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Even if we get cognitive radio and share spectrum there are still fundamental and engineering limits that mean spectrum will remain scarce. You're either sharin

Even if we get cognitive radio and share spectrum there are still fundamental and engineering limits that mean spectrum will remain scarce. You're either sharing one spectrum with the entire world for HF (because of ionosphere bouncing) or everything that is in line of sight for the vast majority of the spectrum. That means a lot of people are using the same 0.1-18 GHz. Once you get above 18 GHz or so then the propagation gets a lot worse, so it's less than even line of sight, but engineering problems with phase error start meaning higher order modulations are much more difficult to achieve. Spectrum is always going to be scarce. That's why cables and fibers are always going to be important. Each one allows you to use the entire span all to yourself.

deleted 6y ago
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hinkley 6y ago
If there are ways to minimize interference, that suggests that there are fractions of the spectrum that work better than others. If that fraction is not enormous, that resource will eventually be constrained. If not everywhere, or all the time, then in certain suboptimal situations. Like a historic neighborhood, in a pocket valley, during bad weather.
user5994461 6y ago
Agreed. The title is disappointing, especially coming from the IEEE. Anybody who works on radio quickly understands that the radio spectrum is the most precious most scarce resource on the planet.
- at-fates-hands 6y ago
  Not knowing much about radio spectrum, but its a finite resource right? There's no way to expand the spectrum, or do something similar like what they did in the early days of wireless technology where they transitioned from TDMA (time division multiple access) to CDMA (code division multiple access) in order to expand the number of user you can put on a data stream. Am I right to look at radio spectrum as a finite resource?
  - sharpneli 6y ago
    Those examples are ways to use the spectrum more efficiently. But the amount we have does not change. It is finite indeed. But it’s also not something that’s consumable. Imagine it as a fixed sized room. If you move stuff out of a corner you can reuse it infinitely, but there can only be so much stuff in there on a particular moment.
- bluedevil2k 6y ago
  With literally an unknown market price. 15 Mhz of spectrum in the United States is worth far more than 15 MHz of spectrum in Norway. As we expand from LTE to 5G to someday 6G, the price changes as well for a block of spectrum. Price is also a factor of competition in the market, and why the current situation in the United States with only 3 major wireless telecom potentially troublesome, with the only reprieve being that companies like Google and Liberty/Dish and private equity getting into the auctions.
jacquesm 6y ago
You are definitely not going to be sharing your spectrum with 'everything that is in line of sight' by default, that only goes for substantial power levels of directed antennae. At low power levels your signal will be below the noise floor long before you get to your line-of-sight limitations, and even if it wouldn't be, someone 'sharing' that frequency with you will be locally much louder than you. IRL the situation is much more complex than that still, but this is a useful approximation to keep in mind when thinking about these matters.
- superkuh 6y ago
  It sounds like you're talking about "IRL" but then ignoring the fact that if you're not a corporation paying the big bucks, you transmit from just above ground level, not from some tower with 30m height above terrain. Line of sight for most people is much shorter than you think because of trees, buildings, hills/valleys, etc. It's the limiting factor for VHF and up, not transmission power or antenna pattern gain.
  - jacquesm 6y ago
    Line of sight at groundlevel (the horizon) is 5 Km or thereabouts. You'll run into some obstacle long before you run out of room unless you are very lucky with your sightlines. The only places where you can get those distances is when you're in relatively open country, even in an urban setting most telco infra is not more than 5-6m above the nearest high building. I had some other trickery in mind such as phased array antenna, frequency hopping and so on.

deleted 6y ago

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hinkley 6y ago

If there are ways to minimize interference, that suggests that there are fractions of the spectrum that work better than others. If that fraction is not enormous, that resource will eventually be constrained. If not everywhere, or all the time, then in certain suboptimal situations. Like a historic neighborhood, in a pocket valley, during bad weather.

user5994461 6y ago

Agreed. The title is disappointing, especially coming from the IEEE. Anybody who works on radio quickly understands that the radio spectrum is the most precious most scarce resource on the planet.

at-fates-hands 6y ago
Not knowing much about radio spectrum, but its a finite resource right? There's no way to expand the spectrum, or do something similar like what they did in the early days of wireless technology where they transitioned from TDMA (time division multiple access) to CDMA (code division multiple access) in order to expand the number of user you can put on a data stream. Am I right to look at radio spectrum as a finite resource?
- sharpneli 6y ago
  Those examples are ways to use the spectrum more efficiently. But the amount we have does not change. It is finite indeed. But it’s also not something that’s consumable. Imagine it as a fixed sized room. If you move stuff out of a corner you can reuse it infinitely, but there can only be so much stuff in there on a particular moment.
bluedevil2k 6y ago
With literally an unknown market price. 15 Mhz of spectrum in the United States is worth far more than 15 MHz of spectrum in Norway. As we expand from LTE to 5G to someday 6G, the price changes as well for a block of spectrum. Price is also a factor of competition in the market, and why the current situation in the United States with only 3 major wireless telecom potentially troublesome, with the only reprieve being that companies like Google and Liberty/Dish and private equity getting into the auctions.

jacquesm 6y ago

You are definitely not going to be sharing your spectrum with 'everything that is in line of sight' by default, that only goes for substantial power levels of directed antennae. At low power levels your signal will be below the noise floor long before you get to your line-of-sight limitations, and even if it wouldn't be, someone 'sharing' that frequency with you will be locally much louder than you. IRL the situation is much more complex than that still, but this is a useful approximation to keep in mind when thinking about these matters.

superkuh 6y ago
It sounds like you're talking about "IRL" but then ignoring the fact that if you're not a corporation paying the big bucks, you transmit from just above ground level, not from some tower with 30m height above terrain. Line of sight for most people is much shorter than you think because of trees, buildings, hills/valleys, etc. It's the limiting factor for VHF and up, not transmission power or antenna pattern gain.
- jacquesm 6y ago
  Line of sight at groundlevel (the horizon) is 5 Km or thereabouts. You'll run into some obstacle long before you run out of room unless you are very lucky with your sightlines. The only places where you can get those distances is when you're in relatively open country, even in an urban setting most telco infra is not more than 5-6m above the nearest high building. I had some other trickery in mind such as phased array antenna, frequency hopping and so on.