Test Results Raise Femto Service Concerns

Policy management techniques used by broadband service providers are a serious threat to the quality of services -- particularly voice -- delivered over femtocell connections, Unstrung has learned.

The issue, which came to light during recent service tests, is a major concern, as the use of policy control technologies could potentially cause major service quality problems for mobile operators when they rely on broadband connections from other operators to backhaul femtocell traffic.

When third-party providers are used for that portion of the network, mobile operators do not have complete control over how their traffic is treated. And, as a result, the quality of femto services, especially voice, could suffer.

Broadband test specialist Epitiro recently evaluated femtocell voice and data service quality over the top ten broadband networks in an unidentified country, which cannot be named for confidentiality reasons.

Epitiro found that even the lowest-end consumer broadband service had enough bandwidth capacity to support a femtocell service, so capacity was deemed not to be an issue.

But in four out of the ten cases, the test results showed poor voice service quality. A closer inspection into the degraded voice services revealed that packet loss was the culprit for the quality problems, according to Jon Curley, chief technology officer at Epitiro.

In Curley's analysis, he concludes the reason for the packet loss in those four cases was the policy management used to control IPsec traffic: That has a direct impact on femto traffic, which is encrypted in IPsec tunnels.

"You can tell [traffic policy] is in place by the number of packet drops and higher latency relative to unmanaged traffic. It's in evidence by the amount of packet loss and jitter levels," Curley tells Unstrung. "If you don't have a traffic policy for IPsec in place, it's fine -- it's only when [ISPs] put traffic policy in place and they look at IPsec and they decide they want to control that."

So, the femto traffic was being treated like BitTorrent Inc. peer-to-peer traffic by those four service providers, Curley explains.

Nothing to see here...
Femto vendors are quick to dismiss this policy management issue.

"We have heard this question raised from time to time, but it’s not really an issue, and one that is easy to blow out of proportion," says Josh Adelson, director of product marketing at Airvana Inc. (Nasdaq: AIRV), in an emailed response to Unstrung.

"In general, femtocell network designs do not assume special treatment from the fixed broadband provider or ISP, something which is vital to their easy deployment," states Adelson.

He notes that reviews of Sprint Nextel Corp. (NYSE: S)'s Airave service, which uses other ISPs' broadband connections, have reported "excellent call quality."

Adelson also thinks it's unlikely that ISPs would intentionally block or degrade femtocell traffic on their networks.

Meanwhile, ip.access Ltd. says policy management isn't a problem for now.

"It's too soon to say definitively that this is not an issue, but so far we have not seen a problem with customers complaining about the quality of voice calls on femtocells running over third-party broadband connections," says Andy Tiller, vice president of marketing at ip.access. "In fact, people often comment that voice quality is better than on the outdoor network."

And Randy Fuller, vice president of business development at policy server specialist Camiant Inc. , says he hasn't seen this problem arise for femtocells.

"The more common problem is insufficient bandwidth," says Fuller.

But Epitiro's test results show that in a worse-case scenario, users would lose service during peak periods, according to Curley. Mobile operators need to be aware of this potential problem, he adds.

— Michelle Donegan, European Editor, Unstrung