[opendtv] Qualcom OFDM networks with MediaFlo
- From: Craig Birkmaier <craig@xxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Wed, 10 Nov 2004 09:40:39 -0400
Please note that I have changed the subject of this thread to
actually identify what we are discussing...
At 4:48 PM -0500 11/9/04, Manfredi, Albert E wrote:
>Ooops. Qualcomm's proposal for 700 MHz is for
>cdma2000 or WCDMA. Not COFDM. This is the big stick
>system designed especially for small portables.
Once again we have caught Bert shooting from the hip, at a target he
missed by a mile.
As is often the case with threads on this list, however, the spread
of disinformation often causes list members to research their
positions in more detail to get to the truth.
After reading the exchanges between Bert and Bob, I decided to look
deeper into what Qualcom is doing with the new MediaFlo service. What
i discovered is not only encouraging, but it may well have a good
chance at success. Most important, however, this is not going to be
another broadcast TV infrastructure.
What it IS, is a creative use of broadcast OFDM technology to ENHANCE
the existing two-way CDMA infrastructure in a backward compatible
way, delivering MANY of the services and benefits that I have been
advocating via the "spectrum utility" concept.
Among the major features of this service are:
1. The ability to download specific content into local cache in cell
phones and other devices including PDAs and portable computers. The
system is designed to use off peak capacity to deliver content to
which the user has SUBSCRIBED to local cache, so that it can be
viewed on demand, rather than initiating a demand based two-way
transaction using the limited capacity of the unicast CDMA network.
2. The ability to deliver a limited number of live streaming video
channels during peak demand periods.
3. The ability to support interactive applications that link IP
multicast content with true two-way back channel services.
4. The ability to deliver multiple channels of live streaming audio services.
The MediaFlo IP multicast network will operate as a utility, allowing
content providers and network operators to create a wide range of
data broadcast services that can incorporate audio and video with
other forms of digital media content. The marketplace will drive the
services that will be delivered via this network.
Now for some specific comments.
The link that Bob Miller posted yesterday is the best resource that I
found regarding the actual technology and structure of the proposed
Qualcom national IP Multicast network using spectrum they have bought
- specifically channel 55 in the 700 MHz band. Here is another with
some additional information:
http://www.wirelessdevnet.com/news/2004/oct/12/news2.html
>The FLO multicast technology under development at QUALCOMM is
>designed for markets where dedicated spectrum is available and where
>regulations permit high-power transmission from one or a small
>number of towers. As in Platinum Multicast, FLO transmits packets
>using OFDM. It is complementary to existing cellular networks
>because interactive services are supported within the mobile device
>using the CDMA2000 1X, 1xEV-DO or WCDMA cellular link. FLO is
>intended as an alternative to other multimedia multicasting
>technologies, such as DVB-H. Compared to other multicast
>technologies, FLO technology is designed specifically for use in
>mobile devices where low battery power consumption is critical,
>enabling it to offer superior mobility, power efficiency and
>coverage characteristics -- considerations that are fundamental to
>the mobile handheld consumer usage environment.
The physical infrastructure that Qualcom will use is virtually
identical to that which I have been describing for COFDM-based SFNs
for DTV. Transmission will come from "one or a small number of
towers," potentially using tall buildings in urban areas. The power
levels are not stated, but high power to a company in the cell phone
business could be 1000 watts. More likely, the system will use power
levels in the range of 10Kw, as is the case with several DVB-T
deployments.
If you dig deeper into the white papers on this system you will learn
that OFDM was chosen in part because of its low power consumption
requirements. The silicon requirements for OFDM are well defined; it
is possible to operate an OFDM receiver at very low power levels,
trickling data into local cache (either flash memory or small hard
drives (or a combination of both to limit drive access). Using CDMA
unicast is highly inefficient, both in terms of spectral efficiency
and power consumption, however, the MediaFlo infrastructure is
designed to leverage the existing CDMA infrastructure in markets
where the new OFDM infrastructure is not yet available. OFDM is just
a power efficient, one-way modulation scheme, which will be used to
carry IP packets that would otherwise clog the CDMA networks.
Please note that this is exactly the same load balancing scheme that
I have been talking about for years with respect to tying DTV data
broadcasting to the Internet. You use IP Multicast to deliver the
content that is in demand by large numbers of users, freeing up the
unicast network to handle demand based data transactions - and, let's
not forget, cell phone services.
Here is another reference that talks about the transmission infrastructure:
http://www.convergedigest.com/Wireless/broadbandwirelessarticle.asp?ID=12815
QUALCOMM said that by deploying high-power transmitters on tall
towers provides superior coverage with 30 to 50 times fewer towers
than cellular and higher frequency-based systems.
For those who are interested in more details about the Qualcom and
MediaFlo, here are two useful links:
MediaFlo
http://www.qualcomm.com/mediaflo/index.html
There is a very good overview document (pdf) located in the press room:
http://www.qualcomm.com/mediaflo/press.html
This link describes the Qualcom technology that extends CDMA to
support multicasts to specific groups of CDMA "clients." This service
is already deployed in many markets and dovetails with the new
Premiere multicast network that will be OFDM based.
1xEV-DO Gold Multicast
http://www.qualcomm.com/technology/1xev-do/goldmulticast.html
Regards
Craig
----------------------------------------------------------------------
You can UNSUBSCRIBE from the OpenDTV list in two ways:
- Using the UNSUBSCRIBE command in your user configuration settings at
FreeLists.org
- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word
unsubscribe in the subject line.
Other related posts:
