MKT,
Sorry, I thought I said it before:
the decision is based on RXLEV(900) only.
For instance, if DL RXLEV(900) > -70dBm and UL RXLEV(900) > -80dBm, then the TCH is allocated in INNER zone.
Once the MS is in inner zone, the DL RXLEV(1800) will probably be equal to -70 – 10dB = -80dBm. The UL RXLEV(1800) will probably be = -90dBm.
Now it’s your job to fine tune the thresholds, so that the MS doesn’t enter the inner zone if the “expected” 1800 level is going to be too low.
Typically:
RXLEV DL ZONE = -80dBm
RXLEV UL ZONE = -90dBm
ZONE HO HYST DL = 15dBm
ZONE HO HYST UL = 12dBm
With this parameters:
if DL RXLEV(900) > -65dBm (-80 +15) and UL RXLEV(900) > -75dBm (-90 +12 +3), then the TCH is allocated in INNER zone.
For the -75dBm in UL, the additional 3dB comes from the difference in the MS TXPWR MAX and MS TXPWR MAX INNER.
You should also set EN_LOAD_BALANCE = DISABLE, in order to load the inner zone as much as possible.
Finally, set EN_LOAD_OUTER = ENABLE, this works better with GPRS.
Ok, I gave you all settings to get a great multiband cell…