Is it possible to install multiple SXT LTE’s right next to each other pointing at the same mast and connecting to the same mobile provider i.e. on the same frequency? Or will they interfere with each other? Otherwise how far apart would they need to be?
I am not a cell phone engineer but to my knowledge yes. Cell phones use TDMA so the SXT LTEs wouldn’t be transmitting at the same time. I wouldn’t install them touching each other, though. The one transmitting will induce currents in close proximity metal objects like a circuit board. One meter apart would be the ideal minimum, but often you don’t have that luxury.
Modern LTE networks are basically either TDD (DL and UL share same channel, very much the same as WiFi) or FDD (DL and UL use different frequencies). Having a few LTE devices close to each other would be a problem in TDD case if one device was transmitting and another one was receiving (too high signal level in receiver). Luckily in LTE TDD there are predefined periods for DL and UL so devices won’t be receiving anything during UL transmission of any of them. In addition to that, all cells that overlap with coverage have to be precisely synchronized (GPS or IEEE1588v2) so that all transmit at precisely same time.
In FDD case, devices in UL actually use OFDMA, so they might transmit at the same time (but using different OFM sub-band) and receiving all of them is base station’s problem anyway. For other LTE terminals in near vicinity this is not a problem, DL channel is offset from UL channel, allowing for proper RF filters to take care about high signal level in another channel.
Disclaimer: until recently I was RF engineer designing and operating LTE network for a major MNO.
Thanks for the (very) detailed responses. Is there any simple way to determine whether the mobile network is TDD or FDD?
But basically, if I understand it correctly, there should not be a problem mounting them together, but ideally a meter apart if possible.
Whether FDD or TDD, is part of LTE band specification: https://en.wikipedia.org/wiki/LTE_frequency_bands