The "FLO" in MediaFLO stood for
Forward Link Only, meaning that the data transmission path is one way, from the tower to the device. The MediaFLO system transmitted data on a frequency separate from the frequencies used by current mobile telephone networks. In the
United States, the MediaFLO system used frequency spectrum 716-722 MHz, which had previously been allocated to
UHF TV channel 55.01Nov2004 Qualcomm press release regarding 700 MHz spectrum usage for MediaFLO FLO was standardized within
ETSI as TS 102 589, and has components standardized within the
Telecommunications Industry Association (TIA 1099, 1102, 1103, 1104, 1120, 1130, 1132, 1146 and 1178.) MediaFLO was a competitor to the Korean
T-DMB, the Japanese
1seg and the European
DVB-H standards. Qualcomm conducted MediaFLO technical trials internationally, with the intention of forming partnerships with existing
multi-channel content providers and service operators, but has since discontinued development. 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-the-air terrestrial digital television signals (
DVB-T) were difficult to implement on mobile devices, due mostly to issues of
power consumption.
ATSC, used only by the
United States and its neighbors, also has difficulty even with fixed reception due to
multipath, and mobile
ATSC-M/H (which is
free-to-air from individual
TV stations) was not finalized until 2008. In addition, the transmission need not convey as high a resolution as would be needed for a larger display. MediaFLO streams are only 200-250 kbit/s, which would be insufficient for a larger screen size. In the now defunct United States implementation, FLO was transmitted by a network of high-power broadcast
transmitters operating at
effective radiated powers as high as 50 kilowatts. This allowed for a coverage area of a transmitter to be as large as . The activation of many of these transmitters were delayed due to the official end of analog TV broadcasting on channel 55
being delayed. Immediately following the transition, the FLO network was expanded to several new markets, and coverage was enhanced in some existing ones. The transmission was an encrypted
OFDM set of
QAM signals sent on a 5.55 MHz channel from 716 to 722 MHz (former
UHF TV channel 55). The
band was
auctioned-off by the
Federal Communications Commission (FCC) and known as the "Lower 700 MHz Block D". Qualcomm also bought, in a later auction, the use of former analog UHF TV channel 56 (722-728 MHz) in Boston, Los Angeles, New York, Philadelphia and San Francisco for additional services. However, this is owned by Manifest Wireless (a subsidiary of
Dish Network's Frontier Wireless) in most other
media markets, where ATSC-M/H signals were
on air. All of the transmitters sent the same signal and used the same frequency, forming a
single-frequency network. This allowed the mobile to decode the signal from more than one transmitter in the same way that it might if it was a
multipath-delayed version from the same transmitter. All stations used
callsign WPZA237, but each has an identifier indicating its group and number. For example, one station in the
metro Atlanta media market was ATL-006, while another was ATL-014. Some other operational parameters of MediaFLO are as follows: All of the bearer (data) traffic occurred 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. There is 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. For
conditional access,
Verizon Wireless utilized its
EVDO network to authenticate mobile handsets and provide the
decryption keys necessary to decode the programming. Because of this, users who block data use to prevent unauthorized charge were also blocked from viewing any channels, including the preview channel. == See also ==