Radio Coverage Prediction in Picocell Indoor Networks Instructor: Prof. Natan Blaunstain Students : Liore Pasco, I.D. 038556189 Yahav Karmy, I.D. 025575002

Research’s Goals Study of Indoor Radio Propagation Parameters such as : Attenuation, Fading … 2. Study of Picocell Environment 3. Analysis of Existing Analytic, Statistic and Empirical Models. 4. Simulation of One Selected Model and Conclusion

Basic Model For Wave Strength: 1/(range)^2 Background 1. Introduction Basic Model For Wave Strength: 1/(range)^2 So Why Not to Use It ??? Reflection – wave which impinges objects larger than it’s wave length goes back decreased by reflection factor. Scattering - wave which impinges a rough surface goes back with different frequency and polarization. ( wave length here is bigger than obstacles dimensions )

Diffraction – wave impinges obstacles between tran. and rec. creates multiple waves with different amplitudes Multi Path Phenomenon: a single wave from the tran. splits to many different waves due to diffraction, reflection and scattering.

Definition : The difference between signal’s energy 2. Attenuation Definition : The difference between signal’s energy at the receiver (Pr) and at the transmitter (Pt) This is a very important parameter when calculating Signal to Noise Ratio ( SNR ) and Coverage Area Basic Formula of Path loss: 10log(Pt) – 10 log(Pr) Attenuation = - Path loss

3. Fading Definition: variation of amplitude and relative phase for one or more of the frequency components of the signal Fading is caused by changes in the characteristics of the propagation path with time Some physical factors that influence fading: Speed of the mobile ( Doppler Shift ) Speed of surrounding objects Channel bandwidth Multi path propagation

4. Main Characteristics of Picocell Environment The cellular system developed at the late 70’s and define segmentation of the coverage area into cells Picocell antenna are designed for indoor environment and each cell cover an area between 1 meter to several tens meters

Indoor environment main losses reasons: Losses due to obstacles at the same floor or room such as: variable indoor architectures and materials cubic and room partitions chairs, doors, tables Partition losses between floors which depends on: - external dimensions of the building - different materials of partitions - number of windows - width of partitions

The Three Approaches 1. Statistic Model Transmitter Receiver Channel Main model concepts: EM field evaluation and diffraction analysis using the: a. Uniform Theory of Diffraction b. Beam tracing algorithm 2. Statistically modeling the impulse response of the channel using a Gaussian function to describe the time delay variance (  )

Results: Channel’s impulse response Power at the Receiver The EM magnitude

2. Empirical Model Transmitter Receiver Channel Main model concepts: Analyzing and measuring the path loss referring to: Distance Angle of incident 2. Analyzing and measuring the diffraction

Results: Prediction results Error analysis

The Selected Model Review 3. Analytic Model The Geometric Problem – The Corridor d – Corridor width,  - Wavelength X – Distance between Receiver And Transmitter Y – Y position between corridor’s walls, W is the middle of it Py - The electric momentum of a point horizontal electric dipole

The electrical properties of walls are defined by surface impedance Where: - The dielectric permittivity of the wall’s surface 0 - The dielectric constant of the vacuum - The conductivity w = 2f - The angular frequency of the radiated wave. d >>  - Allows us to use the approximation of geometrical theory of reflection and obtains : X  30-50 m,  = 3-10 cm, d = 2-3 m The height of the corridor is also >>  therefor we look on a 2D corridor.

After Analyzing the Electromagnetic Fields … The wave guide modes of total field inside the unbroken impedance wave guide are obtained as: Where : Reflection factor for mode n Dipole constant, describes the antenna Wave constant of normal wave guide for mode n n – Mode number k = 2/ - Wave constant in free space X – Distance between Rec and Tran Wave number for mode n

The Reflection in the Corridor

The attenuation can be derived from this condition: Deriving an Expression for the Attenuation and Path Loss … The attenuation can be derived from this condition: This is the threshold for mode effectiveness This factor describes the correlation between distance, number of modes n and their effect on the received power. Normal modes propagate as waves in an ideal wave guide without attenuation

Finally after some mathematical calculations the attenuation is: Let’s look at some MATLAB simulations and on some experimental data to clear the picture … The parameters in our simulation are: Conductivity of the walls – 0.0133 S Signal frequency – 900 MHz Corridor Width – 3 meters

Simulations Results and Analysis … CHI Value and mode number See that for ~50 meters the 2 first modes are most effective for Path loss

Path loss for the different modes

Total Path loss

Conclusions In this model, we based on analytic transforms and equations in order to obtain expressions for the electromagnetic field, the path loss and attenuation of a propagated radio wave in corridor.   This model handles only the case of a corridor but radio wave propagation expressions for rooms and between floors can be developed in a similar way depends on the description of the geometric problem. Using this model we can predict the power of a received signal and decide where to place our amplifiers and receivers.

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