LTE eNodeB Troubleshooting Guide – utilizing Anritsu’s Handheld BTS Master™, Cell Master™ or Spectrum Master™ with Options 0541, 0542 and 0546

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Start Here Use Over-the-Air (OTA) tests to spot-check a transmitter’s coverage and signal quality. Use the Direct Connect tests to check transmitter power and EVM when the OTA test results are ambiguous.

Troubleshooting Hints These two tables provide guidance from the first indication of a fault, a poor Key Performance Indicator (KPI), to the BTS Master, Cell Master or Spectrum Master test, and finally, to the field replaceable unit.

Key Performance Indicators vs. Test

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Call/Session Blocking Power shortage x x x

Resource Block shortage x xx xx

UL Interference x xx

Call/Session Drop

Radio Link Timeout x x x x x x x

UL Interference x x

DL Interference x x x x x x

Test vs. BTS Field Replaceable Units Freq Ref Signal

Generation MCPA Filters Antenna

Antenna Down Tilt

Sync Power x xx x

RS Power x xx x

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Spectral Emission Mask (SEM) x x xx x

Error Vector Magnitude Peak (EVM pk)

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Error Vector Magnitude EVM (rms)

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Frequency Error xx

OTA EVM x x x x x

x = probable, xx = most probable  

  

Locating Over-the-Air Test Spots To test an eNodeB Over-the-Air (OTA) it is necessary to find a location with good Sync Signal (SS) dominance. The SS dominance measurements are ideal for this task. OTA testing requires SS dominance readings higher than 10 dB.

To find a good OTA test site, look for a place squarely in the sector, a block or two from the tower, and away from surfaces that may reflect radio waves. A directional antenna will help to screen out unwanted signals.

In some urban areas, locating a good OTA site can be difficult. In these cases, it may be quicker to connect to the BTS for testing.  

 Anritsu BTS Master™

Direct Connect Transmitter Tests Transmitter tests can be run while connected to the:

Output of the eNodeB (Point ”A”).

Test port (Point “B”) which is essentially the output of the Multi-Carrier Power Amplifier (MCPA).

Input to the MCPA (Point “C”) if the signal is accessible

Frequency reference system (Point “D”) for carrier frequency errors

The goal of these measurements is to increase data rate and capacity by accurate power settings, low out-of-channel emissions, and good signal quality tests. Good signals allow the cell to generate more revenue and provide a better return on investment.

The antenna is the last link in the transmission path. If connected at point “A”, it is helpful to sweep the antenna(s) at the same time, to ensure a high quality signal.

Multiple Sector Coverage Checks Sync Signal Power, Dominance, Cell ID, and EVM

Sync Signal (S-SS) affects cell size. S-SS is also used OTA to check coverage. It should be highest near the tower, declining to a minimum level at the handoff point. More information on SS is provided elsewhere in this guide.

Dominance: The strength of the strongest S-SS compared to the others.

EVM, RSRP, RSRQ, and SINR all indicate the quality of the received signal. In this screen, EVM is measured on the PBCH signal, so as to not be affected by traffic.

Cell, Group, and Sector ID: Identifies the source of the OTA signals detected.

Guidelines:

Dominance: Higher than 10 dB for OTA signal quality testing.

EVM: Established from a known good base station at a location where the dominance figure is over 10 dB.

Cell, Group, and Sector ID: Should be set as defined by engineering.

Consequences:

Poor Dominance: Poor spot to test the BTS OTA. May be a result of excessive coverage, which will result in a loss of system capacity due to excessive co-channel interference.

Poor EVM: Call drops, call blocking, low data rate, and low capacity.

Wrong Cell, Group or Sector ID: Dropped handoffs and island sectors.

Common Faults: Antenna down tilt, damaged antennas, control channel power settings, and co-channel interference.

Pass Fail measurements simplify OTA and Direct Connect Transmitter Test with user specified Limit sets

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