Aussie telcos mull mixed cellular-Wi-Fi networks

Network equipment makers are pushing technology that enables mobile data traffic to be "steered" in real-time between cellular and Wi-Fi networks, but Australia's telcos are unlikely to have a use for it in the short to mid term.

Are carriers steering towards mixed cellular-Wi-Fi networks?

Ericsson and Nokia-Siemens Networks used the CTIA 2013 wireless event in Las Vegas late last month to unveil separate but similarly-targeted technologies that build on the concept of heterogeneous networks ('HetNets').

A HetNet architecture sees traditional macro cells augmented with — or deconstructed into — a dense network of smaller cells, coupled with intelligent software to manage data traffic.

It is meant to relieve congestion issues in large cells and is seen as an alternative to current strategies such as cell splitting.

Independent telecommunications analyst Chris Coughlan told iTnews that carriers, such as Telstra, have been busy splitting congested macro cells into, for example, four or five smaller cells. However these smaller cells still operate with traditional base station equipment.

"Cell splitting from a CapEx perspective is really expensive," he said, noting a greenfields cell site could cost upwards of $250,000.

"HetNets basically take cell splitting to another level".

HetNet talk to date has been about the use of cheaper, shrunken base stations, such as lightRadio devices by Alcatel-Lucent and Liquid Radio boxes by Nokia-Siemens Networks. Such boxes require less power and bandwidth than a traditional macro base station, and can be stacked together or distributed across areas of high mobile data demand.

Equipment vendors are also pushing for carrier-grade Wi-Fi to be added to the HetNet mix.

In such a scenario, "real-time" or "dynamic" traffic-steering software in the network would direct users into LTE, 3G or Wi-Fi cells, depending on which offered the best, least-congested browsing experience.

However, with all three of Australia's mobile carriers holding considerable spectrum assets, the need to branch out into mixed Wi-Fi/cellular networks is likely to be some way off.

Early adopters

Australia's telcos are a mixed bag when it comes to HetNet adoption.

Telstra is known to be toying with HetNets, but as a point solution at stadiums and racecourses — basically areas that can become highly-congested at certain points in time. Last year, it trialled an unnamed small cell technology at Flemington Racecourse (pdf).

It appears the telco isn't necessarily thinking about HetNets yet as a ubiquitous mobile network architecture strategy. Comment is being sought from a Telstra spokesman.

Spokespeople for Optus and Vodafone Hutchison Australia (VHA) say that they are tracking the development of HetNets closely, but both are yet to really dip a toe in.

Equipment vendors vying for a piece of the HetNet action in Australia believe carrier interest in the concept is there, but that it will ultimately take time to achieve broad-scale adoption.

The vendors agree that small cell technologies will only proliferate when telcos have exhausted options to optimise existing macro cell sites.

"Once the macro network has been optimised, that's when small cells come into play and that's when Wi-Fi can play a role as well," Ericsson Australia's manager of strategic marketing, Andres Torres said.

Initially, it seems that small cells will use cellular radio technology (based on the 3GPP GSM standard) rather than carrier-grade Wi-Fi, though vendors believe Wi-Fi still has potential.

"It depends on each operator's strategy," Torres said.

Ericsson is coy when it comes to revealing the presence of any local trials of its technology. Nokia-Siemens Networks is less so, noting no current local trials of its competing Smart Wi-Fi steering solution.

NSN's Asia Pacific head of E2E solution architecture, Mike Smathers, believes the opportunity presented by a mixed cellular-Wi-Fi network is still being evaluated.

"I think no doors have been closed," he said.

"[Operators are] faced with looking at all kinds of ways of enhancing the 3GPP macro network that they've got at the moment, and the next step after that would be to deploy small cells.

"Those small cells could be in the form of microcells, picocells, femtocells and even Wi-Fi. I think that these are all options that [operators have] on the table, that they're kicking around."

Read on for views on whether Wi-Fi can cut it.

Can Wi-Fi cut it?

A key challenge when considering the potential of Wi-Fi as a small cell technology is whether it can deliver the type of performance necessary to interoperate with a network of LTE and 3G assets.

"I think there's a reticence to go down the Wi-Fi path," Coughlan said.

"The issue with Wi-Fi is it's unmanaged, unlicensed spectrum, and in areas of high demand, and if you get lots of these hetnets, and you get lots of other private Wi-Fi networks, then the noise floor's going to come up and your throughput on Wi-Fi is just going to decrease.

"That's been a perennial issue generally with Wi-Fi. It can't be relied on.

"Where you're going to want Wi-Fi is where it's going to be subject to interference because that's where people are. Where you need it is where it's going to be least usable".

Torres and Smathers both acknowledge the inherent issues with Wi-Fi, though they say their respective traffic steering systems are designed to alleviate some of the doubts around control of the customer experience.

"[Our technology] looks at trying to understand what the customer experience is, and you can dynamically manage the traffic," Smathers said.

"So if a Wi-Fi cell looks quite heavily loaded you can prevent your customers from using it and keep them on the 3GPP environment."

Deciding to steer users from a cellular to Wi-Fi environment could be application, load or quality-of-service classification-specific, according to Smathers. These rules would be set up by the operator in the base station controller hardware/software.

Torres said that HetNets are really about giving "end users the best possible experience".

"If the end user is better in the LTE network then you say, 'Stay in the LTE network'," Torres said.

"If, on the other hand, they'll have a better customer experience in Wi-Fi then the real time traffic steering feature will be able to steer the users to the Wi-Fi.

"The beauty of this is it's done on a user-by-user basis, so you and I can be in the same room but you are on LTE and I am on Wi-Fi because that's what is best for us.

"The only way to achieve this is with deep integration at the core level between all the mobile technologies."

Torres believes driving intelligence deep into the network is the key.

He cites the example of where smartphone users presently set up their phones to switch from cellular to Wi-Fi networks when at home, but that switch occurs whether or not it results in a better end-user experience.

"We have left too much decision power to the phone, whereas the network is the one that should be making those decisions," he said.

"Real time traffic steering is going to allow the network to make the decision to see what is best for the customer — being Wi-Fi, 3G or 4G."

If it's free...

One of the biggest potential roadblocks to local adoption of mixed Wi-Fi-cellular networks is that carriers aren't exactly short of mobile spectrum assets.

Moving into carrier-grade Wi-Fi is likely to be most attractive to carriers that don't have the spectral assets to otherwise address capacity shortfalls and data growth challenges.

"At the moment the preference is to try and stay with 3GPP type technologies," Smathers said.

"Why not put in a femtocell or picocell base station if you have the spectrum to do so?"

Coughlan believes Wi-Fi could be attractive in the short- to mid-term if such capabilities can be turned on at very little or no extra cost to the carrier.

"The small cells that will be utilised in HetNets will likely support 802.11n and 802.11ac, so adding Wi-Fi as an additional air-interface will be minor, if any, capital cost," he said.

"I think if that's the case and you've got the backend core network that can manage the handoff between Wi-Fi and the LTE network in such a way that end users don't perceive there's any difference, why wouldn't you do that?"

Comment was also sought from an Alcatel-Lucent spokesperson but a response was not received by the time of publication.