As per recommendations of International Mobile Telecommunications-2000 (IMT-2000), the future wireless communication is bound to occupy the features including high-speed data and broadband transmission, high capacity to support a huge number of simultaneous users, global mobility, high security, and scalable quality of service (QoS) along with low cost for both operators and subscribers. The above features are imposing technical challenges on system design and stimulating various research topics on capacity, complexity and performance. In order to increase the capacity of wireless networks, various multiple access schemes have been reported in the literature. The credit of most competent multiple access scheme in 2G systems goes to CDMA scheme which offers an even better bandwidth-efficiency than TDMA and FDMA schemes, however, its implementation is quite difficult due to involvement of rather complex technologies including complex power-control, and multiuser detection techniques etc.
The requirement of alternate mechanism for user separation has been solved by Interleave-Division Multiple-Access (IDMA) scheme, in which, most of above stated problems do not exist due to application of user-specific interleavers having low cross-correlation amongst them. The interleaved data resulted from user-specific interleavers, demonstrates better orthogonality amongst each other in the channel. The condition of orthogonality is maintained for reducing the risk of collision amongst the interleavers during communication process.
In IDMA scheme, orthogonal interleavers are employed as the only means for user separation and, hence, are referred as the heart of the scheme. The selection of interleaver along with optimum design methodology for proposed tree based interleaving (TBI) mechanism for IDMA scheme fulfilling the requirement of orthogonality and easy implementation.
In the beginning of work, the mechanism of interleaving with necessary conditions is presented. Later, the performance and analysis of proposed TBI mechanism with IDMA scheme has been presented. Apart from the bit error rate (BER) performance analysis, the interleavers have also been analyzed on the basis of memory requirement and computational complexity at transmitter and receiver ends. Here, The performance evaluation of IDMA scheme with proposed tree based interleaving (TBI) mechanism, in uncoded and coded environments, has been duly investigated along with its implementation.
Table of Contents
1. Introduction
1.1. Development of Wireless Communication Systems
1.2. Multiple Access Schemes
1.2.1. FDMA Scheme
1.2.2. TDMA Scheme
1.2.3. CDMA Scheme
1.3. Motivation
1.4. Problem Statement
1.5. Research Contributions
1.6. Thesis Organization
2. Overview of Interleave-Division Multiple-Access (IDMA) Scheme
2.1. Introduction
2.2. Interleavers in Digital Communication
2.3. Interleavers in IDMA Scheme
2.4. Mechanism of Interleaving Process
2.5. Interleave-Division Multiple-Access (IDMA) Scheme
2.5.1. Comparison of CDMA and IDMA Schemes
2.5.2. IDMA Transmitter and Receiver
2.5.2.1. Basic Primary Signal Estimator (PSE) Function
2.5.2.2. Algorithm for Chip-By-Chip Detection
2.5.2.3. Decoder (DEC) Function
2.5.3. IDMA over Multipath Channels
2.6. Literature Review
2.7. Simulation of IDMA Scheme
2.8. Conclusions
3. Performance Evaluation of Tree Based Interleaver (TBI) in IDMA Scheme
3.1. Introduction
3.2. Motivation
3.3. Mechanism of Tree Based Interleaver (TBI)
3.4. Performance Evaluation of Tree Based Interleaver
3.5. TBI with Unequal Power Allocation Algorithm
3.5.1. Unequal Power Allocation Mechanism
3.5.2. Numerical Results
3.6. Conclusions
4. Performance Evaluation of Tree Based Interleaver in IDMA Scheme with Maximal Ratio Combining (MRC) Diversity
4.1. Introduction
4.2. Diversity Mechanisms
4.2.1. Frequency Diversity
4.2.2. Time Diversity
4.2.3. Space Diversity
4.2.3.1. Transmit Diversity
4.2.3.2. Receive Diversity
4.3. Combining Mechanisms
4.3.1. Selection Combining
4.3.2. Maximal Ratio Combining (MRC)
4.3.3. Equal Gain Combining (EGC)
4.4. Performance Evaluation of IDMA Scheme with MRC Diversity
4.4.1. IDMA Scheme with Maximal Ratio Receiver Combining (MRRC) Diversity
4.4.2. IDMA Scheme with Maximal Ratio Transmitter Combining (MRTC) Diversity
4.5. Simulation Results
4.5.1. Simulation Results of IDMA Scheme using MRRC Diversity
4.5.2. Simulation Results of IDMA Scheme using MRTC Diversity
4.6. Conclusions
5. Correlation Analysis and FPGA Implementation of Interleavers
5.1. Introduction
5.2. Motivation
5.3. Design Criteria for Interleavers in IDMA Scheme
5.4. Correlation in Interleavers
5.5. Correlation Analysis of Interleavers
5.6. Interleaving Mechanism in IDMA Scheme
5.6.1. Random Interleaving (RI) Mechanism
5.6.2. Master Random Interleaving (MRI) Mechanism
5.6.3. Tree Based Interleaving (TBI) Mechanism
5.7. Performance Comparison of Interleavers on FPGA Implementation
5.7.1. Summary of Hardware
5.7.2. Final Register Report
5.7.3. Device Utilization Report
5.7.4. Timing Summary Report
5.8. Conclusions
6. Conclusions
6.1. Suggestions for Further Investigations
Objectives and Research Focus
The primary objective of this thesis is to propose and evaluate an efficient interleaving mechanism, termed Tree Based Interleaving (TBI), for Interleave-Division Multiple-Access (IDMA) systems. The research addresses the challenges of computational complexity, memory requirements, and bandwidth consumption that are associated with existing random and master random interleaver generation methods, while maintaining robust performance in terms of Bit Error Rate (BER) and hardware implementation efficiency.
- Analysis of Interleave-Division Multiple-Access (IDMA) systems and interleaving techniques.
- Development of the Tree Based Interleaving (TBI) mechanism to optimize computational load and memory usage.
- Performance evaluation of TBI in uncoded, coded, and diverse communication environments.
- Correlation analysis of various interleaver mechanisms to understand their behavior with increasing user counts.
- Hardware implementation and validation of TBI on FPGA systems to compare timing and resource utilization.
Excerpt from the Book
3.3. Mechanism of Tree Based Interleaver
The Tree Based Interleaver (TBI) is basically aimed to optimize the problems of the computational complexity and memory requirement which occurs in MRI [104] and RI [76] respectively. In addition to it, TBI also targets on consumption of optimal bandwidth during communication process.
In case of TBI generation mechanism, two randomly generated master interleavers Π1 and Π2, are taken initially. These interleavers are bound to have orthogonality between each other. The zero cross correlation between two randomly selected interleavers ensures the minimal cross correlation between other generated user-specific interleavers, using tree based interleaver generation algorithm. The allocations of the interleaving masks follow the tree format as shown in figure 3.1 demonstrating tree based interleaver mechanism. The interleaving masking diagram is shown upon fourteen users only for the sake of simplicity. For obtaining the interleaving sequence of the 14th user, the TBI mechanism needs only 2 cycles of clock, as compared to many more cycles needed in case of master random interleaver method.
Summary of Chapters
1. Introduction: Provides an overview of the evolution of wireless communication systems and introduces IDMA as a promising alternative for future mobile communication.
2. Overview of Interleave-Division Multiple-Access (IDMA) Scheme: Explains the technical foundations of interleaving and the specific architecture of IDMA systems, including transmitter and receiver components.
3. Performance Evaluation of Tree Based Interleaver (TBI) in IDMA Scheme: Presents the proposed TBI mechanism, evaluates its performance, and demonstrates its superiority in computational complexity and memory efficiency.
4. Performance Evaluation of Tree Based Interleaver in IDMA Scheme with Maximal Ratio Combining (MRC) Diversity: Investigates the effectiveness of TBI within systems employing various diversity mechanisms to mitigate fading and improve reliability.
5. Correlation Analysis and FPGA Implementation of Interleavers: Details the cross-correlation properties of different interleaver types and validates their hardware feasibility through FPGA implementation.
6. Conclusions: Summarizes the thesis findings and suggests potential future research directions for enhancing IDMA-based communication.
Keywords
Wireless Communication, IDMA, Interleaver, Tree Based Interleaver, Bit Error Rate, Computational Complexity, FPGA, Maximal Ratio Combining, Diversity, Multiple Access Interference, Orthogonality, Memory Optimization, Signal Processing, Telecommunications, BER Performance
Frequently Asked Questions
What is the fundamental focus of this research?
This research focuses on the performance evaluation and optimization of interleaving mechanisms in Interleave-Division Multiple-Access (IDMA) wireless communication systems.
What are the primary challenges addressed by this thesis?
The thesis addresses issues regarding computational complexity, excessive memory requirements for storing interleaver patterns, and bandwidth consumption in IDMA systems.
What is the main goal of the proposed Tree Based Interleaving (TBI) mechanism?
The goal is to provide a user-specific interleaver generation method that is easy to implement, consumes minimal memory, and maintains excellent performance compared to existing random and master random interleaver approaches.
Which methodology is used to validate the proposed interleaver?
The validation is carried out through analytical modeling, extensive MATLAB-based simulations for BER performance, and hardware validation via FPGA (Field-Programmable Gate-Array) implementation on a Xilinx platform.
What is the role of the interleaver in an IDMA system?
In IDMA systems, interleavers serve as the core component for user separation, replacing the traditional spreading sequences used in CDMA to ensure users do not collide.
How does the performance of TBI compare to existing methods?
The TBI mechanism shows significantly lower computational complexity compared to master random interleavers and requires far less memory than purely random interleaver approaches, while delivering similar BER results.
How is MRC diversity applied in this research?
Maximal Ratio Combining (MRC) is incorporated as a diversity technique at the receiver and transmitter to combat multipath fading, further demonstrating the robustness of TBI in real-world propagation conditions.
What are the key conclusions regarding hardware implementation?
The FPGA implementation confirms that TBI requires the least number of hardware components (D-flip-flops, logic slices) and offers the best timing performance among the compared interleaving schemes.
- Arbeit zitieren
- Manoj Shukla (Autor:in), 2011, Performance Evaluation of IDMA Scheme in Wireless Communication, München, GRIN Verlag, https://www.hausarbeiten.de/document/276622
