4 ms·

Maybe a dumb question but I don't see any mention of frequencies/power they use to test in the wiki. I'm a little fuzzy on cell bands but I thought they were a

Maybe a dumb question but I don't see any mention of frequencies/power they use to test in the wiki. I'm a little fuzzy on cell bands but I thought they were all restricted(lots of ham gear has cell bands explicitly locked out).

boxfire 10y ago
Software defined radio such as hackrf can use this.
- nobodyshere 10y ago
  Are you sure? hackrf usually can only provide half-duplex operation, and somewhat full duplex after certain tweaks. Still usb2.0 will be a limiting factor in this case. USRP boards will probably be a lot better.
  - meatmanek 10y ago
    HackRF/USB2 has enough bandwidth to do LTE, particularly since LTE can be configured to use between 1.4 and 20 MHz. I think the lack of full duplex or an FPGA on board would be the major limiting factors.
  - chemeris 10y ago
    As mentioned above, half duplex of HackRF would be a limiting factor, unfortunately.
- vvanders 10y ago
  Obviously but you need to TX/RX on some sort of frequency otherwise it's not really a radio :). I was just wondering if there's spectrum allocated for experimentation or if you'd be stepping on FCC rules by putting this into practice.
  - wolrah 10y ago
    If you're running both sides on SDRs you should be able to tweak the frequencies in use. Several LTE bands neighbor and/or overlap amateur radio bands, so adjusting the settings a bit should allow you to move your test operations in to a range that is trivial to gain permission to use. Bands 30 and 40 actually exist entirely within the amateur 33cm band, band 42 overlaps with 9cm, and band 46 overlaps with 5cm. Two of those also overlap with unlicensed spectrum, so there's extra room to play in that no one reasonable expects those bands to be clean anywhere people have electronics. If you have cooperative endpoint devices you could also bodge other more common LTE bands in to amateur frequencies. Band 31 is just a 20 MHz drop away from fitting in 70cm, and cutting down the duplex spacing could make part of band 8 usable in region 2. If you want commercial hardware to work it's probably best to stick to the first group, but if you're doing SDR on both sides and just want to experiment the second group should technically work.
    - chemeris 10y ago
      Speaking of UEs (aka LTE modems) - there is an open-source implementation add well. See srsUE and srsLTE.
- chemeris 10y ago
  HackRF can't do it, because it's only half-duplex. But there are plenty of full duplex SDR devices - check out UmTRX and USRP B210. We're also developing a really tiny high performance SDR specifically for LTE - http://XTRX.io http://XTRX.io
- kweks 10y ago
  The BladeRF or the upcoming LimeSDR can handle this.
MrRadar 10y ago
LTE in the unlicensed 5 GHz spectrum is coming soon (since the cell companies somehow only just realized that even if it's not pristine spectrum they also don't need to pay billions of dollars to access it) so there will actually be a legal way to use this in the future.
- jeff_marshall 10y ago
  Any details on handset availability (even rumors)? I'd love to get my hands on a phone with an LTE transceiver that can operate in this spectrum range having an unlocked bootloader on the application processor. Setting up a base station at elk camp and being able to use a regular cell phone instead of a dedicated amatuer or FRS/GMRS transceiver would be very cool.
  - MrRadar 10y ago
    Sorry, I don't know when this stuff is coming. In the mean time you could just use a wifi network with a SIP server for voice calls.
- loeg 10y ago
  How is that going to work? I thought 5GHz had really poor penetration and attenuation. Will it trash wifi performance?
  - MrRadar 10y ago
    The cell carriers are mainly planning to use the 5GHz band for small cell indoor deployments (distributed antenna systems). The 3GPP and the Wi-Fi Alliance are going back and forth to ensure that if LTE and Wi-Fi networks are forced to share the same channel that it will at worst degrade the Wi-Fi performance as if there were another Wi-Fi network sharing the channel.
    - superkuh 10y ago
      > ... if LTE and Wi-Fi networks are forced to share the same channel ... at worst degrade the Wi-Fi performance as if there were another Wi-Fi network sharing the channel. All Our Shared Spectrum Are Belong to Us [32c3] https://www.youtube.com/watch?v=9cZxMg8shbA#t=1193 https://www.youtube.com/watch?v=9cZxMg8shbA#t=1193 Unfortunately that's not true in implementation because LTE-U doesn't know or care about the wifi channel announce timings. By piping up whenever it wants to wifi throughput actually degrades more than 70% at minimum LTE-U duty cycle spec (50%) and up to almost completely, ~99% reduction, at max allowed LTE-U duty cycle (90%) spec. No matter what they say this is a spectrum grab and LTE-U will degrade 5 GHz wifi to the point of being unusable.

boxfire 10y ago

Software defined radio such as hackrf can use this.

nobodyshere 10y ago
Are you sure? hackrf usually can only provide half-duplex operation, and somewhat full duplex after certain tweaks. Still usb2.0 will be a limiting factor in this case. USRP boards will probably be a lot better.
- meatmanek 10y ago
  HackRF/USB2 has enough bandwidth to do LTE, particularly since LTE can be configured to use between 1.4 and 20 MHz. I think the lack of full duplex or an FPGA on board would be the major limiting factors.
- chemeris 10y ago
  As mentioned above, half duplex of HackRF would be a limiting factor, unfortunately.
vvanders 10y ago
Obviously but you need to TX/RX on some sort of frequency otherwise it's not really a radio :). I was just wondering if there's spectrum allocated for experimentation or if you'd be stepping on FCC rules by putting this into practice.
- wolrah 10y ago
  If you're running both sides on SDRs you should be able to tweak the frequencies in use. Several LTE bands neighbor and/or overlap amateur radio bands, so adjusting the settings a bit should allow you to move your test operations in to a range that is trivial to gain permission to use. Bands 30 and 40 actually exist entirely within the amateur 33cm band, band 42 overlaps with 9cm, and band 46 overlaps with 5cm. Two of those also overlap with unlicensed spectrum, so there's extra room to play in that no one reasonable expects those bands to be clean anywhere people have electronics. If you have cooperative endpoint devices you could also bodge other more common LTE bands in to amateur frequencies. Band 31 is just a 20 MHz drop away from fitting in 70cm, and cutting down the duplex spacing could make part of band 8 usable in region 2. If you want commercial hardware to work it's probably best to stick to the first group, but if you're doing SDR on both sides and just want to experiment the second group should technically work.
  - chemeris 10y ago
    Speaking of UEs (aka LTE modems) - there is an open-source implementation add well. See srsUE and srsLTE.
chemeris 10y ago
HackRF can't do it, because it's only half-duplex. But there are plenty of full duplex SDR devices - check out UmTRX and USRP B210. We're also developing a really tiny high performance SDR specifically for LTE - http://XTRX.io http://XTRX.io
kweks 10y ago
The BladeRF or the upcoming LimeSDR can handle this.

MrRadar 10y ago

LTE in the unlicensed 5 GHz spectrum is coming soon (since the cell companies somehow only just realized that even if it's not pristine spectrum they also don't need to pay billions of dollars to access it) so there will actually be a legal way to use this in the future.

jeff_marshall 10y ago
Any details on handset availability (even rumors)? I'd love to get my hands on a phone with an LTE transceiver that can operate in this spectrum range having an unlocked bootloader on the application processor. Setting up a base station at elk camp and being able to use a regular cell phone instead of a dedicated amatuer or FRS/GMRS transceiver would be very cool.
- MrRadar 10y ago
  Sorry, I don't know when this stuff is coming. In the mean time you could just use a wifi network with a SIP server for voice calls.
loeg 10y ago
How is that going to work? I thought 5GHz had really poor penetration and attenuation. Will it trash wifi performance?
- MrRadar 10y ago
  The cell carriers are mainly planning to use the 5GHz band for small cell indoor deployments (distributed antenna systems). The 3GPP and the Wi-Fi Alliance are going back and forth to ensure that if LTE and Wi-Fi networks are forced to share the same channel that it will at worst degrade the Wi-Fi performance as if there were another Wi-Fi network sharing the channel.
  - superkuh 10y ago
    > ... if LTE and Wi-Fi networks are forced to share the same channel ... at worst degrade the Wi-Fi performance as if there were another Wi-Fi network sharing the channel. All Our Shared Spectrum Are Belong to Us [32c3] https://www.youtube.com/watch?v=9cZxMg8shbA#t=1193 https://www.youtube.com/watch?v=9cZxMg8shbA#t=1193 Unfortunately that's not true in implementation because LTE-U doesn't know or care about the wifi channel announce timings. By piping up whenever it wants to wifi throughput actually degrades more than 70% at minimum LTE-U duty cycle spec (50%) and up to almost completely, ~99% reduction, at max allowed LTE-U duty cycle (90%) spec. No matter what they say this is a spectrum grab and LTE-U will degrade 5 GHz wifi to the point of being unusable.