I am trying to impliment the new LTE mitigation feature recently relased with firmware version 16.0.1 to reduce the interference from a nearby provider using Huawei gear in 3.65Ghz. I am ok changing the frame period to 5ms but it isn't clear to me what value to choose as the Co-Located LTE Frame Configuration Option.
The other provider supplied the following information regarding his configuartion: Subframe Assignment 2 and Special Subrame pattern 7.
Cambium has provided a handy LTE PMP450 collocation tool. Plug in the values and it will tell you what settings you need.
Thank you Eric!
RCURRIE - once you have exercised the tool please let us know your experience. Did the results of the tool address the issue? Ease of use with the tool? Suggested enhancements?
The co-location tool is great and gives the numbers for downlink, etc
But what is confusing is the LTE Frame configuration options (0,1,2)
The co-loc tool doesn't address this and the documentation is unclear, at least to me.
@Martin Keding wrote:
The co-location tool is great and gives the numbers for downlink, etc
But what is confusing is the LTE Frame configuration options (0,1,2)
The co-loc tool doesn't address this and the documentation is unclear, at least to me.
Hi Martin,
The frame configuration options (0, 1, 2) are literally refering to the LTE standard TDD frame configurations as mentioned here, for example: http://niviuk.free.fr/lte_tdd.php
For colocation with LTE, we can only support frame configurations 0, 1, and 2. LTE frames are 10ms long, but if their periodicity is 5ms (i.e. the DL to UL switch point is every 5ms, like LTE frame configurations 0, 1, and 2) and both halves of the 10ms frame are identical (which leaves out LTE frame configuration 6, which swaps a DL symbol for an UL symbol in the second 5ms interval), they can be temporally shifted to match a 5ms Canopy frame configuration.
For example, taking LTE frame config 1 (and ignoring the special subframe symbols for the sake of simplicity), the LTE symbol pattern is:
|-5ms-|-5ms-|
DUUD DUUD
By shifting the Canopy frame start time to align with the second D symbol, and using a 50% duty cycle with 5ms frame, Canopy neatly aligns with LTE like so:
|-5ms-|-5ms-|
LTE: DUUD DUUD
Canopy: D DUU
|-5ms-|
The same kind of temporal shift can be done with frame 2 along with a 75% duty cycle, and frame 0 is naturally aligned when using a 25% duty cycle in Canopy.
Hope that clears things up!
-Al
@Al You explained this elegantly.
So with LTE Frame Configuration 2 enabled on a PMP450 AP, this shifts the PMP frame start to align with LTE sub-frame 4. I'm guessing this breaks the timing with PMP320/Wimax? I'm wondering if there are any tweaks that we can make to the PMP450 frame to make both 'close enough'?
We're currently aligned with a Wimax operator (utility co) that's running 5MHz and 75% DL. I selected 15 miles, 80%, 4 control slots and 5ms. We went network-wide with this config on our PMP450 sectors and saw a dramatic improvement to our SM uplink SNRs. We were clearly interfering with each other.
15/80%/4 also happens to line up pretty close with LTE 2/7. But we've discovered the obvious issue that this means nothing with the PMP450 LTE co-lo mode disabled. :(
Hey George, what you describe is correct. The default behavior for all 450 products that are running 5ms frame is to align with WIMAX/PMP320 start times, such that configuring the same duty cycles on both devices would result in proper alignment.
Incidentally, LTE Frame configuration 0 also aligns properly to the above described configuration, but because the duty cycles for LTE go hand-in-hand with the frame configurations, this requires a 25% duty cycle (25/75 DL/UL) which doesn't match up with the 75% WIMAX cycle you described.
Unfortunately, the WIMAX/450 duty cycles would have to be changed to match the LTE ones in order to line up properly with LTE Frame Config 0, but that would make everything extremely UL-heavy. I'm not sure there's much that can be done with this without deviating from the LTE spec or introducing interference.