Replacing full cluster of 900 PMP100s with PMP450is

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I took a look at the 450i and 100 colocation whitepaper, and for a full cluster it recommends replacing two 900 PMP100 APs back to back with 450i APs at once.  That leaves me with a bunch of customers without service while I run around upgrading their SMs, which I'm not a huge fan of.  As an additional complication, the white paper states that the PMP100 front to back ratio isn't very good in comparison to the 450i, so you don't want a 450i and 100 opposite one another on the same frequency.

Ideally, I want to play around with frequencies so that I can mount the 450i APs one at a time alongside the PMP100 cluster while I get the SMs upgraded to reduce downtime.  The white paper doesn't mention this case, and I wanted to see if anybody has had any luck migrating without downtime.

I'm seeing two possibilities.  The first is to change the PMP100 cluster to ABABAB, and use channel C for the first 450i AP I put up.  That's tricky, as it would impact performance for customers that aren't in the same direction as the 450i is pointing, so I may not have a viable solution to fix them.

The second possibility is to change the 100 cluster from ABCABC to ACBACB, so that a N facting 450i could use channel C without having either the PMP100 facing that way or the PMP100 facing the opposite direction on the same frequency, but I still have frequency reuse between the 450i and 100 APs so there will be some self interference.

Has anybody tried this, and if so which approach did they find works better?

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Ted,

We have a slightly different setup that yours but we found that going to an ABABAB setup and using a clean 7mhz channel (C) worked best for migrating to the new 450i. In our case the majority of customers were located in the 65degree of covereage of the 450i so we were able to convert without wondering where we would get the extra spectum for the next 450i.

Our next site is setup with a omni on channel A, and we have 40 degree sectors in a B,C,B,C, facing the majority of customers. There is also a C back to back on the second C in that aray.

At that site the plan will be to turn off the B sectors, drop to the omni with those customers ( creating some serious congestion) and then turn the 450i on with B. Having customers lined up for migration based on the highest data users first. We will need 90 degree sectors for the 450i to do this conversion and will buy Mars if we have to but would prefer a Cambium which I am told is on the way.  I will be starting this conversion April 1st.

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I tried ABCABC, and that seems to be working as well.  The dual slant 45 deg antennae seems to make a huge difference in terms of reducing interference.

Really happy with what I'm seeing thus far.

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