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Reply To: call drop radio



yes, sure 🙂
path balance = (rxlev_ul – ms_txpwr) – (rxlev_dl – bts_txpwr)

this path balance is computed every 480ms by the BSC, based on the measurement results.

let’s take an example:
rxlev_ul = -80dBm (measured)
ms_txpwr = 33dBm (calculated, depends on MS_TXPWR_MAX and value of MS_TXPWR attenuation due to UL power control)

rxlev_dl = -70dBm (measured)
bts_txpwr = 42.5dBm (calculated, depends on TRX output power, attenuation by combiner, value of BS_TXPWR attenuation and DL power control)

as you see, in this example, i don’t use power control, all tx power are at maximum output power.

path balance = -80 + 33 – (-70 + 42.5)
= -0.5dB

That’s balanced.
Now let’s assume that there is an issue in UL. What is the impact?
–> The rxlev_ul is decreased, but the MS TXPWR is unchanged (this is a stupid calculation, based on parameters).

path balance = -100 + 33 – (-70 + 42.5) = -20.5 –> value becomes NEGATIVE.

possible cause : all mobiles in the cell are faulty (… impossible …) or the cell is having a poor UL sensitivity due to faulty HW (yes, that must be it !!)

if there is an issue in DL, the result is the opposite : the rxlev_dl is poor –> the path balance is very positive.
possible cause : all mobiles are faulty (iphones??) or the cell is having a faulty transmission.

well, i hope it’s clearer now, let me know.