4 ms·

> LTE has been modified by a few companies so that it can operate in the same unlicensed spectrum that Wi-Fi uses (called LTE-U) It looks like to me that the p

> LTE has been modified by a few companies so that it can operate in the same unlicensed spectrum that Wi-Fi uses (called LTE-U) It looks like to me that the problem is they decided to use the same bands of wifi. If you're going to be using the unlicensed spectrum expect interference.

thfuran 8y ago
So you think instead people should be playing around with SDR on licensed spectrum?
- vvanders 8y ago
  If you've got a license for the bands, sure. I can blast IQ on 14.025Mhz if I feel like it assuming I stay within baud limits. Pretty cheap and easy to get a ham license these days. Cell phones have multiple radio chips, I don't see issues with allowing SDRs on the unlicensed bands.
rayiner 8y ago
But that's what you'd be doing if you permitted user-controlled transmissions from ordinary cell phones. The analog hardware in a cell phone is tied to specific frequency bands. So you'd have user-controlled transmissions, not mediated by the cell towers, on the LTE bands. Also, LTE-U was interfering with Wi-Fi. In general, the unlicensed bands would be a lot more useful if they weren't quite so unlicensed and every radio had to follow certain basic rules.
- namibj 8y ago
  Actually there are rules, at least in Germany, and I assume the same is true for the US. You can use a microwave heating gun, i.e., a device that shoots a beam of microwave energy to serve similar to a leaf-blower sized hair dryer, in the ISM band(s), which might be able to saturate the LNA in 2.4 GHz radios (depending on where it is placed relative to the band-pass), but you are not allowed to use a broad-band, not-caring-about-others telecommunications radio on the same frequency. For some lower frequencies I could use them to transmit power via a resonant, one-wire transmission line to a quadrocopter to save on the weight of insulation, possibly by using aluminium-clad single mode fibers to get data capacity at the same time, so I can reduce the weight of the tether reducing overall power usage, weight and size, but if I were to use the same frequency for a direct-sequence-spread-spectrum (GPS-style) radio-location-beacon network, that would not be allowed, or only within certain restrictions usually based on both EIRP/PEP/PA-in power and techniques that allow for friendly coexistence between users of the same spectrum, i.e. with CSMA/CA or restrictions to send only 1% of the time, averaged over e.g. 24h or so.
  - vvanders 8y ago
    Yup, just because it's an unlicensed band doesn't mean there aren't other restrictions on it.
- vvanders 8y ago
  Pretty sure OP was talking about using the 2.4Ghz/5Ghz unlicensed spectrum. Obviously allowing user transmissions on licensed bands is a bad idea.

thfuran 8y ago

So you think instead people should be playing around with SDR on licensed spectrum?

vvanders 8y ago
If you've got a license for the bands, sure. I can blast IQ on 14.025Mhz if I feel like it assuming I stay within baud limits. Pretty cheap and easy to get a ham license these days. Cell phones have multiple radio chips, I don't see issues with allowing SDRs on the unlicensed bands.

rayiner 8y ago

But that's what you'd be doing if you permitted user-controlled transmissions from ordinary cell phones. The analog hardware in a cell phone is tied to specific frequency bands. So you'd have user-controlled transmissions, not mediated by the cell towers, on the LTE bands. Also, LTE-U was interfering with Wi-Fi. In general, the unlicensed bands would be a lot more useful if they weren't quite so unlicensed and every radio had to follow certain basic rules.

namibj 8y ago
Actually there are rules, at least in Germany, and I assume the same is true for the US. You can use a microwave heating gun, i.e., a device that shoots a beam of microwave energy to serve similar to a leaf-blower sized hair dryer, in the ISM band(s), which might be able to saturate the LNA in 2.4 GHz radios (depending on where it is placed relative to the band-pass), but you are not allowed to use a broad-band, not-caring-about-others telecommunications radio on the same frequency. For some lower frequencies I could use them to transmit power via a resonant, one-wire transmission line to a quadrocopter to save on the weight of insulation, possibly by using aluminium-clad single mode fibers to get data capacity at the same time, so I can reduce the weight of the tether reducing overall power usage, weight and size, but if I were to use the same frequency for a direct-sequence-spread-spectrum (GPS-style) radio-location-beacon network, that would not be allowed, or only within certain restrictions usually based on both EIRP/PEP/PA-in power and techniques that allow for friendly coexistence between users of the same spectrum, i.e. with CSMA/CA or restrictions to send only 1% of the time, averaged over e.g. 24h or so.
- vvanders 8y ago
  Yup, just because it's an unlicensed band doesn't mean there aren't other restrictions on it.
vvanders 8y ago
Pretty sure OP was talking about using the 2.4Ghz/5Ghz unlicensed spectrum. Obviously allowing user transmissions on licensed bands is a bad idea.