Time-division Multiplexing Passive Optical Network Research Articles

Performance evaluation of fault-branch detection in TDM passive optical networks by spectral analysis of interferometric signals

A new fault-branch detection scheme is proposed to troubleshoot the breaks of any distribution fibers in a time-division multiplexing (TDM) passive optical network. We employ a continuous optical frequency sweeper at the optical line terminal (OLT) and an interferometric (IF) device at each optical network unit (ONU). By analyzing the spectrum of the returned combined signals at the OLT, we can obtain the status of all branches. This detection method not only uses a small optical frequency band for surveillance monitoring, but is also simple to operate. Furthermore, a modified architecture is proposed to relax the specifications of IF devices. The tolerance of the IF device length was analyzed using the Monte---Carlo simulation method.

Optical power equalization for upstream traffic with injection-locked Fabry–Perot lasers in TDM-PON

An optical power equalization of upstream traffic in time-division-multiplexed passive optical network (TDM-PON) based on injection-locked Fabry–Perot lasers has been experimentally investigated. The upstream transmitters with stable spectrum are achieved by using an external injection light source in the optical line terminal (OLT). The different upstream powers can be equalized by injection locking a Fabry–Perot laser diode (FP-LD) biased below threshold current in OLT. The dynamic upstream power range from − 8.5 to − 19.5 db m is reduced to a 1.6 dB maximal power variation, when the uplink signal is directly modulated at 1.25 Gb/s.

Experimental demonstration of CW light injection effect in upstream traffic TDM-PON

High capacity time-division-multiplexed passive optical network (TDM-PON) is an emerging fiber access network that deploys optical access lines between a carrier’s central office (CO) and a customer sites. In this investigation, we demonstrate and analyze the continuous wave (CW) upstream effect in TDM-PONs. Besides, we also propose and design a protection apparatus in each optical network unit (ONU) to avoid a CW upstream traffic in TDM-PONs due to sudden external environment change or ONU failure. When an upstream CW injection occurs in TDM access network, the protection scheme can stop the CW effect within a few ms to maintain the entire data traffic.

10 Gb/s-Based PON Over OCDMA Uplink Burst Transmission Using SSFBG Encoder/Multi-Port Decoder and Burst-Mode Receiver

In this paper, we propose a novel 10 Gb/s-based passive optical network (PON) over optical code division multiple access (OCDMA) system to realize the new generation full capacity optical access network which is easily upgraded from existing time division multiplexing PON (TDM-PON) without sacrificing the currently uplink bandwidth assigned to the individual user. 16-ONU (4-OCDMA x 4-packet) uplink burst transmission, an upgrade scenario by a factor of four of conventional 10 Gb/s-based PON, is experimentally demonstrated by using multi-level phase-shift-keying (PSK) super-structured fiber Bragg grating (SSFBG) encoder/multi-port decoder and burst-mode receiver. In the discussions, it will be shown that 32 users can be accommodated in 10 Gb/s-based PON over OCDMA system, and a key is newly introduced multi-level phase-shifted en/decoding, of which auto-correlation waveform can be preferably adopted in the burst-mode reception at 10 Gb/s.

40-Gb/s Time-Division-Multiplexed Passive Optical Networks Using Downstream OOK and Upstream OFDM Modulations

In this investigation, we first propose and investigate a 40-Gb/s time-division-multiplexed passive optical network (TDM-PON) using four wavelength-multiplexed signals in both downstream and upstream traffic. Here, each downstream signal uses 10-Gb/s on-off keying (OOK) format encoded by a Mach-Zehnder modulator (MZM) in 1.5-?m band. And each upstream channel utilizes the highly spectral efficient 10-Gb/s orthogonal frequency-division-multiplexing quadrature amplitude modulation (OFDM-QAM) generated by directly modulating a 1.3-?m laser. Based on the proposed scheme, 40-Gb/s data traffic in a TDM-PON can be obtained easily by using four wavelength-multiplexed channels. In addition, the performance of the proposed PON architecture has also been discussed.

A Novel Scheme of Estimating Link Power Budget using DBA for a 10 Gbit/s TDM-PON Architecture

Passive Optical Network (PON) has utilizes for transporting higher bandwidths with secured triple play services (Voice, Video and Data -VVD) in the fiber based broadband access network applications. Time division multiplexing PON (TDM PON) architecture can be made to support the transmission of higher data rates similar to WDM/DWDM PON. As per the literature analysis, TDM network limitation is to be upgraded still for time slot allocation and synchronization in higher bit rate transmission for more number of end users if required. In this paper we have analyzed the link power estimation for 10 Gbit/s TDM PON downstream transmission based on above issue. Also a complete investigation has done using optical signal delay, Fiber dispersion, splitting loss as major performance parameters. We have taken various measurements such as received signal and noise power, signal delay, extinction ratio, electrical and Optical signal-to-noise ratio (ESNR and OSNR) with respect to Q-Factor and BER with case studies to improve the Quality of service(QoS) for 10G bit/s dynamic bandwidth allocation (DBA) scheme. The entire architecture performance has been found out through simulations with different approaches using normal and sweep iterative mode analysis (NIA and SIA).

Next Generation Optical Access Network: Standardization Outline and Key Technologies for Co-existence with Legacy Systems

Users are increasingly demanding broadband services, and fiber-to-the-home (FTTH) is the main technology to answer these demands. Gigabit-class passive optical network (PON) systems, IEEE802.3ah GE-PON [1] or ITU-T G.984 G-PON [2] have been widely deployed and used by many network operators. The number of FTTH users in Asia is increasing and has exceeded 30 million [3]. Especially in Japan the number of FTTH users surpassed the number of digital subscriber line (DSL) users in 2008. Recently, the number of FTTH users topped 15 million, and the ratio of FTTH services among broadband services went above 50 percent [4]. This means FTTH supports most Japanese broadband services. With the emerging applications such as multi-channel high-density television (HDTV) distribution, broad bandwidths wider than those of the current system will be required. To respond to wider bandwidth demand, several kinds of technologies such as 10-Gbps class time division multiplexing (TDM), wavelength division multiplexing (WDM) [5], optical code-division multiple access (OCDMA) [6] and orthogonal frequency-division multiple access (OFDMA) [7], [8] have been developed and discussed as next generation PON (NG-PON) technologies. As 10 Gb/s Ethernet [9], which was approved in 2002, has been already widely used and 10-Gbps TDM technologies have become mature, the 10-Gbps-class TDM PON system is the most attractive candidate for NG-PON systems. Therefore, standardization development organizations (SDOs) have been discussing 10-Gbps-class TDM PON standards. Recently, the IEEE802.3 committee approved the 10G-EPON standard [10] and ITU-T has been developing an XG-PON standard [11]. This paper reviews NG-PON standardization trends fo-

Traffic Load Distribution-Based Excess Bandwidth Allocation in Time-Division-Multiplexed PONs

Time-division-multiplexed passive optical networks (TDM-PONs) have been successful solutions for providing the huge bandwidth needed for quadruple-play services in last-mile networks. In this paper, the effects of excess bandwidth provisioning applied to a reservation-based TDM are analyzed in detail, and noble adaptive excess timeslot provisioning (ETP) mechanisms are proposed in the interoptical network unit (ONU) and intra-ONU domain in the TDM-PONs. Using traffic load distribution information observed in an optical line termination (OLT), a proposed deficit reservation-based dynamic bandwidth allocation, called dr-DBA, controls the amounts of excess timeslot bandwidths in order to efficiently serve the burst traffic of heavy-loaded ONUs while guaranteeing strict fair link-sharing. The authors also introduce a service work-based ETP bandwidth reservation as well as an optimal reservation class selection mechanism to support prioritized service in an intra-ONU so that serious node light-load penalty and bandwidth overbooking can be minimized. The performance results achieved by numerical analysis and simulations prove that proposed ETP mechanisms provide fair and optimal excess bandwidths to the ONUs according to the changes in traffic load distribution, while compensating the systematic weakness of each mechanism in both ONU domains.

A Seamless Evolution Method With Protection Capability for Next-Generation Access Networks

We propose and demonstrate a seamless evolution method with protection capability for next-generation (NG) access networks. Both a time-division-multiplexing passive optical network (TDM-PON) and a wavelength-division-multiplexing (WDM-PON) can be accommodated in the same fiber infrastructure and failures of feeder fibers and distribution fibers are protected for each service. Remote reconfigurations of the remote node (RN) for protection and/or evolution can be achieved within 48 ms by instantaneous optical powering at the central office (CO) while maintaining the RN in a passive state.

High-Bit-Rate Dynamically Reconfigurable WDM–TDM Access Network

The intensification of traffic in the access network requires the development of novel architectural solutions for a reconfigurable network topology and components based on optical technologies. We present a hybrid ring-shaped wavelength division multiplexing (WDM)–time division multiplexing (TDM) passive optical network (PON) that is capable of providing bandwidth on demand at high bit rates in a transparent and dynamic manner. Our cost-efficient and scalable network architecture is based on integratable components such as a wavelength-agile optical networking unit and a microring-resonator-based remote node. An appropriately modified control layer is introduced to manage the network. We also discuss the implementation of optical codes instead of time slots to take the step toward optical code division multiplexing (OCDM) WDM PONs that relieve the network of strict time scheduling of traffic and ranging. Therefore, an additional reduction of complexity in network management, improvement of network scalability, and a guarantee of fully symmetric traffic are foreseen for every user. Finally, we show a scenario for smooth migration from existing PON solutions to our WDM–TDM PON architecture.

Utilization of four WDM channels with signal remodulation of OFDM-QAM for 10 Gb/s uplink passive optical networks

In this investigation, we experimentally investigate an extended reach (ER) time-division-multiplexed passive optical network (TDM-PON) using four wavelength-multiplexed channels to achieve 16 Gb/s downlink and 10 Gb/s uplink traffic. Each downlink signal uses the highly spectral efficient 4 Gb/s OFDM-QAM, and each uplink signal is generated by signal remodulating the downlink signal via a reflective semiconductor amplifier (RSOA) at 2.5 Gb/s non-return-to-zero (NRZ). In addition, the performance of the proposed ER TDM-PON has also been analyzed and discussed.

Channel Enlargement of PON System Using Nonreciprocal Multiplexing Filter Based on CWDM

We propose a nonreciprocal filter based on coarse wavelength division multiplexing (CWDM) that reduces the upstream channel insertion loss in a passive optical network (PON). We also propose a method to increase the number of channels/optical network units (ONUs) in PON systems using the proposed filter to reduce the service cost per subscriber. Experimental results show that the PON system with the proposed 4-channel filter can reduce the power budget of the upstream and increase the number of ONUs by 3 to 4 times that of a conventional time-division multiplexing PON.

A Remotely Reconfigurable Remote Node for Next-Generation Access Networks

A remotely reconfigurable remote node (RN) for next-generation (NG) access networks is proposed and demonstrated. The RN is remotely reconfigured by instantaneous optical powering at the central office through feeder fiber and maintained in a passive state by employing optical latching switches (OLSs). The feasibility of the proposed RN is demonstrated by investigating the operating conditions of optical powering for the reconfiguration and its nonlinear effect both for time-division-multiplexing passive optical network (TDM-PON) as legacy services and wavelength-division-multiplexing passive optical network (WDM-PON) as NG services. The existence of OLSs for reconfigurability and crosstalk effect between TDM-PON and WDM-PON are negligible on transmission performance.

Fair Bandwidth Allocation Using Effective Multicast Traffic Share in TDM-PONs

In this paper, the effects of optical traffic-sharing on the performance of multicast video delivery in terms of the efficiency of bandwidth allocation and the fairness of link-sharing are discussed for the downstream direction of a time-division-multiplexed passive optical network (TDM-PON). We analyze the practical issues associated with multicast packet switching and transmission control in a TDM-PON and also propose a fair bandwidth allocation mechanism, called share-based proportional bandwidth allocation (S-PBA), to effectively support multicast services. In order to provide an optical network unit with a fair amount of link bandwidth and high throughput independent of traffic type, S-PBA arbitrates the amount of unicast timeslot by using effective multicast traffic share, which is determined based on multicast traffic load distribution and traffic-sharing density. Analytic and simulation results clearly validate the effectiveness of the proposed mechanism. This work is applicable to multicast video delivery or multicast traffic transmission in general, such as voice traffic, or a combination of both in the case of video conferencing, for example.

An Evolution Method From a TDM-PON With a Video Overlay to a WDM-PON

We propose an evolution method from a time-division-multiplexing passive optical network (TDM-PON) with a video overlay to a wavelength-division-multiplexing (WDM)-PON as a next-generation access network. In order to establish a smooth evolution path, a single type of three-port wavelength band combiner/splitter (WC) was used at the remote node and optical network terminations. At the central office, a four-port WC was used to combine the TDM-PON, the video overlay, and the WDM-PON. Crosstalk among those signals is negligibly small.

Evolution from TDM-PON to WDM-overlaid PON employing a wavelength-conversion node

A cost-effective and smooth evolution scheme from a time-division multiplexing–passive optical network (TDM-PON) to a WDM-overlaid PON that can provide high-speed fiber-to-the-home service to a wide area with a high population density is proposed. Existing optical transmitters of TDM-PON optical network units (ONUs) are reusable by employing a wavelength-conversion node at the ONU site, which transforms the wavelength of each ONU to a predefined WDM wavelength. A specially designed optical router is needed at a remote node site; it should broadcast downstream signals to each ONU, routing upstream ONU signals to a wavelength-conversion node and passing the wavelength-converted signal to an optical line terminal. A simple but efficient remote node structure is proposed. A wavelength conversion node should be designed carefully since it repeats burst-mode signals from multiple ONUs. A 2R repeater-based wavelength conversion node is suggested. Performance of various schemes is analyzed and their measurement results are provided.

Self-protecting dual-ring-architecture in time-sharing passive optical network to prevent the occurrence of fiber failure

We propose and experimentally investigate a self-protecting dual-ring-architecture time-division-multiplexed passive optical network (TDM-PON) using bidirectional dual-fiber path against the fiber-fault. By the proposed access network, the ring-based TDM-PON system can be revived promptly under single fiber failure. This restorable time is achieved within a few ms in the proposed ring access network. Moreover, the performance of data traffic in the optical access network has also discussed.

An Efficient Evolution Method From TDM-PON to Next-Generation PON

An efficient evolution method from a time-division-multiplexing passive optical network (TDM-PON) is proposed and demonstrated for a next-generation PON. A single-type three-port wavelength band combiner/splitter enables a simple and efficient evolution of TDM-PON maintaining the current PON infrastructure and wavelength plan. The crosstalk between the TDM-PON and next-generation PON is negligibly small

Efficient resource allocation with service guarantees in passive optical networks

Feature Issue on Passive Optical Network Architectures and TechnologiesWe propose and evaluate a resource allocation scheme for time-division multiplexing passive optical networks (PONs), which supports multiple service classes; dynamic bandwidth allocation for services with varying (in time) capacity demand; and bounded quality of service parameters for services with real-time requirements. Although several algorithms have been proposed in the literature considering several of the above objectives in isolation, our work focuses on the fundamental problem of trading-off between PON upstream channel utilization and strict delay and jitter bounds when supporting a dynamically changing mix of services with different requirements.

Application of 2W-PON in fairness and priority environments

Time division multiplexing-passive optical networks (TDM-PONs) suffer from low upstream bandwidth utilization caused by guard band and various overheads. This degradation depends on optical network unit (ONU) numbers and cycle time, each of which has many effects on cost and quality, respectively. Upstream bandwidth utilization is efficiently increased by using two wavelength types at ONU sites so that overhead parts from two ONUs are overlapped in time. Each ONU is equipped with one of the two transmitting wavelengths, and an optical line terminal (OLT) schedules operation sequence. A utilization increase of up to 30% is achieved for gigabit Ethernet-passive optical network (GE-PON) by using the proposed scheme. Two operation algorithms, based on fairness and priority, are suggested and their performances are analyzed.