Analisis and performance evaluation of OFDM based on DWPT and sliding window techniques

Dissertant

Taha, Haytham Jabbar

Thesis advisor

al-Samarri, Ayid K. M.
Zibun, Hadi T.

University

University of Technology

Faculty

-

Department

Department of Electrical Engineering

University Country

Iraq

Degree

Master

Degree Date

2012

English Abstract

Due to great growth of wireless digital communication systems, they are rapidly expanding resulting in demand for systems that are reliable, have a high spectral efficiency and the need of modulation technique that can transmit high data rates at high bandwidth efficiency.

To fulfill these demands, the multicarrier modulation scheme, often called Orthogonal Frequency Division Multiplexing (OFDM), has drawn appreciable attention.

OFDM is capable of providing very high data rate with strong robustness of multipath delay spread, which makes Intersymbol Interference (ISI) no longer a problem.

Addition of Cyclic Prefix (CP) is the main method for the Fourier based OFDM to eliminate the ISI and Intercarrier Interference (ICI).

To decrease the bandwidth waste, brought about by adding CP.

A Discrete Wavelet Transform-based OFDM (DWT-OFDM) is adopted due to its excellent orthogonality between subcarriers and efficient spectral containment.

In this work, Discrete Wavelet Packet Transform (DWPT) has been studied extensively, and a new structure for DWPT-OFDM that is based on FFT and Sliding Window is proposed.

The purpose of this is to achieve BER performance better than the conventional OFDM based FFT and DWPT.

The proposed DWPT-OFDM systems have been examined in different channel models, mainly, Additive White Gaussian Noise (AWGN) and multipath fading channel.

In this work, many models of DWPT-OFDM are proposed.

In the first model FFT-OFDM system is replaced by the DWPTOFDM modulation.

The simulation results of this model show that the proposed model has better performance in AWGN and flat fading channels compared with the traditional FFT-OFDM model.

The second model is based upon the development of new FFT–OFDM system based on DWPT.

The third model DWPT-OFDM is based on FFT with Sliding Window (SW).

A new scheme, which combines FFT and DWPT with SW, reduces the Bit Error Rate (BER) performance.

The fourth model presents a design of a new DWPT -OFDM with Sub-Sliding window (S-SW).

In this model, the BER is reduced compared with the DWPT-OFDM system without S-SW (Model-1), in AWGN channel and flat fading channel.

The third and fourth models are based on the Sliding window algorithm.

The simulation performance of these models shows that the proposed models improve their performances in AWGN and the flat fading channel when compared with the traditional model.

The BER performance is used as a comparison between the proposed systems for different modulation type of 16-QAM and 64-QAM.

Two types of channels are used, namely the AWGN and multipath fading channel.

The computer simulation test shows that the BER performance of the DWPT-OFDM system based on SW is better than the performance of DWPT-OFDM system over AWGN and flat fading channel by about 9dB (16-QAM) and SNR=16 dB (64-QAM), while the conventional model has SNR=23.5 dB (16-QAM) and SNR=32dB (64-QAM).

In the flat fading channel, the proposed model has SNR=14dB (16-QAM) and SNR=18.5 dB (64-QAM), at BER=10-4 while the conventional model has SNR=37.5dB (16-QAM) and SNR=42.5dB (64-QAM), at BER=10-4 and Doppler frequency 100Hz.

The hardware is implemented using the Small Form Factor (SFF) Software Defined Radio (SDR) Development Platform (DP).

Main Subjects

Electronic engineering

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-419877