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The high capacity of future 5G wireless networks must be supported by equivalent high-capacity fixed networks for backhaul and fronthaul (x-haul) transport. Especially the trend toward densification of radio networks, in which many small cells are located next to macrocells, will call for cost-efficient x-haul solutions to meet the overall business case targets. Optical access technologies bear great potential to offer low-cost solutions for these x-haul transport links. Starting from requirements on bandwidth, latency, and other critical parameters of 5G x-haul transport networks, ITU-T Q2/SG15 has elaborated a generic approach on how to employ PON technologies in various functional split architectures of wireless networks. The proposed PON architectures are presented and discussed in the recently released supplementary document G.Sup66, "5G Wireless Fronthaul Requirements in a PON Context," in October 2018. This article provides a high-level summary of the findings in Supplement G.Sup66.

Now that fiber to the home (FTTH) is commonplace, the industry looks to extend its reach into the home, and fiber to the room (FTTR) has come into focus. This paper outlines such systems, and a method to leverage the PON control plane is highlighted.

We experimentally quantify the performance improvements in bandwidth-limited 50G-PON downstream transmission with receiver-side equalization based on FFE, DFE and MLSE, by bit-interleaving of every four adjacent LDPC codewords, achieving 32-dB power budget with additional margins.

We experimentally demonstrate multi-rate burst-mode transmission at 25, 12.5 and 10Gb/s using a 10GHz-class burst-mode receiver optical sub-assembly (ROSA), respectively achieving receiver sensitivities of −27.7, −31, and −32.1dBm after 20-km SSMF transmission at 1E-2 BER, all with 20-dB dynamic range and 92-ns burst recovery time.

We experimentally show that the dispersion penalty of a 50-Gb/s NRZ signal under 85-ps/nm dispersion can be reduced to below 1 dB via receiver-side equalization, showing the promise of supporting 50G-PON downstream transmission over 20-km SSMF at the 1342-nm wavelength.

Next Generation Passive Optical Network Stage 2 (NG-PON2) features multiple wavelength channels. Channel bonding combines multiple NG-PON2 wavelength connections in parallel to increase the access network throughput beyond the capacity of a single connection. It enhances the access network peak rate provisioning. Channel bonding is actively studied in the ITU Telecommunication Standardization Sector (ITU-T) as a key enhancement to NG-PON2 recommendations. In this paper, we propose a channel bonding scheme by reusing the ITU-T PON data units of XG-PON encapsulation method (XGEM). The bonding system structure is investigated, and the bonding problem is formulated by using integer linear programming (ILP) formulation. A heuristic algorithm is proposed to control data transmission in the bonded channels. Performance is evaluated via network simulations. Simulation results are further analyzed to provide guidance on packet delay control and algorithm key parameter configuration.

Channel bonding is a key endeavor in the ITU Telecommunication Standardization Sector (ITU-T) to increase the peak rate of the Next Generation Passive Optical Network Stage 2 (NG-PON2) system. It manages several parallel wavelength channels in NG-PON2 as a single link. In this paper, we investigate the NG-PON2 layering structure and propose the sublayer changes to support channel bonding. The problem is formulated as an integer non-linear programming (INLP) problem, and is analyzed by using the water filling scheme. Two interleaving heuristic algorithms are proposed to solve this problem. Evaluation results show that full wavelength channel delivery algorithm provides the lowest jitter, and restricted wavelength channel delivery algorithm with a threshold 3 provides the lowest end-to-end delay by reducing envelope headers.

Wavelength channel bonding coordinates multiple physical interfaces for data transmission between the Passive Optical Network (PON) central office and user side equipments. It provides a high speed logical channel to the user services, and the logical channel capacity is the sum of the rates of the bonded wavelength channels. Wavelength channel bonding gains strong support from operators in designing the next generation PONs. In this paper, we propose a channel bonding system structure for 100 Gb/s PON and depict the problem by using integer linear programming (ILP) formulation. Two heuristic algorithms are further proposed to control the bonded traffic transmission in the case of light and heavy traffic load. The algorithms schedule forward error correction (FEC) codeword (CW) transmission among four 25 Gb/s wavelength channels. Simulations have validated the performance of these algorithms, demonstrating that one algorithm provides salient control on delay, and the other increases bandwidth efficiency via threshold management.

We propose a channel bonding system structure and algorithms for 100 Gb/s PON. The algorithms schedule FEC codeword transmission among four 25 Gb/s wavelength channels, and they are demonstrated with high efficiency and low latency.

We discuss hybrid fiber/copper access networks with a focus on XG-PON/VDSL2 hybrid access networks. We present tutorial material on the XG-PON and VDSL2 protocols as standardized by the ITU. We investigate mechanisms to reduce the functional logic at the device that bridges the fiber and copper segments of the hybrid fiber/copper access network. This device is called a drop-point device. Reduced functional logic translates into lower energy consumption and cost for the drop-point device. We define and analyze the performance of several mechanisms to move some of the VDSL2 functional logic blocks from the drop-point device into the XG-PON Optical Line Terminal. Our analysis uncovers that silence suppression mechanisms are necessary to achieve statistical multiplexing gain when carrying synchronous intermediate VDSL2 data formats across the XG-PON.

The next-generation passive optical network stage 2 (NG-PON2) effort was initiated by the full service access network (FSAN) in 2011 to investigate on upcoming technologies enabling a bandwidth increase beyond 10 Gb/s in the optical access network. The FSAN meeting in April 2012 selected the time- and wavelength-division multiplexed passive optical network (TWDM-PON) as a primary solution to NG-PON2. In this paper, we summarize the TWDM-PON research in FSAN by reviewing the basics of TWDM-PON and presenting the world's first full-system 40 Gb/s TWDM-PON prototype. After introducing the TWDM-PON architecture, we explore TWDM-PON wavelength plan options to meet the NG-PON2 requirements. TWDM-PON key technologies and their respective level of development are further discussed to investigate its feasibility and availability. The first full-system 40 Gb/s TWDM-PON prototype is demonstrated to provide 40 Gb/s downstream and 10 Gb/s upstream bandwidth. This full prototype system offers 38 dB power budget and supports 20 km distance with a 1:512 split ratio. It coexists with commercially deployed Gigabit PON (G-PON) and 10 Gigabit PON (XG-PON) systems. The operator-vendor joint test results testify that TWDM-PON is achievable by the reuse and integration of commercial devices and components.

Time synchronization is critical when using Ethernet passive optical networks as a mobile backhaul to support time-sensitive services. This article presents an overview of time synchronization methods over EPON. It outlines the requirements and challenges particular to the EPON link delay asymmetry, and presents the technical solution recently approved by IEEE. Performance analysis and prototype results demonstrate that this technical solution meets various time synchronization requirements. The article then reviews the major standard efforts on EPON time synchronization that employ this solution, IEEE Std 802.1ASTM-2011 Clause 13. With this standard in place, EPON can play its part in time distribution networks.

This paper describes the world's first field trial of XG-PON, which can deliver 10 Gbps downstream and 2.5 Gbps upstream to residential or business customers, and confirmed XG-PON's co-existence with a commercially deployed GPON system.

This paper presents recent research into P2P distribution of video that can be highly localized, preferably sharing content among users on the same access network and Central Office (CO). Models of video demand and localized P2P serving areas are presented. Detailed simulations of passive optical networks (PON) are run, and these generate statistics of P2P video localization. Next-Generation PON (NG-PON) is shown to fully enable P2P video localization, but the lower rates of Gigabit-PON (GPON) restrict performance. Results here show that nearlyallof the traffic volume of unicast video could be delivered via localized P2P. Strong growth in video delivery via localized P2P could lower overall future aggregation and core network bandwidth of IP video traffic by 58.2%, and total consumer Internet traffic by 43.5%. This assumes aggressive adoption of technologies and business practices that enable highly localized P2P video.

Driven by bandwidth-demanding video applications, next-generation access stage 1, proposed by FSAN as the first stage of next-generation passive optical networks, increases the subscriber bandwidth by upgrading the current GPON network. To reduce the upgrading cost, NGA1 conforms to the standardized GPON and the deployed optical distribution network. This article presents the investigation of five candidate NGA1 architectures from the perspective of the MAC-layer bandwidth allocation including the analysis of the traffic characteristics of the subscribers' applications and the criteria in mapping them into proper transmission containers. Extensive simulations were conducted to investigate and compare the performances of the five candidate NGA1 architectures.