The term "white space" refers to portions of the licensed radio spectrum that licensees do not use all of the time or in all geographical locations. As of May 3, 2012, the National Association of Broadcasters (NAB) dropped its objection to white space communications. In an article in the National Journal, Federal Communications Commission Chairman Julius Genachowski was reported as saying that he is personally lobbying the military to help free more airwaves for private companies. And he has made it one of his signature goals to "unleash" more spectrum for mobile broadband.
As reported in an article in Technology Review, published by MIT, much of this activity was associated with Microsoft successfully demonstrating a white space communication system in February that caused no interference and achieved one gigabit per second (1Gbit/s) throughput.
With white space communications, in cities where there are unused UHF TV channels (for example, channels 21-51), this portion of the spectrum can be reused, in this case for a new WiFi upgrade. FPGAs have some unique characteristics -- such as reconfiguration -- that offer a way to solve the problem of needing to search for white space and then send data.
UHF television frequencies.
In the Microsoft system, sections of white space are used as individual channels. These channels are bundled together to get the full data rate. The ability of FPGAs to perform processing in parallel makes them particularly attractive for this type of product. Multiple channels can be dynamically loaded into the FPGA's logic based on current conditions. The inclusion of Ethernet and ARM processors can allow one to implement a DSL or cable modem with white space communication capabilities.
Depending on location, transceiver and user settings, and dynamic conditions, the host processor will load one or more 802.11a/b/g/n, WiMax, or super-WiFi channels into the FPGA. Data could be duplicated on different bundles to give greater range or to make up for intermittent interference -- to make up for errors, for example.
There is much to be considered given the greater bandwidths available. It will be most interesting to see how this all comes together to make a new super-WiFi. What do you think about the idea of having faster, longer-range, interference-free WiFi?
rwender 8/22/2012 5:10:32 PM User Rank Clever Clogs
Reconfigurable IF Filter for Whitespace Apps
How useful do you think a dynamically reconfigurable Intermediate Frequency (IF) filter would be for these Whitespace applications?
We are developing a 125MSPS, 14-bit ADC that has an "Analog FIR" filter in front of the ADC. The filter will be programmed by setting bias currents on a bunch of gm elements (each gm element acts like a tap in a digital FIR filter). With this configurable filter/ADC combination you can change the bandpass in front of the ADC on the fly.
The next Steps by industry include setting standards
The next steps by industry include setting standards for white-space communications, holding technical trials of the standards, and codifying the standards into FCC code.
Duane Benson 8/20/2012 1:59:55 AM User Rank Blogger
Hopping cool
When I first read this, I missed that this involves frequency skipping to hunt down and utilize open bandwidth here and there. That strikes me as being potentially huge.
I can envision a state where different devices follow a protocol to determine who gets priority, what devices can share frequency and what need solo access. With vertually everything on the air being digital these days, Just about any two way communications could get in on the protocol. Very cool.
@Adam: Re: "it would be interesting to see Microsoft doing FPGA work"
Then, you might be interested in the Kiwi project at Microsoft Research :-)
"The Kiwi project aims to make reconfigurable computing technology like Field Programmable Gate Arrays (FPGAs) more accessible to mainstream programmers. FPGAs have a huge potential for quickly performing many interesting computations in parallel but their exploitation by computer programmers is limited by the need to think like a hardware engineer and the need to use hardware description languages rather than conventional programming languages."
Duane Benson 8/16/2012 12:34:58 PM User Rank Blogger
Re: Faster, longer-range, interference-free WiFi
I would say that cross-over point is pretty close. In fact, it we could really look at the way the majority of people use TV and Internet, it would not surprise me if that point has already passed.
My first thought when reading that was that it's pretty important to ensure that there isn't interference with television channels. But then I thought about my own case. My TV is connected via my fiber connection to my phone company so wireless TV transmission isn't an issue at all for me. Even if I did use an antenna, my TV is a 15 year old 19" set that is rarely used for more than a little background noise.
There certainly are some people for whom TV spectrum is important, but it is or has lost its relevance for a very large portion of the population here in the U.S.
Re: "What do you think about the idea of having faster, longer-range, interference-free WiFi?"
Well gee, when you put it like that, who could argue!? :-) I think the longer range potential is something everyone would welcome.
Since the Super WiFi proposals use the white spaces between TV channel frequencies, I think one of the concerns is TV interference. However, I am starting to wonder when we'll hit the crossover point where WiFi is more important to the masses than TV... (It is for me - already!)
When extreme thermal cycling causes circuit boards and chip packages and the silicon die in the packages to expand and contract at different rates, problems may ensue.
In order to simulate a design we need models that represent the functionality and timing characteristics of our design elements, but the timing aspects of these models may be based on uncertain data.
Designing high-temperature electronics can present many challenges for "down-hole" petroleum equipment, ovens and micro-waves, automotive, medical, aerospace, and other applications.
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