TELECOMMUNICATION NETWORK PLANNING AND OPTIMISATION NUMBER

MODULE CODE AND TITLE:
ETTNO801:TELECOMMUNICATION NETWORK
PLANNING AND OPTIMISATION
NUMBER OF CREDITS: 15
B.Tech Electronics and Telecommunication Technology , Academic year 2024/2025 1
Btech in
Electronics and Telecommunication Technology

Mobile Multiple Access Techniques and Interference
Management

Reuse Frequency Distance and Co-channel Interference
• But D (distance between any two cells) is a function of NI and S/I. NI is
the number of co-channel-interfering cells in the first tier.
• Where S is the desired signal power from the desired base station and Ii
is the interference power caused by the ith interfering co-channel cell
base station.

Mobile Multiple Access Techniques
▪ The transmission from the BS in the downlink can be
heard by every mobile user in the cell and is referred to
as broadcasting.
▪ Transmission from the mobile users in the uplink to the
BS is many-to-one and is referred to multiple access.
▪ For voice or data communications, must ensure two-way
communication (duplexing, it is possible to talk and listen
simultaneously).
▪ Duplexing may be done using frequency or time domain
techniques

Mobile Multiple Access Techniques
• Multiple access schemes are used to allow many users
to share simultaneously a finite amount of radio spectrum
resources.
• For high-quality communication this sharing of spectrum
should not degrade performance of the system.
• Duplexing is generally required
• Frequency domain
• Time domain
• Transmission modes can be categorized into three
distinct types: simplex, half-duplex, and full-duplex.

DUPLEXING communication
 What is Duplexing?
• to talk and listen simultaneously is called
duplexing.
• Classification of communication systems
according to their connectivity.

DUPLEXING communication(Cont’d)
▪ In simplex mode, transmission is unidirectional (i.e., transmission
always occurs only in one direction). The simplex mode uses the entire
capacity of the channel to send data in one direction. Examples of
simplex communication are used in commercial broadcasting.
• In half-duplex mode, transmission is bi-directional, but only in one
direction at a time. The end devices can both transmit and receive, but
not at the same time. In half-duplex mode, the entire capacity of the
channel is taken over by whichever of the two devices is transmitting at
the time. Examples of half-duplex communication are walkie-
talkies and CB radios as well as dial-up fax machines.
• In full-duplex mode, transmission is simultaneously bi-directional. The
end devices can transmit and receive simultaneously. A prime example of
full-duplex communications is the PSTN which provides two-way
communications

▪ Frequency division Duplexing (FDD) : Uplink (UL) and
Downlink (DL) communication are separated in the frequency
domain by assigning two different frequency
▪ Time division Duplexing (TDD) : UL and DL communication
take place over the same frequency but at different instants
of time but this time is too small to be perceived by us.
DUPLEXING communication

 FDMA: All users share the available frequency spectrum
at the same time. Each users has its frequency portion.
Channel Capacity of FDMA System:
N=(Bt-2Bg)/Bc Where
:Bc: Channel bandwidth
:Bg: indicates guard band
:Bt: represent transmission
band width
Example: Advanced Mobile Phone System
Frequency Division Multiple Access (FDMA)

EXAMPLE: A DVANCED MOBILE PHONE SYSTEM(AMPS)
 AMPS
 FDMA/FDD
 Analog cellular system
 12.5 MHz per simplex band - Bt
 Bguard = 10 kHz ; Bc = 30 kHz
30E3
N= 12.5E6 - 2*(10E3) = 416 channels
20

FDMA Disadvantages
• FDMA has a drawback that if a channel is assigned to the
user most of the time it is idle.
• Bandwidth requirement is more.
• Lower spectral efficiency

Time Division Multiple Access (TDMA)
 TDMA: A group of users use the same frequency
channel but during different time intervals (Time
Slot).
• TDMA systems divide each FDMA channel line to
time slots
• Each user occupies a cyclically repeating time
slot
• TDMA can allow different number of time slots for
separate user
 Non-continuous transmission
 Most of second generation systems use TDMA
Example: Global
System for Mobile
(GSM)

22
Channel Capacity of TDMA System

EXAMPLE: GLOBAL SYSTEM FOR MOBILE (GSM)
200E3
N= 8*25E6 = 1000 simultaneous users
25
GSM is a TDMA/FDD system that uses 25 MHz for the forward link,
with channels of 200 KHz. If 8 speech channels are supported on a
single radio channel, and if no guard band is assumed, find the
number of simultaneous users that can be accommodated in GSM.
Thus, GSM can accommodate 1000 simultaneous users.

Code Division Multiple Access (CDMA)
 In CDMA, all users use the same carrier frequency
and transmit simultaneously “Wideband system”
 Each user has its own pseudo random
code word which is approximately
orthogonal to other codes.
• CDMA permits using same set of frequencies in
all the cells “ Universal Frequency reuse”. This
eliminates the frequency of planning
•Some second-generation systems use CDMA
• Most of the third-generation systems use CDMA

 SDMA is a multiple access technique, takes the
advantage of the directional nature of space.
Using a directional antenna the transmission
power is focused in a desired direction and
reduces the interferences.
 SDMA can be used in combination with other
multiple access technique, since user in
different space domain can use the same
frequency, time and code resources, without
creating interferences.

Coverage Dimensioning Process
Coverage planning consists of an evaluation of Down Link and
Upper Link radio link budgets. The maximum path loss is
calculated based on service throughput defined by the cell
edge user that requires SINR level at the receiver

Academic Year: 2021-2022
Mechanism of EM Wave Propagation

Mechanism of Wave Propagation
• In general, radio wave propagation consists of three main attributes: reflection,
diffraction and scattering
• Reflection occurs when radio wave propagating in one medium impinges upon
another medium with different electromagnetic properties (permittivity,
permeability, and conductivity).
• Diffraction is a phenomenon by which propagating radio waves bend or deviate in
the neighborhood of obstacles. Diffraction results from the propagation of
wavelets into a shadowy region caused by obstructions such as walls, buildings,
mountains, and so on.
• Scattering occurs when a radio signal hits a rough surface or an object having a
size much smaller than or on the order of the signal wavelength. This causes
the signal energy to spread out in all directions.

▪ The main goal of coverage planning is to estimate the
coverage distance of a BTS with parameter settings
based on actual cell edge coverage requirements to meet
network size requirements
▪ The initial planning of a cellular network is selecting an
adequate propagation model for the frequency range and
type of region considered.
▪ Radio Link Budget is the most prominent component of a
coverage planning exercise
Introduction

▪ The necessary parameter to characterize when the signal
in a mobile receiver is obtained, is the path loss or
propagation loss (L), which is defined by
Propagation Methods
• Then, the main objective of a tool that aims to obtain the
received power based on the positions of the transmitter
(Tx) and the receiver (Rx) is to characterize the propagation
loss in a given environment
Path Loss

Free-Space Attenuation
• The most simple wave propagation case is that of a direct
wave propagation in free space . In this special case of line-
of-sight (LOS) propagation there are no obstructions due to
the earth’s surface or other obstacles.
Attenuation: Reduction in amplitude of signal level

The received power, Pr, at the receiving antenna (mobile station),
located at a distance, d, from the transmitter (base station) is
given for free space propagation as:
If other losses (not related to propagation) are also present, we
can rewrite Equation as

Academic Year: 2021-2022

• Obviously, this situation does not happen in a real
environment, and the loss is modified by different natural
(mountains, vegetation) and artificial (buildings) obstacles
in the environment.

NOISE TEMPERATURE, NOISE FIGURE AND SNR
• The noise introduced by a network may also be expressed as effective
noise temperature (Te).
• Effective noise temperature defined as that fictional temperature at the
input of the network, which would account for additional noise introduced
by the network itself at the output.
• Effective noise temperature (Te) is related to noise figure (F) as follows.
Check Page 84-87: Yadaav

Signal to Noise Ratio (SNR)
• The SNR is defined as the ratio of power received to system noise
power.
in which the system noise power PN (in watts) is related with the
system noise temperature Ts as follows:
• From Friis equation, the received power by an antenna
is

Signal to Noise Ratio (SNR)
If the receiver has its own centre temperature Tr (due to
thermal noise), the system noise power at the receiver
terminals is given by :

• We assume that the base station and mobile station antenna
heights, hb and hm, are much smaller compared to their
separation, d, and the reflecting earth surface is flat.
Attenuation over Reflecting Surface

• The received power at the antenna located at a distance, d,
from the transmitter, including other losses, L0, is given as
• Note that under the assumed conditions the received signal
level depends only on the transmitted power, antenna
heights, and separation distance; no frequency dependence

1ft = 0.3048m

• The expression for the effects of ground reflections from a flat (or
plane) earth provides results that are approximately correct for
• The results are not valid for
In this case, the attenuation factor will be:

Effect of Earth’s Curvature
• The curvature of the earth further affects the propagation of
the space wave since the ground-reflected wave is reflected
from a curved surface.
• Therefore, the energy on a curved surface diverges more
than it does from a flat surface and the ground-reflected wave
reaching the receiver is weaker than for a flat earth
• The divergence factor D that describes this effect is less than unity
and is given as:

Effect of Earth’s Curvature
• D ranges from unity for a small value of d and approaches zero
as d approaches the distance to the radio horizon.
• The equation for calculating the received power in dBm is given
as:

NLO Propagation && Shadowing Effect
• Also called lognormal fading
• Lognormal fading, which could reduce the received power
at any location.

The received power under non-line-of-sight propagation conditions
can be written as:

Propagation Path-Loss Models
• Propagation path-loss models play an important role in the
design of cellular systems to specify key system parameters
such as transmission power, frequency, antenna heights,
and so on.
• Propagation models are used to determine the number of
cell sites required to provide coverage for the network.
• The propagation model is also used in other system
performance aspects including handoff optimization, power
level adjustments, and antenna placements.
• We discuss two widely used empirical models:
Okumura/Hata and COST 231 models.

Okumura-Hata Propagation Model
• Okumura analyzed path-loss characteristics based on a large
amount of experimental data collected around Tokyo, Japan
• He selected propagation path conditions and obtained the
average path-loss curves under flat urban areas. Then he
applied several correction factors for other propagation
conditions, such as:

Typical Urban

Cost 231-Hata Model
• This model is a combination of empirical and deterministic models
for estimating the path loss in an urban area over the frequency
range of 800 MHz to 2000 MHz.

Cost 231-Hata Model

Path Loss Propagation Models

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