LTE Protocol Testing - Log Analysis

4G LTE
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**How LTE Throughput Analysis & Debugging (in order to improve) is done in layer-wise (PHY/MAC/RLC/PDCP) log Analysis"? Please do explain with IEs in it. **

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LTE throughput analysis using protocol logs is generally performed by correlating Layer-1, Layer-2, and Layer-3 messages and identifying where performance degradation occurs. A practical method used during LTE protocol testing is layer-wise log analysis:

:one: PHY Layer Analysis

Start with radio conditions such as SINR, CQI, MCS, and BLER. These parameters indicate channel quality and modulation efficiency. If CQI is low or BLER is high, the scheduler may select a lower MCS, which directly reduces throughput.

:two: MAC Layer Analysis

At the MAC layer, check PRB allocation, HARQ retransmissions, and scheduling decisions. High HARQ retransmissions or insufficient PRB allocation can significantly limit data throughput.

:three: RLC Layer Analysis

RLC logs help identify segmentation, retransmissions (AM mode), and buffer status reports (BSR). If many RLC retransmissions occur, it often indicates poor radio conditions or packet loss in lower layers.

:four: PDCP Layer Analysis

PDCP logs show header compression, ciphering, and packet reordering behavior. Delays or reordering issues here may affect the effective data rate experienced by the user.

:five: Signaling Correlation (RRC / NAS)

Sometimes throughput issues are related to signaling events like RRC Reconfiguration, DRX configuration, bearer setup, or handover procedures. Correlating these events with throughput drops helps identify the root cause. In LTE protocol testing, engineers typically analyze logs captured using tools like Wireshark, QXDM, or protocol analyzers, which decode signaling and user-plane messages across LTE interfaces for troubleshooting.

Understanding the end-to-end message flow across PHY → MAC → RLC → PDCP → RRC layers is essential because each layer processes and forwards data differently during transmission.

For learning LTE protocol log analysis step-by-step, this video might also be helpful: https://www.youtube.com/watch?v=YTAq3eqcdDM⁠