EL ALCAZAR REAL

This correction is only applied when the path loss is to be calculated over land paths, and over a transmitter-receiver distance less than 16 km. This correction gives more precise field strength prediction over small reception areas. The correction is added to the field strength and is given by:

Where , , and

is the clearance angle in degrees determined from:

• : The elevation angle of the line from the receiver which just clears all terrain obstructions in the direction of the transmitter over a distance of up to 16 km but not going beyond the transmitter.

• : The reference angle, .

Where and are the heights of the transmitter and the receiver above sea level, respectively.

2.10.1.6 Step 6: Calculation of Path Loss

First, the final field strength is calculated from the interpolated/extrapolated field strength, , by applying the corrections calculated earlier. The calculated field strength is given by:

The resulting field strength is given by , from which the path loss (basic transmission loss, ) is calculated as follows:

2.11 Sakagami Extended Propagation Model

The Sakagami extended propagation model is based on the simplification of the extended Sakagami-Kuboi propagation model. The Sakagami extended propagation model is valid for frequencies above 3 GHz.

d₁₀ = D_0,6f h ₁ h₂=10 m d_h2 = D_0,6f h ₁ h₂ D_0,6 Max 0,001 D_fD_h

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The Sakagami-Kuboi propagation model requires detailed information about the environment, such as widths of the streets where the receiver is located, the angles formed by the street axes and the directions of the incident waves, heights of the buildings close to the receiver, etc. The path loss formula for the Sakagami-Kuboi propagation model is [1]:

Where,

• W is the width (in meters) of the streets where the receiver is located

• is the angle (in degrees) formed by the street axes and the direction of the incident wave

• h_s is the height (in meters) of the buildings close to the receiver

• H₁ is the average height (in meters) of the buildings close to the receiver

• h_b is the height (in meters) of the transmitter antenna with respect to the observer

• h_b0 is the height (in meters) of the transmitter antenna with respect to the ground level

• H is the average height (in meters) of the buildings close to the base station

• d is the separation (in kilometres) between the transmitter and the receiver

• f is the frequency (in MHz)

The Sakagami-Kuboi propagation model is valid for:

Studies [2] have shown that the Sakagami-Kuboi propagation model can be extended to frequencies higher than 3 GHz, which also allows a simplification in terms of the input required by the model.

The path loss formula for the extended Sakagami-Kuboi propagation model is:

Where a is a corrective factor with three components:

• W is the width (in meters) of the streets where the receiver is located

• H₀ (= h_s = H₁) is the height (in meters) of the buildings close to the receiver

• h_b (= h_b0) is the height (in meters) of the transmitter antenna with respect to the ground

• h_m is the height (in meters) of the receiver antenna

• H is the average height (in meters) of the buildings close to the base station

• d is the separation (in metres) between the transmitter and the receiver

• f is the frequency (in GHz)

Studies also show that above 3 GHz, the path loss predicted by the extended model is almost independant of the input parameters such as street widths and angles. Therefore, the extended Sakagami-Kuboi propagation model can be simplified to the extended Sakagami propagation model:

The extended Sakagami propagation model is valid for:

The path loss calculation formula of the Sakagami extended propagation model resembles the formula of the Standard Propagation Model. In Atoll, this model is in fact a copy of the Standard Propagation Model with the following values assigned to the K coefficients:

For more information on the Standard Propagation Model, see "Standard Propagation Model (SPM)" on page 65.

2.12 Free Space Loss

The calculation of free space loss is based on ITU 525 recommendations.

where,

f is the frequency in MHz, d is the Tx-Rx distance in km, Free space loss is stated in dB.

2.13 Diffraction

The calculation of diffraction is based on ITU 526-5 recommendations. General method for one or more obstacles (knife-edge diffraction) is used to evaluate diffraction losses (Diffraction loss in dB). Four construction modes are implemented in Atoll.

All of them are based on this same physical principle presented hereafter, but differ in the way they consider one or several obstacles. Calculations take the earth curvature into account through the effective Earth radius concept (K factor=1.333).

2.13.1 Knife-edge Diffraction

The procedure checks whether a knife-edge obstructs the first Fresnel zone constructed between the transmitter and the receiver. The diffraction loss, J(), depends on the obstruction parameter (), which corresponds to the ratio of the obstruction height (h) and the radius of the Fresnel zone (R).

10 m < h_b < 100 m

0.1 km < d < 3 km

3 GHz < f < 8 GHz

1.5 m < h_m < 5 m

K1 65.4

(calculated for 3.5 GHz)

K2 40

K3 -30

K4 0

K5 0

K6 0

K7 -5

References:

• [1] Manuel F. Catedra, Jesus Perez-Arriaga, "Cell Planning for Wireless Communications," Artech House Publishers, 1999.

• [2] Koshiro Kitao, Shinichi Ichitsubo, "Path Loss Prediction Formula for Urban and Suburban Areas for 4G Systems," IEEE, 2006.

L_Model = 54+40Log d –30Log h _b +21Log f –5Log h _m

L_FS = 32,4+20log f +20log d

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where,

n is the Fresnel zone index,

c₀ is the speed of light (2.99792 x10⁸ ms^-1), f is the frequency in Hz

d₁ is the distance from the transmitter to obstacle in m, d₂ is the distance from obstacle to receiver in m.

We have:

where,

h is the obstruction height (height from the obstacle top to the Tx-Rx axis).

Hence,

For 1 knife-edge method, if , Else,