serving 2G, 3G, and LTE systems are combined and shrunken into a single multi-frequency, multi-standard wideband active array antenna that can be mounted on poles, sides of buildings or anywhere else there is power and a broadband connection.

In short, the company aims to bring together technology that enables macros cells to be distributed along with small cells. Other vendors are working on similar products.

A recent report released today by Mobile Experts predicts a 3000 percent increase in small-cell deployment for mobile data networks.

"The good old days of Tower and Power are ending," said Joe Madden, principal analyst. "Mobile data has moved indoors, and the network is moving indoors as a result. We will see dramatic growth in femtocells, picocells, and DAS networks, as well as ongoing strength in microcells and repeaters. Relays will also be entering the market, adding a new dimension to the HetNet."

But let's get real. Won't small-cell architectures become the next backhaul headache? The notion of backhauling traffic coming from a large cluster of  small-cell nodes will skyrocket backhaul costs if there is little innovation on the backhaul side. I foresee lots of backhaul aggregation techniques that need to come into play.

Interestingly, Vodafone is demonstrating the concept of using LTE TDD technology to backhaul an LTE small cell. The equipment operates in 2.6GHz spectrum and reaches 60 Mbps on the downlink and up to 25 Mbps on the uplink.

Last summer, wireleline and wireless switching vendor Taqua announced it was branching out into the wireless backhaul market by proposing a new platform that can be used in new cellular topologies that that may include picocells, outdoor femtocells and WiFi hotspots. Rather than replacing the backhaul network, the platform would function as a last-mile extension for backhaul linking up remote sites.

Still, we could use some guidance from the backhaul giants in the market about how to keep small cells from becoming the next data traffic nightmare.--Lynnette

P.S. We'll be observing President's Day and won't be publishing Monday.

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