Access Passive Optical Network Research Articles

Orthogonal Frequency Division Multiple Access Passive Optical Network for 5G Deployment

Orthogonal Frequency Division Multiple Access Passive Optical Network for 5G Deployment

Resilient architecture for optical access networks

This work proposes a resilient wheel-based wavelength-division-multiplexed passive optical network optical access network architecture for backhauling network traffic. This proposed resilient architecture can efficiently support not only the fixed users but also the mobile users in the downstream direction under normal and failure operating scenarios, while minimizing the average traffic delivery time and without using extra redundant fibers for protection purposes.

A Green Converged TWDM-PON and 5G HetNet Catering Applications Demanding Low Latency

Abstract Integration of Passive Optical Network (PON) and wireless network technologies can offer a high data rate with ubiquitous Internet access to the end-users. Due to the growing importance of reducing the carbon footprint of telecommunication networks, energy-saving mechanisms are dispensed in the networking equipment. One of the commonly used approaches to reduce energy consumption is the “sleep mode” in which a network equipment periodically turns off some of its components so as to reduce energy consumption. Note that, the current PON and wireless access network technologies have their own power-saving modes. In order to gain power-saving and meet latency of applications in an integrated PON and wireless access network technologies, both optical and wireless access technologies need to have consent on how traffic management (bandwidth allocation, traffic forwarding path), as well as power-saving modes, should be managed in the network. That is, there needs to have synchronization of these two network segments. Otherwise, the end-users would experience longer delay and lower throughput. In this paper, we introduce a Delay-Aware Integrated Sleep Mode (DISM) solution designed considering 5G Heterogeneous Networks (HetNets) architecture which connected with core networks through Time and Wavelength Division Multiplexed Passive Optical Network (TWDM-PON). In particular, we propose a power saving mechanism using sleep mode for TWDM-PON taking into account packet forwarding delay from the optical network termination point to the end-users’ mobile terminal so as to maximize energy-saving in TWDM-PON while meeting latency requirements of applications with stringent latency requirements. Results obtained through simulations impart that our proposed scheme can significantly satisfy the delay requirement of the traffic while it can still reduce energy consumption in TWDM-PON. Furthermore, the results provide insights on how power saving mechanism in PON should be managed for such 5G HetNet and optical integrated networks in order to satisfy the latency requirement of the traffic.

DEC TDMA: A delay controlled and energy efficient clustered TDMA mechanism for FiWi access network

Integration of passive optical network and wireless access network is referred as FiWi access network. It provides larger bandwidth and flexibility for end users to improve last mile performance. With rapid growth in internet traffic and expansion in ICT, reduction in delay and efficient energy utilization have become major concerns in FiWi network. There has been lot of work done on delay and energy efficiency separately for optical back end and wireless front end to provide desired QoS. But this paper presents a cooperative mechanism namely DEC TDMA which is based on the concept of clustered TDMA. In DEC TDMA cooperation between front end and back end is achieved by providing synchronization using time stamping. Analytical expressions are also derived for energy efficiency, cycle time and delay for proposed and existing methods. Results found that proposed mechanism reduces delay very significantly specially at heavy load. It also provides better energy efficiency for large number of ONUs. Moreover DEC TDMA exhibits better delay performance due to implementation of dynamic bandwidth allocation while providing data slots in TDMA. Therefore proposed mechanism offers delay and energy efficient solution for large sized FiWi access network demanding high bandwidth applications in heavy load conditions.

BER performance of OCDMA system based on optimised 2D PhC passive encoder

This study introduces an accurate design and optimisation of a passive optical code division multiple access (OCDMA) network encoder using the coupled cavity waveguide (CCW) as an optical delay line. Such CCW has the capability of providing more time delay with minimum encoder size. The proposed design and analysis are based on the two-dimensional (2D) photonic crystal (PhC) structure. Additionally, two different 2D-PhC structures are studied, in which a silicon material with an effective refractive index of 3.487 is used. The first structure is a silicon bar in air background, whereas the second one is air holes in a silicon substrate. Furthermore, the behaviour of the proposed 2D-PhC structures is studied over the wavelength, ranging from 1300 to 1600 nm. Since the structure geometry is simple with a clear operating principle, it is sufficient to use in the photonic integrated circuits. Moreover, the performance analysis of such design is investigated in terms of the bit error rate (BER) calculations. Finally, the results showed that a 21% BER performance enhancement was achieved using the optimised silicon bars in air background encoder model and this model can be utilised for the multimedia applications in the OCDMA networks.

Transmission Performance and Cost Analysis of Multi-Carrier-based Wavelength Division Multiplexed Passive Optical Access Network

AbstractMulti-tone-based wavelength division multiplexed passive optical networks are considered to provide cost-effective access network solution. We analysed and revealed the transmission performance, power budget concern and the cost investigation of the multi-tone-based WDM PON. A differential phase shift keying and re-modulated return to zero on/off keying signals for downlink and uplink, respectively, are transmitted via a single-mode fibre. The transmission performance of the proposed architecture is analysed using key parameters of bit error rate and optical signal to noise ratio using different data rates and channel spacing. The simulation results are in agreement with the theoretical analysis. The power budget is calculated for both upstream and downstream data signals showing excellent system margins for any unseen losses. The proposed setup is also analysed in terms of cost to prove it the cost-effective solution for the next-generation optical access networks.

Optimization of an EYDWA Amplifier Parameters for a Gigabit Passive Optical Network (GPON)

Abstract The purpose of this study is to evaluate the impact of the location of the Er3+/Yb3+optical amplifier (EYDWA) in passive optical access network downstream (as a post-amplifier or booster, in the middle) and upstream transmission . This can give us an extended connection and a huge distribution ratio for a beneficial implementation of the optical fiber. The transmission quality was compared on the location of the amplifier as well as the length of the link. According to the results obtained by system simulation one noted that there is a clear improvement of the system performance by the effect of the amplifier (EYDWA). One could obtain a distance of more than 200 km for GPON. Moreover by varying the opto-geometric parameters such as concentration of Ytterbium ions and the length of the guide allowed us to improve the quality factor and binary error rate.

An Energy-Efficient Distributed Dynamic Bandwidth Allocation Algorithm for Passive Optical Access Networks

The rapid deployment of passive optical access networks (PONs) increases the global energy consumption of networking infrastructure. This paper focuses on the minimization of energy consumption in Ethernet PONs (EPONs). We present an energy-efficient, distributed dynamic bandwidth allocation (DBA) algorithm able to power off the transmitter and receiver of an optical network unit (ONU) when there is no upstream or downstream traffic. Our main contribution is combining the advantages of a distributed DBA (namely, a smaller packet delay compared to centralized DBAs, due to less time being needed to allocate the transmission slot) with energy saving features (that come at a price of longer delays due to the longer queue waiting times when transmitters are switched off). The proposed algorithm analyzes the queue size of the ONUs in order to switch them to doze/sleep mode when there is no upstream/downstream traffic in the network, respectively. Our results show that we minimized the ONU energy consumption across a wide range of network loads while keeping delay bounded.

Software-Defined Time-Shifted IPTV architecture for locality-awareness TWDM-PON

IPTV brought great potential to give network providers the capacity to expand their market value and revenue generated by increasing the number of users. Time-shifted IPTV (TS-IPTV) is one way of accomplishment through IP multicasting. Amongst the access network solutions, Ethernet passive optical network (EPON) is regarded as one of the best solutions due to its high bandwidth provision, low operation and maintenance cost. Software-Defined Networking (SDN) separates the network control plane from the data-forwarding plane with the promise to dramatically improve the network resource utilization. Time and wavelength division multiplexed access passive optical network (TWDM-PON) is the ultimate solution for the next generation PON (NG-PON2), in which each wavelength is shared between multiple optical network units (ONUs) by employing the time division and multiplexing access mechanism. Local-awareness based TWDM-PON allows for the higher bandwidth and optimal flexibility, fiber management, service convergence and resources sharing. In this paper, the SDN is integrated into the TWDM-PON architecture to facilitate an orchestrated multicasting time shifted IPTV through the SDN controller to control and manage the traffic. The simulation results show that the proposed architecture and mechanism improves the quality of service (QoS) requirements in terms of the mean packet delay, jitter, throughput and packet loss.

Investigation of a Flexible Downstream Scheme for Sampling Rate and Bandwidth Reduction in Short Reach Communication Systems

We demonstrate a cost- and spectrum-effective orthogonal frequency-division multiple access passive optical network downstream scheme based on multi-band and modified sub-Nyquist sampling over transmission reach of 20km. The sampling rate and bandwidth of ADC are reduced effectively, and double spectrum efficiency is obtained. The aggregate bit rate achieves 50.4 Gb/s. The influence of bit resolution of ADC/DAC is investigated and 8-bit resolution is regarded as a reasonable choice. The performance of receiver sensitivity and nonlinearity tolerance is studied. A 20km PON downstream transmission with splitter ratio of 1:64 is considered and the FEC limit of $3.8\times 10 ^{-3}$ is met. The research results show that the proposed scheme is suitable for the short reach communication systems and could be regarded as a promising candidate for the system beyond NG-PON2.

An optimized architecture to reduce the impact of fiber strands in spectral/spatial optical code division multiple access passive optical networks (OCDMA-PON)

Abstract Exploitation of the spectral/spatial two dimensional optical code division multiple access (2D-OCDMA) systems in passive optical networks (PONs) is not explored extensively due to the fact spatial encoding requires deployment of multiple star couplers in the topology where each coupler is connected to different ends of either transmitter or receiver nodes. As a result, this scheme is not suitable for PON applications because it requires a significant increase in the amount of fiber deployment within the network along with the complexity of implementation to deploy the required star couplers. To deploy spectral/spatial OCDMA systems at PON and reduce the impact of fiber strands, this work proposes and investigates an optimized architecture of 2D-OCDMA for PONs based on enhanced multi-diagonal (EMD) code. Spectral/spatial encoding technique is used to develop 2D-EMD coding algorithm from the existing 1D-EMD scheme. This operation elevates orthogonality between the adjacent codes and supports high capacity through superior noise mitigation at the receiving end. A complete system architecture is developed and implemented in an excessively used software for optical networks implementation and analysis called Optisystem, for analysis under different performance parameters of PON. It is observed that the proposed system provides better performance in terms of transmission capacity, and cardinality, in comparison with existing 1D-EMD code and other 2D-OCDMA counterparts. Analysis shows that for an agreeable BER of 10 - 9 the proposed system can support 192 subscribers each communicating at 2 Gbps of data over 25 km single mode fiber. In terms of capital expenditure (CAPEX), four times cost saving per user is achieved for proposed architecture (PA) over conventional architecture (CA) for nearly similar performance.

Study of burst-mode adaptive equalization for >25G PON applications [Invited

In anticipation of emerging applications such as business services, 5G, and the Internet of Things, research and standardization are working together towards next-generation 25/50 Gbit/s passive optical network access networks. However, the increase in single-channel line rate is limited by the distortion introduced by the low-cost device’s bandwidth limit or the chromatic dispersion in the fiber. Burst-mode electronic distortion/dispersion compensation can be used to mitigate these effects, but requires a burst-mode equalizer (BMEQ) for upstream traffic and introduces many challenges. In this invited paper, the feasibility of single-channel, directly modulated upstream 25 Gbit/s non-return-to-zero transmission is investigated in more detail. By using a linear burst-mode transimpedance amplifier together with an offline BMEQ, specific BMEQ penalties and trade-offs such as limited training time and burst-to-burst phase variation are considered.

DAPSK-OFDM-based coherent PON and IFoF heterogeneous access network with PDM

Heterogeneous access networks with wired/wireless convergence comprise an important trend in the development of access networks because they reduce network investment and operating costs. In this paper, we propose a heterogeneous access network with a coherent passive optical network (PON) and intermediate frequency over fiber (IFoF) within a single wavelength. The coherent PON and IFoF are both DAPSK-OFDM-based and do not involve noise-compensation digital signal processing (DSP), which lowers bandwidth efficiency. DAPSK-OFDM is a differential modulation scheme that eliminates channel and phase noise during the demodulation process. The coherent PON and IFoF with different transmission schemes are combined using polarization division multiplexing (PDM) and a complete heterogeneous network without crosstalk through polarization optimization and maintenance at a transmission distance less than 20 km. The proposed heterogeneous network is experimentally tested, which shows that its performance is similar to that yielded when operating each system independently.

Characteristic evaluation of 20-Bit consecutive codes in high performance optical burst mode receiver configuration

Optical burst mode receivers are indispensable components for Passive Optical Network (PON) and Ethernet Optical Access Network (E-OSAN). An optical burst mode receiver with transfer function <em>G<sub>n</sub></em>(<em>jω</em>/<em>ω</em><sub>0</sub>) = 1 - <em>H<sub>n</sub></em>(<em>jω</em>/<em>ω</em><sub>0</sub>) is proposed, of which better performance is anticipated than that of conventional AC-coupling. Next, an optical burst mode receiver with fast response <em>G<sub>n</sub></em>(<em>jω</em>/<em>ω<sub>F</sub></em>) and slow response <em>G<sub>n</sub></em>(<em>jω</em>/<em>ω<sub>S</sub></em>), whereby <em>G<sub>n</sub></em>(<em>jω</em>/<em>ω<sub>F</sub></em>) switches to <em>G<sub>n</sub></em>(<em>jω</em>/<em>ω<sub>S</sub></em>) right after the DC component of the input burst signal converges to 0 is proposed. Then, an automatically switching circuit that switches fast response <em>G<sub>n</sub></em>(<em>jω</em>/<em>ω<sub>F</sub></em>) to slow response <em>G<sub>n</sub></em>(<em>jω</em>/<em>ω<sub>S</sub></em>) circuits right after the maximum peak value of the output burst <em>G<sub>n</sub></em>(<em>jω</em>/<em>ω<sub>F</sub></em>) is 1/2 and the DC components of the input burst converges to 0 is also proposed. This paper presents the experiments on same consecutive codes in burst mode receivers using the proposed automatically switching circuit, with evaluation on its characteristics made through simulation.

Deep Neural Network Supervised Bandwidth Allocation Decisions for Low-Latency Heterogeneous E-Health Networks

This paper proposes the first use of a deep neural network (DNN) to characterize the dependence of end-to-end latency on key bandwidth allocation decision parameters and diverse network features over heterogeneous body area network (BAN), wireless local area network (WLAN), and passive optical access network (PON) toward ubiquitous e-health. Using the association between latency and bandwidth allocation decisions, the DNN supervises bandwidth values that significantly reduce end-to-end latency. In this paper, we present the proposed DNN architecture and the selection of input features and output targets based on latency tradeoff analysis. We show that with supervised training, the DNN can accurately predict end-to-end latency corresponding to varying bandwidth allocation decisions, thereby critically analyzing the impact that multiple bandwidth decision parameters and network features have on latency. Using the trained DNN, bandwidth allocation decisions, i.e., bandwidth values that reduce the latency in WLAN and PON can be obtained. Our simulation results show that by using such bandwidth values supervised by the DNN in allocating bandwidth in WLAN and PON, the latency in each network segment over a heterogeneous BAN + WLAN + PON can be effectively reduced, regardless of variations in network features during network operation. Overall, an end-to-end latency μ s with a significant 40%–70% improvement is achieved as compared to conventional bandwidth allocation algorithms.

Experimental Demonstration of a Real-Time Digital Filter Multiple Access PON With Low Complexity DSP-Based Interference Cancellation

A four-channel, upstream, digital filter multiple access (DFMA) passive optical network (PON) is experimentally demonstrated for the first time in a 26 km single mode fiber (SMF) intensity modulation and direct detection system employing real-time optical network units (ONUs) and optical line terminal (OLT), which are dynamically reconfigurable in terms of channel spectral allocation and signal modulation parameters. To combat physical channel frequency response-induced cross channel interference (CCI) between spectrally overlaid orthogonal channels, a real-time, reconfigurable CCI cancellation (CCIC) function implemented in the OLT receiver digital signal processing (DSP), is demonstrated to significantly improve the DFMA PON performance and robustness in terms of significant reductions in total channel bit error rates (BERs) and individual subcarrier BERs, substantial increases in channel capacities, considerably reduced sensitivity to ONU synchronization, and excellent transparency to the interfering channel's signal modulation format. The tradeoff between the complexity of the CCIC function's filter, in terms of tap count (multiplier elements) and the DFMA PONs performance is optimized to determine the optimum tradeoff. It is shown that the CCIC filter only requires as few as 42 taps to achieve excellent CCIC performance. We also fully analyze the DSP complexity of the transmit and receive DFMA filters and the CCIC filters for varying DFMA channel counts and varying ratios of AD/DA converter sample rate to digital logic clock rate (parallelization factor). It is shown that DFMA filter complexity is independent of channel count and furthermore that for channel counts ≥ 4 the CCIC filter only needs to process ~10 interference-inducing samples per wanted signal sample, resulting in only ~10 multipliers per parallel filter in the CCIC filter. We have therefore successfully demonstrated an ultra-low complexity, real-time CCIC function, which considerably enhances the performance and robustness of DFMA PONs.

Hybrid DFT-Spread OFDM-Digital Filter Multiple Access PONs for Converged 5G Networks

In this paper, we propose hybrid discrete Fourier transform (DFT)-spread orthogonal frequency division multiplexing (OFDM)-digital filter multiple access (DFMA) passive optical networks (PONs) for the first time to the best of our knowledge. In this case, digital filtering based on digital signal processing is applied to individual DFT-spread OFDM signals from various optical network units, and a single fast Fourier transform operation and its following data recovery processes are implemented in a pipelined approach in the optical line terminal. The proposed networks maintain all salient features associated with previously reported hybrid OFDM–DFMA PONs. More importantly, they additionally reduce the upstream signal peak-to-average power ratios by less than 2 dB. As a direct result, in comparison with the hybrid OFDM–DFMA PONs, the proposed PONs increase the upstream system power budget by more than 3 dB and reduce the minimum required digital-to-analog converter/analog-to-digital converter quantization bits by at least 1 bit.

Cost-optimal cloudlet placement frameworks over fiber-wireless access networks for low-latency applications

In the recent past, we have observed a trend that edge devices are increasingly accessing computational resources through the Internet, preferably via cloud computing technologies. However, cloud servers fail to meet the desired latency requirements of low-latency applications like augmented reality, cognitive assistance, and Tactile Internet applications, primarily due to the high-transmission latency from edge devices. This issue is resolved by augmenting cloud networks with a cloudlet enabled edge computing solution that creates a three-tier network topology. In this paper, we primarily focus on static cloudlet network planning problem and propose a hybrid cost-optimization framework for optimal cloudlet placement over existing passive optical access networks, subject to capacity and latency constraints. We formulate a mixed integer non-linear program to identify ideal cloudlet placement locations over urban, suburban and rural deployment scenarios. We show that the target latency requirement and the type of deployment scenario plays a major role in determining the amount of computational resources to be installed in the cloudlets. We also show that the percentage of the incremental energy budget of the access networks due to active cloudlet installation is under 18%. Overall, we show that the newly proposed hybrid cloudlet placement framework achieves the most cost optimal solution as compared to the field cloudlet placement framework.

Design and Implementation of Two-Dimensional Enhanced Multi-diagonal Code for High Cardinality OCDMA-PON

This paper proposes the design of a novel two-dimensional enhanced multi-diagonal (2D-EMD) code along with the implementation of corresponding architecture for incoherent optical code division multiple access passive optical network (OCDMA-PON). The proposed algorithm is derived by using spatial coding as second dimension in the existing 1D-EMD code to elevate orthogonality within adjacent codes and minimize the interference of subscribers simultaneously accessing the medium. Performance of the proposed 2D-EMD OCDMA system is analyzed through Gaussian approximation and simulation analysis for an agreeable bit error rate (BER) of $$10^{-9}$$ . Analytic analysis shows that the proposed 2D-EMD OCDMA system support more subscribers in comparison with existing systems based on 2D diluted-perfect difference (2D-DPD) and diagonal eigenvalue unity (DEU) codes. Cardinality of the proposed setup surpasses 2D-DPD and 2D-DEU by 5 and 1.8 times for an acceptable BER of $$10^{-9}$$ . Moreover, the optimal communication requirement is satisfied by 2D-EMD system with lowest effective source power of $$-27$$ dBm at 622 Mbps of data. Simulation analysis through a highly recognized software called Optisystem also validates the mathematical analysis and shows that the proposed system can accommodate large number of subscribers at high data rates. Both analytical and simulation analysis proves that the proposed system is able to support next generation PONs.

Performance Investigation of a Cost- and Power-Effective High Nonlinearity Tolerance OFDMA-PON Scheme Based on Sub-Nyquist Sampling Rate and DFT-Spread

We investigate the performance of a cost- and power-effective high nonlinearity tolerance orthogonal frequency-division multiple access passive optical network scheme based on sub-Nyquist sampling and discrete Fourier transform spread. The analog-to-digital converter with a sampling rate below the Nyquist sampling rate is used for signal detection for each optical network unit. The complicated pre-process procedure is located in the optical line terminal. Only Low-point FFT and IDFT procedures are required in the ONU, reducing the computational complexity and power consumption in the ONU, and the sampling rate of ADC, and improve the cost- and power-efficiency effectively. Moreover, the peak-to-average power ratio is reduced effectively with the scheme. The simulation results show that the measured bit error ratio of each ONU signal well less than the forward-error correction limit of 3.8 × 10 -3 is obtained after 40-km standard single mode fiber transmission.