Wireless May Boost Pseudowire

The growing backhaul demands of mobile operators have at last given specialist pseudowire vendors such as Axerra Networks Inc. and RAD Data Communications Ltd. something to shout about.

Pseudowire technology, which enables legacy services to be transported over IP-based networks, is being touted as a potential cost saver and revenue generator for carriers by a number of vendors, but the takeup has been patchy at best. (See Pseudowires and How Far Can MPLS Go?)

But the benefits of transporting growing volumes of voice and data traffic across IP networks, rather than via costly E1 and T1 lines, is starting to appeal to mobile operators.

Evidence of this comes from Axerra and RAD, which have both been promoting pseudowire's possibilities in the wireless world, and now have the deployments to show for it: RAD at Time Warner Cable Inc. (NYSE: TWC), which is backhauling at least one wireless carrier's traffic across its network; and Axerra at Hong Kong Broadband Network Ltd. (HKBN) , which is carrying backhaul traffic for several of Hong Kong's six mobile operators across its Ethernet infrastructure. (See Time Warner Gets RAD, Axerra Gets Pseudo-Wireless, and HKBN Uses Axerra for Backhaul.)

Axerra says the Hong Kong operator isn't its only customer using pseudowire to carry wireless backhaul traffic. The vendor's VP of marketing, Steve Byars, says KT Powertel, a subsidiary of Korean incumbent KT Corp. that specializes in business mobile services, is using Axerra's kit for the same purpose, and he cites other deployments in Africa, Europe, and the U.S. with carriers that can't yet be named. (See KT Powertel Picks Axerra.)

Axerra, which recently announced a new round of funding, also benefits from an OEM deal with the No. 1 GSM network equipment vendor, Ericsson AB (Nasdaq: ERIC). (See Ericsson: Every Vendor's Best Friend and Axerra Scores Extra Funding.)

RAD, meanwhile, is taking its pseudowire campaign to the 3GSM World Congress, to be held this year in Barcelona in mid-February. (See RAD Previews 3GSM Exhibits.)

And with 3G starting to take off around the world, carriers will be looking for ways to keep their costs in check as data traffic volumes rise.

"When operators move to 3G, backhaul costs can be huge, especially if it means adding multiple E1/T1s to every cell tower and expanding optical or microwave backhaul links within the radio access network," says Heavy Reading chief analyst Scott Clavenna, who identified wireless backhaul services as one of the key potential uses of pseudowire technology in his report Pseudowires and the Future of Transport and Access Networks.

"Add to that, some of the backhaul links will be carrying data only, others voice. Pseudowire is a way to glom voice and data together over a single connection, usually Ethernet. Since it packetizes all services, you can perform statistical multiplexing and improve backhaul efficiencies."

But while that's the upside, there's naturally a downside, too.

"Pseudowire is a new technology with immature standards," says Clavenna. "Pseudowire solutions typically require fiber-based backhaul, and so, at present, they can most often only be used in aggregation points in the radio access network [RAN], not all the way out to cell towers.

"That's what confuses a lot of people about pseudowires and backhaul -- they immediately think it means the connection all the way to the cell tower. Where it will be most prominent is in the links from aggregation points in the RAN to large POPs in the metro or regional network. In that area you have plenty of fiber, so pseudowire is a way to converge all traffic onto a common link. In that case, it is just replacing what ATM is already doing in those networks today. There is a ton of ATM in radio access networks today. Pseudowire is really just part of the ATM-to-MPLS migration in the network."

And then there's the fear of the unknown. "TDM emulation over pseudowire works, but most mobile operators are afraid of using it widely because of performance concerns, for example, issues with unmanageable jitter and wander. Plus, depending on the network, circuit emulation can add considerable overhead, which negates the value of backhaul efficiency."

So despite some initial successes, "I don't think 2006 will be a big year for pseudowire in mobile operators, but just one where they start to test it more widely in the RAN and take some toddler steps in deployment."

Other vendors with pseudowire solutions looking to get a piece of that slowly emerging action include Alcatel (NYSE: ALA; Paris: CGEP:PA), Corrigent Systems Inc. , Hammerhead Systems Inc. , Mangrove Systems Inc. , Overture Networks Inc. , and Telco Systems (BATM) . (See Alcatel Taps Layer 2, Corrigent in HR Pseudowire Report, Mangrove Releases Piranha, and Telco Rides T-Metro .)

And it's not as if the pseudowire approach is the only alternative to traditional ATM-based backhaul. Aperto Networks Inc. , for example, is touting its WiMax technology as suitable for the backhaul of cellular voice and data traffic. (See Aperto Offers TDM Wireless B'band.)

— Ray Le Maistre, International News Editor, Light Reading