The mobile operators in Libya, as many other operators, use some propagation models to predict the receiver signal strength, but without studying what is the best model for the Tripoli area. The work proposed in the current research involves the comparison of four radio propagation models based on LTE technology to be applied in the Tripoli environment. Then the tuning of the best model depending on real data from the local environment will be carried out.

1. Abstract
The mobile operators in Libya, as many other operators, use some propagation
models to predict the receiver signal strength, but without studying what is the best
model for the Tripoli area.
The work proposed in the current research involves the comparison of four radio
propagation models based on LTE technology to be applied in the Tripoli
environment. Then the tuning of the best model depending on real data from the
local environment will be carried out.

2. Introduction
Cell planning in the mobile communication system is one of the most important
operations that, must be done before the installation of the system.
Cell planning means studying the geographic area where the system will be installed
and the radius of each area coverage.
Radio propagation modelling is a key part of the cell planning of wireless
communication systems.

3. LITERATURE REVIEW
Propagation model
A radio propagation model is an empirical mathematical formulation for the
characterization of radio wave propagation as a function of frequency, distance,
and other conditions.
The main goal of propagation models is to predict signal strength as accurately
as possible, allowing the range of a radio system to be determined before
installation.

4. Some of the commonly used outdoor propagation models are now illustrated.
Cost 231 Model

5. Environment Type
Rural 45.95 100.6 12 0.1
Suburban 43.20 68.63 12 0.1
Urban 36.20 30.20 12 0.1
Ericson 9999 Model

6. Okumura model

7. This model incorporates the graphical information from the Okumura model and
develops further to realize the effects of diffraction, reflection, and scattering
caused by city structures.The model served as a base for the Hata Model and the
following assumptions apply to the use of the Okumura Hata model.
Okumura-HataModel
Frequency: 150 MHz to 1500 MHz
Mobile Station Antenna Height: between 1 m and 10 m
Base station Antenna Height: between 20 m and 200 m
Link distance: up to 20 km.

9. Radio Link Budget Calculation
The link budget calculation in the cell is calculates for the farthest point from the
cell tower.
In order to calculate the maximum coverage, Consideration must be given to the
minimum signal intensity received by the receiver. The most important parameters
of the budget calculation is discussed in the following definitions:

10. • Transmitter Power: The total transmission power from cell towers antenna
• EPRE: Indicate power for one resource element (RE). This can be used for any
channel (e.g, Reference Signal, PDSCH etc).
• EPRE = total Tx power - 10 Log(Number of RB x 12)
• Antenna Gain: Antenna gain depends mainly on carrier frequency, size of
antenna and device type. The cell tower antenna gain is a typical 15-18 dBi.

11. Losses: Includes cable and body losses on both sides (cell tower antenna and
phone). Cable losses depend on the length and type of cable and frequency.
EIRP: Is a stand for Effective Isotropic Radiated Power, the term is used to express
how much transmitted power is radiated in the desired direction. It takes into
account all type of losses and the gain of the transmitter antenna as:
EIRP (dBm) = Pt (dBm) + Ga (dBi) – Cable losses
Where: Pt(dBm): Cell tower transmitting power
Ga(dBi): Antenna gain in reference to isotropic antenna.

12. RX Level:
Is a stand for received signal level, which considered the signal strength obtained by the
mobile phone from cell tower antenna. It is importing factor who determines that the
reception was good or not.
The mathematical formula to calculate the Rx level is:
• RxLev (dBm) = EIRP - Pl – L+G (10)
• Where: EIRP (dBm)= Effective Isotropic Radiated Power.
Pl (dB) = path loss propagation model.
L (dB) = other loss and margin (Interference margin, slow
fading margin, body loss and penetration loss)
G (dB) =other gain (pilot boosting gain, MIMO gain, Handoff.
Gain, HARQ gain and coding gain).

13. ModelAssessmentMethod
Pm: Measured path loss (dB)
Pr: calculated PL from the models (dB)
N: Number of measured data points.

14. ModelTuningMethod
Simple linear regression has been used for model tuning which is a model with a
single independent variable x that has a straight-line relationship with a dependent
variable y.
• E(y/x)=β0+β1x
Eestimate Least Squares has been used as numerical method for linear regression

15. Results and Discussion
Practically, the signal strength is measured by a drive test in cell in Tripoli city. This
cell has been chosen in a building environment with a maximum tall 10 m as most
of Tripoli streets. Figure below. shows the location maps of the computerized areas
of the cell towers (urban) under study in which the driving test was applied.

16. TEMS discovery releases 20.3.0 has been used to perform drive tests, which is the
wireless industry’s most comprehensive network analytics and optimization
platform for mobile network performance testing, providing you with unparalleled
insight into network performance as perceived by your subscribers at the device,
application, and network level.

17. Matlab software was used in all calculations and plots of the formals.
The path loss propagation of four models (Cost-231 Model, Ericsson 9999 Model,
Okumura Model, and Okumura-Hata Model) are calculated using the parameters shown
in the next table .

18. Parameter Value
Frequency (MHz) 1855
Total Tx Power (dBm) 43
EPRE (dBm) 12.2
EIRP using eq. 28.7
Allocated RB 100
Tx Antenna Gain (dBi) 17
Tx Cable Loss (dB) 0.5
Tx Body loss (dB) 0
Rx Antenna Gain (dBi) 0
Interference Margin (dB) 3.67
Penetration Loss (dB) 18
Tx Antenna Height (m) 22
UE Antenna Height (m) 1.5
Slow Fading Margin (dB) 7
coding gain 0
Multi-Antenna Combining Gain 3
Pilot Power Boosting 3

20. Table below represent Receiver Signal strength (RSS) equations using propagation
loss equations illustrated before and with input data from table of data.
Model Path loss eq. RxLev. Eq.
Okumura
Okumura-Hata
Ericsson 9999
Cost 231

21. RMSE has been calculated for each model as you can see in table below.
From the table above it appears that Okumura-Hata has the lowest RMSE value
Model RMSE value
Okumura 13.506497
Okumura-Hata 5.463687
Ericsson 9999 17.7229359
Cost 231 5.831957
Models Assessment using RMSE

22. Okumura-Hata Model tuning

23. Value
-32.3407609
0.66587573
RMSE value using modified equation equal 3.07221339

24. Thank you