Multi-Gigabit Radio System Demonstrators for Next Generation Mobile Networks

Driven by the exponential growth in mobile broadband subscriptions and mobile data traffic, transport capacity of mobile networks has to be enhanced accordingly, including wireless backhaul and the emerging fronthaul networks. Utilizing wide bandwidth is the most straightforward way to capacity upgrade. Millimeter-wave frequency bands with large available bandwidth offer the opportunities to realize high capacity wireless links. However, there are challenges associated with the radio link implementation. For example, wide bandwidth is required for components like low noise amplifiers, power amplifiers, modulators and demodulators (modems). Another challenge is the signal quality degradation due to high frequency impairments. The solutions presented in the thesis are applicable to implementations based on commercially available hardware. Multi-gigabit modems are proposed using simple modulation differential quadrature phase shift keying (DQPSK), which do not need carrier recovery and power hungry mixed signal devices. To improve spectral efficiency, a 16-QAM modem is designed with optimized hardware efficiency. This in turn relaxes the demand on the sampling rate of analog to digital converters (ADC) and the resource requirement on digital signal processing. As proof-of-concept demonstration, DQPSK modems are implemented and verified at 2.5 and 5 Gbps. A 5 Gbps radio system based on the hardware efficient 16-QAM modem is also demonstrated at 70/80 GHz (E-band). The presented modems and systems address challenges in applying wide bandwidth/high symbol rate to realizing high capacity. Moreover, it defines the baseline for further capacity enhancement when combined with high spectral efficiency techniques. Besides the mobile backhaul application, high capacity wireless links are required to support the mobile fronthaul as a new network segment, which connects a centralized baseband pool to distributed remote radio units. A data-rate adaptable DQPSK modem solution is proposed for digital wireless fronthaul to transmit multi-gigabit CPRI (common public radio interface). An E-band digital fronthaul link is implemented using this modem at 5 Gbps. To overcome the low bandwidth efficiency of the digital fronthaul, an analog fronthaul technology is introduced as an enabler for cost efficient and scalable fronthaul networks. An analog fronthaul link is demonstrated at E-band complemented with phase noise mitigation for 64-QAM LTE transmission

Multi-Gigabaud Solutions for Millimeter-wave Communication

With the growing number of mobile network and internet services subscriptions, faster communication will provide a better experience for users. In the next generation mobile network, the fifth generation (5G), communication data rate will achieve several Gigabits per second with ultra-low latency. The capacity enhancement of the mobile backhaul and fronthaul is a challenge. The transmission capacity can be enhanced by increasing the bandwidth, increasing the spectrum efficiency and increasing both the bandwidth and the spectrum efficiency at the same time. \ua0Millimeter-wave frequency bands have the bandwidth in the order of GHz which provide great opportunities to realize high data rate communications. In this case, millimeter-wave frontend modules and wideband modems are needed in communication systems. In this thesis, a 40 Gbps real-time differential quadrature phase shift keying (DQPSK) modem has been presented to support high-speed communications [A]. As a complete system, it aims to work together with the D-band frontend module published in [1] providing more than 40 GHz bandwidth. In this modem, the modulator is realized in a single field programmable gate array (FPGA) and the demodulator is based on analog components. Although millimeter-wave frequency bands could provide wide available bandwidth, it is challenging to generate high output power of the carrier signal. In addition, the transmitter needs to back off several dB in output power in order to avoid the non-linear distortion caused by power amplifiers. In this thesis, an outphasing power combining transmitter is proposed [B] to use the maximum output power of power amplifiers while maintaining the signal quality at the same time. This transmitter is demonstrated at E-band with commercially available components.Increasing the spectrum efficiency is an additional method to enhance the transmission capacity. High order modulation signals such as quadrature amplitude modulation (QAM) signals are commonly used for this purpose.\ua0 In this case, receivers usually require coherent detection in order to demodulate the signals. Limited by the sampling rate of the analog to digital converters (ADCs), the traditional digital carrier recovery methods can be only applied to a symbol rate lower than the sampling rate. A synchronous baseband receiver is proposed [C] with a carrier recovery subsystem which only requires a low-speed ADC with a sampling rate of 100 MSps

Recent Trends in Communication Networks

In recent years there has been many developments in communication technology. This has greatly enhanced the computing power of small handheld resource-constrained mobile devices. Different generations of communication technology have evolved. This had led to new research for communication of large volumes of data in different transmission media and the design of different communication protocols. Another direction of research concerns the secure and error-free communication between the sender and receiver despite the risk of the presence of an eavesdropper. For the communication requirement of a huge amount of multimedia streaming data, a lot of research has been carried out in the design of proper overlay networks. The book addresses new research techniques that have evolved to handle these challenges

Efficient Management of Flexible Functional Splits in 5G Second Phase Networks

The fifth mobile network generation (5G), which offers better data speeds, reduced latency, and a huge number of network connections, promises to improve the performance of the cellular network in practically every way available. A portion of the network operations are deployed in a centralized unit in the 5G radio access network (RAN) partially centralized design. By centralizing these functions, operational expenses are decreased and coordinating strategies are made possible. To link centralized units (CU) and distributed units (DU), and the DU to remote radio units (RRU), both the midhaul and fronthaul networks must have higher capacity. The necessary fronthaul capacity is also influenced by the fluctuating instantaneous user traffic. Consequently, the 5G RAN must be able to dynamically change its centralization level to the user traffic to maximize its performance. To try to relieve this fronthaul capacity it has been considered a more flexible distribution between the base band unit (BBU) (or CU and DU if enhanced common public radio interface (eCPRI) is considered) and the RRU. It may be challenging to provide high-speed data services in crowded areas, particularly when there is imperfect coverage or significant interference. Because of this, the macrocell deployment is insufficient. This problem for outdoor users could be resolved by the introduction of low-power nodes with a limited coverage area. In this context, this MSc dissertation explores, in an urban micro cell scenario model A (UMi_A) for three frequency bands (2.6 GHz, 3.5 GHz, and 5.62 GHz), the highest data rate achievable when a numerology zero is used. For this, it was necessary the implementation of the UMi_A in the 5G-air-simulator. Allowing the determination of the saturation level using the results for the packet loss ratio (PLR=2%). By assuming Open RAN (O-RAN) and functional splitting, the performance of two schedulers in terms of quality-of-service (QoS) were also studied. The QoS-aware modified largest weighted delay first (M-LWDF) scheduler and the QoS-unaware proportional fair (PF) scheduler. PLR was evaluated for both schedulers, whilst analyzing the impact of break point distance while changing the frequency band. The costs, revenues, profit in percentage terms, and other metrics were also estimated for the PF and M-LWDF schedulers when used video (VID) and video plus best effort (VID+BE), with or without consideration of the functional splits 7.2 and 6, for the three frequency bands. One concluded that the profit in percentage terms with functional split option 7.2 applied is always slightly higher than with functional split option 6. It reaches a maximum profit of 366.92% in the case of the M-LWDF scheduler, and 305.51% in the case of the PF scheduler, at a cell radius of 0.4 km for the 2.6 GHz frequency band, considering a price of the traffic of 0.0002 €/min.A quinta geração de redes móveis (5G), oferece ritmos de transmissão melhorados, atraso extremo-a-extremo reduzido, e um vasto número de ligações de rede. A 5G promete melhorar o desempenho das redes celulares em praticamente todos os aspectos relevantes. Uma parte da operação da rede é colocada numa unidade centralizada na rede de acesso de rádio (RAN) 5G com dimensionamento parcialmente centralizado. Ao centralizar estas funções, os custos operacionais decrescem, viabilizando-se as estratégias de coordenação. Para ligar as unidades centralizadas e unidades distribuídas, e por sua vez, unidades distribuidas e unidades de rádio remotas, ambos os midhaul e fronthaul devem ter uma capacidade mais elevada. A capacidade da fronthaul necessária é também influenciada pela flutuação do tráfego instantâneo dos utilizadores. Consequentemente, a RAN 5G deve ser capaz de alterar dinamicamente o seu nível de centralização para o tráfego de utilizadores, com objetivo de maximizar o seu desempenho. Para tentar aliviar o aumento da capacidade suportada pelo fronthaul, tem sido considerada uma distribuição mais flexível entre a unidade de banda base, BBU (ou unidade central e unidade distribuída se a interface de rádio pública comum melhorada, eCPRI, for considerada), e a unidade de rádio remota, RRU. Em áreas densamente povoadas, pode ser um desafio fornecer serviços de dados de elevada velocidade, particularmente quando existe uma cobertura deficiente ou interferência significativa. Por este motivo, o desenvolvimento de macrocélulas pode ser insuficiente, mas este problema para utilizadores em ambiente de exterior pode ser mitigado com a introdução de nós de potência reduzida com uma área de cobertura limitada. Neste contexto, esta dissertação de mestrado explora, num cenário urbano de microcélulas caracterizado pelo modelo A (UMi_A) para três bandas de frequência (2.6 GHz, 3.5 GHz, e 5.62 GHz), o débito binário máximo que se pode alcançar quando se utiliza numerologia zero. Para tal, foi necessária a implementação do UMi_A no 5G - air - simulator. Determinou-se o nivel de saturação, considerandose os resultados para a taxa de perda de pacotes (PLR=2%). Estudou-se o desempenho de dois escalonadores de pacotes em termos de qualidade de serviço (QoS), assumindo-se o OpenRAN (O-RAN) e as divisões funcionais (functionalsplitting). Um dos escalonadores é ciente da QoS, e é de atraso máximo-superior ponderado primeiro (M-LWDF), enquanto que o outro não é ciente da QoS, e é de justiça proporcional (PF). Avaliou-se o PLR para ambos os escalonadores de pacotes, estudando-se o impacto da distância de ponto de quebra (breakpointdistance), variando-se a banda de frequências. Foram também estimados os custos, proveitos, o lucro (em percentagem), e outras metricas, para os escalonadores PF e M-LWDF, considerando o vídeo (VID) e vídeo mais besteffort (VID+BE) como aplicações, com ou sem a consideração das divisões funcionais 7.2 e 6, para as três bandas de frequência. Concluiu-se que o lucro em termos percentuais, com a escolha da opção de divisão funcional 7.2, é sempre ligeiramente mais elevado do que com a opção de divisão funcional 6. Atingese um lucro máximo de 366,92% no caso do escalonador M-LWDF, e de 305,51% no caso do escalonador PF, para um raio de célula de 0,4 km, para a banda de frequência de 2,6 GHz, considerando-se um preço do tráfego de 0,0002 €/min

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

Efficient sharing mechanisms for virtualized multi-tenant heterogeneous networks

The explosion in data traffic, the physical resource constraints, and the insufficient financial incentives for deploying 5G networks, stress the need for a paradigm shift in network upgrades. Typically, operators are also the service providers, which charge the end users with low and flat tariffs, independently of the service enjoyed. A fine-scale management of the network resources is needed, both for optimizing costs and resource utilization, as well as for enabling new synergies among network owners and third-parties. In particular, operators could open their networks to third parties by means of fine-scale sharing agreements over customized networks for enhanced service provision, in exchange for an adequate return of investment for upgrading their infrastructures. The main objective of this thesis is to study the potential of fine-scale resource management and sharing mechanisms for enhancing service provision and for contributing to a sustainable road to 5G. More precisely, the state-of-the-art architectures and technologies for network programmability and scalability are studied, together with a novel paradigm for supporting service diversity and fine-scale sharing. We review the limits of conventional networks, we extend existing standardization efforts and define an enhanced architecture for enabling 5G networks' features (e.g., network-wide centralization and programmability). The potential of the proposed architecture is assessed in terms of flexible sharing and enhanced service provision, while the advantages of alternative business models are studied in terms of additional profits to the operators. We first study the data rate improvement achievable by means of spectrum and infrastructure sharing among operators and evaluate the profit increase justified by a better service provided. We present a scheme based on coalitional game theory for assessing the capability of accommodating more service requests when a cooperative approach is adopted, and for studying the conditions for beneficial sharing among coalitions of operators. Results show that: i) collaboration can be beneficial also in case of unbalanced cost redistribution within coalitions; ii) coalitions of equal-sized operators provide better profit opportunities and require lower tariffs. The second kind of sharing interaction that we consider is the one between operators and third-party service providers, in the form of fine-scale provision of customized portions of the network resources. We define a policy-based admission control mechanism, whose performance is compared with reference strategies. The proposed mechanism is based on auction theory and computes the optimal admission policy at a reduced complexity for different traffic loads and allocation frequencies. Because next-generation services include delay-critical services, we compare the admission control performances of conventional approaches with the proposed one, which proves to offer near real-time service provision and reduced complexity. Besides, it guarantees high revenues and low expenditures in exchange for negligible losses in terms of fairness towards service providers. To conclude, we study the case where adaptable timescales are adopted for the policy-based admission control, in order to promptly guarantee service requirements over traffic fluctuations. In order to reduce complexity, we consider the offline pre­computation of admission strategies with respect to reference network conditions, then we study the extension to unexplored conditions by means of computationally efficient methodologies. Performance is compared for different admission strategies by means of a proof of concept on real network traces. Results show that the proposed strategy provides a tradeoff in complexity and performance with respect to reference strategies, while reducing resource utilization and requirements on network awareness.La explosion del trafico de datos, los recursos limitados y la falta de incentivos para el desarrollo de 5G evidencian la necesidad de un cambio de paradigma en la gestion de las redes actuales. Los operadores de red suelen ser tambien proveedores de servicios, cobrando tarifas bajas y planas, independientemente del servicio ofrecido. Se necesita una gestion de recursos precisa para optimizar su utilizacion, y para permitir nuevas sinergias entre operadores y proveedores de servicios. Concretamente, los operadores podrian abrir sus redes a terceros compartiendolas de forma flexible y personalizada para mejorar la calidad de servicio a cambio de aumentar sus ganancias como incentivo para mejorar sus infraestructuras. El objetivo principal de esta tesis es estudiar el potencial de los mecanismos de gestion y comparticion de recursos a pequei\a escala para trazar un camino sostenible hacia el 5G. En concreto, se estudian las arquitecturas y tecnolog fas mas avanzadas de "programabilidad" y escalabilidad de las redes, junto a un nuevo paradigma para la diversificacion de servicios y la comparticion de recursos. Revisamos los limites de las redes convencionales, ampliamos los esfuerzos de estandarizacion existentes y definimos una arquitectura para habilitar la centralizacion y la programabilidad en toda la red. La arquitectura propuesta se evalua en terminos de flexibilidad en la comparticion de recursos, y de mejora en la prestacion de servicios, mientras que las ventajas de un modelo de negocio alternativo se estudian en terminos de ganancia para los operadores. En primer lugar, estudiamos el aumento en la tasa de datos gracias a un uso compartido del espectro y de las infraestructuras, y evaluamos la mejora en las ganancias de los operadores. Presentamos un esquema de admision basado en la teoria de juegos para acomodar mas solicitudes de servicio cuando se adopta un enfoque cooperativo, y para estudiar las condiciones para que la reparticion de recursos sea conveniente entre coaliciones de operadores. Los resultados ensei\an que: i) la colaboracion puede ser favorable tambien en caso de una redistribucion desigual de los costes en cada coalicion; ii) las coaliciones de operadores de igual tamai\o ofrecen mejores ganancias y requieren tarifas mas bajas. El segundo tipo de comparticion que consideramos se da entre operadores de red y proveedores de servicios, en forma de provision de recursos personalizada ya pequei\a escala. Definimos un mecanismo de control de trafico basado en polfticas de admision, cuyo rendimiento se compara con estrategias de referencia. El mecanismo propuesto se basa en la teoria de subastas y calcula la politica de admision optima con una complejidad reducida para diferentes cargas de trafico y tasa de asignacion. Con particular atencion a servicios 5G de baja latencia, comparamos las prestaciones de estrategias convencionales para el control de admision con las del metodo propuesto, que proporciona: i) un suministro de servicios casi en tiempo real; ii) una complejidad reducida; iii) unos ingresos elevados; y iv) unos gastos reducidos, a cambio de unas perdidas insignificantes en terminos de imparcialidad hacia los proveedores de servicios. Para concluir, estudiamos el caso en el que se adoptan escalas de tiempo adaptables para el control de admision, con el fin de garantizar puntualmente los requisitos de servicio bajo diferentes condiciones de trafico. Para reducir la complejidad, consideramos el calculo previo de las estrategias de admision con respecto a condiciones de red de referenda, adaptables a condiciones inexploradas por medio de metodologias computacionalmente eficientes. Se compara el rendimiento de diferentes estrategias de admision sobre trazas de trafico real. Los resultados muestran que la estrategia propuesta equilibra complejidad y ganancias, mientras se reduce la utilizacion de recursos y la necesidad de conocer el estado exacto de la red.Postprint (published version

6G Wireless Systems: Vision, Requirements, Challenges, Insights, and Opportunities

Mobile communications have been undergoing a generational change every ten years or so. However, the time difference between the so-called "G's" is also decreasing. While fifth-generation (5G) systems are becoming a commercial reality, there is already significant interest in systems beyond 5G, which we refer to as the sixth-generation (6G) of wireless systems. In contrast to the already published papers on the topic, we take a top-down approach to 6G. We present a holistic discussion of 6G systems beginning with lifestyle and societal changes driving the need for next generation networks. This is followed by a discussion into the technical requirements needed to enable 6G applications, based on which we dissect key challenges, as well as possibilities for practically realizable system solutions across all layers of the Open Systems Interconnection stack. Since many of the 6G applications will need access to an order-of-magnitude more spectrum, utilization of frequencies between 100 GHz and 1 THz becomes of paramount importance. As such, the 6G eco-system will feature a diverse range of frequency bands, ranging from below 6 GHz up to 1 THz. We comprehensively characterize the limitations that must be overcome to realize working systems in these bands; and provide a unique perspective on the physical, as well as higher layer challenges relating to the design of next generation core networks, new modulation and coding methods, novel multiple access techniques, antenna arrays, wave propagation, radio-frequency transceiver design, as well as real-time signal processing. We rigorously discuss the fundamental changes required in the core networks of the future that serves as a major source of latency for time-sensitive applications. While evaluating the strengths and weaknesses of key 6G technologies, we differentiate what may be achievable over the next decade, relative to what is possible.Comment: Accepted for Publication into the Proceedings of the IEEE; 32 pages, 10 figures, 5 table

Utilization of cloud RAN architecture with eCPRI fronthaul in 5G network

With increased reliability, massive network capacity, and extremely reduced latency, 5G expands the mobile ecosystem into new realms. 5G impacts every industry and innovation, making transportation and conveyance safer, remote healthcare, accuracy agriculture, digitized logistics, and much more. In this age, 5G calls for new levels of flexibility and broadness in architecting, scaling, and deploying telecommunication networks, which need a further step ahead in technology and enter Cloud Technology. Cloud technology provides fascinating possibilities to complement the existing tried and tested technologies in the Radio Access Network (RAN) domain. Cloud RAN (CRAN) refers to relying on RAN functions over an inclusive platform instead of a purpose-built hardware platform. It represents a progression in wireless communication technology, leveraging the Common public radio interface (CPRI) standard, Dense Wavelength Division Multiplexing (DWDM) innovation, and millimeter wave (mmWave) propagation for extended-range signals. A CRAN network comprises of three fundamental elements. The initial element is the Distant Wireless Unit (DRU) or Remote Radio Component (RRH), utilized within a network to link wireless devices to entry points; these units are equipped with transceivers for transmitting and receiving signals. Next, a Baseband Unit (BBU) centre or hub serves as a centralized site functioning as a data processing hub. Separate BBU modules can be assembled independently or interconnected to distribute resources, adapting to the network's changing dynamics and needs. Communication among these modules boasts remarkably high bandwidth and exceptionally low latency. The BBU can be further segmented into DU (Distributed Unit) and CU (Centralized Unit). The third crucial component is a fronthaul or conveyance network – the connecting layer between a baseband unit (BBU) and a set of RRUs, utilizing optical fibres, cellular links, or mmWave communication. The goal of this thesis is to find a way to utilize the 5G RAN Architecture as efficiently as possible and for this purpose, Enhanced Common Public Radio Interface (eCPRI) or enhanced CPRI fronthaul is adopted instead of CPRI as it is a manner of splitting up the functions performed by baseband unit and putting some of that in the RRU so it can reduce the burden on the fibre. Enhanced CPRI makes it possible to send some data packets to a virtual Distributed Unit (vDU) and others to a virtual Centralized Unit (vCU) which results in reduced data traffic on fibre. The first part of this research paper focuses on considering and learning about the 5G Cloud RAN architecture's main components, some cloud RAN history, and important components included in the 5G Cloud RAN. In the second part, research goes in depth about the fronthaul gateway technology that is eCPRI structure, its functional split, its difference from CPRI in structure and functionality, and how it is enhanced and developed. Considering CRAN specifications, it will also include some eCPRI protocol delay management and timing studies. Finally, Test cases are developed that can authenticate the low latency and high throughput of data with eCPRI fronthaul in 5G Cloud RAN as compared to CPRI fronthaul. The inspiration behind this is to recreate the model with substantial changes that work with an ideal behaviour of a subsystem, with this a tool or an environment can be obtained that maximizes the efficiency of 5G CRAN. It will also permit network architects and designers to experiment with new features, which can reduce costs, save time, improve latency. It can also provide a tool to verification engineers that will help them to generate optimal replies of the system necessary for evaluating the practical realization of that system