Bandwidth is key

Until recently, bandwidth constraints have held back IPTV’s progress. Currently, DSL (Digital Subscriber Line) is used to deliver Internet services to most homes and businesses. DSL was originally intended for access to the Internet at faster speeds than traditional dial-up modems.

DSL’s limitation on network and distance therefore makes it difficult to deliver consistent high-speed data, a necessity for IPTV. For instance, one would need to be in close proximity to a telephone company’s CO (central office) to be able to receive data at rates of at least 6/8 Megabits per second (Mbps). As it was only for Internet access, some DSL lines were designed to hold less than 2 to 3 Mbps. On DSL, data speed varies with distance; the farther you are from the central office, the lower the data rate. Most central offices use DSLAMs (Digital Subscriber Line Access Multiplexers) to link customers to an ATM (Asynchronous Transfer Mode) network, ,but as speed over DSL lines increase, loop lengths had to be reduced with DSLAMs being placed closer to the customer.

As demand for bandwidth increased, new technologies such as Asymmetric Digital Subscriber Line (ADSL) 2 and ADSL 2 Plus were introduced, but bandwidth has not been sufficient for IPTV. To give an example, a standard definition channel requires around 3.5 Mbps. To compete in the video delivery market, you must have at least three premium channels of real-time viewing per household, and for a basic broadcast an operator needs at least 10 Mbps. As you can see, bandwidth plays a pivotal role for IPTV and its vast array of interrelated services. Therefore the advanced encoders that use the new compression technologies, such as MPEG-4 Part 10, are likely to act as the catalyst for operators looking to introduce IPTV.

New Compression technology

The MPEG-4 Part 10, H.264 or AVC (Advanced Video Coding) encoders have been designed to yield better picture quality, even at significantly lower bit rates. It is able to deliver up to 50 percent more compression efficiency when compared to MPEG-2, and it also helps ensure that picture quality is retained even at low bit rates like 2-3 Mbps.

MPEG-4 Part 10 is one of the best solutions for widespread IPTV deployment. For operators, not only does it lower overall system cost, it also reduces infrastructure requirements. MPEG-4 Part 10 enables the transmission of DVD quality video over existing networks and nearly halves the bandwidth requirements for digital video delivery to around 2 Mbps. Crucially, MPEG-4 Part 10 gives Telecoms operators the opportunity to broadcast HD (High Definition) over IPTV.

As satellite, cable and telecoms operators vie for their share of the highly competitive market for entertainment video delivery, the ability to offer HDTV is a key competitive differentiator. Whilst HD has grown rapidly in the U.S., demand in Europe has been slower. However, as prices of "HD ready" screens have steadily declined and the number of events being broadcast over HD has increased, operators in the region have turned their attention to delivering HDTV.

For xDSL networks, providing HD will pose a challenge when providing more than one channel per home in addition to a simultaneous high-speed Internet connection, even when new technologies like ADSL2 Plus are used. Therefore, MPEG-4 Part 10 makes it possible to broadcast HD content over next generation DSL networks.