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4G/3G/WiFi

Is Backhaul Bottlenecking Verizon's LTE?

Verizon Wireless 's backhaul strategy could be a reason why its LTE network did not perform as well as AT&T Inc. (NYSE: T)'s during a drive test in one U.S. market, according to Signals Research Group.

A Verizon press officer, however, disputes the suggestion that it is presently throttling back on the backhaul connections, which link the radio network to the wired Internet, for its new 4G network.

After conducting drive tests of mobile broadband networks in the U.S., Signals Research Group has produced further analysis of LTE network performance in a new installment of its report series, "The Mother of All Network Benchmark Tests."

As Light Reading Mobile previously reported, Signals Research Group found that in Houston AT&T's LTE network was markedly better than Verizon's on data throughput and that the difference in performance showed, more than anything else, just how immature LTE technology is today, rather than any fundamental advantages one operator has over the other. (See LTE's Immaturity in the US and AT&T LTE Test-Drive Results Revealed.)

The latest analysis of the benchmark test data delves into the underlying causes of the performance differences. While Signals Research Group did not reveal its detailed conclusions to Light Reading Mobile, CEO and founder of Signals Research Group Mike Thelander shared some insights about those LTE networks based on his analysis of the data.

For certain, according to Thelander, the performance differences were not due to network loading, or the number of users on the network.

Rather, Thelander believes that a factor contributing to Verizon's LTE network performing less well than AT&T's in the Houston market is how Verizon configured its backhaul network.

"My understanding is that [Verizon] has limited the amount of capacity provided to their LTE network," he said. "While they may have architected just as good of an LTE network … they're not necessarily leveraging all the capabilities for their own needs."

But this is something that Verizon can change when needed, he explained.

"It's an artificial constraint … not a technical issue," Thelander said. "It's a business decision. It's one of those limitations that can go away overnight."

Verizon disagrees with the analyst's conclusion about backhaul, while not offering much detail on its LTE approach. "As for backhaul, not going to comment on our strategy other than to say that what your Signals Research source offers ... is false, and I’m not sure where the info is coming from," said a spokeswoman in an email reply to questions.

Alcatel-Lucent v. Ericsson
The study also shows that the differences in uplink throughput performance were down to which vendor's equipment was being used. Both Verizon and AT&T used RAN gear from Alcatel-Lucent and Ericsson. In Houston, AT&T outperformed Verizon on uplink speed and in that market, it has deployed Ericsson equipment.

The average uplink speed on AT&T's network (which was measured at 15.2 Mbit/s) in Houston was up to three times better than Verizon's.

This is an advantage that Ericsson may have for now, but it will not last forever as vendors continue to optimize their equipment.

"Certain vendors may do one thing very well but could be abysmal at something else; and that's for all vendors," said Thelander.

"Those differences will quickly go away and be less noticeable," he added. "They're exaggerated just because of the immaturity of LTE."

Big difference, but big deal?
While Signals Research Group can pick up these performance differences on drive tests, will any LTE users actually notice? Maybe not, but it would depend on what kind of application they're using. That is, the differences would be more noticeable when downloading large amounts of data as opposed to just browsing the Web.

"The typical user may not notice or appreciate the advantage that AT&T has," said Thelander. "You're not going to notice it, unless you're testing."

Whether users actually detect such differences or not, this research provides a perspective on the state of LTE technology development in the U.S.

— Michelle Donegan, European Editor, Light Reading Mobile

Michelle Donegan 12/5/2012 | 5:43:24 PM
re: Is Backhaul Bottlenecking Verizon's LTE?




Signals Research Group's Mike Thelander followed up with us and provided additional comment about Verizon's backhaul/transport network. Here's what he sent in:


"I don’t know the specific details of what VZW is and isn’t doing with its backhaul/transport network but I know from people very familiar with the network that in its current configuration there is a throughput limitation.  It may not be “throttling” in the truest sense of the word but in its current configuration there isn’t enough throughput capacity relative to the capabilities of LTE and that some of the backhaul capacity could be used to support other business opportunities.  With test equipment, it is also clearly evident in the log files that the higher throughput that we and others observed in AT&T’s network had absolutely nothing to do with better RF conditions or loading since in most instances the conditions were very similar in nature."


 






 

 




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