i’m really surprised that there is an impact on your HO-Level ratio ! It means your cell coverage has reduced !

But ok, let’s *assume* it’s an interference problem, and let’s check your FHS configuration again:

you are doing a 1×1 strategy, yes?

most important:

how many frequencies did you put within the FHS ? from 26 to 50, that’s 25 frequencies.

how many “non-bcch” TRX per cell do you have, in average, in your FHS zone ?

With 25 frequencies, you are limited to 3 “non bcch” TRX/cell, so 4 TRX/cell including the Bcch Trx. More than that, and you’ll have interferences.

Why do you apply a MAIO of 10 and 20 between different TRX ?

HSN is the same within cells of one BTS, but should be different between cells of different BTS.

BTS 1

— cell A : HSN = 1, FHS = (26, 50)

—— TRX 2: MAIO = 0

—— TRX 3: MAIO = 6

—— TRX 4: MAIO = 12

— cell B : HSN = 1, FHS = (26, 50)

—— TRX 2: MAIO = 2

—— TRX 3: MAIO = 8

—— TRX 4: MAIO = 14

— cell C : HSN = 1, FHS = (26, 50)

—— TRX 2: MAIO = 4

—— TRX 3: MAIO = 10

—— TRX 4: MAIO = 16

BTS 2

— cell A : HSN = 2, FHS = (26, 50)

—— TRX 2: MAIO = 0

—— TRX 3: MAIO = 6

—— TRX 4: MAIO = 12

— cell B : HSN = 2, FHS = (26, 50)

—— TRX 2: MAIO = 2

—— TRX 3: MAIO = 8

—— TRX 4: MAIO = 14

— cell C : HSN = 2, FHS = (26, 50)

—— TRX 2: MAIO = 4

—— TRX 3: MAIO = 10

—— TRX 4: MAIO = 16

and so on…

finally, you must apply the FHS 1×1 only among cells with the same layer, for instance, all your macro cells. In other words, you should ensure that there is no overlap (or not TOO MUCH) between two cells using the same FHS.

For instance, if you have umbrellas, minis and micro cells, then you should apply the FHS only on mini cells, and ensure that umbrellas and micros are using different frequencies.

let me know if you have any other idea regarding your problem. what about drive tests ? do you see a level degradation ?

best regards,

pix