Backhaul key as small cells enhance LTE performance, increase network complexity

While tower-based and rooftop-based macro cells continue to play a key role in delivering base-level LTE coverage, deploying small cells and indoor-building solutions is critical to ensure that users realize the kind of coverage and data speeds that they expect—and those small cells require adequate backhaul to meet this goal, according to speakers at the recent LTE North America conference in Dallas.

The number of small cells being deployed in major carrier network is expected to result in a tenfold increase in the total number of access points available to customers, according to Michael Freiberger, a senior network planner for Verizon.

“For the sake of argument, let’s say there are 30,000 macro towers in a [wireless carrier’s] network today,” Freiberger said during a conference session entitled “The Economies of Backhaul.” “The expectation is that, with the fill in that’s going to happen, that’s going to be more like 300,000. Think about 300,000 new access points in the network—that’s an order of magnitude and potentially higher.

“When you start looking at that scale, things become very clear. Things like repeatability, simplicity, cost—of course—and maintainability [matter]. Because, when you start looking at a network that large—not only the LTE radio side but just the backhaul complexity—that’s a very large, complex network.”

While small cells like micro cells, pico cells and distributed antenna systems (DAS) do not provide the large coverage footprint of a macro cell, they do provide the same capacity, which increases network efficiencies and lets users experience greater data throughputs via enhanced coverage.

For network operators, the biggest challenge is not deploying the small-cell access points but providing adequate backhaul from each of these small cells to enable maximum performance, according to Sue Rudd, director of service provider analysis for Strategy Analytics.

“The economics of the backhaul is turning out to be a more major expenditure than the RAN (radio access network),” Rudd said during the session. “I’ve worked with a couple of companies to increase their expenditure on the backhaul. We’ve seen it go up from 17% of total cost of operations to about 20%. The good news is that operators now are quarterly doing planning to upgrade the backhaul and mesh it with the wireless assets, so it has to be part of the traffic planning.

“It really is an important part of customer satisfaction. How many of you have had great bars [on a wireless device] and access to Wi-Fi, but you have no throughput to the Internet? That’s a Wi-Fi backhaul problem. All of these networks have to balance their backhaul connectivity.”

Freiberger echoed this sentiment.

“50% of all negative customer experiences are rooted in the backhaul, and we’re going to make that backhaul expand by a factor of 10,” Freiberger said. “If you look at video over LTE—and who knows what’s coming next—that’s going to be latency and jitter dependent, those new things are going to—and are currently—testing backhaul in ways it has never been tested before.”