MediaFLO
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MediaFLO is Qualcomm's new technology to broadcast data to portable devices such as cell phones and PDAs. Broadcast data will include multiple real-time audio and video streams, individual, non-realtime video and audio "clips", as well as IP Datacast application data such as stock market quotes, sports scores, and weather reports.[1]
The "F-L-O" in MediaFLO stands for Forward Link Only [2], meaning that the data transmission path is one-way, from the tower to the device. The MediaFLO system transmits data on a frequency separate from the frequencies used by current cellular networks. In the United States, the MediaFLO system will use frequency spectrum 716-722 MHz, which was previously allocated to UHF TV Channel 55.[3][4]
It is a competitor to the Korean T-DMB standard and the European DVB-H standard. Devices including MediaFLO were first introduced by LG and Samsung at CES 2006 in Las Vegas. On December 1st, 2005 Verizon Wireless and Qualcomm announced partnership for the launch of the MediaFLO network, and Verizon launched the service commercially as part of its VCAST offering on March 1, 2007, marketing the MediaFLO-specific technology/service as "VCAST TV"[5]. A similar announcement was made by AT&T Mobility in February 2007.[6] AT&T Mobility launched their MediaFLO servce in May 2008[7]. Qualcomm is also conducting MediaFLO technical trials internationally, with the intention of forming partnerships with existing multi-channel content providers/service operators.
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[edit] Technology
The protocol was developed because of the inherent spectral inefficiency of unicasting high-rate full-motion video to multiple subscribers. Additionally traditional analog television and over-air digital television signals (DVB-T) were difficult to implement on mobile devices due mostly to power consumption issues. In addition, the transmission need not be as high a resolution than would be needed for a larger display. MediaFLO streams are only 200-250 kbit/s, which would be insufficient for a larger screen size.[8]
[edit] Modulation and Coding
In the current US implementation, FLO is transmitted by a network of high-power broadcast transmitters operating at powers as high as 50 Kilowatts. This allows for a coverage area of a transmitter to be as large as 30-40 km. [8]
The transmission is an encrypted OFDM set of QAM signal sent on a 5.55 MHz channel centered at 719 MHz (The former UHF TV Channel 55). All of the transmitters send the same signal and use the same frequency. This allows the mobile to decode the signal from more than one transmitter in the same way that it might if it was a delayed version from the same transmitter.[8]
Some other operational parameters of MediaFLO are as follows:
| Parameter | Value |
|---|---|
| Total number of QAM sub-carriers | 4096 |
| Number of guard sub-carriers | 96 |
| Number of pilot sub-carriers | 500 |
| Multicast Logical Channels (MLC) | 1-7 |
| Modulations used | QPSK (4 symbol constellations), 16QAM (16 symbols) |
| Spacing between sub-carriers | 1.355 kHz (5.55 MHz / 4096 sub-carriers) |
| Modulated symbol (chip) duration | 0.18 μs (1/5.55 MHz) |
All of the barrier (data) traffic occurs within an MLC using the 3500 non-overhead subcarriers. The protocol also contemplates a certain amount of inter-symbol time spacing, to allow for the effects of multi-path transmission and reception.
| Parameter | Value |
|---|---|
| Total OFDM symbol interval (TS) | 833.33 μs |
| Bearer Data traffic (TU) | 738.02 μs |
| Window interval (TWGI) | 3.06 μs |
| Cyclic Prefix (TFGI) | 92.25 μs |
There's a window time TWGI included both before and after each OFDM symbol. However, since this window is shared between each two consecutive symbols, TS = TU + TWGI + TFGI.
[edit] Commercial Deployment
As of December 2007, Verizon Wireless was the only wireless provider selling equipment and subscriptions for Qualcomm's MediaFLO service. Verizon Wireless utilizes its EVDO network to authenticate mobiles and provide the decryption keys necessary to decode the programming.
There are currently 9 channels being broadcast[9]:
- CBS Mobile, containing a mixture of sports and other CBS content
- Fox Mobile
- NBC 2GO
- NBC News 2GO which sometimes has a live feed of MSNBC while other times has repeats of CNBC programming.
- Comedy Central
- ESPN MobileTV, frequently simulcasting live sporting events from their family of networks
- MTV
- Nickelodeon, 24/7 children's programming.
- A free preview channel.
However, starting on Sunday May 4, 2008, AT&T will be launching a MediaFLO powered broadcast TV service[10]
[edit] References
- ^ Qualcomm press release on "Live Datacasting", 05Apr2006, http://www.qualcomm.com/press/releases/2006/060405_mediaflo_usa_demonstrates.html
- ^ Origins of "FLO" name; main page, FLO Forum website (http://www.floforum.org)
- ^ 01Nov2004 Qualcomm press release regarding 700 MHz spectrum usage for MediaFLO -http://www.qualcomm.com/press/releases/2004/041101_mediaflo_700mhz.html
- ^ Dailywireless.org- http://www.dailywireless.org/2007/01/07/verizon-launching-mediaflo/
- ^ 01Dec2005 Qualcomm press release regarding commercial launch of MediaFLO on Verizon Wireless Network - http://www.qualcomm.com/press/releases/2005/051201_verizon_wireless_announce.html
- ^ AT&T Selects QUALCOMM’s MediaFLO USA for Mobile Entertainment Services - http://www.qualcomm.com/press/releases/2007/070212_att_selects_s.html
- ^ NYTimes.com via Yahoo! Finance: Mobile TV Spreading in Europe and to the U.S., May 6, 2008
- ^ a b c d e IEEE Transactions On Broadcasting, Vol. 53, No. 1, March 2007, http://www.qualcomm.com/common/documents/articles/FLO_physical_layer_IEEE.pdf
- ^ MediaFLO USA - On Air Now
- ^ AT&T goes with the FLO for mobile TV
[edit] See also
- Mobile TV a term for the category of techniques
- DVB-H (Digital Video Broadcasting - Handheld)
- DVB (Digital Video Broadcasting)
- DMB (Digital Multimedia Broadcasting)
- DAB (Digital Audio Broadcasting)
- DRM (Digital Radio Mondiale)
- Electronic Service Guide
