GSM Network Quality Audit and Coverage Assessment in a Mountainous Island Region of Europe

1. Context

I was hired as an RF Engineer for a two-month project to support a GSM900 radio network quality audit in a mountainous island region of Europe. The mobile operator was a small regional provider that had not yet introduced 3G, so the objective was to evaluate the health of the existing 2G network, identify performance gaps, and recommend targeted network improvements.

The scope of the audit included:

• Conducting field-based RF measurements using TEMS Investigation tools (phones and laptop software).
• Assessing voice call quality, handover performance, and dropped call rates as primary focus areas.
• Evaluating SMS delivery reliability and basic mobile data performance.
• Identifying and analyzing network issues, including coverage gaps, interference, and signal quality degradation.
• Providing recommendations for optimizing network performance while maintaining cost efficiency.

During the project, I worked closely with the Head of Engineering and the RF team to conduct the audit, analyze data, and propose actionable network improvements.

2. Challenge

Key challenges included:

• Challenging terrain and coverage gaps: The region’s mountainous landscape and scattered islands created natural obstacles for RF signal propagation, leading to coverage gaps and handover difficulties between macro and micro cell sites.
• Tunnel coverage limitations: Several long tunnels lacked continuous macro cell coverage, requiring strategically placed repeaters to extend service. Optimizing handovers between outdoor macro sites and in-tunnel repeaters was essential to maintain seamless call continuity.
• Interference challenges:
  • Signal reflections from rocky terrain caused inter-symbol interference (ISI), degrading call quality and reducing effective coverage in some areas.
  • Co-channel and adjacent channel interference needed to be analyzed and mitigated to ensure frequency planning remained efficient for the operator’s GSM/GPRS network.

3. Approach

To conduct a comprehensive network audit, I worked closely with the RF team, teaming up with a senior RF engineer to perform extensive drive testing across the islands:

• Drive testing and data collection support:
  • Conducted extensive drive testing across all islands in the archipelago, including repeated testing in some areas based on initial findings.
  • Tested all undersea tunnels, focusing on handover continuity and coverage challenges.
  • Some tests were driven by customer feedback, allowing us to investigate specific problem areas reported by users.
• Voice call quality & continuity focus:
  • Prioritized voice quality testing, troubleshooting handover issues, dropped calls, and poor audio quality.
  • Also tested SMS delivery and mobile data performance, though voice remained the key focus.
• Daily briefings with the Head of Engineering:
  • Participated in technical review meetings, validating TEMS log data and identifying software-related anomalies affecting network behavior.
• Analysis and troubleshooting:
  • Processed TEMS logs to map coverage gaps, interference zones, and weak handover points across the network.
  • Worked with senior RF engineers to analyze signal quality trends and propose targeted network optimizations.
• Network improvement recommendations:
  • Handover challenges: Recommended frequency and software-based network tuning to improve transition stability.
  • Tunnel coverage gaps: Identified the need for repeaters at certain sites, with implementation later carried out by the mobile operator.
  • Adjacent channel interference: Provided frequency planning adjustments to minimize interference and improve signal clarity.
• Post-implementation validation:
  • Conducted retesting after frequency updates, ensuring that adjustments effectively mitigated interference and improved network performance.
  • The operator continued monitoring network performance using network-based measurements to track long-term trends.

4. Role & Achievements

As part of the RF team, I:

• Specialized in RF network testing, ensuring seamless TEMS Investigation setup, operation, and real-time data validation.
• Managed device connectivity, troubleshooting TEMS software issues, and assisting with log file validation to ensure high-quality test results.
• Worked closely with the Head of Engineering to review daily test findings and prioritize network optimizations.
• Contributed to network improvement recommendations, including software-based tuning, frequency adjustments, and network configuration refinements.
• Validated post-adjustment network performance through drive testing and network-based measurements, ensuring implemented changes led to measurable improvements.

5. Results & Post-Project Impact

• The audit led to measurable network improvements, enhancing GSM900 network quality and handover performance across the region.
• The operator adopted recommended solutions for tunnel coverage enhancements, interference mitigation, and frequency tuning to improve service reliability.
• The project validated efficient network optimization strategies, helping the operator improve service quality while maintaining cost-effectiveness.

Post-Project Impact & Career Progression

• Following this project, I deepened my expertise in TEMS and RF measurement tools, leading to a later role in a TEMS-focused team.
• Worked with more advanced RF measurement tools, including RF Scanners and DSP-based PESQ measurement tools for UMTS networks.
• Conducted TEMS product training sessions for mobile operators, further developing my technology consulting and training expertise, which later extended to product managing network optimization services for GSM, UMTS, and LTE.