LTE: A Latent Problem?

Analysts are divided about how latency might affect the performance of Long Term Evolution (LTE) networks in the U.S., following the publication of recent network test results. (See AT&T LTE Test-Drive Results Revealed.)

Signals Research conducted a drive test of AT&T Inc. (NYSE: T)'s LTE network in Houston, using measurement gear from Accuver, which provided the first performance metrics of the newest LTE network in the U.S. The test measured downlink and uplink speed, latency and handover times between LTE and 3G networks, and Light Reading Mobile reported the high-level results here when they were released.

According to Mike Thelander, CEO and founder of Signals Research, the latency times on AT&T's LTE network were disappointing but in line with other LTE networks in North America. The average latency was 49 milliseconds with a minimum of 40 milliseconds, which was "higher [worse] than we were expecting based on the capabilities of LTE and our experiences with testing networks in Europe," noted Signals Research in its report.

By comparison, on LTE networks in Europe, the consultancy has found average latency times of 15 milliseconds to an external server. And back in Houston, Signals also recorded a minimum round trip latency of 27 milliseconds on a commercial 3G network, which was not identified.

But a latency measurement of less than 50 milliseconds is not something to be disappointed about, according to Gabriel Brown, senior analyst at Heavy Reading. "It's a bit like saying, I'm disappointed in this BMW because it's not a Rolls-Royce."

Brown added, "It’s a new technology and there is scope for optimization -- for example, of the EPC architecture and underlying IP network -- that could help drive this figure lower in future."

And that's something the analysts do agree on -- that the LTE networks have yet to be optimized fully. And there are myriad network design and architecture choices that affect latency.

According to Thelander, the latency issue on U.S. networks could be related to how the carriers have integrated their wireline and wireless networks, for example. "They could do a better job of leveraging their wireless assets and do a better job with how they connect to the Internet," he said.

Why this matters
Bandwidth and latency are the two key elements that determine the perceived performance of a network connection. Latency refers to the time it takes to process data on a network, and excessive latency can lead to wobbly connections and delays.

Network latency, perhaps more so than average downlink speeds alone, can affect users' experience, especially for real-time services like video calling, VoIP and even gaming applications.

For more
Check out these other early results from new LTE networks in the U.S. and Europe to see how they compare to AT&T:

— Michelle Donegan, European Editor, Light Reading Mobile

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[email protected] 12/5/2012 | 4:51:27 PM
re: LTE: A Latent Problem?

Just to add on the last 2 comments:

the end 2 end delay is comprise out ofr the RAN delay, mobile backhual delay, EPC delay and "Internet" delays.

the "internet" delays and the EPC delay may very and greatly reduced if for example, the information is locally cached within the EPC.

the mobile backhaul delay is&nbsp;dependent on 2 main critiria: number of hops and VPN technology. L2VPN technology present significantly lower delay as packet processing is very short, where L3VPNs present much longer delay.

One way to cut delays is to do the right choices while designing the mobile backhaul network


giles0 12/5/2012 | 4:51:23 PM
re: LTE: A Latent Problem?

you seriously think L3VPN presents much longer delay than L2VPN?


which decade are you living in?

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