Wireless Focus: Delivering Mobile Video:DVB-H, MediaFLO

The development of cellular mobile video technology in the US has intensified over the past several months. Two specification technologies, DVB-H (Digital Video Broadcast - Handheld) and MediaFLO from Qualcomm Inc of the US, are leading the charge to deliver large video applications to cell phone subscribers. Both technologies propose to deliver data over stand-alone networks that lie outside of 3G cellular networks, thereby saving bandwidth.
DVB-H: Tried & Tested
DVB-H, an open European standard based on terrestrial satellite broadcasting technology, has been tested extensively in Germany, Singapore and the UK. More recently, it has been tested in the US.
In late 2004, Crown Castle Inc of the US, a wireless network infrastructure provider, performed field testing of DVB-H technology in the 1.4GHz frequency using handsets provided by Nokia Corp of Finland. The system used a network of digital TV towers to catch signals from satellites and transmit the signal to the handsets. The US currently uses ATSC (Advanced Television Systems Committee) for digital TV, but it is an older standard unsuitable for mobility.
Crown Castle already possesses the spectrum needed to provide DVB-H broadcasts. Last year, it paid US$12 million for an exclusive terrestrial license to use 5MHz of US L-band spectrum, which extends from 1440-1790MHz. The company plans to establish a nationwide network for mobile TV broadcasting and lease the network to cellular operators.
Texas Instruments Inc of the US provided its so-called Hollywood chipset for handsets. Made specifically for the DVB-H standard, the Hollywood chip "will use a separate air interface, not the cellular network, to transmit the TV signal. This will enable live digital TV to be broadcast in real-time (25-30 frames per second) rather than streamed over the network (1-15 fps)," said an October 2004 press release from TI.
DVB-H has several important characteristics. One is "time splicing," which transmits information to a portable device by organizing data in 1- to 2- Mbit bursts. The concept makes it possible to switch off the radio tuner, thereby helping to achieve significant power savings over current video streaming technologies.
DVB-H also utilizes MPE-FEC (multi-protocol encapsulation forward error correction), a more robust transmission decoder that is considered advantageous when considering the hostile environments many mobile handsets encounter.
TI expects to provide samples of the Hollywood chip to vendors by 2006. It takes the traditional three-chip solution - tuner, OFDM demodulator and channel decoder processor - and merges it onto a single chip for mobile TV handsets. The DVB-H standard uses the H.264 Codec (also known as MPEG-4, part 10) for audio/video and transmits in the 8MHz frequency at a data rate of 31 Mbits/s using COFDM modulation.
European DVB-H chip suppliers include Philips Semiconductors of The Netherlands, SIDSA of Spain and Imagination Technologies Ltd of the UK.
MediaFLO Network
Qualcomm plans to have its MediaFLO network ready for commercial service in 2006. The MediaFLO network will operate on Qualcomm‘s proprietary FLO (Forward Link Only) multicasting technology, which uses multicasting rather than the on-demand/individual bit stream approach of previous mobile video technologies. The network transmits content to users in a one-to-many fashion at no incremental cost to subscribers.
The MediaFLO network will ultimately operate over the 700MHz spectrum frequencies that Qualcomm acquired in June 2003. The network will eventually support 50 to 100 national and local content channels, including more than a dozen live streaming channels and numerous audio channels. MediaFLO will also offer what Qualcomm calls "clip-casting," which is delivery of content at times designated by the user.
The current market leader for mobile video in the US is Idetic Inc‘s MobiTV multimedia service, offered by operators Sprint PCS and Cingular (by way of its recent acquisition of AT&T Wireless). The service delivers video clips over the operators‘ cellular networks. Content partners include some of the largest media organizations in the country. The problem is that its frame rates are between six and 10 fps, below the 10 to 15 fps rate that is often considered the minimum for decent video viewing.
by Michael Thuresson

(March 2005 Issue, Nikkei Electronics Asia)
_xyz