Meta Data in Log File

This page is not about testing anything. This is more of information purpose. This is about the meta data in a log file. If you open up a saved log file in text editor, you will see a list of important informations at the beginning of the file. It is called meta data. You would not see this information in WebGUI, you need to open it in text editor to see this part of the log. The contents of this part is not usually documented in official document and tend to change with different releases. So what you see in your log from current setup may not be same as what you see in this page.

Personally I am referring to this information for following cases. You may have your own reasons for the reference.

• MIB / PBCH log is not directly printed out in gNB log, but I can get most of gNB MIB information from the Meta data (NOTE : Since 2022-06-17, MIB logging is supported. Check out this)
• In LTE, I can get the summary of resource allocation for PUCCH and figure out how much of resources are available for user data (Check out this tutorial on how to interpret / utilize this information)
• I can get the configuration data for each component (i.e, enb, mme. ims) and convert it into Amarisoft *.cfg file (Check out this tutorial on how to do this).

The initial version of this page is based on 2022-02-23 release and I will update/add items when there is any outstanding changes/additions.

Table of Contents

• Meta Data in Log File
• Introduction
• Summary of the Tutorial
• Examples of Meta Data
• enb - LTE log
• enb - NR NSAlog
• enb - NR SAlog
• mme
• ims
• Descriptions
• CFG
• Cell - NR

Introduction

Log file metadata plays a crucial role in the analysis, debugging, and interpretation of system and network behavior, especially in telecommunications environments such as LTE and 5G NR. Metadata refers to the structured information embedded at the beginning of a saved log file, which provides essential context about the recorded data, including configuration parameters, software and hardware versions, timestamps, network identifiers, and other environment-specific details. Unlike the main log content that represents event sequences and operational data, metadata is generally not visible through standard Web Graphical User Interfaces (WebGUIs) but requires direct access via a plain text editor. This information is vital for engineers, analysts, and developers who need to correlate log data with network topology, software releases, or specific test scenarios. Furthermore, the format and content of log file metadata are often undocumented and may vary between different software releases, making it necessary for users to familiarize themselves with the structure present in their current setup. The metadata section can reveal valuable insights such as gNB MIB (Master Information Block) information, resource allocation summaries for LTE PUCCH (Physical Uplink Control Channel), and detailed configuration data for network components like eNodeB, MME, or IMS. By leveraging this metadata, professionals can perform advanced troubleshooting, optimize resource usage, generate configuration files for platforms like Amarisoft, and gain a deeper understanding of system behavior across network generations.

• Context of Log File Metadata
  • Definition: Metadata in a log file consists of structured information headers that precede the main log entries, offering valuable context about the logging environment.
  • Access Method: Typically accessible only by opening the log file in a text editor, not through standard WebGUI interfaces.
  • Variability: The structure and content of log metadata may change across software releases and are often not officially documented.
• Relevance and Importance of Metadata Analysis
  •   Enables extraction of key network parameters, such as MIB and PBCH details, not directly available in standard logs.
  •   Facilitates the interpretation of resource allocations (e.g., LTE PUCCH), aiding in performance optimization and capacity planning.
  •   Provides configuration snapshots for critical components (e.g., enb, mme, ims), which can be converted into configuration files for simulation or deployment.
  •   Offers a foundation for advanced troubleshooting and root cause analysis by correlating log data with specific network setups and software versions.
• What Learners Will Gain from This Tutorial
  •   Comprehensive understanding of log file metadata structure and its significance in telecom log analysis.
  •   Skills to extract and interpret key metadata fields relevant to various network operations.
  •   Ability to convert metadata-derived configuration data into formats compatible with tools like Amarisoft.
  •   Awareness of best practices for leveraging metadata in troubleshooting, resource planning, and network optimization.
• Prerequisite Knowledge and Skills
  •   Familiarity with telecommunications concepts such as LTE, 5G NR, gNB, eNodeB, and network configuration parameters.
  •   Experience with log file analysis and use of text editors for file inspection.
  •   Basic understanding of networking components (e.g., MME, IMS) and their configuration mechanisms.
  •   Exposure to software tools or platforms such as Amarisoft is beneficial but not mandatory.

Summary of the Tutorial

This tutorial provides examples and explanations of meta data found in LTE and NR (NSA and SA) logs for the 2022-02-23 release, as well as descriptions of specific metadata fields that may require additional clarification.

• Meta Data Log Examples:
  • enb - LTE Log:
    • Presents a sample log header with information such as version, license, system configuration (e.g., SMP, PRACH, DRBs, RF), and log file format.
    • Includes detailed cell configuration parameters (e.g., earfcn, pci, mode, n_rb_dl/ul, cyclic prefix) and resource allocations (e.g., PUCCH, SR, CQI, SRS, GBR limits).
  • enb - NR NSA Log:
    • Shows similar header and cell information for an NSA configuration, including dual RF chains (RF0 and RF1) and additional NR cell data (e.g., nr_arfcn, ul_nr_arfcn, rat, n_rb_dl/ul, dl_mu, ul_mu).
    • Highlights resource allocation and scheduling parameters, such as auto k1/k2 configuration and msg3_k2.
  • enb - NR SA Log:
    • Provides SA-specific NR cell configuration, focusing on fields such as nr_arfcn, ul_nr_arfcn, mode, rat, n_rb_dl/ul, dl_mu, ul_mu, and associated GBR limits and scheduling indexes.
• Metadata Field Explanations:
  • CFG:
    • Represents a compressed version of all test configurations.
    • Can be converted into a readable test format, as explained in the referenced tutorial.
  • Cell - NR:
    • Describes individual NR cell parameters, such as nr_arfcn, ul_nr_arfcn, pci, mode, rat, n_rb_dl/ul, dl_mu, ul_mu, ssb_mu, ssb_arfcn, ssb_prb, k_ssb, coreset0_prb, and coreset0_idx.
    • Provides further explanation for certain fields:
      • mu: Subcarrier spacing index (0=15KHz, 1=30KHz, 2=60KHz, 3=120KHz).
      • ssb_prb, k_ssb, coreset0_prb, coreset0_idx: Values determined by MIB in NR cell; for details, refer to 3GPP 38.211, 38.213, and 38.331.

No explicit test procedures or step-by-step methodologies are described in the tutorial. The focus is on presenting example meta data logs and providing explanations for specific configuration fields relevant to LTE and NR test environments.

Examples of Meta Data

Followings are the examples of Meta data for enb, mme, ims logs for 2022-02-23 release.

enb - LTE log

I use the LTE header to check the cell settings and the resources reserved for uplink control. The example comes from /tmp/enb0.log and identifies lteenb version 2022-02-23. (NOTE : The detailed contents in this section may vary depending the version of the installed software package. so just try to capture the high level meaning and purpose of this section)

Cell 0x01 uses earfcn=3350, pci=1, and mode=FDD. Both n_rb_dl and n_rb_ul are 100, with cyclic_prefix=0. The uplink settings include prach_config_index=4 and prach_freq_offset=4.

The PUCCH allocation lists formats 2/2a/2b with RBs=1 and n=6. Start of PUCCH ACK/NACK is 11. The RBs reserved for PUCCH line contains ten entries, all set to 7.

The SR resource count is 220, and the CQI resource count is 240. SRS resources are offsets=8, freqs=20, and total=320. The GBR limits are DL=10.035 Mre/s and UL=10.535 Mre/s.

Text Version Example :

This text example uses lteenb version 2022-12-06 and a different LTE configuration. Both resource block counts are 25, prach_freq_offset is 2, and each PUCCH reservation entry is 3. The SRS total is 80, with GBR limits of DL=2.475 Mre/s and UL=2.492 Mre/s.

enb - NR NSAlog

I check both cell entries in the NSA header because the same log contains LTE and NR settings. This /tmp/gnb0.log example identifies the LTE cell as 0x01 and the NR cell as 0x02.

The LTE cell uses earfcn=300, pci=1, and mode=FDD, with 100 resource blocks in both directions. Its PUCCH reservation entries are all 7. The LTE GBR limits are DL=10.035 Mre/s and UL=10.535 Mre/s.

The NR cell uses nr_arfcn=632628, ul_nr_arfcn=632628, pci=500, and mode=TDD. It has n_rb_dl=273, n_rb_ul=273, dl_mu=1, and ul_mu=1. Its GBR limits are DL=50.319 Mre/s and UL=14.676 Mre/s.

The header also lists Auto k1=[8,7,7,6,5,4,12,11], k2=[7,4], and msg3_k2=8. The SMP line includes RF0=1/1 and RF1=3/3.

Text Version Example :

This text example uses version 2022-12-06, with RF0=2/1 and RF1=2/1. Its NR cell has 51 resource blocks in each direction, rather than 273 in the earlier NSA example. The NR cell line is truncated at ssb_mu before the GBR limits, so it does not provide a complete set of SSB fields.

enb - NR SAlog

The SA header provides the NR cell information directly under Cell 0x01. I use this entry to check the frequency, resource block counts, and numerology for the standalone cell.

This /tmp/gnb0.log uses nr_arfcn=632628 and ul_nr_arfcn=632628, with pci=500, mode=TDD, and rat=nr. Both n_rb_dl and n_rb_ul are 51. The dl_mu and ul_mu values are both 1.

The GBR limits are DL=9.400 Mre/s and UL=2.742 Mre/s. The timing line lists Auto k1=[8,7,7,6,5,4,12,11], k2=[7,4], and msg3_k2=8. The CFG line follows these cell details.

Text Version Example :

This text example uses version 2022-12-06 and keeps the NR resource block counts at 51 in each direction. The cell line is truncated at ssb_mu before the GBR limits. The final timing line also contains trailing text after msg3_k2=8.

mme

The MME header identifies the core network software and defines the columns used by its log entries. I check /tmp/mme.log when I need this information for the MME component.

The software line reports ltemme version 2022-02-23 with gcc 9.2.1. The log format is time layer dir [enb_id|mme_ue_id] message. This differs from the radio log format with cell_id, rnti, sfn, and channel fields.

The CFG entry appears after the log format definition and before Started. It belongs to the MME log, so use this entry when extracting the MME configuration.

ims

The IMS header identifies the software used for the IMS component and includes its configuration data. I check /tmp/ims.log separately from the eNB and MME logs.

The software line reports lteims version 2022-02-23 with gcc 9.2.1. A license line is followed by CFG and Started. This example does not include a Log file format section.

Descriptions

You may understand the meaning of the information in Meta data section without any further explanation. So I would not explain those information in this page. In this section, I will explain only on those information that would require additional description.

CFG

CFG is the compression version of the all the configurations that are used for the test. You can convert this into readable test format as explained in this tutorial.

Cell - NR

Cell data for NR carries information as shown below.

Cell 0x01: nr_arfcn=632628 ul_nr_arfcn=632628 pci=500 mode=TDD rat=nr n_rb_dl=51 n_rb_ul=51 dl_mu=1 ul_mu=1 ssb_mu=1 ssb_arfcn=632544 ssb_prb=12:20 k_ssb=0 coreset0_prb=0:48 coreset0_idx=10

Some information that you want to have explanation would be as follows.

• mu : subcarrier spacing. 0 = 15Khz, 1 = 30 Khz, 2 = 60 Khz, 3 = 120 Khz
• ssb_prb, k_ssb, coreset0_prb, coreset0_idx: all determined by MIB in NR Cell. For the details, refer to 3GPP 38.211, 38.213, 38.331