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700 MHz Explained in 10 Steps
Last week we reported on the web giants Google, Yahoo and eBay setting aside their differences and joining forces with satellite television providers, demanding that they should have some say in what the FCC does with the 700 MHz spectrum.
The spectrum, currently owned by broadcasters, has been used for analog television. But it is set to be turned over to the government in 2009. Due to its broadcast-attractive physics (like its ability to penetrate walls), this spectrum is desirable for both broadband communications in general and public-safety uses in particular.
The FCC has described the 700 MHz as beachfront property, and has talked up the broadband capabilities of this spectrum swath. About 60 MHz of the former UHF (TV) spectrum is going to be reclaimed by the U.S. government and will be reallocated for public safety and commercial broadband networks. The TV channels using this spectrum are going to go dark on Feb. 19, 2009, if all continues as planned.
This is going to be an area of active debate for months to come, and we have prepared a little cheat sheet for you to better understand the past, the present and the future of 700 MHz.
The 700 MHz band is divided into two categories – the lower 700 MHz band and the upper 700 MHz band. The lower band is 48 MHz while upper band is 60 MHz.
In 2002, FCC re-allocated the 698-746 MHz band (Lower 700 MHz band) that was originally used by TV Channels 52-59. The upper band was for TV Channels 60-69. The reallocations come as FCC pushes hard for the television business to transition to DTV.
This is all part of the Ultra High Frequency (UHF) band, which once inspired a movie, UHF, starring Weird Al Yankovic and Michael Richards of Seinfeld. A large swathe of UHF spectrum has been reallocated for different uses. (#)
Aloha Partners is the largest owner of lower band 700 MHz spectrum. Qualcomm is another owner of this slice of the spectrum, and is currently deploying its MediaFLO Mobile TV network over these frequencies. Aloha has a plan to use former channels 54 and 59 for its HiWire Mobile TV.
In February 2006, the U.S. House of Representatives voted 216-214 and approved a budget package that would require analog television broadcasters to clear the 700 MHz airwaves on Feb. 17, 2009. President George W. Bush signed the transition package into law and approved $1.2 billion in funding for public safety communications.
Of the total 60 MHz, 24 MHz of the spectrum is reserved for public safety, while rest is going to be auctioned off. The auctions are expected to fetch $10 billion, though the total could hit the $30 billion mark.
Frontline Wireless, a company co-founded by former FCC chairman Reed Hundt, wants to build a contiguous nationwide broadband public safety network that uses 12 MHz from public safety spectrum, and 10 MHz from the commercial spectrum. Frontline rival Cyren Call Communications, started by Nextel founder Morgan O’Brien, has proposed a similar network but that uses 30 MHz of the 60 MHz that is part of the commercial spectrum. Cyren Call wants the government to award it the spectrum, while Frontline plans to bid competitively.
How will current analog TV users still get signals once the switch is made? Via set-top converter boxes, which the government will help pay for (each household will be able to apply for two $40 vouchers). This could be the biggest fly in the auction ointment, especially if the transition looks like it won’t go smoothly. Already, the administration is drawing criticism for dragging its feet. Watch for TV commercials to start soon.
Alcatel-Lucent have developed a CDMA 2000 system that uses the 700 MHz frequencies and is targeted at the public safety agencies. It has push to talk and multimedia capabilities.
According to some estimates, the cost of building a nationwide wireless network over the 700 MHz spectrum is around $2 billion versus a nationwide 1900MHz PCS that costs approximately $4 Billion. The costs are lower in rural areas, due to less interference issues and wide-open spaces. That’s because each tower broadcasting at 700MHz covers twice as many square miles. Some estimates say that a single 700 MHz tower can cover 20-miles. (#)
Further reading: Mobile Radio Technology, Daily Wireless.
Om, while 700 MHz has superior penetration, aren’t there tradeoff’s in bandwidth vs. 1900 and 2400 MHz?
Very informative !
Rob,
while there seem to be some trade offs, I am not exactly sure on the bandwidth limitations and have a few phone calls out and will answer your question after I get a chance to report some more on this.
Appreciate your patience!
Rob,
Absolutely there is a tradeoff in bandwidth. Coverage and penetration are phenomenal, but 700MHz is damn near useless for anything even approaching even the low end of “broadband”. Raindeer explained this very well here, I thought:
http://gigaom.com/2007/03/09/google-ebay-yahoo-700mhz/#comments
With similar factors to weigh, this is why so many municipalities and terminals have upgraded from 900 to 2.4 and/or 4.9
Nice post Om, very informative info on the spectrum. Thanks!
-Michael
When does satelite telephony re-emerge?
Very informative.
Some basic spectrum tradeoffs:
The flip side of better propagation is that lower frequencies make for a more difficult or more broadly spaced out sprectral re-use plan. Modern mobile networks maximize their spectrum by re-using the same frequency blocks/pairs in non-adjacent cells.
The physics lead to economics. The UHF band is best suited to sparse and distributed demand sets or broadcast type applications. Thus the discussions about public safety (smaller demand set, lower cost network, value of broad coverage and penetration) and broadcast to mobile devices.
Om, I don’t know who you are calling, but as an actual RF Engineer who has designed and optimized netowrks at 800 MHz, 1.9 GHz, 2.4 GHz, 2.6 GHz, and other frequencies, I can tell you that the above post by H is pretty much spot on as a generality.
Jesse
First of all you really got to take me off your spam list. I know i trouble you a lot but then, so does everyone else.
I emailed folks from some of the vendors to get a better sense of the spectrum potential, and also some carriers in case you were interested.
Also, there might be an email waiting for you somewhere in your trash folder.
H: thanks for your kind comments and feedback.
OM, does this mean that the GOOG / YHOO / DISH / DTV / EBAY consortium, which was set-up to petition the FCC on the upcoming 700 mhz spectrum auction is just a waste of time (as goes broadband)? In other words, that group, or a sub-set of that group can’t team up to build a broadband network in the 700 mhz band b/c the 700 mhz spectrum doesn’t work well for broadband? If that’s the case, then why would they be petitioning the FCC on it?
If anybody could give some concrete calculations on how much bandwidth one could stuff in 60Mhz of spectrum I would be much obliged. I only have a degree in Public Administration, so for most people I’m not worthy to sharpen pencills
But my understanding has been that jamming more than two bits in the 700 Mhz spectrum is a bit tough, which leave at most 120Mbits in 60Mhz block. One has to share this and therefore as our good friend H sais. Broadcast or maybe, emergency services. Both ofcourse being limited, though probably firefighters would be very happy with having indoor coverage.
Just a quick note to clarify my points earlier.
700Mhz can be used for traditional commercial mobile type applications. The original US and Canadian cellular networks are at 800MHz so the economics and performance can be reasonable. However, a 700Mhz network is more complex to design and can be more expensive and less efficient, because of spectral reuse challenges, for high demand urban environments than a 1.7Ghz to 2.1Ghz type design. It can be done with a positive business case but it’s not the ideal spectrum for a high traffic dense urban demand set.
I would think that a greater question regarding the Ebay/Google/etc. interest is whether the US market can support a 5th, 6th, or 7th service provider in a capital intensive business.
Raindeer, 60 MHz is plenty of spectrum for a single carrier and could probably support 2 carriers just fine. BUT there is not 60 MHz of spectrum available, there is only 36 MHz that is going to be auctioned off. The 24 MHz that is going to public safety has all kinds of weird rules applied to how it can be channelized that make it unsuitable for things like WiMAX and LTE. This channelization was done so that voice oriented networks would have a consistent set of channels nationwide, but like most things the FCC does, it is based on the technology of 10 years ago, not the technology of today or 5 years from now.
By the way, here is how I would estimate per cell throughput: Expected efficiency at N=3 reuse is 2 bits/Hz. N=3 reuse means 1/3 of total spectrum per cell. So, for 60 MHz of spectrum, per cell throughput would be 40 Mbps. Once you factor in Layer 2 and 3 overhead you are down to about 30-35 Mbps (note that this is aggregate, not full-duplex).
PS Om, you are not on MY spam list. I don’t see any e-mails from you in my Comcast screened mail, either. Internet gremlins?