3G SHORT NOTES

1.Ec/Io

we have the signal power=P

the chip rate=W

the user bit rate=R

the noise=PN

the interference= I (interference between users)

Ec=P/WIo=I/WN0=(I+PN)/WEb=P/R

RSSI= RSCP-Ec/Io

Question: Explain Ec/Io and RSCP; on what channel are they measured on?

Answer:  Ec/Io = energy of carrier over all noise.

RSCP = Receive Signal Code Power. In FDD mode (what we normally deal with) they are measured on the CPICH (pilot).

Bonus if they know that Io is the sum of all interference: thermal/bg noise + interferers + own cell and is wideband.

Bonus if they understand that RSCP is actually measured AFTER despreading (i.e. narrowband)

RSSI - Receive Signal Strength Indicator

Meaning of RSSI - "Receive Signal Strength Indicator", is a circuit to measure the strength of an incoming signal.

The Received Signal Code Power(RSCP) is the received power on one DPCH, PRACH or PUSCH code after de-spreading, defined on the pilot symbols.RSSI is an indication of the power level being received by the antenna. Generally, the higher the RSSI level is the stronger the signal.

Meaning of RSSI - "Receive Signal Strength Indicator", is a circuit to measure the strength of an incoming signal. The basic circuit is designed to pick RF signals and generate an output equivalent to the signal strength. The ability of the receiver to pick the weakest of signals is referred to as receiver sensitivity. Higher the receiver sensitivity, the better. There are circuits which measure the signal strength based on the output voltage. If the signal strength is good the output voltage is higher and the output voltage is poor if the signal strength is low. Some indicators are designed to flash one of their lights indicating the signal strength. Depending on the received signal power, an amplifier can be used to boost the signal.

Question: All Rf condition ok and no alram on the site then rscp bad how can i improve the rscp and what parameter i will checked

Answer: Hi below is the checklist

1) Antenna obstruction2) Mechanical and electrical tilt3) Check for CPICH power.4) Check for VSWR Threshold.5) Once again check for Alarms mainly VSWR.This should solve the issue.

And finally we say RF condition is good only when the level and quality of signal is good.

RSCP is more or less similar to RX level of 2G,similarlyEc/Io to C/I

The range of RSCP is similar to RX level but the range of Ec/Io is from 0 to -30. Greater the Value better is the quality. The value is -ve as the Io includes Iown, I others and noise.(I=interferece).

Note: Unlike in GSM if u miss defining any neighbor site as neighbor there will be a call drop. This is because we are operating the whole Network on one single frequency and missing neighbor of that same frequency is considered as interfernce and the Ec/Io value becomes poor and thus leads to a call drop.

EcNo: energy per chip over the noise, a measure of the quality of the signalRSCP: Energy after processing ie with gain from coding etcRSSI: A dB measure of the signal arriving at the antenna before gain from processingCPICH: Pilot Channel of the cell.