SIB 7 UL Interference

[Kalvera]

SIB 7 Interference

What this IE calculates? is it external interference on UL air interface?

Or it is RTWP value sent from NodeB in SIB 7 to inform UL noise at antenna connector?

It is usually -103 ~ -107, let's assume if it is <-105 (for example -110) can i consider it as interference causing problem for RACHing?

thanks in advance

[dremka]

Hi.

The value <-105 is ok, it's a normal noise floor for UMTS. Values too low (e.g. -110 and lower) may indicate some problem with the hardware - faulty rx modules or sth.

BR
Dremka

[firstmaxim]

SIB 7 Interference

What this IE calculates? is it external interference on UL air interface?

Or it is RTWP value sent from NodeB in SIB 7 to inform UL noise at antenna connector?

It is usually -103 ~ -107, let's assume if it is <-105 (for example -110) can i consider it as interference causing problem for RACHing?

thanks in advance

SIB7 broadcast contains NodeB transmit power (of CPICH), UL interference level and a constant value (operator controllled margin parameter).
These parameters help the UE to estimate uplink transmit power at initial access. The preamble initial power of PRACH is estimated by using the equation:

Pramble initial power= primary CPICH DL tx power - CPICH_RSCP + UL interference + constant value. So, lower value of UL interference reflects on the lower cell loading on uplink . Therefore, the effort needed by the UE to be heard above the WDMA uplink noise floor is less.

Regards.

[mobilink999]

Value of -105 or greater is ok. It becomes issue after -98....