Jhong-Yue Lee

Generic QoS-Aware Interleaved Dynamic Bandwidth Allocation in Scalable EPONs

The Ethernet passive optical network is being regarded as one of the best solutions for next-generation optical access solutions. In time-division multiplexing-passive optical network technology (TDM-PON), the dynamic bandwidth allocation (DBA) plays a crucial role in efficiently and fairly allocating the bandwidth between all users. Moreover, the quality of service (QoS) is also an essential requirement to support triple-play services. However, many proposed DBA mechanisms are still unable to solve the idle period problem and enhance the differentiated services (DiffServ), which will decrease the quality of overall system performance. Therefore, this paper proposes a generic QoS-aware interleaved dynamic bandwidth allocation (QA-IDBA). The QA-IDBA can operate adaptively bi-partitioned interleaved scheduling with QoS-based predictive limit bandwidth allocation (QP-LBA) and excess bandwidth reallocation (EBR) with the remaining bandwidth compensation scheme to eliminate the idle period, enhance QoS, and effectively reduce high-priority traffic delay and jitter. We conduct detailed simulation experiments with 16 and 32 optical network units (ONUs) to show the scalability. Simulation results show that our proposed algorithms can accommodate the growth of ONUs and achieve better overall quality of system performance even if the high-priority traffic is increasing from 20%, 40%, and 60%.

Comprehensive performance assessment of bipartition upstream bandwidth assignment schemes in GPON

With the emerging diversified services, the gigabit-capable passive optical network (GPON) has emerged as one of the most important technologies to support the next-generation broadband access networks. Dynamic bandwidth assignment (DBA) avoids transmission collision in the upstream direction and improves the efficiency of the PON upstream bandwidth by dynamically adjusting the bandwidth among the optical network units (ONUs) in response to the ONU burst traffic requirement. Instead of using GATE and REPORT control messages in Ethernet PON DBA, the buffer REPORT/GRANT message is embedded into a GPON encapsulation mode (GEM)/GPON transmission convergence (GTC) frame, and all ONUs are essentially polled simultaneously within a GEM/GTC frame in GPON DBA. This paper proposes a bipartition DBA (BI-DBA) mechanism in GPON that divides the transmission cycle time into two groups and adjusts the bandwidth dynamically. Two cases are considered: in the first case, there is a first group for high priorities T-CONT 1 and T-CONT 2 and a second group for low priorities T-CONT 3 and T-CONT 4, called class based scheduling (CBDBA). In the second case, the first and the second group are created according to the number of ONUs, called group based scheduling (GBDBA). Moreover, the T-CONT 2 traffic has a prediction mechanism and recycles the remaining unused bandwidth for the low-priority T-CONTs. The GBDBA has better system performances in terms of the average bandwidth utilization, packet latency, and drop probability; on the other hand, the CBDBA has better packet delay performance when the proportion of T-CONT 1 traffic is higher and has better fairness performance.

Fault-tolerant architecture with dynamic wavelength and bandwidth allocation scheme in WDM-EPON

This study proposes a novel cost-based fault-tolerant WDM-EPON (CFT-WDM-EPON) to provide overall protection. It only equips a backup feeder fiber to recover the system failure. Additionally, a prediction-based fair wavelength and bandwidth allocation (PFWBA) scheme is proposed to enhance the differentiated services for WDM-EPON based on dynamic wavelength allocation (DWA) and prediction-based fair excessive bandwidth reallocation (PFEBR) from our previous work. PFEBR involves an early-DBA mechanism, which improves prediction accuracy by delaying report messages of unstable traffic optical network units (ONUs), and assigns linear estimation credit to predict the arrival of traffic during waiting time. DWA can operate in coordination with an unstable degree list to allocate the available time of wavelength precisely. Simulation results show that the proposed PFWBA scheme outperforms WDM IPACT-ST and DWBA3 in terms of packet delay, jitter performance, throughput, wasted bandwidth, gain ratio of bandwidth, and packet loss.

A novel dynamic bandwidth allocation mechanism for star-ring-based EPON

Ethernet Passive Optical Network (EPON) is proposed as a simple, cost-effective and scalable solution for bandwidth bottlenecks in access networks which can enhance the system performance because it transmits the aggregated high-speed traffic from hundreds of subscribers. Dynamic Bandwidth Allocation (DBA) mechanism has not yet been seriously considered for use in star-ring EPON architecture. In this paper, a distributed QoS-based dynamic bandwidth allocation (DQ-DBA) scheduling mechanism for the star-ring-based EPON architecture including optical line terminal (OLT), Sub-OLT and ONUs has been proposed to improve the system performance of traditional tree-based EPON architecture. In DQ-DBA, the highest-priority traffic of each ONU is directed to the OLT by the tree structure; moreover, the lower-priority traffic on each ONU is transmitted to the Sub-OLT by ring architecture. This approach can effectively resolve the idle period problem and reduce the overloading of OLT in conventional DBA mechanisms. Exhaustive simulation experiments are performed to compare the system performance between the tree and the star-ring architectures and validate the effectiveness of the proposed mechanism. Simulation results show that the proposed DQ-DBA mechanism in star-ring architecture can reduce packet delay and jitter for the high-priority traffic, thus ensuring the quality of service (QoS) regardless of subscriber numbers.

A Novel Distributed QoS-Based DBA Scheduling Mechanism for Star-Ring Architecture on Ethernet Passive Optical Access Networks

In this paper, a distributed Dynamic Bandwidth Allocation (D-DBA) scheduling mechanism for star-ring protection architecture is proposed in Ethernet Passive Optical Networks (EPONs). The D-DBA mechanism can effectively resolve the idle period problem and reduce overload of OLT in traditional DBA mechanism. We perform exhaustive simulation experiments to study the performance and validate the usefulness of the proposed mechanism. The simulation results show that the proposed D-DBA mechanism can reduce the packet delay and packet delay variation for high priority ONUs to ensure Quality of Service (QoS).

Mitigating the IPTV Zap time in enhanced EPON systems

Zap time (channel switching time) is a critical quality of experience (QoE) metric for IPTV systems where synchronization, signaling, and propagation delays are the components under consideration. An Ethernet passive optical network (EPON) is one of the main infrastructures in broadband access networks that provides high bandwidth with low propagation delay. The functionality of the EPON hardware architecture can be extended by adding programmable networking engine (PNE) and programmable sub-system (PSS) components in the optical line terminal (OLT) and optical network unit (ONU) as described in this paper to improve IPTV delivery performance for synchronization and signaling delays in terms of traffic localization. Furthermore, a new IPTV delivery mechanism is proposed to eliminate synchronization delay by buffering the current I-frames of broadcasted channels in the OLT for possible new coming requests and dropping additional streams along with the main stream. The OLTand ONUs implement a multicasting mechanism to handle part of the IPTV request as intra-domain traffic. Simulation results show that the proposed mechanism significantly improves the QoE and quality of service (QoS). IPTV bandwidth usage and system throughput have improved mean packet delays and packet loss in enhanced EPON architecture.

A novel hybrid dynamic bandwidth allocation and scheduling scheme for the integrated EPON and WiMAX architecture

The integrated architecture of complementary Ethernet Passive Optical Network (EPON) and Worldwide Interoperability for Microwave Access (WiMAX) technologies combine the benefits of optical fiber capacity and wireless network mobility, which will become one of the promising broadband access technologies for next-generation network. In this paper, we propose a novel hybrid dynamic bandwidth allocation (DBA) and scheduling scheme for the integrated EPON and WiMAX in the access network to support quality of service (QoS) and class of service (CoS). The simulation results demonstrate that the proposed scheduling scheme enhanced performance in terms of drop probability, average queue length and average end-to-end packet delay, respectively.

Two Phase Bandwidth Allocation Mechanism with Adaptive Prediction for Differentiated Services on EPONs

This study proposes a novel Two Phase Bandwidth Allocation (TPBA) mechanism incorporated with a prediction-based scheme in Ethernet passive optical networks (EPONs). Two phase dynamic bandwidth allocation mechanisms are designed in the proposed TPBA. In the first phase, the TPBA can resolve the idle time problem in traditional DBA mechanism. Furthermore, the TPBA can predict and allocate the excess bandwidth fairly and improve overall system in the next phase. The traffic characteristic in differential traffic class is also considered in the proposed prediction scheme to provide more accurate prediction. Simulation results using OPNET show that the proposed TPBA mechanism with adaptive prediction scheme performs better than well-known DBA methodologies in terms of wasted bandwidth, throughput end-to-end delay and queue length.

Hybrid Uplink Traffic Scheduling Algorithms in FMC Networks: A Comparative Study of Performance

Todate, the integration between EPON and WiMAX to form a Hybrid ONU-BS (Optical Network Unit-Base Station) Architecture in a Fixed Mobile Convergence (FMC) network rapidly matures and represents one of the promising candidates for next generation network (NGN) broadband access networks. In this paper, first we propose a new QoS mapping policy between two types of networks to enable a dedicated transmission across wireless and optical networks; and propose a hybrid uplink scheduling algorithm which the intra-ONU-BS scheduler employs queue scheduling only on the packets that arrive before sending the REPORT message, and the inter-ONU-BS scheduler employs the transmission time slot assignment based on the REPORT message information. Lastly, the paper provides a comparative performance study to find a decent combination of hybrid uplink traffic scheduling in terms of classic well-known traffic scheduling algorithms. Simulation results show that the inter uplink scheduling has significant impacts on the overall packet delay, loss rate and jitter performance; on the other hand, the intra uplink scheduling has significant influences on the packet delay, loss rate, jitter and fairness performance. Both inter and intra uplink traffic scheduling have particular functions to enhance the QoS and Class of Service (CoS) of system performance, respectively.

Performance assessment between tree- and star-ring-based EPONs

Ethernet Passive Optical Network (EPON) was proposed to overcome the bandwidth bottleneck at the Access Networks due to its simplicity, cost effectiveness and wide spread deployment. The architecture in access networks can affect the system performance, because access networks transmit aggregated high-speed traffic from hundreds of subscribers. Dynamic bandwidth allocation (DBA) mechanisms have been applied in backbone networks, but are not considered significantly in the scope of star-ring architecture. In this paper, we propose a distributed QoS-Based Dynamic Bandwidth Allocation (DQ-DBA) scheduling for a modified star-ring-based EPON architecture. The modified star-ring architecture includes OLT, Sub-OLT (an intermediary between OLT and ONUs) and ONUs. The DQ-DBA is making the highest priority traffic (EF) of each ONU is sent to OLT by tree structure, and the minor priority traffic (AF and BE) of each ONU are transmitted to Sub-OLT by ring architecture. Furthermore, this approach can effectively resolve the idle period problem and reduce overload of OLT in traditional DBA mechanism. We perform exhaustive simulation experiments to study the system performance between tree architecture and star-ring architecture to validate the usefulness of the proposed mechanism. The simulation results show that the proposed DQ-DBA mechanism in modified star-ring architecture can reduce the packet delay and packet delay variation for high priority ONUs to ensure Quality of Service (QoS).