Aksum University

Aksum Institute of Technology

Faculty of Electrical and Computer Engineering
Department of Electronic Communication Engineering

TITLE:-Performance analysis of
SCFDMA and OFDMA in LTE system
Semester project proposal
Submitted by

Name ID
TEKEBA ALEMU TAMALEW 0904974

AMENU HAILE AMERA 0900581

ASFAW TILAHUN AREGA 0900718

2012 E.C
 Table of Contents page
ABSTRACT……………………………………………………………..….1

1. INTRODUCTION ………………………………………………………
2. Statement of the problem……………………………………………….
3. Objectives…………………………………………………………………
3.1 General Objective………………………………………………….
3.2 Specific Objectives……………………………………………….
4. Significant of the project………………………………………………………….
5. Scope of the project………………………………………………………………..
6. Methodology ……………………………………………………..
7. Materials ………………………………………………………
8. Time schedule ……………………………………………………………….
9. REFERENCES ………………………………………………………………………..

List of figure
1 Figure 1.1: Methodology used in our project ………………………………………………….

2
3

List of table
1
2
List of Acronyms

3G …………………………. Third Generation

3GPP …………………………. Third Generation Partnership Project

4G …………………………. Fourth Generation

% …………………………. Percentage
ADC …………………………. Analog to Digital Converter

ADSL …………………………. Asymmetric Digital Subscriber Line

AWGN …………………………. Additive White Gaussian Noise

BER …………………………. Bit Error Rate

BPSK …………………………. Binary Phase Shift Keying

BRAN …………………………. Broadband Radio Access Network

BS …………………………. Base Station

CCDF …………………………. Complementary Cumulative Distribution Function

CP …………………………. Cyclic Prefix

DAB …………………………. Digital Audio Broadcasting

DAC …………………………. Digital to Analog Converter

dB …………………………. Decibel

D-BPSK …………………………. Differential Binary Phase Shift Keying

D-QPSK …………………………. Differential Quadrature Phase Shift Keying

DVB-T …………………………. Digital Video Broadcasting Terrestrial

Eb …………………………. Bit Energy

Page
FD …………………………. Frequency Domain

FDD …………………………. Frequency Division Duplex

FFT …………………………. Fast Fourier Transform

IFFT …………………………. Inverse Fast Fourier Transform

ISI …………………………. Intersymbol Interference

LTE …………………………. Long Term Evolution

MATLAB …………………………. Matrix Laboratory

MHz …………………………. Megahertz

MOD …………………………. Modulator

MS …………………………. Mobile Station

No …………………………. Noise Power Spectral Density

OFDM …………………………. Orthogonal Frequency Division Multiplexing

PAPR …………………………. Peak to Average Power Ratio

PDF …………………………. Probability Density Function

P/S …………………………. Parallel to Serial

PSK …………………………. Phase Shift Keying

PTS …………………………. Partial Transmit Sequence

QAM …………………………. Quadrature Amplitude Modulation

QPSK …………………………. Quadrature Phase Shift Keying

SC-FDMA …………………………. Single Carrier Frequency Division Multiple Access

SLM …………………………. Selective Mapping

SNR …………………………. Signal to Noise Ratio

S/P …………………………. Serial to Parallel

SSPAs …………………………. Solid State Power Amplifiers

TD …………………………. Time Domain
…………………………. Time Division Duplexing
TDD

ABSTRACT
Recently, Long Term Evolution (LTE) has been deployed by many operators to address the
growing data needs. As other new emerging technologies, LTE wireless communication
system uses Orthogonal Frequency Division Multiplexing (OFDMA) for down link and single
carrier frequency division Multiplexing (SC-FDMA) for uplink direction. OFDM is a
bandwidth efficient multicarrier modulation where the available spectrum is divided into
subcarriers, with each subcarrier containing a low rate data stream. OFDM has gained a
tremendous interest in recent years because of its robustness in the presence of severe
multipath channel conditions with simple equalization, robustness against Inter-symbol
Interference (ISI), multipath fading, in addition to its high spectral efficiency. However, the
Peak-Average Power Ratio (PAPR) is a major drawback of multicarrier transmission system
such as OFDM. Therefore it is necessary to overcome the PAPR of the transmit signal in
OFDM systems. Among different PAPR reduction techniques the three reduction techniques
(SLM, PTS and Clipping) are proposed to overcome this problem. In this project, we
investigated the PAPR reduction performance with hybrid selective mapping (SLM) &
clipping. The clipping scheme clips out the peak of the transmitted signals larger than the
given level which reduce the PAPR. Though clipping degrades BER performance of the
system as the transmit signals are heavily distorted. Hence, the proposed scheme can provide
more PAPR reduction without degradation of the BER performance. The results are verified
using MATLAB software.

1. INTRODUCTION
Ethio-telecom expands the network frequently to satisfy the
customer need. Now a day’s long term evolution (LTE) or 4G
is deployed in some part of Addis Ababa city. LTE (Long
Term Evolution) is a standard for 4G wireless broadband
technology that offers increased network capacity. It uses
 OFDMA for downlink and single carrier orthogonal frequency
division multiple access (SC-FDMA) for uplink.
Orthogonal frequency division multiplexing is a form of
multicarrier modulation that divides a high data rate
modulating stream, placing them on to many narrowband
closely spaced subcarriers, making it less sensitive to
frequency selective fading. Its advantages include high spectral
efficiency; multi path delay spread tolerance, immunity to
frequency selective fading. But one of the challenging issues of
an OFDM system is its high peak to average power ratio
(PAPR). The highest Peak to average power ratio (PAPR)
which cause non-linearity at receiving end, reduce power
efficiency of the RF power amplifier at transmitter and
decrease the performance of the transmitted signal. The large
peak to average power ratio (PAPR) push the power amplifier
to work in nonlinear area which result in band and out of band
distortion. This causes significant signal distortion at the output
of the power amplifier. In addition, the high PAPR can cause
saturation at the digital to analog converter, leading to
saturation of the power amplifier. Therefore, the power
amplifier must operate with a large power back-off,
approximate to that of PAPR which lead to insufficient
operation [7].
Single carrier frequency division multiple access (SCFDMA)
which utilizes single carrier modulation at the transmitter and
frequency domain equalization at the receiver is a technique
that has similar performance and essentially the same overall
structure as those of an OFDMA system. One prominent
advantage over OFDMA is that SC-FDMA signal has lower
peak-to average power ratio (PAPR) [10].

2. Statement of problem
Ethio-telecom implemented LTE (4G) in some part of Addis
Ababa city to address the subscriber high demand of
throughput. LTE uses OFDM modulation techniques in down
link scheme. High PAPR is one of the biggest problems in
OFDM system. To transmit signals with high PAPR, it requires
 power amplifiers with very high power scope. These kinds of
amplifiers are very expensive and have low efficiency-cost.
When peak power is too high, it could be out of the scope of
the linear region of a power amplifier. This gives an increase to
non-linear region distortion which that affects and changes the
superposition of the signal spectrum resulting degeneration in
performance. OFDM system has encountered many restrictions
in practical applications if there is no PAPR reduction. But in
reality due to high Peak to average power ratio the BER is
high, the performance of signal reliability is low and due to
high computation of digital to analog converter the signal
makes delay.
In general high PAPR consumes more power in MS and BS in
wireless communication system. Not only in OFDM, had
PAPR had also a negative impact in SCFDMA system
practically. Apart from various demerits in OFDM but still it is
used for communication between transmitter and receiver as if
the signal is not orthogonal then there can be chances of
crosstalk distortion in a signal.
3. Objectives of the project
3.1 General Objective:
 To analyze and simulate the performance of SCFDMA
and OFDMA in terms of PAPR and BER comparison
Parameters.
3.2 Specific Objectives:

 To reduce PAPR value of OFDMA system using different reduction techniques

 To select the best PAPR reduction technique in OFDM system
 To analyze the BER performance of best selected PAPR reduction technique in OFDM system

 To select the best digital modulation technique by comparing BER value of SCFDMA system

 To reduce power consumption in mobile station (MS) and base station (BS)

4.Significant of the project

This project is highly significant for LTE system and other technology that uses OFDM and SC-
FDMA modulation techniques. The standard quantity of PAPR enables a power amplifier to
work in linear region. This leads to efficient power amplifier, low signal distortion, low BER,
low digital to analog and analog to digital computation. Therefore the quantified PAPR leads to
reliable communication and high throughput. Also this project will have a contribution to reduce
power consumption in MS and BS and improves the performance of the system.

5.Scope of the project

 Understand the concept of LTE, OFDM, SCFDMA, CCDF, PAPR and BER.
 Analyze PAPR of SCFDMA and OFDMA theoretically.
 Analyze PAPR reduction techniques used in OFDMA
 Analyze BER performance of SC-FDMA with different modulation technique
 Selecting best PAPR reduction technique used in OFDMA
 Analyze the BER performance of the best selected PAPR reduction technique used
in OFDM system
 The simulation tool used is Matlab.
6. Methodology used in the project
▪ Title selection: the title is selected because LTE is a promising standard in
the world as well as in our country and analysis of the two schemes (OFDM
and SCFDMA) in LTE is highly related to our stream
▪ Literature Review: Literature Review is done using different techniques
by using magazines, books, research paper and others
▪ Mathematical analysis and system design: mathematical equation and
instruction is used to model and draw algorithm that analyzes the
performance of OFDM and SC-FDMA in terms of PAPR and BER
parameters
▪ Simulation result and discussion: the simulation is done by using
MATLAB software using complementary cumulative density function
(CCDF) probabilistic model and BER.
 Start

Title Selection

Literature Review

Mathematical
analysis and system
design

Simulation result
and Discussion

End Figure 1.1: Methodology used in our project.

 Material requirements:-
 software MATLAB