Mobile TV should not be confused with the 3G video streaming services available today. These services use IP video streaming and tend to be a waste of spectrum because they are point-to-point and a new stream has to be initiated for each viewer. Mobile TV is a point-to-multipoint, broadcast technology, sending a single stream to multiple viewers simultaneously.

There are currently three different technologies vying for top position: DVB-H (Digital Video Broadcasting - Handheld), MBMS (Multimedia Broadcast and Multicast Services), and the satellite-based DMB (Digital Media Broadcasting) being rolled out in South Korea and Japan.

DVB-H is terrestrial broadcasting technology with the signals broadcast from a standard TV mast. The existing TV broadcasting network is used and a service provider creates the content, adapts it for mobile media and sends it to terminals equipped with TV receivers. DVB-H is simply another flavor of the DVB standard, which includes DVB-S for satellite broadcasting, DVB-T for over the air broadcasting and DVB-C for digital cable broadcasting. More information can be found at the DVB Project website. Earlier this year, UK Operator O2 and the broadcast division of NTL announced a trial project using DVB-H technology.  A trial has also been launched in Pittsburgh in the US.

South Korea's SK Telecom, in a joint venture with Japan's Mobile Broadcasting Corp., has launched a DMB satellite to offer the service in both countries. In Malaysia, telecom operators Maxis and Digi have begun offering live satellite feeds to mobiles. DMB is currently only being promoted in Asia and the technology has many obstacles to overcome, primarily that satellite signals have poor reception indoors.

MBMS currently has no installed base, but is getting a great deal of attention from telecom operators for a number of reasons. MBMS is an integral part of 3GPP's strategy. MBMS can be offered via existing GSM and UMTS networks and also includes an uplink channel, not available in DVB-H or DMB, which opens the possibility for user interaction.

From a service perspective, MBMS simplifies the simultaneous delivery of content to multiple destinations. From a network perspective, MBMS reduces overall bandwidth consumption and load in the servers and terminals, by replicating the data at appropriate points in the network rather than in the end systems. Scalability is achieved by distributing the management of group members to local networks.

Because data is sent to a multicast group with a common address, other service possibilities become available, principally, content subscription services.  Consumers will be able to subscribe to specific video streams that will be pushed to them when they are available. This also facilitates simpler billing schemes.

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By John Maxwell Hobbs