What is Video Share?

IMS

IMS (IP Multimedia Subsystem) is an architecture framework for delivering IP multimedia to mobile devices. It was originally designed by 3GPP as part of its vision for evolving mobile networks. Since then, it has been adopted by other standardization organizations such as 3GPP2, TISPAN and CableLabs as the architecture of choice for Next Generation Networks (NGNs).

IMS requires the use of IP over the mobile network. As current mobile networks have limited IP support, IMS-based services are being deployed on the network gradually over time, as the capacity and characteristics of networks improve.

As a result, combinational services are the first ones to be introduced. These services take advantage of existing circuit-switched networks and technology, but combine them with IP-based technologies to provide new and exciting user services. Video Sharing is one example; it combines a circuit-switched speech call with an IP-based video stream.

Video Sharing Scenario

Video Share is essentially one-way live video streaming that lets users share live video streams or video recordings while on a mobile call. Users can “share the moment” with others by showing them what the user see, when they see it.

Basically, a Video Share session comprises the following steps:

Circuit-switched call setup Capability query Invitation procedure (SIP) Video transmission (RTP) Teardown of video session Teardown of circuit-switched call

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In Video Share, there is an initial, regular, circuit-switched (CS) voice call between two parties. At any given point in time, a call participant presses a button on the phone, and a video session opens between the user and the other participant over SIP and RTP.

Specification Overview

Video Share is a one-to-one combinational service utilizing a 3GPP-compliant IMS core system and a 3GPP CSI (TS 24.279)-based solution. A session is set up using SIP, while video is transferred using RTP. Video Share uses the P2P model, meaning that applications are built in terminals so that a separate Application Server is not needed in the network.

The 3GPP TS 24.279 specification (Combining Circuit-Switched and IP Multimedia Subsystem Services) deals with general combinational services and does not address the Video Share service directly. This provides high flexibility with regard to the services that can be developed using this specification, but it does not address the issue of building an interoperable service. For this reason, the GSMA (GSM Association) has published the Video Share Interoperability Specification (IR.74), which sheds light on how to develop an interoperable Video Share service.

Video Share is the first real IMS client application to be deployed by operators around the world for commercial use. The reasons for its relatively early adoption are varied, but include the following:

• Video Share does not require servers in the network besides IP access and network registration. For operators, this reduces the cost of deployment as well as the resources that need to be added to the network.
• Video Share is standardized and specified by the GSM Association in its IR.74 specification. This makes it easier to implement in an interoperable fashion.
• Interoperability of Video Share is covered by the IMTC IMS Activity Group, enabling companies to focus on interoperability issues during development. Companies such as Nokia, Ericsson, Motorola, Sony Ericsson, and RADVISION are active member of this Activity Group.
• Video Share is a video-based service that emphasizes the difference between 2G and 3G networks.