This thesis provides a detailed comparison and a classification study for a large number of DBA algorithms with respect to time delay and throughput as performance indicators. The study shows that IPACT WITH CBR, UDBA, IPACT with two stages and CPBA are the optimum DBA algorithms regarding both time delay and throughput at highly loaded scenarios.
Dynamic bandwidth allocation in Ethernet passive optical networks (EPON) presents a key issue for providing efficient and fair utilization of the EPON upstream bandwidth while supporting the quality of service QoS requirements of different traffic classes. Rare literatures have addressed a qualitative and quantitative comparison of large numbers of DBA algorithms based on their performance indicators. These algorithms are enrolled in a parametric optimization process targeting performance enhancement at highly loaded scenarios this increasing upstream line rates, changing distance between the OLT (Optical Line Terminal) and ONU (Optical Network Unit), increasing size of an Ethernet packet and changing maximum cycle time to 1 ms and altering guard time value). This process reduces time delay around 3.5% for IPACT WITH CBR, 1.725% for UDBA, 1.167% for IPACT with two stages and (1.167% for CPBA. Also, the optimization increases the throughput by 1.3% for IPACT WITH CBR, 1.795% in UDBA, 2.5% for IPACT with two stages and 1.684% for CPBA.
Table of Contents
CHAPTER 1 INTRODUCTION
1.1 History
1.2 Objective of Thesis
1.3 Organization of Thesis
CHAPTER 2 BACKGROUND AND LITERATURE REVIEW
2.1 Introduction
2.1.1 Traffic Growth
2.1.2 Evolution of the “First Mile”
2.1.3 Next-Generation Access Network
2.2 Overview of PON Technologies
2.2.1 Optical Splitters/Combiners
2.2.2 PON Topologies
2.2.3 WDM vs. TDM PONs
2.2.4 Burst-Mode Transceivers
2.3 Ethernet PON (EPON) Access Network
2.3.1 Why Ethernet?
2.3.2 Principle of Operation Ethernet PON
2.4 BANDWIDTH ALLOCATION
2.4.1 DBA METHODS
2.4.1.1 DBA Algorithms without QoS Support
2.4.1.2 DBA Algorithms with QoS Support
2.4.1.2.1 DBA Algorithms with QoS Support locally
2.4.1.2.2 DBA algorithms with QoS support globally (universally)
CHAPTER 3 BASIC MODEL AND ANALYSIS
3.1 Introduction
3.2 Time Delay
3.3 Throughputs
3.4 Basic Model
3.5 Mathematical model
3.5.1 Arishtat- Limited Service IPACT- FSD-SLA
3.5.2 CDBA-IPACT
3.5.2.1 CDBA Principle
3.5.3 EBDBA-YDBA-SDBA-ADBA
3.5.4 CPBA- IPACT with two stages- IPACT with CBR credit
3.5.5 e-DBA n-DBA
3.5.6 TLBA-Two Stage Queue
3.5.7 IFLDBA- BP
3.5.8 UDBA-MSARF-CPBA SLA
CHAPTER 4 RESULTS AND DISCUSSIONS
4.1 Introduction
4.2 Simulation
4.3 Throughput Performance
4.4 Time delay performance
4.5 Selection of optimum DBA algorithms
4.6 Optimization Process
CHAPTER 5 CONCLUSION AND FUTURE WORK
5.1 Introduction
5.2 Conclusion
5.3 Future Work
Objectives and Research Focus
This thesis aims to perform a detailed qualitative and quantitative comparison of a wide range of Dynamic Bandwidth Allocation (DBA) algorithms for Ethernet Passive Optical Networks (EPON), specifically evaluating them based on time delay and throughput metrics in highly loaded network scenarios to identify the most efficient algorithms and optimize their parameters.
- Comparative analysis of 23 distinct DBA algorithms.
- Evaluation of network performance using OPNET/C++ simulation.
- Parametric optimization of selected optimum DBA algorithms.
- Focus on enhancing throughput and reducing time delay in high-load scenarios.
- Investigation of Quality of Service (QoS) support across various traffic classes.
Excerpt from the Book
2.4.1.1 DBA Algorithms without QoS Support
The first DBA algorithm for EPON that can be found in the literature is Interleaved Polling with Adaptive Cycle Time (IPACT) [20]. In IPACT, the OLT polls ONUs and grants the bandwidth to each ONU in a round-robin fashion according to the ONU bandwidth demand. Each ONU is served once per round-robin polling cycle. The length of the polling cycle is not fixed where it adapts to the bandwidth requirements of the ONUs. The dynamic cycle length may result in the monopolization of bandwidth for ONUs with high traffic load. In order to prevent this, IPACT introduces maximum transfer window, Wmax. IPACT studies on several bandwidth allocation schemes namely fixed, limited, gated, constant credit, linear credit, and elastic.
Among all the six disciplines, limited scheduling discipline exhibits the best performance in IPACT. The advantages of the IPACT algorithm are that it improves bandwidth utilization by reducing the overhead occurrence from propagation delay and it allows statistical multiplexing. It also deploys an efficient in-band signaling approach that prevents the usage of extra Ethernet frames for control.
Other algorithms that do not support QoS are [21-23]. In [21], a multiple-access control scheme is proposed to provide bandwidth guaranteed (BG) service for high demand ONUs, while providing best effort (BE) service to low-demand ONUs according to the service level agreement (SLA). SLA is a contract between a network service provider and a customer that specifies what services the network service provider will furnish in measurable terms. ONUs are partitioned into two subgroups with some overlap. While frames are collected from the ONUs in one subgroup, the OLT performs DBA for ONUs in the other. Hence, the OLT continuously receives frames from the ONUs without any interruptions in [22]. REPORT messages are arranged by the request length at the next transmission cycle as long as at least one ONU requests a long enough Wmax. Alternatively, when no grant length is long enough, then some requests are laid out together in the idle period to utilize the wasted idle time in [23].
Summary of Chapters
CHAPTER 1 INTRODUCTION: Covers the evolution of PON technologies and the transition toward Ethernet-based passive optical networking.
CHAPTER 2 BACKGROUND AND LITERATURE REVIEW: Provides a detailed review of access network architectures, traffic growth, and the taxonomy of existing DBA algorithms.
CHAPTER 3 BASIC MODEL AND ANALYSIS: Outlines the mathematical modeling and evaluation metrics for 23 specific DBA algorithms under study.
CHAPTER 4 RESULTS AND DISCUSSIONS: Presents the simulation results comparing throughput and delay, followed by the optimization process for selected algorithms.
CHAPTER 5 CONCLUSION AND FUTURE WORK: Summarizes the key findings regarding optimized DBA performance and suggests directions for future research in EPON integration.
Keywords
Ethernet Passive Optical Network, EPON, Dynamic Bandwidth Allocation, DBA, Quality of Service, QoS, Time Delay, Throughput, Interleaved Polling with Adaptive Cycle Time, IPACT, Service Level Agreement, SLA, Network Performance, Bandwidth Optimization, TDM PON.
Frequently Asked Questions
What is the primary focus of this research?
This research focuses on the performance optimization of Dynamic Bandwidth Allocation (DBA) algorithms within Ethernet Passive Optical Networks (EPON) to improve efficient bandwidth utilization.
What are the main performance indicators used?
The two primary indicators used to evaluate the efficiency of the DBA algorithms are network throughput and average packet delay.
How many DBA algorithms are analyzed in this thesis?
The thesis provides a comparative study and mathematical analysis for 23 different DBA algorithms.
Which scientific methodology is employed?
The research utilizes OPNET/C++ simulation to apply mathematical models and generate comparative data for the DBA algorithms under various load conditions.
What is the main objective of the thesis?
The goal is to identify the most effective DBA algorithms that offer remarkable throughput and low time delay in highly loaded networks, and subsequently optimize their parameters for better performance.
What types of traffic are supported by these DBA algorithms?
The algorithms generally categorize traffic into high priority (Expedited Forwarding), medium priority (Assured Forwarding), and low priority (Best Effort) to support different Quality of Service requirements.
How does the Arishtat algorithm function?
Arishtat uses auction theory, where the OLT manages an auction process to allocate bandwidth to ONUs based on their priority and maximum waiting time requirements.
What is the significance of the "near-far" problem mentioned in the background?
The "near-far" problem occurs because ONUs are at different distances from the OLT, resulting in unequal signal attenuation; this necessitates burst-mode reception at the OLT to correctly identify incoming data bits.
What is the result of the parametric optimization process?
The optimization process resulted in reduced time delays and increased throughput across the selected algorithms (such as IPACT with CBR, UDBA, and CPBA) by adjusting parameters like line rates and cycle times.
- Quote paper
- Mohamed Maher (Author), 2021, Ethernet passive optical networks performance optimization. An extensive comparative study for DBA algorithms, Munich, GRIN Verlag, https://www.grin.com/document/1066406
