Many of the systems on the market already run within far less than 10 dB of the Shannon bound, so beware of any coding or modulation methods that claim that much system margin improvement. Obviously there are other techniques like beamforming and MU-MIMO, although I’ve also run into too many vendors who talk about beamforming and it turns out they are just picking the best signal from multiple antennas. I’m not saying any of this applies to Telrad. Just that after decades of improvement in microwave modulation and coding, there isn’t 10 dB of low hanging fruit lying around for the picking. And whenever someone tells you they picked up a bunch of dB by going to 3x3 or 4x4 or 6x6 MIMO, make sure they are dialing back the EIRP on each stream so the total meets regulatory specs. Carrier class basestations are not like UBNT Rockets, the assumption is they are being installed and operated by sophisticated users, and the software may not prevent you from exceeding regulatory specs. The vendor may be giving you legit numbers, but a WISP giving a testimonial may have unwittingly left the xmt power at max. (Although CPE usually cannot perform that trick.)
From: Adam Moffett Sent: Thursday, January 08, 2015 12:14 PM To: af@afmug.com Subject: Re: [AFMUG] interesting telrad video Oh one other thing....I have no idea where the supposed +10db system gain comes from. They do have spatial diversity at the tower side....which theoretically gives them a little something extra in the uplink direction. They obviously still have the same 1W/mhz EIRP limit and the CPE (currently) has the same size antenna, and their base station antennas are still around 17dbi......so I can't see where that 10db comes from. They have 18 and 20dbi CPE coming down the pipe. Maybe they count 6db from the bigger CPE and allow themselves a little extra for the antenna diversity? https://www.youtube.com/watch?v=dzAkMGKT5_M I feel like there might be some koolaid here somewhere -- All parts should go together without forcing. You must remember that the parts you are reassembling were disassembled by you. Therefore, if you can't get them together again, there must be a reason. By all means, do not use a hammer. -- IBM maintenance manual, 1925
