Multiplexing Ethernet Passive Optical Network Research Articles

Improving quality of service in four-channel WDM ethernet passive optical network

Energy-efficiency and green communications have become dominant topics related to access network implementation, since their energy consumption is a major contributor of energy consumption within the Internet. In this paper we analyze an implementation of a new energy-efficient dynamic bandwidth algorithm in a four-channel Wavelength Division Multiplexing Ethernet Passive Optical Network (WDM EPON), in which wavelength assignments take place per service class and not per Optical Network Unit (ONU). The improved Dynamic Bandwidth Allocation (DBA) algorithm introduces independent bandwidth allocation for each wavelength, which results in efficient bandwidth management and utilization. The mathematical model for new DBA algorithm is described, as are changes to the Multi-Point Control Protocol (MPCP), necessary for its implementation. The obtained results show that the redefined DBA algorithm improves Key Performance Indicators (KPIs) and as a consequently enables delivery of enhanced services to end-users. Significant energy savings are achieved without Quality of Service (QoS) degradation, and without network or equipment architecture changes.

Traffic Classification and Sifting to Improve TDM-EPON Fronthaul Upstream Efficiency

Mobile fronthaul (MF) provides connectivity between a remote radio head (RRH) and base-band processing unit (BBU) in a cloud radio access network. Dedicated MF connections between RRH and BBU are costly due to high bandwidth requirements. The cost issue becomes more pressing as cell densification increases the number of connections. A time-division multiplexing Ethernet passive optical network (TDM-EPON) is a promising solution to reduce MF cost, as it can multiplex several fronthaul flows in the MF network. However, even though mobile users transmit intermittently, RRH samples radio signals continuously, resulting in large constant line-rate connections between RRH and BBU that require huge aggregated bandwidth and render statistical multiplexing gain marginal. To improve upstream transmission efficiency by utilizing statistical multiplexing in an MF network, we propose to enhance the conventional TDM-EPON architecture. The enhanced architecture employs two techniques: (1) traffic classification (classifying upstream traffic into useful and useless by using machine-learning classifiers); and (2) useless-data sifting (sifting useless traffic to avoid the transmission of unnecessary EPON frames). We explore two feature-selection methods together with classifier biasedness in the first technique to achieve the best classification results, which then serve as input to our proposed sifting-based hybrid bandwidth allocation scheme in the second technique. Simulation results show significant improvements in terms of per-RRH traffic load, number of RRHs supported by same EPON, and signal-to-noise ratio, while keeping the end-to-end delay under 100 μs.

Mode transformation and united control mechanism supporting wavelength division multiplexing Ethernet passive optical network and orthogonal frequency division multiplexing passive optical network in multi‐subsystem‐based virtual passive optical network

In this study, mode transformation and united control mechanism for multiple subsystems in metro-access optical network (MAON) are proposed to realise multi-subsystem-based virtual passive optical network. By combing the characteristics of multi-point control protocols (MPCPs) of wavelength division multiplexing Ethernet passive optical network (WDM-EPON) and orthogonal frequency division multiplexing passive optical network (OFDM-PON), a unified MPCP (U-MPCP) is proposed. Based on the U-MPCP, flexible control node and central node are constructed to achieve asynchronous unified control of multiple subsystems. By designing new control frames, the mode transformation between two subsystems (WDM-EPON and OFDM-PON) can be carried out. It can not only finish the flexible transformation of optical network unit's (ONU's) working modes but also make the MAON have the backward compatibility to the existing access technologies. By creating transformation algorithm of ONU's working modes, the transmission delay of over-load subsystem can be effectively reduced when ONU meets the condition of the mode transformation and finishes the transformation. Finally, by simulation, the effectiveness of the proposed scheme is demonstrated.

Performance analysis of bidirectional hybrid orthogonal frequency division multiplexing-Ethernet passive optical access network

For the bottleneck problem of broadband access networks, the Ethernet passive optical network comes out as a striking and promising solution. Even though, Ethernet passive optical network nodes necessitate a cost-effective up-gradation. Accordingly, we propose and demonstrate a hybrid orthogonal frequency division multiplexing-Ethernet passive optical network employing an optical single side band modulation scheme. Case A demonstrates a contrast between a symmetric bidirectional single channel orthogonal frequency division multiplexing-Ethernet passive optical network at a data rate of 10 and 5 Gbps after a fiber link of 20 km. Case B targets the transmission of a symmetric bidirectional single channel orthogonal frequency division multiplexing-optical single side band-Ethernet passive optical network system and achieves a fiber link of 20 km with a split ratio of 8. Afterwards, eight upstream channels are transmitted simultaneously and successfully obtained at the optical linear terminal side to make a bidirectional Ethernet passive optical network system. Further, a contrast between transmission at a data rate of 10 and 5 Gbps is carried out that achieves a fiber link of 20 km with a split ratio of 8.

Dynamic bandwidth allocation in heterogeneous WDM EPONs

Several dynamic bandwidth allocation algorithms have been introduced to schedule upstream wavelength channels in wavelength division multiplexing Ethernet passive optical networks (WDM EPONs), but mostly for homogenous WDM EPON networks with the same distance between each optical network unit (ONU) and the optical line terminal. For WDM EPON with heterogeneous round trip times (RTTs), we propose two algorithms for ONU scheduling, called nearest first and early allocation (EA); and a wavelength assignment algorithm, called best fit (BF). Both ONU scheduling algorithms take RTT dissimilarities into account, thus minimizing packet delay and packet drop ratio at ONUs. Additionally, EA can relive the common drawback of offline scheduling, i.e., channel idle time. On the other hand, the BF wavelength assignment is proposed that assigns the best wavelength to each ONU in order to improve network performances in terms of packet queuing delay and packet drop ratio at ONU sides.

Editoral: Special Issue on Photonic and RF Communications Systems

Editoral: Special Issue on Photonic and RF Communications Systems

Delay analysis of converged optical‐wireless networks with quality of service support

The convergence of two popular access technologies, namely Worldwide interoperability for Microwave Access (WiMAX) and passive optical network (PON) is a promising access solution that combines the mobility feature of WiMAX and the ample bandwidth of PONs. In such a converged optical-wireless access network, the provision of quality of service (QoS) support is a challenging issue, mainly because of the different bandwidth allocation mechanisms of the two access technologies. Since the considered convergence seems to be dominant, it deserves assiduous analysis and evaluation. In this study, the authors investigate the delay performance of a converged optical-wireless network that provides QoS support by considering multiple service-classes with different priorities. In the wireless domain, the IEEE 802.16 standard is applied, whereas in the optical domain a wavelength division multiplexing ethernet PON provides connectivity to both wired and wireless users. The authors present an analytical framework for the calculation of the average end-to-end packet delay of each service-class, by developing two queuing models for each domain of the converged network. The end-to-end delay is calculated as the sum of the queuing delay in both domains, and the transmission and propagation delay in the optical domain. The accuracy of the proposed analysis has been verified by simulation and found to be quite satisfactory.

A Wavelength and Bandwidth Assignment Algorithm to Support Guaranteed Bandwidth Levels in Hybrid Time Division Multiplexing/Wavelength Division Multiplexing Ethernet Passive Optical Networks

A novel bandwidth assignment algorithm in wavelength division multiplexing Ethernet passive optical networks, called a dynamic wavelength assignment service level agreement, is proposed to efficiently provide subscriber differentiation. Simulation results show that the dynamic wavelength assignment service level agreement outperforms other bandwidth allocation algorithms in wavelength division multiplexing Ethernet passive optical networks, as it makes a fairer bandwidth distribution than other methods and is able to overcome the non-allowed packet fragmentation of the Ethernet passive optical network standard. Consequently, it greatly increases the achieved throughput and always ensures a minimum guaranteed bandwidth to every priority subscriber. Furthermore, the new algorithm obtains lower mean packet delay and packet loss rate for the highest priority subscribers when compared with other bandwidth distribution schemes in wavelength division multiplexing Ethernet passive optical networks.

Group-synchronized polling algorithm in WDM-EPON

Wavelength division multiplexing-ethernet passive optical network (WDM-EPON) technology yields evolutionary advantages which enable next generation broadband access networks to overcome the bandwidth limit of EPON. To effectively share uplink resources of inter-optical network units (ONUs) in WDM-EPON, we propose a group-synchronized polling algorithm (GSPA). In GSPA, ONUs are partitioned into g (> 2) groups and each group fully uses one among m (ges 2) uplink wavelengths during a predetermined time TRef. Since the starting times of groups are inter-weaved with different wavelengths to enable groups to transmit frames to an optical line terminator (OLT), the GSPA can perform dynamic bandwidth allocation (DBA) in parallel without wasting uplink resources. Comprehensive simulation results show that GSPA yields better performance compared with both the existing offline and on-the-fly algorithms.