Project Background: Weak GSM Signal Inside a Hospital Building
The Foshan Fifth People’s Hospital in Guangdong, China, recently opened a new convalescent building. Soon after the building was put into use, staff and patients began reporting a serious issue: mobile signal inside the building was extreely weak, and voice calls were often unstable or impossible to complete.
For a healthcare environment, reliable mobile communication is essential. Medical staff need stable connectivity for coordination, patients need dependable communication with family members, and daily operations cannot be interrupted by indoor signal dead zones. To solve the problem, the hospital chose a professional Callboost hospital signal booster solution designed specifically for indoor GSM coverage.
Part 1: Site Survey – Identifying the Root Cause
Before system design began, Callboost engineers carried out a full on-site signal survey. The team tested rooftop signal conditions, corridor coverage, and patient room signal levels across all three floors of the building. The survey showed that while rooftop GSM signal was relatively strong at around -75 dBm, signal levels dropped significantly indoors. Some patient rooms measured between -110 dBm and -115 dBm, which made normal voice calls unreliable or completely unusable.
The main cause was building attenuation. The convalescent building used reinforced concrete, metal-framed windows, and Low-E glass, all of which reduced GSM signal penetration from outside to inside the building. This meant that although outdoor carrier signal was available, indoor coverage remained too weak for practical use.
Pre-Installation Measured Data
Analysis
The convalescent building is a newly built reinforced concrete structure with thick walls, metal-framed windows, and low-emissivity glass. These materials create a Faraday cage effect for 900 MHz GSM signals. Although the outdoor signal from the tower is strong (approx. -75 dBm at roof level), it attenuates by 35–40 dB once inside, rendering most indoor areas unusable for voice calls.
Part 2: Custom GSM Signal Booster Design for 3-Floor Coverage
Based on the site survey, Callboost designed a custom hospital signal booster system using three GSM repeater units, one for each floor, to improve indoor mobile coverage throughout the building. Each repeater was connected to an independent donor antenna for more stable source signal reception. During system tuning, the first unit was set to 65 dB gain, while the second was adjusted slightly lower to prevent over-coverage. The third floor was covered through four ceiling antennas connected by power dividers. Engineers also completed VSWR testing, with results of 1.2, 1.3, and 1.2 respectively, and all units passed 72-hour burn-in testing before deployment. To improve long-term stability, the system included remote monitoring, automatic gain adjustment, and oscillation protection. After installation, the three repeaters worked together to provide a stable indoor signal coverage solution for the hospital building.
System Overview
Technical Specifications
Signal Source Capture: High-gain Yagi antennas installed on the rooftop, precisely aimed at the carrier tower 1 km away. Each Callboost booster uses industrial-grade low-noise amplifiers.
Zoned Independent Coverage: The building was divided into three independent coverage zones, with one GSM repeater installed on each floor to improve indoor mobile signal coverage and prevent interference. All units featured Automatic Gain Control (AGC) for stable performance, with the first unit set at an AGC threshold of -20 dBm. The system also delivered strong technical performance, including a 3.8 dB noise figure, 20 dBm output power, EMC-tested reliability, and built-in lightning protection. After on-site tuning, the three repeaters worked together to provide a stable and efficient hospital signal booster solution.
Indoor Antenna Layout: Omni-directional ceiling antennas were evenly distributed along corridors and inside patient rooms to eliminate dead zones.
Cabling and Connectors: Low-loss 1/2-inch RF coaxial cable (total 500 meters) with 42 N-type connectors.
Oscillation Prevention: All units have built-in oscillation protection. Sufficient vertical and horizontal separation was maintained between rooftop Yagi antennas and indoor ceiling antennas.
Part 3: Installation Process and System Deployment
Callboost’s technical team provided full on-site support throughout the signal booster installation process. The project was completed in three phases: antenna positioning and cable routing, equipment connection and initial tuning, and final system optimization with acceptance testing. During installation, engineers carefully inspected all connectors, resolved a cable length issue on site, and re-measured VSWR after deployment to ensure all parameters passed. The entire signal booster installation was completed in three working days.
To support future maintenance, all antennas were clearly labeled, a hospital technician participated in the installation process, and Callboost provided both a detailed installation manual and on-site staff training. Every step was documented with text and photos, and the final acceptance report was signed by both parties. The project not only delivered a stable indoor coverage system for the hospital, but also provided valuable experience for similar hospital signal booster installation projects in the future.
Post-Installation Measurements
Customer Feedback
The facility’s operations manager commented: “Callboost’s engineers were highly professional, from initial survey through final tuning. Now our entire convalescent building has full signal. Elderly patients can video call their families anytime, and staff productivity has greatly improved. This system runs stably with almost no maintenance.”
Part 4: Why This Solution Is Worth Emulating
Custom Design, Not One-Size-Fits-All
Hospitals and convalescent facilities have unique architectural features and coverage requirements. Callboost follows a survey → design → install process, ensuring each Callboost booster is placed exactly where needed.
Proven GSM Coverage Technology
Even as 5G networks expand, GSM remains the foundation for voice communication in many regions. Callboost’s mobile coverage extender series supports multi-band operation and can be customized for single-band or dual-band use.
Professional Installation Guidance
Proper signal booster installation is the key to performance. Callboost provides end-to-end technical support—antenna alignment, cable selection, system tuning.
Comprehensive After-Sales Support
The hospital received a one-year equipment warranty and long-term technical consulting. Each connectivity amplifier comes with a detailed factory test report and on-site acceptance record.
In hospital and convalescent environments, building structure, room layout, and reliability requirements are very different from those of ordinary offices or residential spaces. A proper hospital signal booster system must be planned according to the actual site. That is why a custom solution is often more effective than a one-size-fits-all setup.
Part 5: Callboost’s Customization Capabilities
This type of indoor mobile coverage solution is also suitable for:
hospitals
nursing homes
rehabilitation centers
clinics
healthcare office buildings
convalescent facilities
If a healthcare facility has strong outdoor signal but weak indoor coverage, a professionally designed signal booster system can help solve the last-meter communication problem and restore stable voice and mobile service indoors.
Conclusion
This hospital project demonstrates that even in a reinforced concrete building with Low-E glass and serious indoor attenuation, full indoor GSM coverage can still be achieved through a properly designed signal booster system. From site survey to installation and final acceptance testing, the project shows the value of custom engineering for healthcare signal coverage.
If your hospital, nursing home, or rehabilitation center is facing similar indoor mobile signal problems, a custom Callboost hospital signal booster solution may be the next step.