Drive Test Lesson

Drive Test Lesson By Oka Handiman

Introduction The Purpose of drive test activity is to capture actual data of the current CDMA Network. Drive test data (log file) show the condition of the RF environment. They are the primary gauges used to guide CDMA optimization and troubleshooting.

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Performance Indicator • FER • Mobile Receive Power • Ec/Io • Mobile Transmit Power

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FER FER stand for Frame Erasure Rate FER is an excellent call quality “summary” statistic FER is the end-result of the whole transmission link • if FER is good, then any other problems aren’t having much effect • if FER is bad, that’s not the problem - it is just the end-result of the problem – we must investigate other indicators to get a clue what is going on • FER Value (%)

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Mobile Receive Power Mobile Receive Power expressed in dbm. Measured all signal receive power at handset side. Receive power is important, - too little receive signal (-100 or weaker) would leave to much noise in the signal , bad FER and other problems. - too much received signal (-35 dbm or higher) could drive the phone’s sensitive first amplifier into overload, causing intermod and code distortion on received CDMA signals RX Level 5

Ec/Io • Ec is the energy of a single sector’s Pilot • Io is the power sum of all the signals reaching the mobile. • Ec/Io is the important indicator for network performance • Bad Ec/Io can indicate problems like pilot pollution, forward link interference (indicate neighbour list problems. • Ec/Io also indicate traffic load at the sector.

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Mobile Transmit Power Mobile Transmit Power the actual RF power output of the handset transmitter Maximum handset transmit power is 23 dbm. Mobile Transmit Power is indicator for Reverse link interference. If only this parameter is bad, it means there is external reverse link interference. Typical Tx power - +23 dbm in a coverage hole - 0 dbm near middle cell - -50 dbm up close to BTS

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Conclusions • Mobile Receive Power and Mobile Transmit power are the indicator for coverage signal. • If these two indicators show weak value it is show that the coverage at that area is weak. • Ec/Io and FER are the indicator for call performance. • Weak Ec/Io will be followed with 8 weak FER. It means there is problem