How do you plan your frequency, Sector placement and tilt?
Even using sync interference problems can be seen very fast in dense deployments.
We’ve the problem that our coverage area is not plain. So unexpected interference
happens even at higher distance due to unwanted LOS conditions to the wrong
sector.
As I’ve learned Fractional Frequency Reuse would help but is not implemented.
So how do you plan? What signal level do you use for planning. What signal level
can be seen at the cpe from the wrong sector to work properly.
Do you use radio mobile or something else?
we really haven’t had problem with self interference, and we are the only source of 3.65 noise in our area.
our closest towers are just short of 3 miles apart, those base station antennas are tilted 4 degrees so the center of the beam stops short of the opposing tower, also we usually don’t mount above the peak of the roof so the home can help with SNR from opposing towers, but as far as base stations directly interfering with each other, we haven’t seen any such issue. I did notice that if you max out the transmission power (26db) it does hurt the SNR for whatever reason. We don’t go past 22 to keep the signal clean… And it wasn’t self interference because this was observed with our first and only base station we put up for testing.
all of our base stations are down tilted to get the outside of the beam 5 miles out, some are 3… Some are 3.5 our exact tilt changes with each base station, but we use a tilt calculator to get the other -3db edge about 5 miles out.
also all of our base stations are at least 200’ above ground level, and from the terrain, some times as much as 500’ above the subscribers they are using.
we are planning on trying many base stations about a mile apart with omnis to try and fill in a area the terrain in just crazy. we are only going to put them 80’ up. we plan to do this with 5 base stations…
what is your setup like?
mgthump wrote: ...
all of our base stations are down tilted to get the outside of the beam 5 miles out, some are 3... Some are 3.5 our exact tilt changes with each base station, but we use a tilt calculator to get the other -3db edge about 5 miles out.
...
I used to have a down-tilt calculator that I downloaded from moto back in 2005, but I can't seem to find it anywhere in my archives or on Cambium's site. What are you using to calculate down-tilt? Would be great to have a tool that showed inner, center, and outer radius based on AGL and down tilt on ap's.
mgthump wrote: we really haven’t had problem with self interference, and we are the only source of 3.65 noise in our area.
our closest towers are just short of 3 miles apart, those base station antennas are tilted 4 degrees so the center of the beam stops short of the opposing tower, also we usually don't mount above the peak of the roof so the home can help with SNR from opposing towers, but as far as base stations directly interfering with each other, we haven't seen any such issue. I did notice that if you max out the transmission power (26db) it does hurt the SNR for whatever reason. We don’t go past 22 to keep the signal clean.. And it wasn’t self interference because this was observed with our first and only base station we put up for testing.
all of our base stations are down tilted to get the outside of the beam 5 miles out, some are 3... Some are 3.5 our exact tilt changes with each base station, but we use a tilt calculator to get the other -3db edge about 5 miles out.
also all of our base stations are at least 200' above ground level, and from the terrain, some times as much as 500' above the subscribers they are using.
we are planning on trying many base stations about a mile apart with omnis to try and fill in a area the terrain in just crazy. we are only going to put them 80' up. we plan to do this with 5 base stations...
what is your setup like?
We've a non flat terrain so it's difficult to reach cpes without shooting at the next tower in some positions. But our main problem I guess are the old antennas. Looking at the antenna patterns they shoot at the other antennas on the same tower. We'll replace them soon.
What omnis you plan to use?
the Omni idea was a complete bust, we used vericals and multipol and mixed them… terrible… terrible… I’m thinking a peice of stripped LMR might do better LOL…
we ultimately decided to copy cell carries and dropped cabiums base station antennas and went with 2x 17db terra wave vertical pol antennas, we spaced them 12’ apart on the tower and they have been working EXTREAMLY well with AWBs indoor CPEs, we have been able to maintain qam 16 1/2 down to -85 -86 in 5mhz …
also the indoor units stay in MIMO B until 71 db 
this setup is WONDERFUL for our more metro deployments, within about 1 mile to 1.5 miles of the tower, we don’t even send a truck anymore, we just get a credit card and mail it to them lol
we use 430 and hopefully soon 450 for the PTMP for metro access, mostly LOS or close too, we do use some 320 CPEs, but the wimax has turned into our lazy deployment for people wanting basic services / basic service w phone
mgthump wrote: also the indoor units stay in MIMO B until 71 db :)
:O At 3 KM the Gemtek SMs drop MIMO B if you sneeze at the base of the tower
Is it recommended to do two v pole antennas with diversity rather than dual pole ?
No, the 802.16 MIMO is designed to work with 90 degrees of spatial diversity.