Exploding video consumption on mobile devices is a well-documented phenomenon by now. The advent of higher speed radio networks and more video-capable devices like the Apple iPad, Samsung Galaxy, Amazon Kindle, and RIM PlayBook, along with the proliferation of compelling applications and content, will no doubt continue to fuel this trend.
In previous posts we discussed the underlying effects of more mobile video traffic and surveyed general optimization techniques mobile broadband operators are using to manage this deluge of rich media traffic in the networks. In this post, we'll focus specifically on IP video optimization. Numerous approaches exist to more efficiently carry video over a mobile network, including:
- Broadcast and Multicast Video over Mobile - This approach uses mobile spectrum as a video broadcast platform. The motivation is to save RF and network bandwidth by broadcasting TV and video flows rather than spectrally inefficient unicasting. Qualcomm's Media FLO Service and Digital Video Broadcast - Handheld (DVB-H) are two examples of this technique. But neither technology has achieved widespread deployment (or subscriber acceptance) due to the need for dedicated spectrum, radio and network upgrades and, most importantly, a lack of compelling devices. In addition, the total number of broadcast sessions is limited to a few channels of pre-determined TV. And as we all know, trying to predict what videos users will want to view and when they will want to view them is an impossible task.
- Video Transcoding - This technology uses various compression algorithms, encoding schemes, and rating mechanisms to modify the source video files and streams to match the display capabilities of the device. Transcoding adjusts the video resolution, frame-rate, and compression ratios to reduce the payload required to send and display the video. This technology can improve network bandwidth utilization and render video suitable for feature phones, but it also reduces the video's fidelity and requires significant processing and storage capabilities in the Mobile Core. The rapid growth of powerful, video-capable smartphones and smart devices on mobile networks is diminishing interest in this technology.
- Video Pacing - This technology smooths out the delivery of the video download to more closely match the playback speed of the user's device. This can result in a two-fold improvement in network efficiency: first, by allowing more concurrent video sessions on the same network bandwidth, and second, by reducing the quantity of actual video bytes carried over the network if the user abandons the download mid-stream (a very common occurrence).
Video Pacing Example: By more closely matching the download speed to the playback speed - peaks are lowered, more users can be serviced and less bandwidth is wasted.
- Adaptive Video Streaming - This approach maximizes the number of video users on the network by adjusting the video quality and delivery rate 'on the fly' depending on congestion conditions and available network bandwidth. In some cases, this requires a specialized video viewer application on the user device.
- Video Caching - Basically a subset of core-based web caching techniques described in a previous post, this technology involves serving complete video files (but not streaming video!) from a platform in the operator's Mobile Core. The primary benefit is a reduction in the Internet interconnection capacity required.
A rapidly growing number of user devices on the network are now capable of delivering a full fidelity video experience, so any attempt to control data traffic that also reduces video viewing quality will be instantly noticed by users. This implies the number of transcoded video sessions, adapted video streams, and cached videos that can be delivered over the network at any given moment (let alone during peak periods) will be constrained by practical service and operational considerations.
Video optimization is one of several tools operators can deploy along with other optimization techniques such as RAN-based data reduction and service/policy management to more efficiently manage the explosion of video traffic on their mobile broadband networks. Any technique that impacts the quality of the content delivered to mobile broadband subscribers, however, runs the risk of losing favor with mobile operators over time, given subscribers' rapidly increasing expectations for a high-quality, full-fidelity viewing experience.