ELEC-E7120 Wireless Systems (5 cr)

Presentation of the Group Assignment

Group Number 8

Aalto School of Electrical Engineering,

Aalto University, Espoo, Finland

Content

• Introduction• Problems• Assumptions• Measurements• Conclusion• Solution

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Introduction

• Week 38• Signal measurement• Netradar and OpenSignal• Operators

– Saunalahti– Sonera– DNA

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Some data from Netradar

Problems

• Poor service• Low/bad quality of phone calls• Dropped phone calls• Bad data coverage

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The chosen location

• Jämeräntaivel 3

• Bad signal quality

• Operator: Saunalahti

• Environment– Close to the sea– Surround by forest– Buildings with

thick walls

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Assumptions (1)

• There is no Base Station near by:

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• Reflection from vegetation, which cause attenuation

Source: ITU-R, Vol. V, Rep. 236-6

Assumptions (2)

• There is not enough flat surfaces where the signal can be reflected

• The antenna is not directive in the direction of the building

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Building

Assumptions (3)

• The signal from the BS could not achieve the building, since it is located in downhill

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Measurement Campaign

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Result and Analysis (1)

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Result and Analysis (2)

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Result and Analysis (3)

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Result and Analysis (4)

• According to 3GPP TS 27.007, which is implemented in Android, the table below summarizes how the ASU and Received power is calculated

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ASU Received Power01

2...303199 not known or not detectable

-113 dBm or less-111 dBm-109... -53 dBm-51 dBm or greater

Result and Analysis (5)

• The fomula used to calculate power in dBm is – P(dBm) = 10 · log10( 1000 · P(W) / 1W) = 10 · log10( P(W) / 1W) + 30

• 1W = 30dBm

• In Netradar application Signal Strength is calculated in % by using the below formula

– Percentages within range 0-100. 0 = no signal at all, 100 = the best possible signal.

– Raw signal strength value (ASU) is converted to a percentage using a conversion formula (ASU / 97.0 * 100) for LTE network and (100.0 / 31.0 * ASU) for GSM networks (2G and 3G).

• In opensignal, the dBm values are available in the application

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Result and Analysis (6)

• The received power inside the building is much lower than other measurements

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Conclusion

• The fact of building is in downhill • Walls are too thick • There is a lot of attenuation from the vegetation• No reflection from flat surfaces

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Solutions (1)

• Cell Phone Signal Booster: designed to amplify a weak outside signal and provide a strong signal inside.

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Solutions (1)

• Repeater: a possible solution should be to put a repeater above Taffa, so the signal could achieve the building

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