The Orthogonal Frequency Division Multiplexing (OFDM) is an important aspect of multicarrier digital data transmission system where a single data stream is transmitted into a several number of lower rates subcarrier signals. In this thesis, there are five different types of the techniques introduced to strengthen the communication quality and capacity.
This kind of new standard of transmission of data is the first one to perform with OFDM in data packet based communication system. In wireless communication network, the abstraction of parallel transmission of data symbols is implemented to attain high throughput and effective transmission quality. The OFDM is a method to deal with parallel transmission.
Table of Contents
Chapter 1
INTRODUCTION
1.1 Overview of OFDM
1.1.1 Modulation and Demodulation of OFDM
1.1.2 Advantage of OFDM System
1.2 History of Channel Estimation and Selection
1.2.1 Pilot Assisted Channel Estimation
1.2.2 Cyclic Prefix
1.3 Overview of PAPR
1.4 Motivation
1.5 Objective of the Research Work
1.6 Methodologies of Research Work
1.6.1 Addition of Cyclic Prefix
1.6.2 Comb type and Block type Pilot Schemes
1.6.4 Clipping based SLM PTS Technique
1.7 Thesis Organization
Chapter 2
LITERATURE REVIEW
2.2 Review on Inter Carrier Interference Reduction in OFDM
2.3 Survey on Peak Cancelation Techniques
2.4 Overview of Power Line Communication System in OFDM
2.5 Review on MIMO OFDM System
2.6 Existing Techniques for BER and SNR Analysis
2.7 Survey of Earlier Schemes for PAPR Reduction
2.8 Summary
Chapter 3
ENHANCEMENT OF COMMUNICATION QUALITY AND CAPACITY IN OFDM SIGNAL
3.1 Problem Statement
3.2 Contribution of the Research Work
3.3 Significant Principle of an OFDM System
3.4 Overview of Power Line Communication
3.4.1 Single Carrier Technology
3.4.2 Spread Spectrum Technique
3.5 FFT and IFFT based Peak Cancellation
3.6 Traditional ICI Reduction Techniques
3.6.1. Frequency Domain Equalization
3.6.2 Time Domain Windowing
3.6.3 Maximum Likelihood Estimation
3.7 Proposed Communication Quality and Capacity Enhancement Techniques
3.7.1 Wavelet OFDM for Power Line Communication
3.7.2 Peak Cancellation of the Digital OFDM Symbol
3.7.3 ICI Reduction Technique for OFDM with Phase Noise over Fading Channels
3.8 Result and Discussion
3.8.1 Evaluation Metrics
3.8.2 Performance Analysis of Wavelet Transform for PLC
3.8.3 Performance Analysis of Peak Cancellation of the OFDM
3.8.4. Performance Analysis of ICI Cancellation of the OFDM
3.9 Summary
Chapter 4
WAVELET TRANSFORM BASED BER AND SNR ESTIMATION IN MIMO OFDM
4.1 Problem Statement
4.2 Contribution of the Research Work
4.3 Overview of MIMO OFDM
4.3.1 Channel Estimation
4.4. Wavelet Technique in OFDM
4.5 Existing HAAR DWT Technique in OFDM
4.6 Proposed Techniques for Turbo HAAR DWT
4.6.1 System Model
4.6.2 Turbo Code using MIMO OFDM System
4.6.3 Modulation
4.6.4 Proposed HAAR DWT Technique in the MIMO OFDM System
4.6.5 Orthogonal Space Time Block Code
4.6.6 Turbo Decoder
4.7 Result and Discussion
4.7.1 Evaluation Metrics
4.7.2 System Specification
4.7.3 Performance Analysis of BER vs SNR for Different modulations with AWGN Channel
4.7.4 Performance Analysis of BER vs. SNR for Different Modulations with Rician Channel
4.7.5 Performance Analysis of BER vs. SNR for Different Modulations with combination of AWGN and Rician Channel
4.8 Summary
Chapter 5
CLIPPING BASED SLM PTS TECHNIQUE FOR PAPR REDUCTION IN OFDM SYSTEM
5.1 Problem Statement
5.2 Contribution of the Research Work
5.3 Definition of PAPR
5.3.1 Impact of PAPR
5.3.2 Basics for PAPR Reduction Method Selection
5.3.3 PAPR Reduction based on Traditional SLM PTS Technique
5.4 Proposed Clipping SLM PTS Technique
5.4.1 Clipping with SLM PTS technique
5.4.2 Analysis of the Computational Complexity
5.5 Result and Discussion
5.5.1 Experimental Setup
5.5.2 Evaluation Metric
5.5.3 Performance Analysis of Existing and Proposed PAPR Reduction Technique
5.6 Summary
Chapter 6
CONCLUSION AND FUTURE SCOPE
6.1 Conclusion
6.2 Future Scope
Research Objectives and Themes
The thesis aims to enhance the communication quality and capacity of Orthogonal Frequency Division Multiplexing (OFDM) systems by proposing novel techniques for mitigating challenges such as High Peak to Average Power Ratio (PAPR), Inter-Carrier Interference (ICI), and Inter-Symbol Interference (ISI). The primary research questions revolve around developing efficient channel estimation techniques, reducing information loss in fading channels, and optimizing transmitter performance through advanced signal processing methods, including wavelet transforms and clipping-based reduction strategies.
- Enhancement of OFDM system spectral efficiency and throughput.
- Reduction of high PAPR using combined Clipping, Selective Mapping (SLM), and Partial Transmit Sequence (PTS) techniques.
- Mitigation of Inter-Carrier and Inter-Symbol Interference using Turbo codes and HAAR Discrete Wavelet Transform (DWT).
- Performance analysis in diverse channels, including Additive White Gaussian Noise (AWGN) and Rician fading channels.
- Optimization of communication quality for Power Line Communication (PLC) and MIMO-OFDM environments.
Excerpt from the Book
1.1 Overview of OFDM
The main objective of OFDM system be about to divide maximum rate of data into small data rates, after that transfer of these data in parallel employing numerous orthogonal SCs which is also known as Parallel Transmission. This Parallel Transmission technique involves the time period of data symbol rises therefore reduces the correlative amount of scattering of period affected by delay which happen in multipath spread. An OFDM is possible to use in multiplexing strategy or modulation technique. The approach of utilizing parallel data transmission as well as OFDM was introduced in the mid period of 1860s. U S patent was filled but has issued during January 1970. Currently in conventional parallel data transmission system, entire signal bandwidth or frequency band is separated into number of frequency sub channels which are non overlapping [1].
Every frequency sub channels are modified along with distinct symbol after that the sub channels are frequency multiplexed. By this the overlapping spectral can be reduced, Inter Carrier Interference (ICI) is minimized to better extent, channels are removed from SCs thus leads to ineffective support of the enable spectrum [2].
Summary of Chapters
Chapter 1: Provides an introduction to Orthogonal Frequency Division Multiplexing (OFDM), its fundamental principles, the modulation/demodulation process, and the specific objectives of the research work.
Chapter 2: Presents a comprehensive literature review covering existing methods for Inter-Carrier Interference (ICI) reduction, Peak Cancellation, and PAPR mitigation in both MIMO-OFDM and Power Line Communication (PLC) systems.
Chapter 3: Details proposed techniques for enhancing communication quality and capacity in OFDM signals, specifically focusing on wavelet-based OFDM for PLC and linear peak cancellation methods.
Chapter 4: Discusses the implementation of Turbo coding and HAAR Discrete Wavelet Transform (DWT) within a MIMO-OFDM system to optimize BER and SNR performance under various channel conditions.
Chapter 5: Explores a hybrid clipping-based SLM and PTS technique designed to minimize PAPR in OFDM systems, including experimental setups and computational complexity analysis.
Chapter 6: Summarizes the key findings of the research and outlines potential future developments in OFDM and MIMO-OFDM communication systems.
Keywords
OFDM, MIMO, PAPR, Inter-Carrier Interference, Inter-Symbol Interference, Channel Estimation, Wavelet Transform, HAAR DWT, Selective Mapping, Partial Transmit Sequence, Turbo Coding, Power Line Communication, Bit Error Rate, Signal to Noise Ratio, Peak Cancellation
Frequently Asked Questions
What is the core focus of this thesis?
The work primarily focuses on enhancing the spectral efficiency and communication quality of OFDM and MIMO-OFDM systems by developing advanced signal processing techniques to mitigate interference and signal distortion.
What are the primary challenges addressed by this research?
The research addresses high Peak to Average Power Ratio (PAPR), Inter-Carrier Interference (ICI), and Inter-Symbol Interference (ISI), which significantly degrade system performance and efficiency.
What is the main objective of the proposed methodologies?
The primary objective is to design and develop efficient algorithms to reduce information loss, minimize PAPR, and improve Bit Error Rate (BER) and Signal to Noise Ratio (SNR) in complex communication channels.
Which scientific methods are employed for validation?
The research utilizes MATLAB-based simulations to evaluate the proposed techniques, comparing them against existing standards and traditional models in various fading channel environments.
What topics are covered in the main body of the work?
The main body covers a thorough review of existing technologies, the proposal of wavelet-based OFDM for PLC, peak cancellation for digital symbols, and a hybrid SLM-PTS clipping technique for PAPR reduction.
Which keywords best characterize this research?
The work is defined by terms such as OFDM, MIMO, PAPR reduction, HAAR DWT, Wavelet Transform, and Interference Cancellation.
How does the Turbo HAAR DWT technique improve MIMO-OFDM systems?
The Turbo HAAR DWT technique integrates turbo coding for error correction and DWT for efficient CP generation, which together mitigate ISI and ICI and significantly improve overall system spectrum efficiency.
What role does the hybrid Clipping SLM PTS technique play?
This technique combines the strengths of Clipping, SLM, and PTS to achieve superior PAPR reduction while managing the trade-off between computational complexity and signal distortion.
- Quote paper
- Dr. Lokesh Chikkananjaiah (Author), 2019, The Orthogonal Frequency Division Multiplexing (OFDM). Introduction and explanation of five different types of techniques, Munich, GRIN Verlag, https://www.grin.com/document/980234
