group assignment wireless systems. contents introduction & hypothesis measurements analysis...

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?