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Advancements in communications technology can be seen everywhere today, but the most prevalent trend is mobile video. Mobile video and data demand is exploding, driven primarily by the growing popularity of mobile video applications. Mobile video traffic could reach 66% of all mobile data traffic by 2015 according to a recent Cisco report.
This mobile video growth is driving operator investments in LTE networks, but LTE alone isn’t sufficient to meet growing subscriber demand. Other steps are needed to reduce stresses on the network. This is where an IP multimedia subsystem (IMS) with multimedia resource function (MRF) support plays an important role. IMS is an IP-based multimedia service delivery framework built specifically to manage and generate revenues from the large volume and variety of video services in a modern mobile network. By including MRF capabilities, operators can support increasing video capacities, as well as required video transcoding and transrating for the large variety of two-way interactive and one-way video streaming services now in demand. While mobile video is growing fast, the MRF must also support voice over LTE (VoLTE), as mobile voice services will continue to be a significant source of mobile operator income.
A brief architecture orientation: MRF in the IMS
The evolved packet core (EPC) is the foundation of an LTE radio access network (RAN) and enables backward compatibility with 3G and 2G networks. Inside the EPC is the IMS. It is within the IMS that the MRF equipment will deliver the IP media processing essential for LTE services. The MRF’s primary role is to provide the underlying IP media processing features, performance and scalability requirements in the network. This means support for various subscriber services in a packet data network, including VoLTE.
MRF at the center of ubiquitous device convergence
4G/LTE will support a wide-range of mobile devices and emerging applications, requiring the MRF to support interoperability across the various codec and picture size formats between these devices.
MRF performs codec conversion – transcoding and transrating − allowing diverse devices to share information. Transcoding converts one type of digital encoding standard to another while transrating converts a high-resolution video to lower-resolution for small screen devices.
However, LTE networks must also support voice. This is why LTE standards have defined VoLTE, the specification outlining the requirements for supporting the huge variety of audio services available today. The MRF plays a critical role in supporting IP audio packet processing for VoLTE, including support for adaptive multi-rate wideband (AMR-WB) between LTE audio endpoints and transcoding of AMR-WB to other legacy audio codecs.
Overcoming media processing challenges in 4G/LTE deployments
Understanding the MRF’s growing importance will be essential as the industry migrates from today’s 3G networks to 4G/LTE. MRF suppliers will need to address five emerging media processing challenges.
Challenge No. 1: High variability in access network throughput.
Even in LTE, there may at times still be insufficient voice and video throughput in some locations. In addition, the traffic flowing through a cell site is dynamic and the available bandwidth might change at any time.
Solution: The MRF must dynamically adjust the media stream bandwidth in response to traffic congestion.
Challenge No. 2: Increasing density and bandwidth needs.
The increasing levels of traffic, particularly mobile video traffic, on 4G/LTE networks will drive the need for more real-time transport protocol (RTP) media processing.
Solution: Operators can leverage large-capacity centralized MRF deployments, possibly architected with smaller distributed MRFs in high-traffic hotspot locations in the LTE access network.
Challenge No. 3: Increasing diversity of codecs.
IP telecommunications has introduced new audio and video codec standards, meaning additional complexity in processing this growing variety of incompatible media streams.
Solution: The MRF can deliver efficient, economical and automatic transcoding across many legacy and emerging audio and video codecs.
Challenge No. 4: Audio/video quality.
Compared to circuit-switched technology used in 3G networks, IP-based packet communications on 4G/LTE networks is more susceptible to delay and echo.
Solution: Operators can implement distributed MRFs that reduce local and regional delays and increase the performance of real-time interactive services.
Challenge No. 5: Increasing need for policy based controls.
In this migration to LTE, operators are looking for greater flexibility in setting-up plans to control data usage, bandwidth and quality of service.
Solution: MRF capabilities are expected to evolve to include aspects of a policy enforcement function (PEF); MRF could then adapt media streams based on service priority, bandwidth utilization and other policy based services tailored to users’ subscription profile.
Emerging LTE networks will deliver significant improvements in mobile broadband speeds, allowing mobile subscribers to consume and generate mobile video content like never before. But to support these growing video volumes, MRF vendors must address some key LTE deployment challenges. Flexible and scalable MRF equipment, in an IMS architecture, can help mobile operators monetize VoLTE and interactive and streaming video services − a key to success in this increasingly diverse and mobile world.
