[opendtv] RadioScape queries viability of DVB-H for mobile multimedia

  • From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
  • To: "OpenDTV (E-mail)" <opendtv@xxxxxxxxxxxxx>
  • Date: Mon, 16 May 2005 15:44:09 -0400

This article refers to the transmitter power required for
large area coverage of wide band signals, vs the same
wide area coverage of narrow band signals. Even if the
duty cycle is short, as it is in DVB-H, this doesn't
change the propagation characteristics of the signal.
The main advantage of the short duty cycle is to the
receiver's power requirement.

Of course, they too have their agenda to push.

Bert

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RadioScape queries viability of DVB-H for mobile multimedia

John Walko
(05/16/2005 8:01 AM EDT)
URL: http://www.eetimes.com/showArticle.jhtml?articleID=3D163103709

LONDON - Digital radio specialist RadioScape has raised
serious concerns about the technical and commercial
viability of using Digital Video Broadcast-Handheld (DVB-H)
technology for delivering multimedia services to mobile
handsets, suggesting that the alternate Digital Multimedia
Broadcasting (DMB) technology favoured by carriers in the
Far East is superior. Addressing the GSPx Mobile Conference
in Eindhoven, the Netherlands Tuesday (May 17), Les Sabel,
vice president of technology for RadioScape will outline
the results of the trials in Cambridge, England, that he
says show that the design of DMB networks can proceed using
essentially the same rules as for current DAB audio
networks.

He will stress that DMB, unlike DVB-H, is based on proven
DAB technology with spectrum, transmission towers and
capacity already available for it in most countries.

Sabel will note during his presentation that DVB-H is a
modification of Digital Video Broadcast - Terrestrial
(DVB-T) for handheld devices but has spectrum allocation
issues as many countries are currently using these
frequencies for analogue television.

"DMB is viewed by many as the next logical step in the
evolution of DAB," says Sabel. "More importantly, it could
also represent the next step in the evolution of mobile
phones delivering the vision of video and data on the move
that 3G promised but cannot deliver in a cost effective
and efficient manner. A one-to-many broadcast technology,
such as DMB, provides a broadband pipe of multimedia
services that the one-to-one approach of 3G can only
provide in small numbers and expensively."

Despite the huge impetus building around DVB-H , Sabel
says indications are that for that technology to work
effectively in mobile and indoor environments it will need
to use transmission parameters similar to DAB. This will
eliminate any real capacity advantages and still leave
DVB-H with the issue of transmission power requirements
due to its larger bandwidth.

"Our field trials show that good DMB reception can be
achieved with existing DAB transmitters that only use low
amounts of power to cover a large footprint," says Sabel.
He adds: "I have yet to see any comparative, quantitative
evidence for DVB-H but, recent discussions indicate that
for DVB-H to achieve the same footprint, network
providers will typically require a five times greater
density of transmitters."

According to Sabel, this will make DVB-H very expensive to
establish and run - let alone the possibility of public
concerns over yet more transmission towers. "DMB clearly
offers a much better, more cost effective solution for
operators that can be implemented now as it based on
proven DAB technology as can be evidenced by DMB pioneers
in countries such as Korea and China where trial systems
are already up and running."

He adds that recent studies of the power requirements
suggest that reliable mobile operation is unlikely with
DVB-H unless the network uses QSPK modulation. Coupled
with the propagation issues this throws up, Sabel says a
DVB-H network is likely to need a transmitter density that
is at least five times that of DAB/DMB networks.

The WorldDAB organization has been enhancing the existing
Eureka 147-based standard, notably adding an outer layer
coding (OLC) scheme. Service based enhancements, such as
Electronic Program Guides, conditional access and
multimedia object transfer have also been added and are
expected to be agreed and standardized within months.

RadioScape believes that these and the introduction of
Enhanced Stream and Packet modes provide the additional
error protection necessary for the robust delivery of
multimedia content mobile operators are seeking.

All material on this site Copyright 2005 CMP Media LLC.
 
 
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