The recent surge in data usage on 3G networks is pushing mobile operators to adopt flat, all-IP architectures before the arrival of 4G, but the technology choices are hotly disputed among equipment suppliers, according to a new report from Heavy Reading. (See Data Prices Fall, Usage Booms.)

The move to flat, packet-oriented architectures in mobile networks mirrors the shift to all-IP networks in fixed-line networks, but it's happening four or five years later. The drivers are the promise of lower latency, lower cost per bit, support for multiple access networks, and preparation for next-generation 4G, according to the report, Flat IP Architectures in Mobile Networks: From 3G to LTE.

But how operators arrive at a flatter data network architecture is much debated.

The first step on the way to flattening the 3GPP architecture is to implement the Direct Tunnel specification in the core network. In the Direct Tunnel architecture, the Serving GPRS Support Node (SGSN) is removed from the bearer path so that a direct tunnel is created between the radio network controller (RNC) and the Gateway GPRS Support Node (GGSN). The end result could be reduced SGSN cost savings of about 50 percent because operators would not have to deploy extra SGSN capacity as data traffic increases, according to the report.

Ericsson AB (Nasdaq: ERIC) and Nokia Networks are big supporters of Direct Tunnel. Both suppliers say they will have operator customers that have implemented Direct Tunnel in their networks carrying live, commercial traffic in the second quarter of this year.

But Huawei Technologies Co. Ltd. and Starent Networks Corp. (Nasdaq: STAR) do not share the enthusiasm for the architecture and see less near-term interest from operators. While these vendors have Direct Tunnel in their product roadmaps, they are developing more powerful SGSN platforms that can handle bigger traffic loads at lower latency, which would allow operators to delay the decision to implement Direct Tunnel.

Alcatel-Lucent (NYSE: ALU), meanwhile, plans to double the capacity of its Advanced Telecom Computing Architecture (ATCA)-based SGSN by the middle of this year, while it also plans Direct Tunnel products for trials in the middle of next year.

"While Direct Tunnel is clearly useful, in the context of the wider network it is an incremental change," writes Heavy Reading senior analyst Gabriel Brown in the report. "It is not enough on its own to create a step-change in cost, performance, or flexibility."

The architecture decisions operators make today will affect how they implement next-generation Long-Term Evolution(LTE)/System Architecture Evolution (SAE). Some vendors are already touting SGSNs that can be upgraded to support LTE's mobility management entity (MME) functions while others are marketing GGSNs that will support SAE gateway functions. But it is not yet clear whether deployed 3G equipment can be repurposed for 4G's evolved packet core, according to the report.

The report profiles the product strategies of equipment suppliers evolving the classic 3G network to towards flat, all-IP networks and 4G radio access. It includes analysis of flat 3G RAN architectures as well as SGSN, GGSN, MME, and SAE Gateway applications and the underlying hardware platforms. For more information on the report, click here.

— Michelle Donegan, European Editor, Unstrung