Wireless VoIP not ready for prime time
Harlin McEwen, chairman of the International Association of Chiefs of Police (IACP) technology committee, released a white paper last month saying broadband voice will not replace LMR for “many years, if ever.” He was sounding the alarm over the misinformation he was hearing among policy-makers in Washington, D.C., around the notion that broadband voice could replace LMR, therefore allowing public safety to use narrowband spectrum for a broadband network in the near future.
He’s right. If one looks at the commercial world, you have to wonder whether IP will ever replace voice either.
Verizon Wireless is one of the most aggressive operators in the world in terms of migrating to Long Term Evolution (LTE), with plans to roll out 20 to 30 markets next year. While the network will be all IP, it will actually become a long process before all traffic, primarily voice, is running on the LTE network. Analysts say it could be another 10 years before Verizon offers true VoIP services. It will be relying on its circuit-switched networks to support voice services.
“Everyone wants to go to IP. It makes sense when you are talking about the transports costs associated with delivering data services,” said Peter Jarich, research director with Current Analysis. “But it will be a big deal when an operator decides to go all IP and push 2G and 3G traffic over the network. Whatever operator does, that is going to be talked about.”
Primarily, there are two main problems with moving to all IP. Voice is the main problem. The architecture to support VoIP in LTE is known as IP Multimedia Subsystem (IMS). The industry today announced it is backing an IMS voice solution, but it’s far from mature. Meanwhile, Vendors have developed a compromise called voice over LTE via generic access, or VoLGA, that breaks mobile voice and messaging apart from the IP-based LTE network and allows voice to travel over LTE via a generic-access approach. It’s not clear how many operators might use that approach given the fact that they see LTE as a data-only network initially.
Secondly, synchronization of the base stations is critical and is used in current networks, but moving to a packet infrastructure makes the implementation more problematic. Delivering timing information is more complicated over IP networks, Jarich said.
As such, it is going to be a long time before any network operator declares that the network is all IP.
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