AliAkbar Nikoukar

Scalable architecture for VOD service enhancement based on a cache scheme in an Ethernet passive optical network

Video on demand (VOD) is becoming one of the most important services for many network operators. VOD needs a huge bandwidth to deliver data in a real-time network. Ethernet passive optical networks (EPONs) provide a low-cost and high-speed solution for multimedia services such as VOD. In this paper, we propose a scalable architecture based on an EPON, using single copy broadcast in the downstream direction and a special caching mechanism responsible for VOD requests, to improve VOD services. Our architecture consists of an optical network unit (ONU) with an associated storage unit and optical line terminal (OLT) components. We set a “broadcast” logical link identifier in the video packets so that all of the ONUs can accept them. Therefore, when the movie is sent from the OLT to the ONUs after it is requested by the user, each ONU accepts the movie packet and saves it in its own storage. In this architecture, the OLT just needs to send each video to the ONUs once, and the attached storage is responsible for future requests. With this architecture, at least 60% of VOD traffic can be saved in the feeder fiber. Simulation results show that our architecture can improve the overall quality of service in terms of packet loss, mean packet delays, jitter, and system throughput.

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.

QoS Enhancement of Live IPTV Using an Extended Real-Time Streaming Protocol in Ethernet Passive Optical Networks

Internet protocol TV (IPTV) is one of the most important multimedia applications for next-generation networks. IPTV provides triple-play services that require high-speed access networks with the functions of multicasting and quality of service (QoS) guarantees. Among access networks, Ethernet passive optical networks (EPONs) are regarded as among the best solutions to meet higher bandwidth demands. In this paper, we propose a new architecture for multicasting live IPTV traffic in EPONs. The proposed mechanism involves assigning a unique logical link identifier to each IPTV channel. To manage multicasting, a table in the optical line terminal (OLT) and in each optical network unit (ONU) is constructed. These tables are maintained in the reconciliation sublayer to deliver the IPTV traffic. We extend the message passing of the original real-time streaming protocol (RTSP), called the extended RTSP (ERTSP), to handle the IPTV requests. A mechanism is proposed to handle the IPTV requests as intra traffic in the ONU without sending the request to the OLT. Handling the live IPTV channel as intra traffic can save bandwidth in the feeder fiber and increase the system throughput. Simulation results show that our proposed architecture can improve the system performance and QoS metrics in terms of packet delay, jitter, system throughput, and packet loss.

Distribution drop fiber in-service fault management in enhanced EPON system

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.

P2P Live-Streaming Application-Aware Architecture for QoS Enhancement in the EPON

Managing a single state-of-the-art ethernet passive optical network optical line terminal (EPON OLT) that can support many customers with different multimedia services and quality of service (QoS) is a challenge. Peer-to-peer (P2P) live streaming is one of the most popular multimedia applications in access networks, especially in the Asia-Pacific region, which requires higher QoS, but such streaming is difficult to manage. Therefore, a new approach is required that can provide flexible control to Internet service providers (ISPs) over their networks. In this paper, we propose a P2P application-aware architecture at the OLT and optical network unit (ONU) that aims to improve overall QoS and, at the same time, preserve user-perceived quality and provide ISPs with flexible control over P2P live-streaming traffic. Finally, a new application-aware dynamic bandwidth allocation (ADBA) is presented. Simulation results show that the proposed architecture can improve the overall QoS in terms of mean packet delay, system throughputs, and jitter, and it can also alleviate inter-ISP traffic bandwidth.

OLT energy savings via software-defined dynamic resource provisioning in TWDM-PONs

Time and wavelength division multiplexed passive optical network (TWDM-PON) standards dramatically increase the performance of PON systems and address ever-increasing demands for bandwidth. However, these schemes increase the complexity and energy consumption of PON systems because they exploit multiple wavelengths, which requires multiple transceivers in the optical line terminal (OLT). In this paper, we propose to integrate software-defined networking (SDN) into standard PON architectures to facilitate an orchestrated energy-efficient operation in which the SDN controller dynamically provisions the number of wavelengths, link-rates, and timeslot assignments depending on the global traffic conditions. The simulation results show that the proposed architecture and mechanism improves the energy-saving performance of OLTs if the traffic load is less than 80%, while guaranteeing the quality of service requirements in terms of the mean packet delay, jitter, queue length, throughput, and packet loss ratio.

Decentralized SIEPON-based ONU-initiated Tx/TRx energy-efficiency mechanism in EPON

An Ethernet passive optical network (EPON) has the least energy consumption among access network technologies and is the best candidate for improving energy consumption by time utilization. Current studies have proposed OLT-initiated schemes to turn off the transmitter/ receiver of an optical network unit (ONU) for a substantial time in order to achieve energy savings. In this paper, a new SIEPON-based ONU-initiated energy-saving mechanism is proposed in which the ONU calculates the transmitter (Tx) sleep duration based on the current queue state and maximum boundary delay requirements and forwards it to the OLT; then, the OLT calculates the ONUs receiver (Rx) sleep duration and decides the ONUs sleeping mode in Tx or TRx sleep mode. Furthermore, the Sleep manager and Green DBA and TRx controller components are proposed in the OLT and ONU architectures to more precisely manage the energy-saving mechanism. Simulation results show that the proposed energy-saving mechanism significantly improves energy savings up to 47% and 42% in the up- and downstream directions, respectively, and guarantees the QoS requirement in terms of mean packet delay, packet loss, throughput, and jitter. Moreover, the proposed energysaving mechanism has better delay performance compared with the OLT-initiated energy-saving mechanism such as upstream centric scheduling.

A new QoS-aware Green Dynamic Bandwidth Allocation in Ethernet Passive Optical Network

Electricity consumption grows rapidly in the recent years. To reduce global greenhouse gas (GHG), it is necessary to utilize the energy consumption of the networks. In the broadband access network, Passive Optical Network (PON) refers as a green network which uses less power consumption compared to the other technologies. Optical Line Unit (ONU) potentially can be chosen to implement energy-saving methods in PON. There are two ways to improve the energy-efficiency based on the hardware redesign or/and software-based schemes. Sending the ONU to sleep mode is a common method which is proposed by researchers or industries. Sleep mode is referred to turn off the transmitter and/or receiver to save energy. However, this method can cause the packet delay and reduce the Qos/QoE metrics. In this paper, we introduce a software-based Green Dynamic Bandwidth Allocation (DBA) to reduce the ONU energy consumption and guarantee overall QoS metric. Simulation results show that the proposed Green DBA can improve the power saving without affecting the overall 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.

Delay analysis of dynamic bandwidth allocation for triple-play-services in EPON

Today, triple play services may be regarded as required services in telecommunication sector. In the access network, Ethernet Passive Optical Network (EPON) is considered as one of the best solutions to provision triple-play-services. In EPON, the Dynamic Bandwidth Allocation (DBA) algorithm plays a key role to meet the Quality-of-Service (QoS) requirements. Therefore, in this paper, we conduct the delay analysis of DBA so that it can provide a better understanding for the network operators when designing and implementing a DBA algorithm. We use machine learning algorithm such as Random Forest, Decision Tree, kNN, and Naives Bayes and R-programming to build a prediction model and find the important factors affecting the packet delay in EPON system. We run extensive simulation scenarios to build appropriate dataset for training set and testing set. We found that the cycle time selection has a significant impact on the EF delay, AF delay and BE grant. We also found that there was a strong relationship between the EF delay and AF GRANT. Lastly, we conduct performance evaluation to justify what we found. Simulation results show that cycle time is indeed has significant effect on system performances.