This is a guest post by David Zhang, CTO of Aicent
LTE, a radio access technology used to support only data access, was developed to carry all services as IP applications over an all-IP network, from mobile devices to the IP world. With this all-IP network deployed, mobile operators are migrating their existing services, such as voice and SMS, into an all-IP implementation in order to offer better quality voice services and make the most efficient use of the LTE spectrum compared to the legacy 2G and 3G voice.
Voice over LTE (VoLTE) is VoIP over LTE under the IMS framework. VoLTE was first introduced in 2010 by the GSMA, with detailed specifications of IMS for voice and SMS defined in GSMA PRD IR.92. Included in this definition is the Adaptive Multi-Rate Wideband (AMR-WB) protocol which allows for High Definition (HD) voice. It is used for superior sound quality over legacy standard voice protocols. Since HD voice can only be supported in an IP network instead of a TDM network, it has become a key differentiating feature for VoLTE in comparison to other voice services.
The benefit of offering VoLTE is not only to make it possible for mobile operators to offer better quality voice services, but also as an enabler allowing them to expand to other services such as rich communications, while at the same time making efficient use of spectrum for voice services and saving extra capacity for data services. By combining data and voice services on the same LTE data access network, mobile operators are able to integrate network resources, optimise network and service management, and simplify service delivery, resulting in a significant reduction of OPEX. In addition, the introduction of VoLTE enables mobile operators the capability to offer other innovative services, such as those from unified communications, social networking, and Rich Communication Suite. Further, VoLTE implementations can also be a strategy for mobile operators looking to distinguish themselves from Over-The-Top (OTT) players.
The first step for mobile operators is to deploy their VoLTE services for their domestic markets, followed by the interconnection between mobile carriers for the international markets. Besides VoLTE interconnection, VoLTE roaming is also a new area to be addressed. VoLTE roaming can be implemented using a local breakout approach just like today with voice roaming in TDM. We may also see that some operators start with VoLTE using home bound routing similar to today’s data roaming.
One implementation option defined by GSMA is to use IPX as the recommended infrastructure platform to VoLTE interworking and roaming, with the key components of the IPX platform containing QoS IP transport, Diameter Agent and SIP Proxy.
The LTE North America 2012 conference is taking place on the 14-15th November 2012 at the Fairmont Dallas Hotel, Texas. Click here to download a brochure.
Put the date in your diary now for the inaugural LTE Voice Summit, taking place in London on the 23rd-24th October 2013.