Wavelength Division Multiplexing Passive Optical Network Research Articles

Research of hybrid WDM-PON data transmission system with embedded ASE-powered stealth channels for steganography applications

Abstract The frequency spectrum is becoming busier, thereby it might be appealing for more and more, for instance, eavesdroppers to try to gather some valuable data or identify the transmission frequencies for this specific data. To mitigate the possible risks concerning that, not only data encryption but also hiding of the data channels (creation of stealth channels) is necessary. For the success of stealth signal integration, channel spacing, and power customization is required. During this research, in the simulation environment, we show a successful realization of the 8-channel 10 Gbit/s non-return-to-zero on–off keying (NRZ-OOK) modulated wavelength-division-multiplexed passive optical network (WDM-PON) with the embedded additional amplified spontaneous emission (ASE) powered hidden 7-channel 2.5 Gbit/s NRZ-OOK modulated spectrum-sliced data transmission system. Such as a hybrid optical transmission system can be used to improve the protection of sensitive data. Our results show that the introduction of the stealth data transmission system leads to an estimated power penalty below 0.02 dB at the pre-FEC BER level of 10−3, which may be considered as negligible and shows the viability of this hybrid system. The proposed approach can be applied not only in the WDM-PON architecture but also in other types of fiber optical access or metro-access systems.

Ring based latency-aware and energy-efficient Hybrid WDM TDM-PON with ODN interconnection capability for smart cities

Abstract In the current scenario, there is a huge advancement in Information and Communication Technology (ICT), and almost most of the devices used in a smart city are the Internet of Things (IoT) based smart devices. To support high-speed IoT devices, wavelength division multiplexed passive optical networks (WDM-PON) is one of the most promising and most commonly used technology in optical distribution network (ODN). With the exponential growth of WDM-PON and its applications, energy consumption, operational expenditure (OPEX), communication latency between different users, reliability of service etc. are becoming the most challenging issues to implement the WDM-PON networks in the smart cities. In this paper, we propose a ring based latency aware and energy efficient PON architecture which is capable of providing point to point downstream, upstream, inter-ODN, intra-ODN and inter-ODN broadcasting transmission. Proposed architecture reduces the significant amount of transmission latency, energy consumption, operational expenditure and reduces the emission of Green House Gases (GHGs). The architecture also reduces the downstream and upstream bandwidth consumption by avoiding the transmission of the inter-ODN signal to optical line terminal (OLT) and back to destined ODN. The architecture seems appropriate for supporting various real-time high-speed ICT and IoT applications of a smart city.

Flexible coherent UDWDM-PON with dynamic user allocation based on limited-tunability lasers

Coherent wavelength division multiplexing (WDM) technologies have leveraged the optical communication systems in core networks, increasing the fiber capacity by transmission with advanced modulation formats and mitigation of impairments with digital signal processing. However, these solutions are too expensive for access networks, where cost, power budget, and footprint are limited. Hence, the key technology will be developing low-cost coherent transceivers providing an excellent selectivity and giving high sensitivity, which allows high splitting ratios. This paper reports an experimental design of a low-cost coherent ultra-dense WDM passive optical network (UDWDM-PON) with 6.25 GHz channel spacing. The users’ optical network unit (ONU) is built employing coherent transceivers with two paired low-cost distributed feedback (DFB) lasers, one as the local oscillator and another as the transmitter, offering simplicity and low-cost hardware; likewise, the optical line terminal (OLT) at the central office can profit from the same design. The ONU DFB lasers have wavelengths with limited thermal tunability, controlled by a thermo-electric cooler, which is used to allocate the wavelengths. A medium access control (MAC) at the OLT manages the spectrum channel allocation for ONUs, demanding connection when activation is requested: the OLT furnishes an optical carrier wavelength for the ONU to obtain connection by a control algorithm, assigning a down-channel and another paired up-channel assigned to the ONU DFB transmitter. The MAC can reassign the channels because of interference or collision in a dynamic wavelength allocation. Measures in an activation process and in channel reassignment have been performed in environmental conditions, including control signals and the physical parameters of DFB lasers, demonstrating the practical viability of the PON scaling from 32 up to 256 wavelength channels.

LDPC-Coded Probabilistic Shaping PAM8 Employing a Novel Bit-Weighted Distribution Matching in WDM-PON

We propose and experimentally demonstrate a wavelength-division-multiplexing passive optical network (WDM-PON) employing low-density parity-check (LDPC) coded probabilistic shaping 8-level pulse amplitude modulation (PS-PAM8). In such a splitter-based WDM-PON system with direct detection, a novel probabilistic shaping (PS) method based on a bit-weighted distribution matching (BWDM) for near-Gaussian distribution (NGD) is proposed for the first time. For typical PS schemes based on typical arithmetic distribution matching (ADM) and constant composition distribution matching (CCDM), refining intervals continuously is needed to find the target symbol probability, which will necessarily introduce a plenty of additional redundant bits in the process of the target symbol probability distribution (SPD) emulation from data source. Different from ADM and CCDM, the PS scheme based on BWDM is realized by a simple bit-weight intervention algorithm with low hardware and calculation complexity, which only includes weight-marking bit insertion and bit inversion processes for adjustable SPD kurtosis. The experimental results show that by employing the proposed PS-PAM8, the receiver power sensitivity and system fiber nonlinear effect tolerance can be dramatically improved compared with the unshaped signal. Thus, the WDM-PON employing PS-PAM8 is of cost-effective advantage, which can serve more available optical network units due to the enlarged system loss budget for the optical distribution network.

Performance Analysis of Full-Duplex NG-PON2-RoF System with Non-linear Impairments

The motivation of this study springs from the need of exploiting the advantages of high data rate and increased mobility of the transmitted signal in the Next Generation Passive Optical Network stage 2 (NG-PON2) incorporated into Radio over Fiber (RoF) system. Nonetheless, such system is prone to degradation due to the nonlinear effects, namely, the non-linear impairments. Accordingly, this study suggests a design for a full-duplex NG-PON2-RoF system and it investigates the impact of the nonlinear effects on the performance of system, such as; Self-Phased Modulation (SPM), Cross-Phase Modulation (XPM), and Four-Wave Mixing (FWM). However, these effects would result in a significant data loss in Time and Wavelength Division Multiplexing-Passive Optical Network (TWDM-PON). To achieve the intended purpose of this investigation, both the performance of the suggested system and the nonlinear effects of SPM, XPM, and FWM are measured with reference to the qualitative parameters, such as; Bit Error Rate (BER), Q-Factor, Power link Budget, and the Eye-diagram. The results show that the system performs efficiently; however, in the presence of the nonlinear effects, the performance of the systems degrades significantly affecting the signal quality. It is worth noting that the FWM effect yields the most negative impact followed by the XPM, and the SPM effect yields the least significant impact on the system. Also, the system yields the capacity of transmitting range of 20-100 Km, and it results in data rate of 40-80 Gbps. The proposed system is simulated using the software Optisystem 15.

Performance Analysis of 16-Channel Hybrid WDM- CSRZ-DQPSK PON for Different Transmission Speeds and Distances

Sixteen channel wavelength-division-multiplexed passive optical network (WDM-PON) based on one Mach-Zehnder modulator and carrier suppressed return to zero differential quadrature phase-shift keying (CSRZ-DQPSK) transmitter is designed and evaluated for various bit rates (20 Gbps to 80 Gbps). The effect of changes in transmission distance with increased bit rate is also discussed and hence quality factors and bit error rates are analyzed to evaluate their performances. The relation between transmission distance, quality factor (Q factor) and bit error rate (BER) have been focused to determine optimized result.

Technologies for future wavelength division multiplexing passive optical networks

This study reviews key technologies of next generation wavelength division multiplexing passive optical networks (WDM-PONs). The authors have studied WDM-PONs with centralised lightwave source and direct detection, where a wavelength-reuse system is employed to transmit the uplink data by using a colourless transmitter at the optical network unit (ONU). WDM-PON system was demonstrated using a Fabry-Perot laser diode as a colourless transmitter at the ONU for differential phase-shift keying (DPSK) downlink signals and on-off keying uplink signals. The constant-amplitude feature of the DPSK modulation could retain a great extinction ratio of the downlink signal and decrease the noise to the uplink signal. The proposed scheme offers a promising solution for future PONs.

Research on Power Optimization Based on Adaptive Passive Optical Networks

Abstract For the commercial wavelength division multiplexing passive optical network (WDM-PON) with standard single-mode fiber SSMF-28 and 1:64 passive fiber branching at its far end (RN) and 100 GHz C-band continuous wavelength (CW) lasers, the maximum coverage and optimal transmission power of STM-16 and STM-64 with external modulators at different speeds and wave numbers (4λ, 8λ and 16λ) are obtained, respectively. The performance parameter of the high data rate WDM-PON system is analyzed with respect to a number of channels and reach. In order to improve the network utilization and receiving efficiency, the influence of different channels and transmission distances on the performance of high data rate WDM-PON system is analyzed. Simulation analysis with Optisystem15.0. The maximum transmission power required to achieve the maximum transmission distance under the condition of nonlinear constraints is obtained. In order to save power consumption, the configuration of each multi-band PON is optimized in terms of transmission power. It is found that WDM-PON system has to compromise between aggregated data rate and system reach. Future software defined access network reconfigure the access network depending on the dynamic demand and the resources available. Hence depending on the distance between the optical line terminal (OLT) and optical network unit (ONU) guaranteed data rate can be estimated. ONU is equipped with a tunable optical filter (TOF) hence future wavelength can be reconfigured by both service provider and user. It makes it possible for software to customize optical access network.

A Comparative Study of Performances Between the WDM PON System and the CWDM PON System in an Optical Access Network

Abstract The growth of optical technology is currently being studied extensively to meet the significant demand for bandwidth. The passive optical network (PON) solves the problem of bandwidth as it extends the optical network to individuals and businesses [Sifta R, Munster P, Krajsa O, Filka M, “Simulation of bidirectional traffic in WDM-PON networks", Brno University of Technology, ISSN 0033–2097, R. 90 NR 1/2014.]. In this paper, a comparative study is made between the WDM PON system and the CWDM PON system using two different architectures, one for the WDM PON and the other for the CWDM PON, to illustrate the appropriate technique for the PON network by increasing the Q factor and the OSNR ratio while minimizing the bit error rate (BER < 10–9 ). Both systems are simulated at 10 Gbps for four users of bidirectional SMF (Single Mode Fiber) fiber lengths and different powers. In order to determine the transmission performance for both systems, the link was designed for fiber lengths of 20, 30, 40, 50 and 60 km as well as for powers from −10 dBm up to 10 dBm for four users. The use of the EDFA amplifier in the WDM PON system is required in this document to minimize degradation caused by attenuation [Parkirti RDK, Singh R. Cost-efficient Colorless WDM-PON Based on RSOA for High Capacity. Int J Adv Res Comput Eng Technol (IJARCET). 2016;5]. On the contrary, in the CWDM PON system, the amplification is not essential because the wavelengths used in this system are not affected by the water peak which causes a strong attenuation of the wavelengths in the 1370–1410 nm range on optical fibers [Nazir M, Arshad F, Asif R. Design and evaluation of power budget for a bidirectional CWDM-Passive Optical Network. In: International Conference on Communication, Computing and Digital Systems (C-CODE), Islamabad, Pakistan, 04 May 2017.]. The peak of water vapor absorption is close to 1383 nm.

METAhaul framework of HPON for smart city access networks

ABSTRACTThis work presents, a novel, Mobile Evaluation Transport Architecture haul (METAhaul) of Hybrid PON (HPON), that integrates mobile backhaul (MBH), mobile fronthaul (MFH) and smart devices in one platform. It forms a unified analytical framework, that comprehensively accounts for both fiber/copper (FiCo) and METAhaul broadband access networking technologies, to accommodate the fifth generation (5G) Radio Access Network (RAN) evolution and smart sensor devices. Our framework is flexibly designed to roll out while adopting 5G into the smart city. HPON allows the coexistence of the Time Division Multiplexing Passive Optical Network (TDM-PON), Wavelength Division Multiplexing Passive Optical Network (WDM-PON), hybrid Time-Wavelength Division Multiplexing Passive Optical Network (TWDM-PON), multi-gigabit fast access to subscriber terminals (G.mgfast), and Radio over Fiber (RoF) architecture. It can reduce the power consumption by 78.13%, 79.62% at Sub-6GHz, and 77.7%, 79.21% at mmWave against Optical Transport Network (OTN) and Carrier Ethernet (CE), respectively. Specifically, HPON grants a higher Energy Efficiency Rating (EER) of 65.58%, 67.34% when compared to OTN, and CE each while deploying 15 Radio Units (RU). The proposed next-generation PON architecture can benefit the design and operation of smart city access networks, with its large capacity, multilevel of service, and energy saving.

ITU TWDM-PON module for ns-3

Optical fiber access systems are one of the driving forces behind the success of the Internet. Time- and wavelength-division multiplexing passive optical network (TWDM-PON) is regarded as the key technology for future Internet access networks. In this paper, we propose an ITU TWDM-PON module for the ns-3 network simulator and describe its concept and design specifications. The proposed module is developed based on the XG-PON module for ns-3. It can simulate G.989 standard-compliant data packet transmission in the upstream and downstream directions using multiple wavelength channels. It enables us to evaluate the performance issues that arise with the TWDM-PON development, including various dynamic bandwidth allocation and dynamic wavelength allocation algorithms. The proposed module is expected to become a good platform for studying future access networks composed of TWDM-PON and mobile networks by enabling us to simulate dynamic wavelength and bandwidth allocation.

Improving FWM efficiency in bi-directional ultra DWDM-PON networking centered light source by using PMD emulator

The optical networks provides a high performance data networking and secured way to communicate. New generation optical networks demands high input power and low channel spacing in Wavelength-Division Multiplexing (WDM). Using WDM can lead to some nonlinearities in the system such as Four Wave Mixing (FWM). FWM is a phenomena in which two optical pulses are converted into four pluses after traveling in optical fiber. In this paper Polarization Mode Dispersion (PMD) is used by applying PMD emulator at input to suppress FWM. To analyse the effect of PMD a Dense Wavelength-Division Multiplexing-passive optical network (DWDM-PON) is used with centerlized source over the transemission distance longer than 50 km. System’s performance is carried out on the basis of Q factor, optical signal to noise ratio (OSNR), bit error rate (BER), received power and FWM efficiency. Exhaustive sets of simulations are carried out in “Optisystem” on a eight channel system having 25 GHz spacing, operating at 5 Gbps. Results show 7 dB and 5 dB of improved FWM efficiency in downlink and uplink respectively.

LDPC-coded Probabilistic Shaping PAM4 Based on Many-to-One Mapping in WDM-PON

In this article, a 5 × 25-GBaud wavelength division multiplexing passive optical network (WDM-PON) is reported and experimentally demonstrated with each channel carrying a low-density parity check- (LDPC-) coded probabilistic shaping 4-ary pulse amplitude modulated signal (PS-PAM4). In such a splitter-based WDM-PON system, 8-point 3-bits/symbol PAM8 is mapped into 4-point PAM4 by adoption of a many-to-one mapping scheme, which enables improved receiver power sensitivity and increased spectral efficiency, compared with the uniformly-distributed PAM4. Different from the typical constant composition distribution matching method for PS, no shaping codes or PS overheads are needed in our PS-PAM4 signal which is to be encoded and decoded in a LDPC-based bit-interleaved coded modulation iterative decoding (BICM-ID) system for the compatibility with the forward error correction (FEC) applied in most of the optical transponders currently. In the BICM-ID system, the extrinsic messages are delivered circularly between the PS de-mapper and the LDPC decoder to deal with PS many-to-one mapping ambiguity. The experimental results strive to make the WDM-PON system better spectrum efficiency, as well as superior receiver power sensitivity and fiber nonlinear effect tolerance, thus maximizing the input power at the optical line terminal and economic efficiency of the system due to ampler loss budget provided for the legacy optical distribution networks.

Fiber- and FSO-Protected Connections for Long-Reach TWDM Access Architecture With Fault Protection

In this paper, we propose a long-reach star-ring-based timeand wavelength-divisionmultiplexing passive optical network (TWDM-PON) by using fiberand free space optical (FSO)-protected architecture against fiber breakpoint. Here, the new fiber-based and FSO-based optical network unit (ONU) modules are designed in the PON system to achieve the self-protected operation. Thus, the adjacent ONU is linked to produce the fiberor FSO-based reconnections. Thus, 4 × 10 Gbit/s downstream and 10 Gbit/s upstream signals can be reached through 70 km fiber transmission and a length of free space link without signal amplification and dispersion compensation. Moreover, the relationships of splitter ratio and FSO link length in the proposed TWDM access network are also analyzed and discussed.

100 Gb/s (4 × 25 Gb/s) real-time coherent UDWDM-PON with a large power budget

We propose a 100-Gb/s coherent ultra-dense wavelength-division multiplexing passive optical network (UDWDM-PON) structure with a large power budget by placing an erbium-doped fiber amplifier at the optical line terminal side for amplification of optical signals in both the uplink and downlink. Then we experimentally demonstrate a real-time 4 × 25 - G b / s coherent UDWDM-PON at 12.5-GHz spacing over 50-km standard single-mode optical fiber. A high sampling rate analog-to-digital converter is designed for the 25-Gb/s real-time coherent optical module. Experimental results show that 100-Gb/s bidirectional transmission can be realized. The downlink power budget can be more than 44 dB, which can support more than 1000 users based on the proposed structure. The effects of several parameters have also been investigated in the experimental demonstration. The 24-h real-time performance evaluation for bidirectional transmission is conducted to prove the feasibility of real-time field-programmable gate array based transceivers in the proposed UDWDM-PON structure. An off-line experimental demonstration is also conducted to verify the feasibility of burst-mode operation in the uplink.

Improved self-seeding and carrier remodulation performance for WDM-PON by means of double RSOA erasure

In this work, we investigated a novel wavelength division multiplexing passive optical network (WDM-PON) configuration, based on cascaded reflective semiconductor optical amplifiers (RSOA) data erasure for combined self-seeding and wavelength reuse. Improved performance is achieved by enhanced erasure efficiency using a self-seeded double-RSOA cavity at the optical line terminal (OLT) and cascaded RSOAs at the optical network terminal (ONT). To carry out the study, our experimental results for our earlier combined topology layout operating at a symmetric transmission were used to validate the simulation framework for the proposed double-RSOA erasure configuration. Using our original single-cavity self-seeding WDM-PON architecture as a benchmark, downstream extinction ratio (ERD) margins of 6.5 dB and 9.0 dB are obtained, for generating self-seeded downstream signals and upstream remodulation, respectively. Also, bidirectional transmission of 1.25 Gb/s over links reach up to 45 km is achieved by the double-RSOA cavity, surpassing in 25 km our original combined topology. The results indicated that our proposition effectively addresses a fundamental trade-off for WDM-PONs based on the wavelength reuse and/or self-seeding techniques. Specifically, the double erasure procedure allows the use of relatively high levels of ERD, thereby providing improved bit error rate (BER) at the ONT, while assuring high-quality generation of the self-seeding carrier and loopback operation.

DSP-Based Flexible-Waveform and Multi-Application 5G Fiber-Wireless System

This article reports the implementation and experimental performance investigation of a DSP-based flexible-waveform fiber-wireless (FiWi) system for 5G enhanced mobile broadband (eMBB) and new vertical applications. Our radio over fiber-based fronthaul solution uses a wavelength-division-multiplexing passive optical network (WDM-PON) infrastructure, from a commercial Internet service provider, to enable 5G operation over multiple frequency bands, including: a DSP and flexible waveform-based signal at 788 MHz, which can be set as generalized frequency division multiplexing (GFDM) or filtered orthogonal frequency division multiplexing (F-OFDM); 5G new radio (NR) signals at 3.5 or 26 GHz in accordance to 3GPP Release 15; an additional vector 26 GHz signal with bandwidth of up to 800 MHz. The DSP-based functionality provides digital pre-distortion (DPD), besides the real-time waveform generation. Experimental results demonstrate 4.41 Gbit/s total throughput in the air in accordance to the 3GPP requirements, as well as an innovative low-latency M2M application based on PROFINET standard.

Experimental demonstration of wavelength-division-multiplexing passive optical network employing probabilistic shaping 4-level pulse amplitude modulation

A 5 × 25-Gbaud wavelength-division-multiplexing passive optical network (WDM-PON) employing probabilistic shaping 4-level pulse amplitude modulation (PS-PAM4) with direct detection is proposed and experimentally demonstrated. Each optical carrier at the optical line terminal (OLT) carries a 25-Gbaud PS-PAM4 signal based on Maxwell–Boltzmann distribution. By employing PS-PAM4, the receiver power sensitivity (RPS) and fiber nonlinear effect tolerance of the system can be significantly improved and enhanced compared with the unshaped one, which can provide abundant system loss budget for the legacy optical distribution networks. The experimental results show that, compared with the WDM-PON employing uniform PAM4, the superior RPS of 1.44 dB and the fiber nonlinear effect tolerance improvement of 3.07 dB over 20-km standard single-mode fiber transmission are obtained for the proposed system. In addition, the system performance by introducing a blind adaptive pre-equalization based on the joint applications of constant modulus algorithm and decision-directed least-mean-square error algorithm, which can accurately compensate for the signal high-frequency loss caused by the electro-optical components, such as digital-to-analog converter, optical modulators, and electrical drivers at the OLT, is also experimentally investigated.

Joint Allocation of Radio and Fronthaul Resources in Multi-Wavelength-Enabled C-RAN Based on Reinforcement Learning

Cloud radio access network (C-RAN) is a key technology for the new-generation mobile network (5G). Multi-wavelength passive optical networks (PONs) such as wavelength division multiplexing (WDM) and time wavelength division multiplexing (TWDM) PONs are outstanding solutions for providing a sufficient bandwidth to support mobile fronthaul in C-RAN-based 5G architecture. In this paper, a joint allocation framework for multi-wavelength PONs fronthaul uplink resources and C-RAN radio interface uplink resources is presented. From the principle that the uplink resource allocation in mobile networks is an NP-hard optimization problem, this paper proposes a novel uplink scheduling algorithm based on reinforcement learning (RL). The performance of the algorithm is evaluated with numerical simulations and compared with two other algorithms from the literature; namely genetic algorithm (GA) and tabu search (TS) algorithm. The simulation results show that the new algorithm achieves higher system throughput, faster convergence and lower scheduling latency compared to the two other algorithms. Also, show that RL-based adaptive allocation of fronthaul transport block size based on actual radio resource block capacity can significantly reduce the capacity required on fronthaul link and decrease the total end to end uplink scheduling latency compared to the static allocation method.

Comparative Analysis of High Speed 20/20 Gbps OTDM-PON, WDM-PON and TWDM-PON for Long-Reach NG-PON2

Abstract Nowadays, bandwidth demand is enormously increasing, that causes the existing passive optical network (PON) to become the future optical access network. In this paper, next generation passive optical network 2 (NG-PON2) based, optical time division multiplexing passive optical network (OTDM-PON), wavelength division multiplexing passive optical network (WDM-PON) and time & wavelength division multiplexing passive optical network (TWDM-PON) systems with 20 Gbps (8 × 2.5 Gbps) downstream and 20 Gbps (8 × 2.5 Gbps) upstream capacity for eight optical network units has been proposed. The performance has been compared by varying the input power (−6 to 27 dBm) and transmission distance (10–130 km) in terms of Q-factor and optical received power in the presence of fiber noise and non-linearities. It has been observed that TWDM-PON outperforms OTDM-PON and WDM-PON for high input power and data rate (20/20 Gbps). Also, TWDM-PON shows its superiority for long-reach transmission up to 130 km, which is a cost-effective solution for future NG-PON2 applications.