The launch of the 5th Generation (5G) mobile network allows for wireless communication at increased throughput rates and reduced latency compared to its predecessors and has opened for new possibilities in terms of computation offloading where demanding processes can be referred to powerful servers.User equipment (UE), i.e. wireless devices connected to a network, can benefit from offloading computational tasks to servers. Not only does it extend UE's computational resources, but also has the potential to reduce its energy consumption as it effectively redistributes the computational load to the server.This thesis is a study into the energy consumption trade-offs of this procedure for which a case study is done on a computer connected to a 5G network and tasked with the computation of a specific algorithm. Specifically, a comparison is made on the power consumption of computing the algorithm on the UE's central processing unit (CPU) and offloading it via a 5G modem, respectively, and a theoretical framework describing algorithms in terms of their utilization of these components is presented. By experimentally profiling the power consumption of the components and an algorithm's utilization thereof, these trade-offs can be quantified for a variety of signalling conditions. While the empirical study is a test case of a characteristic algorithm on a specific set of hardware components, the developed theoretical framework and methodology allows for the results to be extended to other hardware and algorithms, and general conclusions to be drawn on the energy consumption trade-offs in computation offloading. The results show that computation offloading is overwhelmingly beneficial in terms of power consumption and that the trade-offs only become comparable in certain edge cases. In particular, unless the CPU has an uncommonly low power consumption, the signal quality conditions are very poor or if the algorithm to be offloaded has a combination of low CPU load and high throughput requirements, offloading should always be considered a viable computational procedure in terms of energy consumption.

Internet of Things (IoT) has come in reality to improve our living quality. Automation is embraced in all the possible business verticals that have diverse communication needs ranged from static devices’ sporadic transmission to mobile devices’ every minute transmission. Despite, there are many technologies available today to support IoT services; cellular systems can play a vital role for IoT services, like wearables, vehicular, and industrial IoT, rollout which have either mobility or security concern.  IoT services generated traffic are foreseen as a sporadic-bursty traffic. As the cellular networks are designed to serve continuous data traffic, the existing system’s access control mechanism cannot efficiently conform to the burstiness of traffic. This limits the scope of the network scalability in terms of simultaneous serving devices’ capacity. Also, this bursty pattern can extensively increase the rate of network’s congestion incident. In this thesis, we focus on these underlying challenges to support a large number of heterogeneous IoT services with existing services over the same radio network. An important question for supporting IoT services over cellular networks is how detrimental are the effects of IoT services on other services of cellular networks. This dissertation seeks to answer this with quantitative results to indicate the real constraints of existing networks. An important conclusion is that existing cellular system is incompetent to support the bursty arrival of massive IoT devices in terms of radio networks’ access control plane’s scalability. Therefore, this dissertation presents solutions to overcome the identified limitations of access control planes. To improve the performance of the access control plane, we incorporate a vertical core network controlled group management scheme that can assure the operator’s granular control over capillary gateways. Besides, this introduces a unique handover opportunity between cellular and capillary network vertices. Then, we present a simple but efficient initial access mechanism to overcome the initial access collision at the very early stage. Finally, we show the impact of access collision and retransmission on the initial access resource dimensioning.We present a practical traffic model that is realistic for the traffic scenario for mixed-traffic. Our presented results and analysis depict the trade-offs between access rate, retransmission and resource allocation over time and frequency.Our results reveal that with proposed schemes of the cellular system’s access control plane can be scalable and resilient to accommodate a large number of IoT devices without incurring extra delay or need of resources to the system. / <p>QC 20170928</p>

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No description available.

In this era of rapid wireless technological advancements, wireless connectivity between humans, humans with machines, and machines with machines is gradually becoming an absolute necessity. The initial motivation for wireless connectivity was to enable voice communication between humans over a geo-graphical area. Thanks to cellular communications advancements in the past decade, cellular wireless connectivity has become a global success, starting from 1G to the present generation 5G. However, the needs of humans often evolve with time, and now the world is witnessing an ever-growing demand for the internet with high data rates besides reliable voice communication. Current cellular networks suffer from non-uniform data rates across a cell, i.e., users at the cell center and the cell edges experience significant variations in signal-to-noise ratio, making the cellular technology less reliable to meet the future data demands. Moreover, cellular networks operating as cells, i.e., an access point (AP, the term we would use instead of base station) serving the users within its geographical location, cannot leverage the network’s total capacity without cooperation among APs of the neighboring cells. One potential solution is moving away from the cell to cell-free networks wherein all the APs will serve all the users within the geographical coverage area. Thus, there is a need for a paradigm shift in how cellular networks operate. Towards the goal mentioned above to fully leverage the network capacity, the Cell-Free Massive multiple-input-multiple-output (MIMO) technology is expected to be the next potential technology beyond 5G combining the benefits of Massive MIMO and cell-free distributed architectures.  Distributed architectures require distributed signal processing algorithms, and also energy consumption of the network is crucial. Keeping in view the practical ease in deployment, we consider a sequentially connected Cell-Free Massive MIMO network called a “radio stripe”. In the first part of the thesis, we focus on developing an optimal sequential algorithm in the sense of mean-square-error (MSE) which has the same performance as that of centralized Cell-Free Massive MIMO implementation with the minimum MSE (MMSE) receiver. We also develop an optimal sequential algorithm that decentralizes the centralized bit LLR computation. Another attractive aspect of these proposed algorithms is that the fronthaul (number of real symbols required by the central processing unit (CPU) to decode the transmitted signal) is independent of the number of APs. On the contrary, centralized implementation fronthaul is dependent on the number of APs, causing scalability problems with the increase in APs.  In the second part of the thesis, we develop an algorithm focused on maximizing the energy efficiency of the RadioWeave network in an underlay spectrum sharing. RadioWeave is a technology envisioned to combine Cell-Free Massive MIMO and possibly large intelligent surfaces. We first present the energy efficiency problem, which is non-convex in its original form. Then, a convex lower bound on the problem is provided with an iterative algorithm to solve the problem efficiently. / I denna tid av snabba trådlösa tekniska framsteg blir trådlös anslutning mellan människor, mellan människor och maskiner och mellan maskiner och maskiner gradvis en absolut nödvändighet. Den ursprungliga motivationen för trådlös anslutning var att möjliggöra röstkommunikation mellan människor över ett stort geografiskt område. Tack vare framsteg inom mobilkommunikation under det senaste decenniet har mobil trådlös anslutning blivit en global framgång, från 1G till den nuvarande generationen 5G. Men människors behov utvecklats med tiden, och nu bevittnar världen, förutom pålitlig röstkommunikation, en ständigt växande efterfrågan på internet med höga datahastigheter. Nuvarande cellulära nätverk lider av olikformiga datahastigheter över cellen, d.v.s. användare i cellcentret och cellkanterna upplever betydande variationer i signal-brusförhållande, vilket gör den cellulära tekniken mindre lämplig för att möta framtida databehov. Dessutom kan cellulära nätverk som fungerar som celler, d.v.s. att varje accesspunkt (AP, termen vi använder istället för basstation) betjänar användarna inom dess geografiska område, inte utnyttja nätverkets totala kapacitet utan samarbete mellan AP:er i de angränsande cellerna. En potentiell lösning är att gå från cellulära till cellfria nätverk där alla basstationer betjänar alla användare inom det geografiska täckningsområdet. Det finns alltså ett behov av ett paradigmskifte i hur cellulära nätverk fungerar. För att fullt ut utnyttja nätverkskapaciteten, förväntas Cell-Free Massive MIMO vara nästa potentiella teknik bortom 5G som kombinerar fördelarna med Massive MIMO och cellfria distribuerade arkitekturer. Distribuerade arkitekturer kräver distribuerade signalbehandlingsalgoritmer, och även energiförbrukningen i nätverket är av stor vikt. Vi studerar sekventiellt anslutna Cell-Free Massive MIMO-nätverk som kallas “radio stripe”, eftersom dessa är enkla att placera ut. I den första delen av avhandlingen fokuserar vi på att utveckla en optimal, ur ett MSE perspektiv, sekventiell algoritm som har samma prestanda som den för centraliserad Cell-Free Massive MIMO-implementering med en MMSE-mottagare. Vi utvecklade också en optimal sekventiell algoritm som decentraliserar den centraliserade bit LLR. En kritisk aspekt av dessa föreslagna algoritmer är att fronthaul (antal reella symboler som krävs av CPU:n för att avkoda den sända signalen) är oberoende av antalet AP:er. Tvärtom är fronthaulen i en centraliserad implementering beroende av antalet AP:er, vilket orsakar skalbarhetsproblem med ökningen av AP:er. I den andra delen av avhandlingen utvecklar vi en algoritm fokuserad på att maximera energieffektiviteten i RadioWeave-nätverk med en underliggande spektrumdelning. RadioWeave är en teknik som är tänkt att kombinera Cell-Free Massive MIMO och möjligen stora intelligenta ytor. Vi presenterar först energieffektivitetsproblemet, som är icke-konvext i sin ursprungliga form. Sedan förses en konvex nedre gräns för problemet med en iterativ algoritm för att lösa problemet effektivt.

In this information society, wireless network is an indispensable technology supporting the daily information communication and various interaction services. With the motivation to improve the user experience of Wi-Fi service, this thesis presents the front-end development process of a visualization application for home Wi-Fi testing and optimization. To provide the desired service to the users, it is important to understand what they need. With prompt feedback, the development process can have much more customized schedule and specific aim. In this thesis, different methods are adopted to get the valuable feedbacks from potential users. Brainstorming and originality interview support the basic designing of application, which is presented by the wireframe prototype. The prototype were used for a test-run and get feedbacks in order to develop a web application front-end assimilating the ideas and suggestions from real users. As more detailed functionality are designed, the feasibility and practicability should be investigated. Questionnaires are used to do larger scale ranges of user investigation. The front-end is designed using HTML, CSS and JavaScript with Bootstrap framework. The elements within all the pages could be able to interact with each other to give the customers a visualized experienced of service. The web application provides the users with the functions to test the real-time Wi-Fi performance, check the performance trend of data history from a specific time period and get useful optimization solutions. The designing is aiming to synthesize enough accessible information and provide the users with self-helpful testing and optimization of home Wi-Fi, which can increase the efficiency of technical support and reduce the workload of customer service. / I detta informationssamhälle är trådlöst nätverk en oumbärlig teknik som stöder den dagliga informationskommunikationen och olika interaktionstjänster. Med motivationen att förbättra användarupplevelsen av Wi-Fi tjänsten presenterar denna avhandling utvecklingsprocessen för fronten av en visualiseringsapplikation för Wi-Fi-test och optimering av hemmet. För att tillhandahålla önskad service till användarna är det viktigt att förstå vad de behöver. Med snabb feedback kan utvecklingsprocessen ha mycket mer anpassat schema och specifikt syfte. I denna avhandling antas olika metoder för att få de värdefulla feedback från potentiella användare. Brainstorming och originalitet intervju stöder den grundläggande utformningen av applikationen, som presenteras av wireframe prototypen. Prototypen användes för en testkörning och fick feedback för att utveckla ett webbapplikationsfrontend assimilera id´eer och förslag från riktiga användare. Eftersom mer detaljerad funktionalitet är utformad bör genomförbarheten och genomförbarheten undersökas. Frågeformulär används för att göra större omfattning av användarutredningen. Fronten är utformad med hjälp av HTML, CSS och JavaScript med Bootstrap-ramverket. Elementen inom alla sidor skulle kunna interagera med varandra för att ge kunderna en visualiserad erfarenhet av service. Webapplikationen ger användarna funktionerna för att testa Wi-Fi-prestanda i realtid, kontrollera prestandatrenden i dataloggen från en viss tidsperiod och få användbara optimeringslösningar. Designen syftar till att syntetisera tillräckligt tillgång till information och ge användarna självhjälpt testning och optimering av Wi-Fi i hemmet, vilket kan öka effektiviteten av tekniskt stöd och minska arbetsbelastningen hos kundtjänst.

The traffic volume in wireless communication has grown dramatically in the last decade and is predicted to keep increasing in the future. In this thesis, we focus on the densification dimension for capacity improvement, which has been proved to be the most effective in the past. The current gain of network densification mainly comes from cell splitting, thereby serving more user equipments (UEs) simultaneously. This trend will decelerate as base station (BS) density gets closer to or even surpass UE density which forms an ultra-dense network (UDN). Thus, it is crucial to understand the behavior of ultra-densification for future network provisioning.   We start from comparing the effectiveness of densification with spectrum expansion and multi-antenna systems. Our findings show that deploying more BSs provides a substantial gain in sparse network but the gain decreases progressively in a UDN. The diminishing gain appears in a UDN make us curious to know if there exists a terminal on the way of densification. Such uncertainty leads to the study on the asymptotic behavior of densification. We incorporate a sophisticated bounded dual-slope path loss model and practical UE densities in our analysis. By using stochastic geometry, we derive the expressions and prove the convergence of the coverage probability of a typical UE and network area spectral efficiency (ASE). Considering the large portion of dormant BSs in a UDN, it is an interesting question whether we can utilize these dormant BSs to improve system performance is an interesting question. To this end, we employ joint transmission (JT) techniques into a UDN. Two types of cooperation schemes are investigated: non-coherent JT and coherent JT depending on the availability of channel state information (CSI). Our results reveal that non-coherent JT is not beneficial in a UDN while coherent JT are able to increase UE spectral efficiency (SE) depending on the environmental parameters. / <p>QC 20170117</p>

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The next generation of mobile communication (5G) is upon us, and with that newtypes of technologies are needed for improved data rates, reliability, response timeand increased utilization. In this report, two highly efficient linear power amplifiersare characterized and tested with simulated communication signals. The purpose ofthe amplifiers is to be integrated into antenna arrays that will transmit amplifiedcommunication signals to mobile users.One of the amplifiers is tested with modulated communication signals with anoptimized gate bias value. The amplifier shows during the final tests high-efficiencylevels of up to 40% and is still able to behave linearly with&gt;20 dB gain and lowerror vector magnitude below 1%.The fundamental theory for signal processing is described at the beginning of thereport, followed by an overview of the experimental setup built during the thesis formeasuring modulated signals through amplifiers.

Society as we know it today would not have been possible without the explosive and astonishing development of telecommunications systems, and optical fibers have been one of the pillars of these technologies. Despite the enormous amount of data being transmitted over optical networks today, the trend is that the demand for higher bandwidths will also increase. Given this context, a central element in the design of telecommunications networks will be data security, since information can often be confidential or private. Quantum information emerges as a solution to encrypt data by quantum key distribution (QKD) between two users. This technique uses the properties of nature as the fundamentals of operation rather than relying on mathematical constructs to provide data protection. A popular alternative to performing QKD is to use the relative phase between two individual photon paths for information encoding. However, this method was not practical over long distances. The time-bin- based scheme was a solution to the previous problem given its practical nature, however, it introduces intrinsic losses due to its design, which increases with the dimension of the encoded quantum system. In this thesis we have designed and tested a fiber-optic platform using spatial-division- multiplexing techniques. The use of few-mode fibers and photonic lanterns are the cornerstone of our proposal, which also allow us to support orbital angular momentum (OAM) modes. The platform builds on the core ideas of the phase-coded quantum communication system and also takes advantage of the benefits proposed by the time-bin scheme. We have experimentally tested our proposal by successfully transmitting phase-coded single-photon states over 500 m few-mode fiber, demonstrating the feasibility of our scheme. We demonstrated the successful creation of OAM states, their propagation and their successful detection in an all in-fiber scheme. Our platform eliminates the post-selection losses of time-bin quantum communication systems and ensures compatibility with next-generation optical networks and opens up new possibilities for quantum communication.