In the first large survey of live packet backhaul deployments, Heavy Reading finds that the transition from circuit-based time division multiplexing (TDM) technologies to packet-based transport is still in its infancy.
As of the end of April 2009, there were fewer than than 55,000 cell sites live with packet backhaul worldwide out of a global total of 2.4 million cell sites, according to the report.
Deploying packet backhaul is critical for mobile operators if they are to improve their profit margins, which are under threat from ever-increasing amounts of data traffic on their networks. With higher levels of data usage, traditional circuit-switched transport does not offer the flexibility and capacity or the right cost per bit to cope with the traffic on the network.
And if the rate of adoption of packet backhaul does not accelerate fast enough, the risk for mobile operators is that they could be forced to throttle back data usage allowances or even slow down subscriber acquisitions to protect their profit margins, warns the report.
So, what's holding operators back? In this case, the global recession is not to blame, although it has been a contributing factor. Instead, the main reasons for the low adaption are organizational issues at operators and their perceptions of the technology risks. Even though mobile operators have already made the circuit-to-packet transition in their core networks, that shift has yet to take place in the departments that run the backhaul networks. (See Carriers Don't Trust Ethernet Backhaul?)
Of all the deployments studied, most operators have opted for a hybrid approach to packet backhaul, whereby high-speed data traffic is carried by the packet network and voice and low-speed data traffic is still carried by the T1/E1 or SDH/Sonet circuits.
Despite a slow start, the report concludes that there is still a big opportunity for equipment vendors because substantial growth in this market is inevitable.
You make a good point, and one that isn't brought out often enough. The Wimax carriers don't have a lot of demand for voice service or for seamless handoff between cell sites, let alone for seamless hand off of voice services between cell sites. Hence why pure Ethernet backhaul works for Wimax carriers today but isn't yet working in large volume for the cellular carriers.
CLWR management crows about their all-IP broadband network for WiMax. What backhaul are they using? Perhaps IP backhaul is just easier to manage in a greenfield environment.
Yes, synchronization is certainly a factor in many cases. And it will be featured as the subject of one of our panel sessions at our "Backhaul Strategies For Mobile Operators" conference in New York later this month.
As my report shows, there are very, very few operators that have turned up IEEE 1588 to commercial service at the cell site as of today. The large majority of early live packet backhaul deployments are leaving a T1/E1 at the cell site. That certainly provides the synchronization but it does so at the expense of preventing the cellular operator from maximizing the cost savings that are meant to accrue with the transition to packet backhaul.
More broadly the issue is the challenge that the cellular operators face in building the capability to handle voice and data over packet end to end across the whole network, especially in a multi-vendor network.
The reason could be that there are'nt yet roboust packet based synchronization mechanisms, and every synchronization mechanism ( IEEE 1588, SyncE) has some limitations.
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