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GROUP ASSIGNMENT
Wireless Systems
CONTENTSINTRODUCTION & HYPOTHESISMEASUREMENTSANALYSISCONCLUSIONS
INTRODUCTION & HYPOTHESIS
Achieving consistent user experience across mobile systems has been challenging
Challenges: - Terrain effect- Interferences- Noises- Propagation Loss
Procedures of this campaign:
- Discover a spot with low signal strength and construct an hypothesis for the scenario
- Intensive Measurements- Data analysis and validation of the hypothesis- Conclusion
Scenario:
A lecture room with metal walls that shield electromagnetic waves
Geographical info: F147, ground floor in Otakaari 5
Hypothesis:
Faraday’s Cage
MEASUREMENTS
Networks tested:
- DNA- Sonera- Elisa
Mobile Apps used:
- Network Signal Info- OpenSignal
Measurements in Otakaari 3 Lecture Hall 1- Inside/Outside
INSIDESignal Strength: -113dBmCell Id: 35734 (Short), 6851478 (Long).Network: DNA
OUTSIDESignal Strength: -93dBm
OPEN DOOR
Signal Strength: -109dBm
Measurements in Otakaari 3 Lecture Hall 1- Around
LECTURE HALL 2Signal Strength: -97dBm
FIRST FLOOR – SAME LOCATIONSignal Strength: -87dBm
DISTANCE TO BSFew hundred meters
OTHER OPERATORSSimilar results (+-1dBm)
ANALYSIS
PATH PENETRATION LOSS Discarded
Based on the measurements now we can greatly state that we have a Faraday’s Cage case
An external field causes electrical charges in the material that cancels the fields inside
The lack of windows enhance the effect
Eventhough the Base Station is in the nearby of the Lecture room, there’s a complete cancellation of the signal
VERY STRONG EFFECT
CONCLUSIONS
•Using big pieces of conductive material as art is bad, or even dangerous
• Signal jamming using active devices is illegal• Conductive materials gray zone
• Solution: replace conductive materials with similar looking non-conductive ones
•Mobile signal strength is taken into consideration by building’s contractor
• Was the indoor design party different from the contractor• Design field should be informed of avoiding usage of
conductive materials• Subject for cross-field student project? Perhaps in Aalto?
•WiFi APs easiest and fastest solution in the University’s spaces
•Rural areas most critical with already weak signal strength• Problem especially in scarcely populated Finland
•Bathrooms and cellars are problematic• Elders might require critical aid
•The Finnish law is currently paradoxical• Energy efficiency requirements for new buildings and for
renovations• Personal signal boosters illegal• Communications marketing law (Viestintämarkkinalaki § 6
a) states that everyone has a right to a working mobile line
Comprehensive publication done by the Finnish Ministry of Transport and Communications in 2013 suggests
•RF-value of walls heavily recommended or imposed•“Signal holes” required for buildings
• Wall structures• Windows without conductive coating
•Femto-cells! (also introduced in our course’s lectures)• Cell sizes already vary in size. Should and could it vary
more? More energy efficient in urban areas? What about rural areas?
THANK YOU FOR YOUR ATTENTION
Questions?