Free Space Path Loss and Received Power Calculations

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ASSESSMENT 2
Task and design Project

Table of Contents
List of Figures.............................................................................................................................................. 2
Introduction.................................................................................................................................................. 3
Objective...................................................................................................................................................... 4
Received power formula.............................................................................................................................. 5
Task 1.......................................................................................................................................................... 5
Calculations for path loss & Received power:.......................................................................................... 5
Code and plots......................................................................................................................................... 7
Task 2........................................................................................................................................................ 10
1-base station location, area and antenna selection overview...............................................................10
2-Base station cell (Justification of Design)...........................................................................................10
Conclusion................................................................................................................................................. 11
References................................................................................................................................................ 12
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List of Figures
Figure 1 Propagation of a signal from transmitter to receiver...............................................................4
Figure 2 Path loss occurring in free space............................................................................................. 5
Figure 3 Code for path loss and received power....................................................................................7
Figure 4 plot between received power and distance at 1000MHz..........................................................7
Figure 5 plot of path loss vs distance...................................................................................................... 8
Figure 6 plot between received power and distance at 400MHz............................................................8
Figure 7 plot of path loss vs distance...................................................................................................... 8
Figure 8 plot between received power and distance at 150MHz............................................................9
Figure 9 plot of path loss vs distance...................................................................................................... 9
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Introduction
In wireless propagation, free space path loss is the loss in the signal strength when it propagates through
free space. The extent of the signal falls when travels faraway from the location wherever it's been
emitted. (Ali & Razak, 2010)
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Objective
The main objectives of this task and design project are
To understand wireless networking, its real-time applications and the calculations involved in free
space path loss and received power in wireless propagation.
To propose a design for a given cellular architecture
To analyze networking concepts and techniques
Figure 1 Propagation of a signal from transmitter to receiver
As solely a tiny low fraction of radiated power is received at the receiver from an isotropous radiator in
free area, however the received signals, should be 10-20 decibel on top of the receiver noise to complete
the link between transmitting and receiving antenna. (Martijn & Herben, 2003)
Path loss between transmitter and receiver end can be calculated. It varies directly with the square of the
distance between TX and RX ends (Li & Chen, 2004).
Free space pathloss=[ 4 πd
λ ]2
As
λ=c / f
So,
Free space path loss=[ 4 πdf
c ]2
In terms of decibels:
Free space path loss(dB)=10 log 10[4 πdf /c ]2
¿ 20 log 10[4 πdf /c ]
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¿ 20 log 10 [ 4 π
c ]+20 log 10 [ d ] +20 log 10[ f ]
¿ 32.46+20 log[f ( MHz )∗d ( Km ) ]
here,
f=the frequency in MHz
d= the distance between transmitter and receiver
c = the speed of light
Received power formula
Figure 2 Path loss occurring in free space
Task 1
Calculations for path loss & Received power:
Given data:
d=30km
gt=1, gr=1
pt=100
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Frequency =150Mhz
Path loss ( dB ) =32.46 +20 log [ f ( MHz )∗d ( Km ) ]
Path loss(dB)=105.53
lambda= c
f =2
Received power=( pt∗¿∗gr) /(( 4∗pi∗d )/lambda)2
¿ 2 . 817 e−9 watts
Frequency =400Mhz
Path loss(dB)=32.46+20 log[f (MHz)∗d ( Km)]
Path loss(dB)=114.05
lambda=c/f=0.75
Received power= pt∗¿∗gr
( 4∗pi∗d
lambda )
2 =3.96 e−10 watt
Frequency =1000Mhz
Path loss(dB)=32.46+20 log[f (MHz)∗d ( Km)]
Path loss(dB)=122.01
lambda=c/f=0.3
Received power=( pt∗¿∗gr) /(( 4∗pi∗d )/lambda)2
¿ 6 . 3389 e−11 watts
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Code and plots
Figure 3 Code for path loss and received power
.
At frequency =1000MHz
Figure 4 plot between received power and distance at 1000MHz
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Figure 5 plot of path loss vs distance
At frequency =400MHz
Figure 6 plot between received power and distance at 400MHz
Figure 7 plot of path loss vs distance
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At frequency =150Mhz
Figure 8 plot between received power and distance at 150MHz
Figure 9 plot of path loss vs distance
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Task 2
1-base station location, area and antenna selection overview
The central part of the entire base station cell is considered as the urban area. We can truly consider the
tower surrounded part to be the urban part (Shi, 2008, April). The higher speed connections of urban
areas require a large number of towers around itself, where the city is well developed and the place is
manageable (Zhang, 2013). The areas where the towers are informally situated are the rural area regions
which are numbered as 8. The number 20 cell is the area situated as urban area. The area which is less
condensed than the Urban area and high dense than the Rural area is the Suburban area which is
marked as number 12.
2-Base station cell (Justification of Design)
When we come to know the desired cell shapes, the most enhanced form for the shape of base station is
Hexagon. Hexagon shape is selected because of the network area optimization in it, in which all networks
are viewed at each and every point. We have decided this shape because of the consideration of every
shape in base station (Ganz, 1997).
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Conclusion
It is concluded from this task and design project that in wireless networking extent of the signal falls when
it travels faraway from its source that is emitting it. Received power also decreases when signals move
from transmitter to receiver. The path loss in free space varies directly with the frequency and distance.
Greater the frequency of the signal, greater will be the loss. Formulas for path loss and received power
have been observed and calculations are done for different frequencies at a given transmit power. For a
given cellular architecture a design has been proposed and it is analyzed which serves a greater
understanding of wireless networking. A code was also developed on octave and different plots of
received power and path loss Vs distance have been obtained.
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