Pre-defined reports overview -> Modulation and Coding Scheme

PERFORMANCE MANAGEMENT

4. Pre-defined reports overview -> Modulation and Coding Scheme

• Modulation and coding scheme subset provides statistics of data volumes, transmissions, share of transmissions and successful transmissions per MCS.

This reports should be used to understand the quality of data volumes transmissions and DL Adaptive

Modulation and Coding (AMC) algorithm performance to improve system capacity and peak data rate.

This Subset is divided in six reports:

• Transmissions and Volume per Low/High MCS

PDSCH and PUSCH transmissions using low/high MCS

Percentage of DL/UL traffic volume using Low/High MCS codes

• Percentage of transmissions per MCS PDSCH and PUSCH

PDSCH and PUSCH

• PUSCH 1^ST transmission per MCS

• Unsuccessful Transmissions per MCS

• NACK MCS time division

•Data Volume per MCS

MAC PDU volume on PDSCH/PUSCH per MSC

Share of DL/UL Traffic per MCS

4. Pre-defined reports overview -> Integrity

• With Integrity subset is possible to analyze delays, congestions and encryption/decryption metrics. These reports should be used to understand delays in

different protocols levels.

This Subset is divided in six reports:

• IP Packet integrity

ESP packets encryption SR

Dropped packets due to ingress rate limiting Discarded packets due to Filtering violations

• Packet delay

PDCP SDU delay UL/DL (min, max and avg) DL/UL SCH TB Retransmissions and error ratio RLC PDU Retransmissions

For internal use

RLC PDU Retransmissions

• BLER per Modulation QPSK, 16 QAM Gain using HARQ

•Congestion per QoS classes for IP PHB IP PHB Packets to send drop rate and data volume lost due to congestion per QoS class

•Congestion per QoS classes per VLAN

IP VLAN PHB Packets to send drop rate and data volume lost due to congestion per QoS class

• IPsec packets

ESP bypassed (ingress/egress)

4. Pre-defined reports overview -> Usage

• With Usage subset is possible to analyze throughputs, resources utilization, power and number of active users.

• With these reports, throughputs at different levels should be checked to see if it matches the network configuration. They are also very important to understand the Physical Resource Blocks utilization for issues like network upgrades, power analysis with downgrades/upgrades in scheduler and MIMO

This Subset is divided in seven reports:

•Throughput at PDCP level and per QoS class PDCP UL/DL thp (min, max and avg) PDCP SDU THP and data volumes QCI

• Physical Resource Block utilization PRB utilization UL/DL

DL/UL PRB Analysis per TTI, per UE DL/UL PRB utilization level per TTI

• RLC, SDU, RRC, analysis

RLC SDU data volume per channel MAC SDU volume per channel

For internal use

with downgrades/upgrades in scheduler and MIMO performance. They are also very important to understand the throughputs per Quality of Service Indicator to check the distribution of network resources per group of users priority.

MAC SDU volume per channel RRC UL/DL Traffic volume

• Power

UE Power HeadRoom for PUSCH per level

UE Power analysis (scheduler upgrades/downgrades)

UE Delta Tx PUSCH/PUCCH per level

• MIMO

Open Loop Diversity/Spatial Multiplexing Mode Usage and Switches

TROUBLESHOOTING

For internal use

PROBLEMS ENCOUNTERED IN LIVE NETWORK LAST 1.5 YEARS RL20+

• RP3 ALARMS

• AUTO CONFIGURATION

• ANR CREATE TOO MANY ADJ

• PCI MANUAL PLANNING MISTAKES

• NETWORK OUTAGE CAUSED BY MME PARAMETER CHANGE

• NETWORK OUTAGE CAUSED BY SIG LOAD ON S1 DUE eNB MASS SW Ug

• SLEEPING CELLS (Related to RP3 Delay)

• CONFIGURATION CHANGE AFTER SW Upgrade

• UE SW Bugs

• THROUGHPUT ISSUES ,FRAGMENTATION FTIB

• LOST VOICE CAPABILITY (CSFB Issues)

• RACH STORMS (eNB SW Bug)

Troubleshooting guidelines – Problem type according to KPI classification

Problem type according to main KPI categories:

- Accessibility problems:

• Service accessibility, e.g. Attach, or EPS Bearer Setup Request success rates - Reliability problems:

• Once established, the reliability of the service, e.g Voip call, or EPS bearer drop rates

For internal use

drop rates

- Integrity/Error rates problems:

• Promised to deliver the service with a certain quality. E.g. Cell throughput, or user data rates, packet delay.

- Availability problems:

• Relationship between service up and down times, e.g. cell, or LTE Network availability

- Mobility problems:

• Different mobility related metrics, e.g. hand-over success or drop rates, latencies.

Troubleshooting guidelines

- The above-mentioned cases it is essential to try to get at least following logs :

• eNB snapshot

• Interface traces S1-C by wireshark

- The eNB is connected to the EPC (S1 interface) by IP switches. The

precondition for capturing traces on these interfaces is the availability of a mirror port on one of the switches. The tracing on these interfaces can done either using wireshark (usually for lab tests) or using commercial protocol

For internal use

either using wireshark (usually for lab tests) or using commercial protocol trace equipment (e.g. NetHawk M5, JDSU SART). If the IP traffic on these interfaces is encrypted (e.g. if IPSec is used) it is necessary to use the deciphering functionality of the protocol tracers.

• Emil logs

- BTS message remote tracing: BTS message remote tracing can be configured, started and stopped. Depending is tracing covering only Control Plane or also User Plane messages, estimated 70-500 3 sector LTE BTS can be traced at the same time with one PC.

• UE trace ( e.g. by using Nemo tool)

• UDP log file by BTSLog tool NWS LTE RA RD eNB I&V

Fault sources

• SW

- eNB SW bugs

• SW not working according to specifications

• Specifications are ambiguous or lead to faulty behaviour

- SCF parameters

• Suboptimal parameters, missing neighbour relations, etc.

- UE SW bugs

• UE is behaving against specifications or against NSN expected behaviour

- EPC SW bugs

For internal use

- EPC SW bugs

• MME/S-GW is behaving against specifications or against NSN expected behaviour

- Backhaul SW bugs

• Backhaul is dropping packets or sending with too high latency/bursts

• HW

- Faulty eNB units - Faulty/instable UEs

• Commissioning

- Wrong antenna tilting, loose cables, wrong commissioning parameters, wrong/missing synch sources

• Network planning

- Too large cells, gaps in geographical coverage, high interference sources, blocking buildings, high mobility Tracing Areas, etc.

• Diagnostics

- Too heavy tracing or logging causes problems

eNB SW bugs

• Symptoms

- No eNB L3 reply for visible UE/EPC signalling - No eNB L3 messages sent when expected

- Rlc Ack visible in call drop after RRC Connection Release - RLF or Errors visible in good signal conditions

- Call drops without any RLF/Errors - Huge amount of Ghost Calls

- Sudden drop of multiple calls at the same time - Sudden drop of multiple calls at the same time - Sudden drop in KPI without parameter changes - Sudden drop of KPI after new feature activation - Sleeping cells

- HO rejections

- RRC connections are reject

- KPI drop correlation with snapshot fetching, SiteManager connectivity or other normal maintenance actions

- DSP crashes

• First step troubleshooting actions - Analyze Emil/UE Traces

- Set triggers and analyze from snapshot TTI Trace and SysLog for unusual behaviour and signal conditions

SCF parameters

• Symptoms

- No UE reply for RRC signalling for multiple UE types - RACH preambles are missed in HOs

- Poor signal quality and RLF failures or Errors indicated in certain call phases

- Errors distributed evenly in the network - PDCCH blocking visible in counters

For internal use

- Errors distributed evenly in the network - PDCCH blocking visible in counters - Timers expire

- High interference visible

- Sudden drop of KPI after parameter changes - Call drops correlate to active UE amount

- HARQ/RLC/Preamble Retransmissions reach maximum value - Measurement reports don’t initiate HO preparation

- HO are started in too poor source cell signal conditions

• First step troubleshooting actions

- Analyze KPI, PM counter and SCF parameter content and interrelations

Call drops UE SW bugs

• Symptoms

- No UE reply for RRC signalling for one specific UE type - A lot of RLF or Error visible for one specific UE type

- KPI drops after new UE type is launched in the network

- KPI drops after new UE SW version is launched in the network - KPI drops after new UE SW version is launched in the network - UE does not reply in good signal conditions and low loaded cells - No recovery method for dongle disconnect (No Detach messages

visible)

• First step troubleshooting actions - Collect UE logs if possible

- Check are the UE types tested in NSN FiVe, IOT or Innovation labs

EPC SW bugs

• Symptoms

- No reply to S1AP messages

- Sudden S1AP Failure indications to multiple eNB - S1 Error indications/Alarms to multiple eNB

- Missing S1 HO command forwarding to target eNB - Delayed reply/forwarding to S1AP messages

- UEContextReleaseCommand without strange cause values

For internal use

- Delayed reply/forwarding to S1AP messages

- UEContextReleaseCommand without strange cause values - Duplicate/Strange MME UE S1AP ID allocations

- KPI drops after new EPC SW upgrade - KPI drops after EPC parameter upgrade

• First step troubleshooting actions - FTM mirror port Wireshark trace - FTM logs

- EPC logs if possible

- In case NSN EPC, contact NSN R&D

- In case other vendor EPC, contact customer

Backhaul SW bugs

• Symptoms

- KPI drops after new Backhaul element type/ SW version/feature is launched or activated in the network

- KPI drops after Backhaul parameters/routing version is launched in the network

- Link breaks for a cluster of eNB (e.g. behind a specific router) - S1 Error indications/Alarms for a cluster of eNB

- Increased latencies in TCP level - Increased TCP re-transmissions - Congestion alarms/indications

- Connectivity problems to certain IP addresses/TCP ports - Throughput can not exceed certain (low) limit

• First step troubleshooting actions - FTM mirror port Wireshark trace - FTM logs

- Backhaul elements logs or Wireshark traces, if possible

Faulty eNB units

• Symptoms

- Raw or Customer Alarms indicating faulty/missing units - Known problematic HW versions are installed in the field - KPI drops after new HW installations

- KPI drops after storms, floods, earth quakes, etc. natural disasters

For internal use

- KPI drops after storms, floods, earth quakes, etc. natural disasters - Call drops located under certain cell away from cell edge

- Long periods/Frequent cell unavailability - Frequent site resets

• First step troubleshooting actions

- Check eNB status with SiteManager - Arrange HW swap

- Check that there is no systematic SW/Comissioning/HW version fault burning HW components

Faulty UE

• Symptoms

- On UE type or user in same location is causing frequent call drops - Call drops follow similar pattern in same cell location and during time

of day

- High interference peaks in same cell location and during time of day - High interference peaks in same cell location and during time of day - Bursts of call drops in one cell for short time period, without the cell

being sleeping/disabled

• First step troubleshooting actions

- Try to find out problematic UE type

- Try to find out problematic subscription IMSI

- In case thousands of call drops, contact customer and ask them to

Commissioning

• Symptoms

- HO fail in target cell for specific eNBs -> frequency sync faulty or missing

- Line code violation (and high amount of ghost calls) -> problems in RP3-01 optical fibres

- Antenna line alarms - > Loose feeder cables

For internal use

- Antenna line alarms - > Loose feeder cables - No S1 connection -> Wrong IP settings

- Start-up problems or alarms-> Invalid commissioning parameters or unsupported configuration

- Call drops inside certain cell area out side cell edge -> antenna tilting - High DL interference -> Wrong cell power settings or antenna tilting

• First step troubleshooting actions - Check status with Site Manager

- In case problems with cabling arrange site visit

Call drops

Network planning

• Symptoms

- There are clear holes in network coverage, when analyzed with NetAct Optimizer (or other application, which displays cell locations)

- There are clear non-line of sight locations for dense populated places

- Cell under Train, boat or bus traffic are configured with basic HO parameters - eNB indicates lack of resources

- eNB indicates lack of resources

- Scheduled UEs per TTI is near maximum continuously during busy hours - Timing Advance values indicate too far distances for used carrier frequency

and fading environment (e.g. urban city with tall buildings) - Call drops in cell edge and no meas report sent

- Signal levels are low in large cell areas

- Frequent call drops in same location with multiple UE types - High DL interference is certain cell locations

• First step troubleshooting actions

- Check status with NetAct Optimizer or site plan - Contact customer for poor coverage

Call drops Diagnostics

• Symptoms

- Contention resolution timer expires and some kind of tracing is active - CPU loads are high (> 80 %) despite of moderate Traffic mix

- Heavy amount of prints in SysLog or short Snapshot SysLog duration - Emil trace activated during heavy CP traffic

For internal use

- Emil trace activated during heavy CP traffic

- Strange R&D flags visible in swconfig.txt or in Start-up syslog prints - UP data traced/uploaded loaded continuously

- Backhaul Traffic >> Air Interface traffic

• First step troubleshooting actions

- Turn of tracing and additional logging - Switch of R&D flags

- Contact tool developers and R&D

TOOLS

Data Collected from eNodeB for Analysis

- The eNB snapshot contains the following information:

• Active alarms and alarm history for this eNB

• Installed SW versions

• eNB configuration (commissioning parameters)

• Internal log files for different eNB components (including MAC TTI traces (10 MB))

BTS Technical Report/BTS Snapshot

For internal use

MB))

• PM counter data for this eNB (starting from the last eNB reset, but max for 24 hours)

- Logs are frozen by eNB when fetch command is received - Saved in .zip file when loaded

- Collection of technical log is triggered by via the

• BTS Site Manager protocol. When technical log is collected from the Site Manager, the term snapshot is used as a synonym.

Measurement Tools (NSN R&D Internal tools)

The following measurement tools have been developed by NSN for R&D that you can also use

• BTSLog

• BTSlog is a testing tool including functionality of:

• System log recording & real-time monitoring tool

• Message trace and recording

• R&D parameters handling

• BTSlog is used for BTS testing and works with Windows

• LTE Browser

• LTE Browser is used to get the real time data about the CPU load, & real time UL PHY measurement

For internal use

• LTE Browser is used to get the real time data about the CPU load, & real time UL PHY measurement data (SNR, BLER etc) memory dump information's from DSPs and static Cell specific configuration information

• Emil

• EMIL is an offline message tracing analyzer tool.

• EMIL parses all the internal messages between different software components,

• EMIL has the capability to show all ASN.1 messages (RRC, S1 AP, X2 AP messages)

• Emil L3 decoding works even if IPsec is used for S1/X2

• TTI Trace Analyzer

• Traces Cell and User specific TTI information

• Helps to analyze the behavior of the DL/UL Packet Scheduler .

For internal use

Analysing BTS message logs with Emil

After Sack and profile configuration trace file can be opened with EMIL.

In document Lte Operations and Maintenance (Page 45-68)

Pre-defined reports overview -> Modulation and Coding Scheme

PERFORMANCE MANAGEMENT

4. Pre-defined reports overview -&gt; Modulation and Coding Scheme

TROUBLESHOOTING

TOOLS

4. Pre-defined reports overview -> Modulation and Coding Scheme