We have a sector that is starting to reach capacity. Is it frowned upon to overlap an existing sector's coverage with another access point (likely using RFE horns) and then just manually load balance customers across the two? If so, how big of a guard band should there be between the two overlapping sectors?
We would use multiple horns, but we need to retain MUMIMO as much as we can, which isn't possible using the 30* horns.
We will soon be releasing a 60 degree horn that is optimized for MU-MIMO operation. Below is the part number and description. To help today can you use freq diversity say if AP one is in 5.8ghz can you use 5.1 etc? This depends on your local regulatory but an example. If you so this you'll want to use the GPS to sync both AP's.
Ok - so the separation needs to be completely different bands? 5.1/5.8/etc?
No. Assuming you're using sync, with ePMP you can use as little as a 5MHz guard band between channels. Horns also have excellent F/B ratios and tight beam patterns with no side-lobes, so you can sometimes get away without using any guard band, depending on physical spacing and coverage overlap.
Do we need to enable "colocation" mode and choose a front/back sector? Isn't that just for frequency re-use?
No, you only use colocation mode when sync'ing with PMP100/PMP450 radios. No, you only choose front/back sector modes when you're using back to back frequency reuse on two radios.
If you are using overlapping AP's, even with GPS sync enabled, you will need to use 20Mhz guard bands as Dmitry advised. The reason is if there is a complete overlap of the APs, then every SM connected to either AP, will see -both- APs at the same RSSI, including the adjacent channel power. This adjacent channel power will reduce MCS rates and overall throughput.
I doctored an online photo to hopefully give a visual of why the 20Mhz guard band is needed for overlapping APs. It uses 2.4ghz, but the you can subsitute 5ghz freqs as well. Same concept, just different bands/freqs. Sectors that do not overlap can use 5mhz guard bands as Eric stated.
Edit: The 20Mhz guard channel below is actually a 30Mhz guard channel due to there already being a 5mhz guard channel between 1 and 6 and another 5mhz guard channel between 6 and 11. Hopefully you still get the gist without this being too confusing.