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The inter-cycle sleep design previously proposed as a power-saving scheme for next-generation Ethernet passive optical networks (NG-EPONs) is able to effectively decrease the power consumption of heavy-load traffic. However, with a medium to high traffic load, these networks may still suffer from a high level of power consumption if no enhanced mechanisms are used. It was noted that the optical line terminal (OLT) often fully opens all communication channels at a medium to heavy load. Moreover, the number of opened channels was changed cyclically according to the traffic loading status. Accordingly, optical network units (ONUs) may be frequently allocated to different channels with changing loads. This may lead to inefficient operation and result in significant channel tuning delays. We thus propose a loading-aware time-division multiple access (TDMA) mechanism that allows the OLT to reserve a maximum bandwidth for each ONU when the network experiences heavy-load traffic. The performance results of our simulations reveal that the proposed scheme is able to reduce power consumption for targeted medium to high loads since ONUs under such loads can extend their sleep time because the cycle length is maximized. Moreover, the total delay is maintained at a relatively low level after applying the proposed scheme since the tuning delay is reduced significantly; however, the transmission delay is slightly increased due to the increased cycle length.

This letter deliberates bridging of overall electricity power requirements of the optical network unit (ONU) with the entropy noted through the ONU state transition models considered in ethernet passive optical network (EPON). The entropy depends on the steady state and transition probabilities of data. On the other hand, the power requirements (consumption) of ONUs depend on the steady sate probability of ONUs. The potential relation derived between the entropy and electrical power reveals that they related exponentially but for their logarithmic reliance. Also, the relation is validated through the numerical simulation. The deduced relation has its importance to understand the nuances of one entity given the other.

As bandwidth requirements of access networks continue to increase rapidly, especially due to the growth of streaming traffic, the need for resolving bandwidth contention among competing users and applications becomes more compelling. The proposed Software-Defined Ethernet Passive Optical Network (EPON) architecture utilizes an application-level feedback from the client side (for video users) to the network through a Software-Defined-Network (SDN) controller to achieve better client-and-service-level differentiation in the downstream direction of an EPON access network Numerical results obtained from simulation experiments demonstrate that the proposed architecture with downstream resource allocation for video streaming applications considerably reduce video stalls and increase video buffer level at the client applications leading to better Quality of Experience (QoE) for users along with better client-and-service-level differentiation.

The next-generation Ethernet passive optical network (NG-EPON) is basically classified into two architectures on the basis of the wavelength sharing by the optical network units (ONUs). The single scheduling domain (SSD) and multi-scheduling domain (MSD) EPON are the two different design architectures for NG-EPON. A vital task in NG-EPON is to design dynamic wavelength bandwidth allocation (DWBA) algorithms that can meet the future demands of the network subscribers. A number of DWBA algorithms have been designed for time and wavelength division multiplex (TWDM) EPON. The existing DWBA algorithms for TWDM-EPON could be used in MSD-EPON by making necessary parametric changes. The design and implementation of new DWBA algorithms for MSD-EPON are still required specifically. In this paper, we have proposed a quality of service (QoS)-based DWBA algorithm for NG-EPON. We have comparatively analyzed our proposed DWBA with the existing algorithms like earlier finished time (EFT), weighted bipartite matching (WBM), and earlier finished time with void filling (EFT-VF). The results show that our proposed DWBA algorithm performs better as compared to EFT, WBM, and EFT-VF on the basis of average packet delay and average completion time for NG-EPON.

Next-generation passive optical networks (PONs) demand power conservation to create a green environment. A reduction in power consumption of the traditional Ethernet passive optical network (EPON) can be achieved by increasing the sleep count in optical network units (ONUs). In this paper, this is accomplished by introducing a first-in-last-out (FILO) polling sequence in the place of a fixed polling sequence to increase the number of ONUs entering sleep mode (sleep count). In a fixed polling sequence, the optical line terminal (OLT) allocates idle time to the ONUs based on the overall load of the ONUs. This leads to a situation that whenever the idle time does not meet the wakeup time threshold of sleep mode, the ONUs are put into doze/active mode, which consumes more power. In the FILO polling sequence, the first polled ONU in the current cycle is made to be polled last in the following cycle. Polling continues in this way, and by this rearrangement, the idle time of delayed poll ONUs increases; hence, it helps to reduce the power consumption. Additionally, a modified load adaptive sequence arrangement (MLASA) method is suggested, where the ONUs are categorized into doze ONUs and sleep ONUs. A numerical simulation of the FILO polling sequence with a vertical cavity surface emitting laser (VCSEL) ONU shows a maximum reduction in power consumption of 15.5 Wand a 20% improvement in energy savings compared with the traditional fixed polling sequence. The MLASA method results in better power consumption with minimum delay than that of the proposed FILO and existing LASA methods.

The increasing use of polymer nanocomposites in armor applications requires an understanding of how these materials behave at strain-rates relevant to ballistic impacts. Of particular interest is the role of the microstructure on the failure of these materials under dynamic tensile loading. In the present study, plate impact experiments were conducted in order to measure the spall strength of a neat epoxy (EPON 828) and an epoxy–carbon nanotube composite. The addition of pristine carbon nanotubes (CNTs) to the epoxy resulted in a composite material with a lower spall strength than the neat epoxy matrix material. Recovered composite fragments were imaged with a scanning electron microscope. Instances of nanotube pull-out were identified on internal fracture surfaces. The lower spall threshold of the epoxy–CNT composite was attributed to the comparatively weak epoxy–CNT interface, which provides potential sites from which spall failure can favorably nucleate.

We present different mechanisms for downstream transmissions in the coax segment of Ethernet Passive Optical Network (EPON) Protocol over Coax (EPoC). EPoC is the transparent extension of EPON over a cable operator's Hybrid Fiber-Coax network. For managing and controlling such a hybrid network, a network operator prefers to have a unified scheduling, management, and quality of service environment that includes both the optical and coax portions of the network. In EPoC, this is achieved by extending the EPON Medium Access Control to run over the coax physical layer, to have a centralized end-to-end network control from the cable head-end to the end users premises. In this paper, we focus on the downstream transmissions in EPoC. We study three different framing approaches for downstream coax frames based on how sub-carriers in an orthogonal frequency division multiplexed symbol are modulated. We discuss the merits and demerits of each approach and then compare them based on their control overheads and the maximum average data transmission rates each of them can achieve. We analyze how different parameters such as modulation profile, symbol duration, number of sub-carriers and length of resource blocks affect the data rates and the performance of downstream transmissions. We present simulation results to examine the implications of these factors on packet-level performance, such as delay. The results indicate that dynamic and hybrid framing approaches tend to perform better than static approaches, when traffic and usage pattern are identical to those in real-world scenarios. Finally, we outline the important engineering and research problems in this area which can be topics of future research.

In the modern data networks, the demand is increasing for interruption free, high speed, and best quality of services to perform successful communications. This paper emphasizes on the high priority (HP) traffic like video conferencing, video streaming, telemedicine, teleconferencing, and interactive gaming for the real time communications. To achieve the best quality data communication for the HP traffic, in this paper, we propose a new dynamic bandwidth allocation (DBA) algorithm called dynamic hybrid slot-size bandwidth allocation (DHSSBA) algorithm, which is the modified version of existing hybrid slot-size/rate (HSSR) algorithm. The performance of the proposed scheme has been analyzed by using numerical simulations in terms of the end-to-end packet delay, absolute delay variation, jitter, and throughput for both the HP and best effort (BE) traffic. We have also compared the simulation results of the proposed scheme with those of the existing modified HSSR (MHSSR), delay variation guaranteed protocol (DVGP), and HSSR schemes. From the comparison of the simulation results, at the highest offered load of 1.0, it can be seen that for the HP traffic the proposed scheme provides 60%, 50%, and 20% less average end-to-end delay than the existing HSSR, DVGP, and MHSSR schemes, respectively. At the highest offered load of 1.0, the proposed scheme also provides about 35% higher throughput than both the HSSR and DVGP schemes with 45% and 35% less jitter variation than the HSSR and DVGP schemes, respectively.

Recently, the IEEE 802.3 Ethernet Working Group has been working to explore new solutions for the next-generation Ethernet passive optical network (NG-EPON). It’s desirable for NG-EPON to support the coexistence of multi-type users and multi-type services (MUMS) on a single access platform. Moreover, in the future, ONU may be equipped with multiple transceivers to break through bandwidth limit of a single wavelength and then achieve greater throughput per ONU. In this paper, a two-dimensional priority queue model is designed for buffer differentiation management. Then, a dynamic bandwidth allocation (DBA) algorithm including joint grant sizing and scheduling is presented to carry out differentiated bandwidth allocation among MUMS. By providing different aggregated data rates and setting scalable wavelength resource pools for different users and services, flexible ONU configurations are allowed. By using time-order filling (ToF) and wavelength-order filling (WoF) in combination to realize grant scheduling, the flexibility of multi-transceiver ONUs gets further exploited. Finally, the simulation demonstrates the effectiveness of the proposed algorithm. Not only each type of service/user can get reasonable network access capacity that matches its bandwidth requirements, but the overall network performance also gets improved compared with other DBAs for NG-EPON.

We investigate the challenges in designing the network architecture for running EPON (Ethernet Passive Optical Network) Protocol over Coax, or EPoC in short. EPoC is the transparent extension of EPON over a cable operator's Hybrid Fiber-Coax (HFC) network, and uses a hybrid of optical and coaxial technologies to carry traffic to and from end-users and the Internet backbone. For managing and controlling such a hybrid network, a network operator will prefer to have a unified scheduling, management, and quality-of-service (QoS) environment that includes both the optical and coax portions of the network. This can be achieved by extending the EPON Medium Access Control (MAC) to run over the coax physical layer, to have a centralized end-to-end network control from the cable head-end to the end-users' premises. The use of the coax portion of the network is transparent to EPON protocol operation in the headend, as the same MAC runs over the entire network. In this article, we describe the architecture of EPoC, and outline how the EPON MAC Control, i.e., the EPON Multi-Point Control Protocol (MPCP) can be extended for designing an end-to-end Multi-Point MAC Control for EPoC. We explain the design of several MAC functions and their operation, including framing for coax, Ethernet frame fragmentation, generation of upstream and downstream Media Allocation Plans, and automatic discovery and registration of user equipment. With strong backing from both service operators and equipment vendors, EPoC is set to become a rapidly-evolving standard within the next few years, and the creation of the IEEE 802.3bn Task Force for EPoC is a major step in that direction.

Geometrically shaped (GS) 8-, 16, and 32- ary modulation formats are investigated for use in coherent passive optical networks. The modulation formats are designed to improve receiver sensitivity when paired with a binary, soft-decision forward error correction code (SD-FEC), such as a low density parity check (LDPC). Herein we consider the LDPC code specified in the draft 50G EPON standard, and show how this type of code can be particularly advantageous in a coherent transmission system. A receiver sensitivity of $-$ 26.7 dBm is achieved at a post-FEC bit error rate below 3.8 $\times 10^{-6}$ for a polarization-scrambled 32- ary GS modulation format at 25 GBd, received using a single-polarization, phase-diverse coherent receiver. This yielded a bit rate of 100 Gbit/s, net of coding and pilot overhead. This modulation format was shown to perform equally well in transmission, with no observed dispersion penalty after 80 km standard single mode fiber. Finally, this modulation format was received, at a reduced data rate of 50 Gbit/s, using a heterodyne coherent receiver based on a single balanced photodiode. The receiver sensitivity for this simplified receiver configuration was $-$ 28.5 dBm, yielding a power budget of 34.2 dB.

The tremendous Internet traffic growth has confirmed that the telecommunications backbone is moving aggressively from a time division multiplexing (TDM) orientation to a focus on Ethernet solution. Ethernet PON, which presents the convergence of low-cost Ethernet and fiber infrastructures, has taken over the market initially dominated by Digital Subscriber Line (DSL) and cable modems. It is a new technology that is simple, inexpensive, and scalable, having the ability to deliver massive data services to end-users over a single network. This paper reviewed the evolution of Ethernet Passive Optical Network (EPON), with focus on the current development process of the future high-data-rate access networks such as Next-Generation Passive Optical Network Stage 2 (NG-PON2), Wavelength Division Multiplexing (WDM) PON, and Orthogonal Frequency Division Multiplexing (OFDM) PON. In addition, the recently concluded 100 Gb Ethernet Passive Optical Network (100G-EPON) is reviewed with the aim of highlighting the recent developments in the field. With this comprehensive and up-to-date review, we equip network operators and interested practitioners to focus on common priorities and timelines. Another goal of this study is to identify technical remedies for future investigation.

In order to manage Quality of Service (QoS) and energy efficiency in the optical access network, an online Dynamic Bandwidth Allocation (DBA) algorithm with adaptive sleep cycle is presented. This DBA algorithm has the ability to allocate an additional bandwidth to the end user within a single sleep cycle whose duration changes depending on the current buffers occupancy. The purpose of this DBA algorithm is to tune the duration of the sleep cycle depending on the network load in order to provide service to the end user without violating strict QoS requests in all network operating conditions.

Based on multi-standard OLT management structure, this paper realizes supporting GPON and EPON simultaneously in metro-access optical network. To adjust VPON structure dynamically, virtual access mechanism is established. To support two different standards, compatible multi-standard management structure for VPONs is proposed. It can also manage dynamic connection between ONU and OLT. To transmit GPON and EPON frames in the same wavelength, this paper proposes shared bandwidth algorithm to allocate bandwidth to GPON and EPON sub-networks fairly. This algorithm can prevent bandwidth monopoly from high load sub-network, when load of one sub-network is much higher than that of the other. To further balance QoS demands for ONUs, different class services will acquire bandwidth by priority. Finally, the simulation results demonstrate a good performance of the mechanism and algorithm.

In this paper, an overview is given on the recent developments in next-generation high-speed PON. A summary is presented on the progress being made by the IEEE P802.3ca task force on the standardization of 25, 50, and 100G EPON. An outline of the physical layer specification for next-generation high-speed PON as well as MAC layer functions such as channel bonding to achieve 100 Gbps line rates is discussed. Also, the wavelength plan for 100G EPON coexistence with the various PON generations are discussed.

We report a new type of negative-tone photoresist in this paper. The resist is based on a composite of EPON resins 154 and 165 (both from Hexion Specialty Chemicals, Inc., Columbus, OH 43215). These two epoxy-based resins were mixed in an optimal ratio and dissolved in gamma-butyrolactone (GBL) solvent. The mixture was then photosensitized by adding a given amount of triaryl sulfonium salt to obtain a new negative-tone photoresist that can be used in for ultra-high-aspect-ratio microstructure fabrication with UV lithography. Preliminary studies have found that microstructures with heights of more than 1000 μm and feature sizes down to 10 μm (aspect-ratios of more than 100) can be obtained using the new resist film with ultraviolet lithography. The microstructures have excellent sidewall quality. In this paper, both the material properties and lithography properties of this new type of UV resist will be presented. The potential applications of the new resist in microfabrication and MEMS systems are also discussed.

We propose a novel candidate wavelength plan for suppressing four-wave mixing (FWM) in 100G-EPON. Advanced simulation using VPI is performed to analyze the FWM induced system distortion. Simulation results indicate that the proposed wavelength plan shows significant advantage in FWM suppression. Besides, an 8-channel wavelength plan is also proposed as an upgrade path to 200G-EPON.

This paper proposes a software-defined EPON architecture which replaces the hardware-implemented DBA module with reprogrammable DBA module. The DBA module allows pluggable bandwidth allocation algorithms among multiple ONUs adaptive to traffic profiles and network states. We also introduce a bandwidth management scheme executed at the controller to manage the customized DBA algorithms for all date queues of ONUs. Our performance investigation verifies the effectiveness of this new EPON architecture, and numerical results show that software-defined EPONs can achieve less traffic delay and provide better support to service differentiation in comparison with traditional EPONs.

Sleep and doze power-saving modes are the common ways to reduce power consumption of optical network units (ONUs) in Ethernet passive optical network (EPON). The doze mode turns off the ONU transmitter when there is no traffic in the upstream direction while the sleep mode turns off the ONU transmitter and receiver. As the result, the sleep mode is more efficient compared to the doze mode, but it introduces additional complexity of scheduling and signaling, losses the clock synchronization and requires long clock recovery time; furthermore, it requires the cooperation of the optical line terminal (OLT) in the downstream direction to queue frames. To improve the energy-saving in the doze mode, a new two-stage mechanism is introduced that the doze sleep duration is extended for longer time with acceptable quality-of-services (QoS) metrics when ONU is idle in the current cycle. By this way the ONU enters the doze mode even in the high load traffic; moreover, the green dynamic bandwidth allocation (GBA) is proposed to calculate the doze sleep duration based on the ONU queue state and incoming traffic ratio. Simulation results show that the proposed mechanism significantly improves the energy-saving 74% and 54% when traffic load is from the light load to the high load in different traffic situations, and also promises the QoS performance.

Ethernet passive optical network (EPON) is considered one of the best candidates for next-generation optical access solutions. Practical and cost-effective survivability and maintenance mechanisms are therefore becoming the key issues for continued development of viable EPON solutions. In addition, 80% of faults occur within the first/last mile. Therefore, in this paper, we propose in-service integrated fault management mechanisms at the distribution drop fibers (DDFs) in EPON. The proposed mechanisms can automatically detect and identify any signal anomalies and DDF faults in the physical layer, thus decreasing the operating expense (OpEx) to be incurred in sending off technicians in the field. The mechanisms are two-fold: pre-fault and post-fault. In the pre-fault mechanism, we use optical receiver type/length/value (TLV) code as a sensor for triggering the embedded miniaturized optical-time-domain reflectometry (OTDR), placed at optical network units (ONUs). This mechanism observes and measures the abnormal condition and reports it to the optical line terminal (OLT), via restoration plan fiber link. In post-fault mechanism, we divide the ONUs into several restoration groups (RGs) to guarantee upstream transmission of the affected ONUs. Lastly, the fault dynamic bandwidth allocation for fault management, referred as FDBA, is presented. Simulation results show that the proposed mechanisms can withstand DDF faults without any significant impact on the overall quality of service (QoS) performance, in terms of mean packet delay, queue length, system throughput, and packet loss.

This paper studies the differences in fracture properties (stress intensity factors and energy release rates) of nanocomposites of thermosetting polymer EPON 862 and its nano-graphene reinforced counterparts. Extremely low (0.1 and 0.5) weight percent nano-graphene platelets were dispersed in EPON 862 matrix and compact tension (CT) fracture experiments were conducted under quasi static loading conditions using displacement control. Significant enhancements in fracture toughness (∼200%), and energy release rate (∼570%) respectively were observed for nano-graphene reinforced matrix for only 0.5 wt% of graphene platelets. Fractography analysis of the fractured CT specimens was used to qualitatively visualize and understand the mechanism(s) responsible for the enhancement in these properties using Scanning Electron Microscopy (SEM). Evidence of crack deflection due to increased surface roughness, graphene platelet pullout and plastic deformation of the matrix causing filler-matrix debonding, was observed from SEM micrographs, caused by the addition of nano-graphene platelets (NGP). Atomic Force Microscopy (AFM) was also used to quantify the magnitude of surface roughness changes between the NGP reinforced and reinforced nano-composite samples, and correlate surface roughness changes due to crack deflection to increased fracture toughness.

The main energy consumption in computer networks is the access networks. The passive optical network (PON) has the least energy consumption among access network technologies. In addition, the time division multiplexing (TDM) Ethernet PON (EPON) is one of the best candidates to improve energy consumption by time utilization. The optical network unit (ONU) can utilize the time and save the energy in the EPON by turning off its transmitter/receiver when there is no upstream/downstream traffic. The ITU-T and IEEE organizations are published standards for energy-saving in the TDM-PON. Although their standards provide the framework to accomplish the energy-saving, the algorithms/criteria to generate events to accommodate various operational policies, time to wake up, parameter values for timers are out of scope of the standards. Many studies have proposed schemes for energy-saving in TDM-PON to achieve maximum energy saving. Even so, these schemes increase the mean packet delay and consequently, reduce the quality of service (QoS). In this paper, first we take a look to the state of the art for PON energy-saving. Additionally, a mechanism based on SIEPON standard in EPON with new components in the ONUs and optical line terminal (OLT) is proposed to save the transmitter energy and guarantee QoS. The proposed mechanism follows the SIEPON standard, considers the QoS first, and then saves the energy as far as possible. The ONU sleep controller unit (OSC) and green dynamic bandwidth allocation (GDBA) are used to calculate the ONU transmitter sleep (Tx) duration and grant the proper time to the ONUs. Simulation results show that the proposed energy-saving mechanism not only promises the QoS performance in terms of mean packet delay, packet loss, throughput, and jitter, but also saves energy in different maximum cycle times.

Ethernet passive optical network (EPON) is a broadband access time-division multiplexing passive optical network technology which can be referred to as green network, as it has less power consumption compared with other networks. The optical network unit (ONU) is the best candidate to implement energy-saving adjustments in EPON. Turning off the ONU transmitter (Tx)/receiver (Rx) for substantial time is a common method to achieve the energy saving. However, setting overlong sleep duration decreases the QoS, while short sleep duration increases the ONU power consumption. The challenging issue is how to balance the trade-off between achieving energy saving and guaranteeing QoS. In this paper, we introduce an enhanced EPON architecture and a QoS-aware energy-saving mechanism to reduce ONU energy consumption and guarantee an overall QoS metric based on the ITU-T standards requirements. To achieve the energy saving in the upstream/downstream direction, two sleep durations are defined for the ONU's Tx/Rx to generate four ONU modes including active, transmission, doze, and sleep. Simulation results show that the proposed scheme improves the energy efficiency 44 % in average to fulfill the QoS metrics in terms of packet loss, delay and jitter, and the buffer requirement.

Time-division multiplexing passive optical network (TDM-PON) is referred to as a green network because it consumes minimum energy compared to the other access networks technologies. The optical network unit (ONU) mainly chooses to adjust energy-saving in TDM-PON by turning off its receiver and/or transmitter for the substantial time that is called doze or sleep mode respectively. The main challenge in the TDM-PON energy-saving is finding acceptable sleep/doze duration time to achieve energy-saving and guarantee the quality of service (QoS). This paper proposes a mathematical model built based on the lattice theory, which is applied to the results of the fixed-point theory. In the domain of nonlinear systems, each monotone function on a chosen complete lattice has a fixed point, and this point can be interpreted as the solution of the system. The output of the mathematical model is the sleep/doze duration domain that satisfies all requirements and guarantees the QoS metrics. The mathematical model is adopted with doze mode conditions to evaluate the system. Simulation results approve our model that achieves energy-saving up to 63% while keeping the QoS parameters in the acceptable boundary.

Ethernet Passive optical network (EPON) considered as an efficient solution for high-speed bandwidth data transmission, is a promising candidate for next generation access network with safety problems such as eavesdropping, forgery and tampering because of its point-to-multipoint (P2MP) shared topology structure and broadcasted data pattern in the downstream direction. Besides, under multi-service circumstances, both encrypting efficiency and effective transmission of high-speed data can be difficult to be guaranteed when traditional single static encryption (TSSE) mechanism focusing on only one encryption method based on DES, AES or TAES for all business flows is adopted. To solve these problems, a multi-service multi-grade encryption (MSMGE) mechanism is presented. In MSMGE, service flows from providers are first divided into four queues according to differentiated service (DiffServ) model, then encrypted by calling relative encryption method on the basis of different security needs of different services and the simulation results indicate the validity of the proposed MSMGE mechanism in packet loss rate and integrity of data transmission.

In an increasingly content-centric world where users consume large amounts of multimedia content, video delivery platforms over packet networks, such as Internet Protocol Television (IPTV), are gaining rapid popularity. At the same time, to serve the ever-increasing bandwidth demand from users, access networks, traditionally the bottleneck for high-bandwidth applications, are also undergoing rapid evolution. Forecasting how streaming IPTV over a network will perform is challenging as the data rate of a video stream varies with scene, time, framerate, and encoding. Nevertheless, it is important to evaluate the performance of an access network for IPTV traffic to ensure good Quality of Service (QoS) for users. Using video traces for such evaluation requires multiple video traces to represent different scenarios and generally involves slow I/O-based operations, such as file reading. To overcome these limitations, in this paper, we explore several aspects of modeling IPTV streaming, and present a synthetic video trace generator that closely resembles the empirical IPTV traces. Our analysis confirms that our synthetic video trace follows the statistical properties of empirical videos, and its resultant data rate is representative of the IPTV video streaming. Next we study the performance of Ethernet Passive Optical Network (EPON) in streaming IPTV by using the generated synthetic trace. Parameters of interest are the number of parallel video streams supported, the effects of the degree of video compression, average and maximum packet delays, and packet delay variances (jitter). It is shown that 10G-EPON can support a large number of parallel IPTV channels at moderate rates of video compression.

Today, the popularity of peer-assisted music-on-demand (MoD) has increased significantly worldwide. This service allows users to access large music library tracks, listen to music, and share their playlist with other users. Unlike the conventional voice traffic, such an application maintains music quality that ranges from 160 kbps to 320 kbps, which most likely consumes more bandwidth than other traffics. In the access network, Ethernet passive optical network (EPON) is one of the best candidates for delivering such a service because of being cost-effective and with high bandwidth. To maintain music quality, a stutter needs to be prevented because of either network effects or when the due user was not receiving enough resources to play in a timely manner. Therefore, in this paper, we propose two genetic expression programming (GEP)-based dynamic bandwidth allocations (DBAs). The first DBA is a generic DBA that aims to find an optimum formula for voice, video, and data services. The second DBA aims to find optimum formulas so that Optical Line Terminal (OLT) can satisfy not only the voice and Peer-to-Peer (P2P) MoD traffics but also reduce the stutter. Optical Network Unit (ONU) traits such as REPORT and GATE messages, cycle time, and mean packet delay are set to be predictor variables. Simulation results show that our proposed DBAs can satisfy the voice and P2P MoD services packet delay and monitor other overall system performances such as expedited forwarding (EF) jitter, packet loss, bandwidth waste, and system throughputs.

Ethernet Passive Optical Network (EPON) is chosen for servicing diverse applications with higher bandwidth and Quality-of-Service (QoS), starting from Fiber-To-The-Home (FTTH), FTTB (business/building) and FTTO (office). Typically, a single OLT can provide services to both residential and business customers on the same Optical Line Terminal (OLT) port; thus, any failures in the system will cause a great loss for both network operators and customers. Network operators are looking for low-cost and high service availability mechanisms that focus on the failures that occur within the drop fiber section because the majority of faults are in this particular section. Therefore, in this paper, we propose an autonomous recovery mechanism that provides protection and recovery against Drop Distribution Fiber (DDF) link faults or transceiver failure at the ONU(s) in EPON systems. In the proposed mechanism, the ONU can automatically detect any signal anomalies in the physical layer or transceiver failure, switching the working line to the protection line and sending the critical event alarm to OLT via its neighbor. Each ONU has a protection line, which is connected to the nearest neighbor ONU, and therefore, when failure occurs, the ONU can still transmit and receive data via the neighbor ONU. Lastly, the Fault Dynamic Bandwidth Allocation for recovery mechanism is presented. Simulation results show that our proposed autonomous recovery mechanism is able to maintain the overall QoS performance in terms of mean packet delay, system throughput, packet loss and EF jitter.

Passive optical networking has been recognized as a solution for next generation mobile backhaul network. Such technology allows service providers to reduce costs by using already deployed fiber to the x systems while simultaneously supporting increasing demands for mobile broadband Internet access. In this article, we describe a QoS provisioning scheme for LTE/ EPON integrated networks. With this approach, the radio resource management functions of an integrated device, known as ONU-eNB, can take advantage of the information available from the LTE and EPON networks to improve performance. Furthermore, as an example, we show how the implementation of the proposed approach can improve network utilization and users' QoS in an integrated network even under variation of the available bandwidth in the mobile backhaul network.

Natural disasters like icing have a strong impact on the power transmission line which is the foundation of safety and stability operation for power system. In this paper, an online transmission line monitoring and patrol system based on Wireless Sensor Network (WSN) and Ethernet Passive Network (EPON) is firstly designed and a model is built to analyze the latency influenced by the number of towers using EPON communication technology which is solved by Lingo 11.

For integration of Ethernet passive optical network and IEEE 802.16 WiMAX, it is imperative to provide end-to-end quality of service due to the heterogeneous MAC nature of EPON and WiMAX. To address this issue, this paper proposes a QoS-enabled transmission mechanism operated on a specially devised hybrid optical network unit-base station architecture for QoS support, especially delay differentiation, between EPON and WiMAX. Simulation results show that the proposed scheme outperforms the existing transmission mechanisms in terms of the end-to-end delay and jitter, due to its QoS continuity between them.

The IEEE 802.3ca task force is studying the next generation Ethernet passive optical network (NG-EPON), which introduces channel bonding to enable optical network units (ONUs) to bundle multiple wavelength channels to achieve higher peak rates. In order to register these multi-channel ONUs, the optical line terminal (OLT) needs to acquire ONUs' device information, assign working parameters, and verify the connectivity of each channel. Traditional ONU registration protocol, designed for singlechannel ONUs, is not suitable for multi-channel ONUs because it cannot guarantee the channel connectivities of all channels. Therefore, it is essential to extend the traditional registration protocol or design a new registration protocol for NG-EPON multi-channel ONUs. In this paper, we first extend the traditional registration protocol directly to satisfy the requirements of registering multi-channel ONUs. Besides, we propose a novel registration protocol based on the coordination of channel terminals. In order to compare the performances of two registration protocols, we model their registration processes, analyze their registration delays, and find their corresponding influence factors. Simulation results show that our proposed registration protocol has a smaller registration delay as well as better horizontal scalability.

Putting no-load Optical Network Units (ONUs) into sleep mode has been recognized as a promising solution to achieve high energy efficiency for Ethernet Passive Optical Networks (EPONs). To minimize ONU active time, the upstream and downstream transmission windows of each ONU should be overlapped as much as possible. However, the existing Dynamic Bandwidth Allocation (DBA) schemes for EPONs only consider the upstream bandwidth requests. In this paper, we design a novel energy-efficient DBA framework to reduce energy consumption, and meanwhile to guarantee network performance based on bandwidth requests in both downstream and upstream directions. Our DBA framework includes an energy-efficient MAC control scheme, a grant sizing policy and two grant scheduling algorithms. With the MAC control scheme, the Optical Line Terminal (OLT) allocates transmission windows to all ONUs and puts them into low power mode (sleep or doze mode) in each polling cycle. We formulate the energy efficient grant scheduling problem and introduce two energy-efficient grant scheduling algorithms to solve this problem. Results show the effectiveness of the proposed framework and highlight the merits of our algorithms.

Performance of four channel WDM RoF-EPON link based on OVSB transmission using SOA is enhanced by compensating dispersion and FWM with DCF and FBG by 10.95% for equal channel spacing and further improvement has been shown up to 23.61% by using unequal spacing for the same transmission link. The performance enhancement by using DCF and FBG is ascertained by evaluating Q factor and eye opening.

A wide array of dynamic bandwidth allocation (DBA) mechanisms have recently been proposed for improving bandwidth utilization and reducing idle times and packet delays in passive optical networks (PONs). The DBA evaluation studies commonly assumed that the report message for communicating the bandwidth demands of the distributed optical network units (ONUs) to the central optical line terminal (OLT) is scheduled for the end of an ONU's upstream transmission, after the ONU's payload data transmissions. In this paper, we conduct a detailed investigation of the impact of the report message scheduling (RMS), either at the beginning (i.e., before the pay load data) or the end of an ONU upstream transmission on PON performance. We analytically characterize the reduction in channel idle time with reporting at the beginning of an upstream transmission compared to reporting at the end. Our extensive simulation experiments consider both the Ethernet Passive Optical Networking (EPON) standard and the Gigabit PON (GPON) standard. We find that for DBAs with offline sizing and scheduling of ONU upstream transmission grants at the end of a polling cycle, which processes requests from all ONUs, reporting at the beginning gives substantial reductions of mean packet delay at high loads. For high-performing DBAs with online grant sizing and scheduling, which immediately processes individual ONU requests, or interleaving of ONUs groups, both reporting at the beginning or end give essentially the same average packet delays.

Current networking equipment usually provides several energy profiles with different performance capabilities. For example, in EPON systems, ONUs are able to switch their transmitters off when there is no data to transmit. This low power mode, known as doze mode, can significantly reduce power consumption in EPONs if wisely used. In this paper, we evaluate through simulation the potential power savings that can be obtained using this mode in many different scenarios. In particular, we analyze the impact of the DBA algorithm and the mode governor on both energy efficiency and frame delay with different implementations of the doze mode.

Long-reach passive optical networks (LR-PONs), as a part of the next generation PON technologies, aim at combining the capacity of metro and access networks so that the telecommunication network topology is simplified and the operational cost is reduced. However, in order to eliminate the delay performance degradation introduced by long propagation distance, LR-PONs call for bandwidth distribution schemes that are different than the existing schemes for conventional PONs. In this paper, we propose a new bandwidth distribution approach which employs a two-stage buffering mechanism at the ONUs and adopts the reduced delay advantage of multi-thread polling. REPORT generator at an ONU generates the requests by using an adaptive burst assembly process. According to the proposed scheme, ONUs maintain time threshold and size threshold values for the upstream input queues. Upon receipt of a GATE message, each ONU runs an adaptive burst assembly procedure to set the appropriate time and size thresholds and determines the bandwidth request of the REPORT message. We evaluate our proposed bandwidth distribution scheme by simulations for the ONU-OLT distances of 20 km and 100 km. The simulation results confirm that consolidation of multi-thread polling and two-stage buffering enhances the delay performance of long-reach EPON (LR-EPON). Furthermore, under heavy loads, the proposed scheme leads to high utilization of the upstream channel.

In this paper, the performance of WDM Ethernet Passive Optical Network (EPON) with radio over fiber (RoF) optical link is enhanced by using a square root module (SRm) at the receiver side. We have proposed that a square root (SQRT) module compensates the square law characteristics for improving the performance of WDM RoF-EPON. The improvement in the performance has been reported four times for successful transmission over the distance of 20 km that has been witnessed by BER, Q factor and eye opening. Moreover the significant improvement in the signal power has been noticed which is 4.675, −47.118 dBm with SRm and −20.563, −84.896 dBm without SRm for ONUs and OLT respectively.

Integrated dynamic bandwidth allocation with an overlap scheme that improves the bandwidth efficiency of aggregated access networks is implemented and demonstrated on the 10 G Ethernet passive optical network (EPON)-based prototype system for the first time. Experiments revealed that the prototype system can achieve more than 99% bandwidth efficiency with only 150 kB aggregation buffers in each optical subscriber unit.

Passive Optical Networks (PON) are recognized as a fundamental component of high-speed network access, and emerge as a solid networking solution for the smart grid. Smart grid aims to incorporate two-way communications between the customers and the utility, for the purposes of advanced monitoring and intelligent control of demand and supply of electricity. At the user-end, Wireless Sensor Networks (WSN) are ideal tools for energy consumption monitoring at residential premises, as well as, event and ambient monitoring at substations, power lines and vaults. In this paper, we target a seamless integration of WSN technology with PONs to provide Quality of Service (QoS) to both the data collected by billions of sensors and to the Fiber-To-The-Home/Building/Curb (FTTX) users in the smart grid environment. We present the design of a Fiber-Wireless Sensor Network (Fi-WSN) gateway where data prioritization is fundamental since ambient data collected from a home will have lower priority than an alarm generated at a smart grid asset. We show that the proposed gateway design is able to offer low delay for high priority packets while maintaining the delay of FTTX traffic and the reliability of the WSN at desired levels under various loads, concentrations of service levels and aggressive/non-aggressive bursting mechanisms.

In this paper, we study the performances of the registration protocol in Ethernet passive optical networks (EPONs). In each registration process, the newly-connected optical network units (ONUs) send their requests to the optical line terminal (OLT) without any scheduling, which may cause collisions and lower the registration success probability. Thus, a random-delay based registration protocol has been defined in the IEEE 802.3av standard to prevent collisions. Intuitively, the registration protocol of EPON possesses similar characteristics as medium access control (MAC) protocols. Based on this principle, we derive the closed-form expression of the registration throughput to evaluate the random-delay based protocol. We show that an optimal discovery-window size can be determined by maximizing the registration efficiency. Our analytical results indicate that the random delay introduced in the protocol is helpful to enhance the registration efficiency when the number of ONUs is large, or if all ONUs are clustered. However, the throughput improvement by random delay is marginal if there is only a small number of evenly distributed ONUs in the vicinity of EPON.

We propose and demonstrate an improved Ethernet passive optical network (EPON) architecture supporting bandwidth-scalable physical layer local area network (LAN) emulation. Due to the use of orthogonal frequency division multiple access (OFDMA) technology for the LAN traffic transmission, there is no need to change the existing EPON architecture. Only one receiver at each optical network unit (ONU) is required to detect both LAN traffic and EPON downstream traffic, which makes the proposed system simple and cost-effective. Moreover, flexible assignment of LAN traffic bandwidth is realized by allocating different number of subcarriers or using different modulation formats. The 250 Mb/s 4-quadrature amplitude modulation (4-QAM) and 500 Mb/s 16-QAM OFDM LAN traffic are successfully emulated with the EPON traffic in our experiment.

For bottleneck problem of the broadband access networks, Ethernet-PON comes out as a striking and promising solution. Even though, EPON nodes necessitate a cost-effective up-gradation, WDM based topology proves to be a vigilant up-grading approach that deals with the deployment of multiple wavelengths in the upstream/downstream directions. Furthermore, only EPON nodes with privileged traffic can be WDM-upgraded. Accordingly, we propose and demonstrate a hybrid multiplexed OFDM/DWDM-EPON access network employing OSSB modulation scheme. Case A demonstrates a single channel OFDM-OSSB-EPON system and achieves a fiber link of 27 km with split ratio of 16. Afterwards, a contrast between OFDM-EPON and conventional EPON (C-EPON) after a fiber link of 20 km with split ratio of 16 is carried out. Case B targets the transmission of two channels with channel spacing of 0.1 nm to realize OFDM-DWDM-OSSB-EPON system and achieves a fiber link of 20 km with split ratio of 32.

To improve the utilization of bandwidth in EPON (Ethernet Passive Optical Network), a novel dynamic bandwidth allocation algorithm is proposed. Logically, all ONUs are divided into two different zones logically. Further, the corresponding scheduling strategies for each zone are designed. As a result, traffic sending and granted can be achieved with the parallel manner by individual ONU in different zone. With our scheduling method, the sending operations of ONUs in different zones are consecutive in time domain, and the idle time can be eliminated effectively. As a result, the system efficiency can be improved. Results show that the performance of uplink throughput is promoted, and the mean delay of uplink traffic is decreased.

This paper analyzes renewal input batch arrival queues with multiple and single working vacation policy. We obtain the steady state system-length distributions at pre-arrival and arbitrary epochs. The Laplace-Stieltjes transforms (LST) of the sojourn time distribution for the first customer and an arbitrary customer in an accepted batch have been derived. Also the probability density function of sojourn time distribution for the first customer in an accepted batch has been obtained. The proposed analysis is based on the roots of the characteristics equations formed using the probability generating functions (p.g.f.) of embedded pre-arrival epoch probabilities. Several performance measures such as the mean system-length and mean sojourn times of first and an arbitrary customer in an accepted batch are presented. The suggested queues have potential application in ethernet passive optical network (EPON).

In passive optical network (PON), the existing energy-saving algorithms are implemented only with one kind of PON. However, as far as Ethernet PON (EPON), good performances cannot be reached simultaneously in both 10G-EPON and 1G-EPON. Although 10G-EPON can provide higher throughput and lower delay than 1G-EPON, it consumes more energy. Currently, there are four types of optical network unit (ONU) sleep modes which are specified by ITU-T. If transmitter and receiver can be turned off independently without upstream traffic or downstream traffic, additional energy can be saved. Therefore, in this paper, to obtain high throughput and low delay with low energy consumption, we propose a new energy saving mechanism based on double-sleep-state and dynamic double-threshold receiver selection (EDDS) with the combination of 1G-EPON and 10G-EPON techniques. In EDDS, ONU's receiver not only can be switched between 1 Gbps receiver and 10 Gbps receiver according to the downstream traffic, but also can be put into sleep state independently when possible. Hereby, EDDS can provide higher throughput and lower delay than 1G-EPON while consume less energy than 10G-EPON. To support EDDS, new structures for optical line terminal (OLT) and ONU are introduced. Simulation results show that EDDS achieves better performances than the traditional schemes.

In this paper we address an issue referred to as "over-granting problem", which is inherent in the existing dynamic bandwidth allocation algorithms for Ethernet-based Passive Optical Networks (EPON), in particular when deployed for multi-threaded scheme in long-reach scenario. In order to solve this problem we design a scheme for the algorithm of Interleaved Polling with Adapted Cycle Time (IPACT) with the limited service discipline. We evaluate the proposed scheme through simulations for single-thread and double-thread cases and demonstrate that, the network performance can be significantly improved by our solution in terms of average delay, jitter, and throughput.