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Google leads 'white-space' trial in South Africa

3/27/2013 10:51 AM EDT
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Bert22306
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re: Google leads 'white-space' trial in South Africa
Bert22306   3/27/2013 8:03:28 PM
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I've never understood why this "white space" concept gets so much media hype. TV channels are very narrow, compared with WiFi, WiMAX, or 3G/4G channels. which means you need to aggregate many of them, at least 3 and often more than that, to begin to match what the broadband wireless standards need. The TV channels, even the UHF channels, are at much lower frequencies than any of the broadband wireless schemes out there now. Which means they are less compatible with cellular schemes, simply because they might just travel far enough to interfere with other cerlls on the same frequency, within a cellular mosaic. So for that reason too, they aren't ideal. If people really do use over-the-air TV, then any close-by "white space" user could easily overwhelm the signal strength of somewhat distant TV stations, on many TV sets curreently on the market. Adjacent channel selectivity, and even selectivity for some channels that are NOT adjacent, can be on the order of 30 dB and sometimes even less than that, in sets on the market. So even in this regard, use of TV white spaces may be ill advised. The math is not difficult. Run some scenarios and see for yourselves. Of course, TV white spaces provide some spectrum that could be put to use doing something other than TV. But they are hardly the only option, and these other uses can easily disrupt that spectrum's primary purpose. Mostly, though, there's nothing magic or even particularly innovative or insightful in any of this.

Mr Quattro
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re: Google leads 'white-space' trial in South Africa
Mr Quattro   3/29/2013 5:30:19 PM
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Bert I have to disagree with quite a lot of what you've said here. There's nothing magic or innovative or insightful about white space but white space is just frequency spectrum. On the other hand, there IS a whole lot of extremely innovative technology required to make dynamic spectrum access work in the real world. And work is does as has been unequivocally demonstrated in trials. You appear to be suggesting that it's no big deal and not very exciting. The rest of the world is pretty excited about the tens of billions of M2M connections that are forecasted for Smart Meters, Grids, Cities around the world and there is an undeniable momentum behind that happening. The value of this ecosystem is estimated variably from $1 trillion to $75 trillion and more depending on who you believe. Cisco recently suggested that it would be worth $14 trillion by 2020. GE published numbers back in December that broadly concur with these forecasts. MIT are more bullish. Whichever way you look at it, it is big and significant. Declaring an interest, I represent the Weightless SIG, an M2M Standards body with an M2M over white space proposition that is difficult to argue against. It provides the template for low cost, low power, ubiquitous connectivity that is simply not possible through legacy technologies. PAN tech (Bluetooth, Wi-Fi, Zigbee) has the right terminal price points but simply cannot provide the coverage required for many M2M applications. 2G/3G/LTE can provide the coverage but not the terminal price points nor the battery life needed to fit and forget wireless sensors. Weightless technology uniquely provides the best of both worlds.

Mr Quattro
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re: Google leads 'white-space' trial in South Africa
Mr Quattro   3/29/2013 5:30:48 PM
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I don't agree with your comments about interference. The FCC has set extremely stringent limits on adjacent channel emission and transmit power level and coupled with effective geolocation databases we are able to eliminate interference both to and from TV broadcast transmissions. The empirical testing and verification of this was one of the key objectives of the many trials that have taken place around the world. Ultra-low out-of-band emissions and reduced impact on TV receivers through waveform shaping mean that we really can deliver to the FCC regulations. The amount of white space that a technology can access is contingent upon the level of interference it causes to TV receivers. Well designed systems have minimal emissions outside of their selected channels and therefore cause little interference. This enables them to access more spectrum than would otherwise be the case. Weightless specifically selected a modulation and encoding technique that would result in best-in-class emissions, enabling the greatest possible availability of white space. The needs of M2M are very different to those for human communications and it's possible that your points about channel width for broadband wireless standards are correct. But for M2M there is no comparison - white space spectrum is superior in every way (notably bandwidth, cost and signal propagation characteristics) to telephony based technologies operating in the GHz bands. It is big and it is clever!

Mr Quattro
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re: Google leads 'white-space' trial in South Africa
Mr Quattro   4/1/2013 3:48:59 PM
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Bert22306 I came across a comment from last year in response to a story on this site about Neul's involvement in the Cambridge white space trial which you critiqued. I have to say that this also contained some fundamental factual errors. Do you have an undisclosed agenda? I'm happy to debate any of these points. Let's hear your objective arguments.

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