Quasi-passive optical infrastructure for future 5G wireless networks: pros and cons

In this paper, we study the applicability of the quasi-passive reconfigurable (QPAR) device, a special type of quasi-passive wavelength-selective switch with flexible power allocation properties and no power consumption in the steady state, to implement the concept of reconfigurable backhaul for 5G wireless networks. We first discuss the functionality of the QPAR node and its discrete component implementation, scalability, and performance. We present a novel multi-input QPAR structure and the pseudo-passive reconfigurable (PPAR) node, a device with the functionality of QPAR but that is pseudo-passive during steady-state operations. We then propose mesh and hierarchical back-haul network architectures for 5G based on the QPAR and PPAR nodes and discuss potential use cases. We compare the performance of a QPAR-based single-node architecture with state-of-the-art devices. We find that a QPAR node in a hierarchical network can reduce the average latency while extending the reach and quality of service of the network. However, due to the high insertion losses of the current QPAR design, some of these benefits are lost in practice. On the other hand, the PPAR node can realize the benefits practically and is the more energy-efficient solution for high reconfiguration frequencies, but the remote optical node will no longer be passive. In this paper, we discuss the potential benefits and issues with utilizing a QPAR in the optical infrastructure for 5G networks.This work has been funded by the Spanish project TIGRE5 CM (grant number S2013/ICE 2919), the EU H2020 5G Crosshaul project (grant number 671598), and the Australian Research Council’s Discovery Early Career Researcher Award (DECRA) funding scheme (project number DE150100924). The authors would also like to acknowledge the support of the Center for Integrated Systems, Stanford University, and Corning Incorporated. for the development of this work

Software Defined Applications in Cellular and Optical Networks

abstract: Small wireless cells have the potential to overcome bottlenecks in wireless access through the sharing of spectrum resources. A novel access backhaul network architecture based on a Smart Gateway (Sm-GW) between the small cell base stations, e.g., LTE eNBs, and the conventional backhaul gateways, e.g., LTE Servicing/Packet Gateways (S/P-GWs) has been introduced to address the bottleneck. The Sm-GW flexibly schedules uplink transmissions for the eNBs. Based on software defined networking (SDN) a management mechanism that allows multiple operator to flexibly inter-operate via multiple Sm-GWs with a multitude of small cells has been proposed. This dissertation also comprehensively survey the studies that examine the SDN paradigm in optical networks. Along with the PHY functional split improvements, the performance of Distributed Converged Cable Access Platform (DCCAP) in the cable architectures especially for the Remote-PHY and Remote-MACPHY nodes has been evaluated. In the PHY functional split, in addition to the re-use of infrastructure with a common FFT module for multiple technologies, a novel cross functional split interaction to cache the repetitive QAM symbols across time at the remote node to reduce the transmission rate requirement of the fronthaul link has been proposed.Dissertation/ThesisDoctoral Dissertation Electrical Engineering 201

Otimização do fronthaul ótico para redes de acesso de rádio (baseadas) em computação em nuvem (CC-RANs)

Doutoramento conjunto (MAP-Tele) em Engenharia Eletrotécnica/TelecomunicaçõesA proliferação de diversos tipos de dispositivos moveis, aplicações e serviços com grande necessidade de largura de banda têm contribuído para o aumento de ligações de banda larga e ao aumento do volume de trafego das redes de telecomunicações moveis. Este aumento exponencial tem posto uma enorme pressão nos mobile operadores de redes móveis (MNOs). Um dos aspetos principais deste recente desenvolvimento, é a necessidade que as redes têm de oferecer baixa complexidade nas ligações, como também baixo consumo energético, muito baixa latência e ao mesmo tempo uma grande capacidade por baixo usto. De maneira a resolver estas questões, os MNOs têm focado a sua atenção na redes de acesso por rádio em nuvem (C-RAN) principalmente devido aos seus benefícios em termos de otimização de performance e relação qualidade preço. O standard para a distribuição de sinais sem fios por um fronthaul C-RAN é o common public radio interface (CPRI). No entanto, ligações óticas baseadas em interfaces CPRI necessitam de uma grande largura de banda. Estes requerimentos podem também ser atingidos com uma implementação em ligação free space optical (FSO) que é um sistema ótico que usa comunicação sem fios. O FSO tem sido uma alternativa muito apelativa aos sistemas de comunicação rádio (RF) pois combinam a flexibilidade e mobilidade das redes RF ao mesmo tempo que permitem a elevada largura de banda permitida pelo sistema ótico. No entanto, as ligações FSO são suscetíveis a alterações atmosféricas que podem prejudicar o desempenho do sistema de comunicação. Estas limitações têm evitado o FSO de ser tornar uma excelente solução para o fronthaul. Uma caracterização precisa do canal e tecnologias mais avançadas são então necessárias para uma implementação pratica de ligações FSO. Nesta tese, vamos estudar uma implementação eficiente para fronthaul baseada em tecnologia á rádio-sobre-FSO (RoFSO). Propomos expressões em forma fechada para mitigação das perdas de propagação e para a estimação da capacidade do canal de maneira a aliviar a complexidade do sistema de comunicação. Simulações numéricas são também apresentadas para formatos de modulação adaptativas. São também considerados esquemas como um sistema hibrido RF/FSO e tecnologias de transmissão apoiadas por retransmissores que ajudam a alivar os requerimentos impostos por um backhaul/fronthaul de C-RAN. Os modelos propostos não só reduzem o esforço computacional, como também têm outros méritos, tais como, uma elevada precisão na estimação do canal e desempenho, baixo requisitos na capacidade de memória e uma rápida e estável operação comparativamente com o estado da arte em sistemas analíticos (PON)-FSO. Este sistema é implementado num recetor em tempo real que é emulado através de uma field-programmable gate array (FPGA) comercial. Permitindo assim um sistema aberto, interoperabilidade, portabilidade e também obedecer a standards de software aberto. Os esquemas híbridos têm a habilidade de suportar diferentes aplicações, serviços e múltiplos operadores a partilharem a mesma infraestrutura de fibra ótica.The proliferation of different mobile devices, bandwidth-intensive applications and services contribute to the increase in the broadband connections and the volume of traffic on the mobile networks. This exponential growth has put considerable pressure on the mobile network operators (MNOs). In principal, there is a need for networks that not only offer low-complexity, low-energy consumption, and extremely low-latency but also high-capacity at relatively low cost. In order to address the demand, MNOs have given significant attention to the cloud radio access network (C-RAN) due to its beneficial features in terms of performance optimization and cost-effectiveness. The de facto standard for distributing wireless signal over the C-RAN fronthaul is the common public radio interface (CPRI). However, optical links based on CPRI interfaces requires large bandwidth. Also, the aforementioned requirements can be realized with the implementation of free space optical (FSO) link, which is an optical wireless system. The FSO is an appealing alternative to the radio frequency (RF) communication system that combines the flexibility and mobility offered by the RF networks with the high-data rates provided by the optical systems. However, the FSO links are susceptible to atmospheric impairments which eventually hinder the system performance. Consequently, these limitations prevent FSO from being an efficient standalone fronthaul solution. So, precise channel characterizations and advanced technologies are required for practical FSO link deployment and operation. In this thesis, we study an efficient fronthaul implementation that is based on radio-on-FSO (RoFSO) technologies. We propose closedform expressions for fading-mitigation and for the estimation of channel capacity so as to alleviate the system complexity. Numerical simulations are presented for adaptive modulation scheme using advanced modulation formats. We also consider schemes like hybrid RF/FSO and relay-assisted transmission technologies that can help in alleviating the stringent requirements by the C-RAN backhaul/fronthaul. The propose models not only reduce the computational requirements/efforts, but also have a number of diverse merits such as high-accuracy, low-memory requirements, fast and stable operation compared to the current state-of-the-art analytical based approaches. In addition to the FSO channel characterization, we present a proof-of-concept experiment in which we study the transmission capabilities of a hybrid passive optical network (PON)-FSO system. This is implemented with the real-time receiver that is emulated by a commercial field-programmable gate array (FPGA). This helps in facilitating an open system and hence enables interoperability, portability, and open software standards. The hybrid schemes have the ability to support different applications, services, and multiple operators over a shared optical fiber infrastructure

Telecommunication Systems

This book is based on both industrial and academic research efforts in which a number of recent advancements and rare insights into telecommunication systems are well presented. The volume is organized into four parts: "Telecommunication Protocol, Optimization, and Security Frameworks", "Next-Generation Optical Access Technologies", "Convergence of Wireless-Optical Networks" and "Advanced Relay and Antenna Systems for Smart Networks." Chapters within these parts are self-contained and cross-referenced to facilitate further study

Advanced Technique and Future Perspective for Next Generation Optical Fiber Communications

Optical fiber communication industry has gained unprecedented opportunities and achieved rapid progress in recent years. However, with the increase of data transmission volume and the enhancement of transmission demand, the optical communication field still needs to be upgraded to better meet the challenges in the future development. Artificial intelligence technology in optical communication and optical network is still in its infancy, but the existing achievements show great application potential. In the future, with the further development of artificial intelligence technology, AI algorithms combining channel characteristics and physical properties will shine in optical communication. This reprint introduces some recent advances in optical fiber communication and optical network, and provides alternative directions for the development of the next generation optical fiber communication technology

Dynamically reconfigurable long-reach PONs for high capacity access

Fibre-to-the-Premises (FTTP) is currently seen as the ultimate in high-speed transmission technologies for delivering ubiquitous bandwidth to customers. However, as the deployment of network infrastructure requires a substantial investment, the main obstacle to fibre deployment is that of financial viability. With this in mind, a logical strategy to offset network costs is to optimise the infrastructure in order to capture a greater amount of customers over larger areas with increased sharing of network resources. This approach prompted the design of a long-reach passive optical network (LR-PON) in which the physical reach and split of a conventional PON is significantly increased through the use of intermediate optical amplification. In particular, the LR-PON architecture effectively integrates the metro and access networks enabling the majority of local exchange sites to be bypassed resulting in a substantial reduction in field equipment requirements and power consumption. Furthermore, the extension in physical reach and split can be coupled with an increased information capacity through the use of time- and wavelength division multiplexing (TWDM) which serve to exploit the large bandwidth capabilities offered by single-mode fibre. In this project, reconfigurable TWDM LR-PON architectures which dynamically exploit the wavelength domain are proposed, assembled and characterised in order to establish an economically viable ‘open access’ environment that is capable of concurrently supporting multiple operators offering converged services (residential, business and mobile) to support diverse customer requirements and locations. The main investigations in this work address the key physical layer challenges within such wavelength-agile networks. In particular, a range of experimental analysis has been carried out in order to realise the critical component technologies which include low-cost, 10G-capable, wavelength-tuneable transmitters for mass-market residential deployment and the development of gain-stabilised optical amplifier nodes to support the targeted physical reach (≥ 100km) and split (≥ 512). Finally, the feasibility of the proposed dynamically reconfigurable LR-PON configurations as a flexible and cost-effective solution for future access networks is verified through full-scale network demonstrations using an experimental laboratory test-bed