First shots in the battle to control all-IP will be fired in the TI replacement

Rethink IT, May, 2005

Most of the talk about the shift to all-IP networks centers on the impact on user access, but equally important is the effect on backhaul strategies and technologies. The days of the T1 line are numbered in the wireless world, and the battle for control between different platforms--notably WiMAX and IP-enabled 3G technologies--will be as fierce in the backhaul as it is at the access level.

Much of WiMAX' early traction is expected to be in backhaul and T1 replacement, for enterprises, Wi-Fi hotspots and cellular base stations. Now the cellular equipment vendors are talking about IP-based backhaul too, using their own platforms, pointing the way to '4G' convergence at the back end.

Nokia recently showed off its Internet-HSPA, and Motorola has a similar technology in the wings. These focus on 'flat networks', which greatly simplify networks by eliminating elements such as signalling gateways. Unlike the much touted '3.5G' upgrade to UMTS, HSDPA (High Speed Downlink Packet Access), and its successor HSUPA for the uplink, technologies like I-HSPA create symmetrical IP networks, which push Layer 3 IP protocols out to base transceivers and provide an intelligent services node to unify IP services for different kinds of traffic in cellular networks.

This is far more coherent and simple than current circuit switched networks and supports higher bandwidth in the core network, necessary to deliver future services such as mobile television. It also supports the shift of backbone and backhaul transport to IP rather than T1 and T3, to create a unified network. Nokia argues that this will have significant impact on providers' costs.

"We hear a lot about the reduction in capex because of elimination of network nodes, and we hear a lot about the overall reduction in opex from a unified IP, since it simplifies traffic," Eric Updyke, vice president of strategic planning and marketing at Nokia Networks, told Comms Design. "What's becoming more clear is that moving to IP also allows the flattening of the network."

While most carriers are still thinking in terms of T1 and T3, they are increasingly starting to consider IP throughout the network and the vendors are fighting for their attention. Some are taking the Nokia approach of incorporating IP into enhanced versions of existing platforms. NEC, for instance, is in the process of switching to IP backhaul in all its cellular backhaul radios and digital microwave products for cellcos, and most vendors of proprietary microwave products--including the high spectrum, point-to-point products targeted at enterprises and ISPs--will be planning similar shifts.

The WiMAX community is promoting its technology as a cellco backhaul option in its own right, and one that is IP-based from day one. In its current sub-6GHz profiles, its range and power is limited to 'middle mile' backhaul to fiber, but in its initial incarnation, the 802.16 standard was focused on higher reaches of the spectrum and on more powerful point-to-point backhaul applications. With the increasing need for backhaul created by the proliferation of cellular traffic, running from larger numbers of smaller 3G base stations, and by the growth of hotspots, the WiMAX groups should look once again at the higher spectrum opportunities, where it could compete with proprietary microwave products from the likes of NEC and Alcatel, and in some environments with fiber.

The recent agreement between Marconi and WiMAX specialist Airspan--under which the partners will cross-sell Airspan's WiMAX gear and Marconi's backhaul radios--showed the importance to 802.16 suppliers of being able to offer a complete network, and one that is as flat as possible to remain cost effective against the cellular giants. Increasingly, manufacturers will expand their ranges or form partnerships to be able to provide the back-to-front network that large operators will expect.

But there is also the potential for WiMAX to move backwards into the network and create a complete infrastructure based on a single platform. RF technologies will always suffer some disadvantages against fiber, notably susceptibility to interference and weather conditions, but in many situations, the trade-off between these downsides and the benefits of flexibility and cost effectiveness results in a net vote for wireless. At the level where wireless competes with fiber--high up in LMDS spectrum, with point-to-point equipment and line of sight--technologies are proprietary and relatively expensive, and so are mainly deployed in areas where fiber is not economically viable to run. However, there is a rising number of success stories combining LMDS technologies with Wi-Fi or other last mile options, and as cellular networks become more complex and expensive to backhaul, there could be increasing demand from mobile operators. All this could reawaken interest in the WiMAX market in the higher frequencies. The original focus of the 802.16 groups, some years ago, was on LMDS spectrum and backhaul.

Whichever platforms become strong in the flat all-IP network, companies providing integration with legacy cellular technologies will take on a new significance. Companies like UTStarcom, which has created mSwitch, an IP soft switch for integrating and aggregating IP and conventional platforms; and FiberTower, whose network management system links microwave backhaul with fiber transport, eliminating the T1 'weakest link'. Its CEO, Keith Kaczamarek, says: "We are prepared for an all-IP backhaul network in the near future."