Top Level Optimization Solutions Access Failure & Call Drops UMTS

Low throughput due to pooer coverge at output at repeater end

Case Name： Description：

Date： 11/28/2011

Top level Optimization solutions UMTS Access Failure & Call drop Analysis Solutions UMTS

Alarm： Handling

How resolve the access failure & call drop In more than 50%

Process

loaded network •

Investigate the reasons for poor 3G radio performance (access failure, call drop, IRAT failures, low throughput)

•

Describe the potential reasons

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Propose actions to improve performance (as top 10 optimisation actions) –

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Both common and service specific (Voice, Video and PS data)

First check could be done with Radio Planning tool or/and Nastar by looking at the CPICH coverage, TP distribution, cell dominance, SHO overhead, service coverage, link imbalance and RTWP interference areas.

•

The main reasons for poor radio performance are related to: –

Non

optimum

cell

design

(location,

antenna

type/height/bearing/tilt) –

Wrong site implementation (antennas, cables, parameters, sector swap)

–

Wrong or bad parameter planning (scrambling code allocations etc, CPICH etc.)

–

2014-6-12

Wrong or missing neighbour relations

Low throughput due to pooer coverge at output at repeater end

Date： 11/28/2011

• Drop Call Rate / SHO Failures and Overhead Missing neighbour •

A good usable neighbour is present within cells coverage area, can cause DL interference if it is not in the active set.

•

Swapped sectors in BTS.

Solutions: Check Nastar data and look for missing neighbours. Check the cabling in antenna line

Too many neighbours •

In SHO area the number of combined neighbouring cells become more than 31. HO list is created using RNC algorithm in the final stage some of the neighbours will randomly be removed.

•

Solutions:

Delete unnecessary neighbours.

High SHO overhead •

No main server in the area, too many cells with weak CPICH level.

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CPICH EcNo is usually very bad even the RSCP is good e.q. RSCP – 80…-90 dBm but EcNo about –10 dB

Solution: Use buildings and other environmental structures to isolate cell(s) coverage. Down tilt antennas to make cells dominant and limit effects of interfering cell(s). Check antenna bearing and height. Add a site.

Access Failures •

Poor coverage in area

•

If problem is poor coverage, this means poor RSCP (