Since the boom of the smart phones, there is a huge amount of applicationsthat deal with data located in the cloud. This fact can makethese applications unavailable when the network is inaccessible due tocoverage or congestion. A solution to these problems have been designedand developed for the Android OS in this master thesis. The approachis the application of location-based pre-caching, downloading the contentof an application before the user enters in the zone where the applicationmay use this content. Network coding has also been introduced in orderto reduce the amount of data sent over the wireless networks. A cachingscheme is introduced in binary network coding and applied to the problemof retransmission in wireless broadcast network. A binary network codingalgorithm is designed which could asymptotically approach the efficiency of linear network coding with a much lower decoding complexity.

This thesis has been carried out on behalf of the department of Power Modules at Ericsson. In a telecom system interface A is a physical point between the power supply system and the telecommunication equipment described in a European standard called ETSI EN 300 132-2. This interface is also described in the American standard ATIS-0600315.2007. For board-mounted products, such as DC/DC converters, a well-defined input interface description is lacking. The goal of this thesis was to evaluate if the requirements in the standards ETSI EN 300 132-2 and ATIS-0600315.2007 are viable for the input interface of DC/DC converters. A part of this goal was also to investigate and analyze how the systems, in which the DC/DC converters operate, works. To be able to determine if any of the two standards, ETSI and ATIS, are viable for use for the input interface, both were reviewed and described with focus on voltage levels and transients. In the information gathering phase it became clear that an extended limitation was needed. Therefore, in order to investigate what happens from interface A to the input interface of DC/DC converters, the system used in this thesis is the EBS LOD (Ericsson Blade System – Low Ohmic Distribution). EBS is one of the systems in Core sites. The report describes the construction of EBS where in the PFM (Power Fan Module), backplanes and various boards are important parts. Furthermore some key principles within Core sites, such as HOD (High Ohmic Distribution), LOD, Two-wire system and Three-wire system, are also described in order to explain how the EBS system works. EBS (including PIM (Power Interface Module)) was modeled in OrCad PSpice, with both one board and 26 boards, and was simulated with different transients at an input to the system. The simulation results show that the high voltages never reach the DC/DC converter and that they therefore are well protected from transients in an EBS LOD system. In order to determine whether the standards ETSI and ATIS are viable for the input interface of DC/DC converters, it is concluded that more investigations, tests and simulations are needed. / Detta examensarbete har utförts på uppdrag av avdelningen Power Modules på Ericsson. I ett telekommunikationssystem är gränssnitt A en fysisk punkt mellan kraftsystemet och telekomutrustningen som beskrivs i en europeisk standard som kallas ETSI EN 300 132-2. Detta gränssnitt är också beskrivet i den amerikanska standarden ATIS-0.600.315.2007. För kortmonterade produkter, såsom DC/DC-omvandlare, saknas en beskrivning av ett väldefinierat ingångsgränssnitt. Målet med detta examensarbete var att utvärdera om kraven i standarderna ETSI EN 300 132-2 och ATIS-0.600.315.2007 är applicerbara på ingångsgränssnittet till DC/DC-omvandlare. En del av detta mål var också att utreda och analysera hur systemen, i vilka DC/DC-omvandlare finns, fungerar. För att kunna avgöra om de två standarderna ETSI och ATIS var applicerbara, granskades de och beskrevs med fokus på spänningsnivåer och transienter. I informationsinsamlingsfasen stod det klart att en utökad avgränsning behövdes. Slutsatsen av denna begränsning var att systemet som skulle användas i detta examensarbete var EBS LOD (Ericsson Blade System – Low Ohmic Distribution), för att undersöka vad som händer från gränssnittet A till ingångsgränssnittet av DC/DC omvandlare. EBS är ett av systemen inom Core sites. I rapporten beskrivs konstruktionen av EBS där PFM (Power Fan Module), backplan och olika kort anges som viktiga delar. Dessutom beskrivs några viktiga principer inom Core sites, såsom HOD (High Ohmic Distribution), LOD, Två-ledar-system och Tre-ledar-system. EBS (inklusive PIM (Power Interface Module)) modellerades i OrCad Pspice, med både ett kort och 26 kort, och simulerades med olika transienter på en av ingångarna till systemet. Simuleringsresultaten visar att de höga spänningarna aldrig når DC/DC-omvandlaren och att dessa alltså är väl skyddade mot transienter i ett EBS LOD system. För att kunna avgöra om standarderna ETSI och ATIS är applicerbara på ingångsgränssnittet till DC/DC-omvandlare är slutsatsen att flera utredningar, tester och simuleringar behöver göras.

In motor vehicles the power and information are distributed by their own separate wiresand the amount of wires over the past decades has increased tremendously due to theever increasing electronics onboard. Solely the average weight of the wires has increasedfrom 4 to 91 kg over the last 50 years and it is therefore clear that a remedy to theever increasing wiring is needed. A possible solution to this could be to introducepower line communication (PLC) onboard a vehicle. The PLC aims at overlaying theinformation on top of the already existing power feed cables and thus eliminating theneed of dedicated wires for communication purposes. The PLC solution would thussimplify the wiring network to a bare minimum, since no additional wires besides thepower cables are needed.During this thesis work the PLC technology was studied as a possible cost and qualityreform of the powertrain sensor network, where it could be used to both reduce the costof wires and increase the system reliability.A theoretical background study was rst performed to investigate the limitations andpossibilities of the PLC implemented in a vehicle, and the PLC technology was alsotested upon the DC-lines of an e6 Volvo FMX truck, between the post catalytic NOxsensor and the ACM with two CAN protocol based PLC modems. The throughput, noiseand the scalar voltage gain was measured in this link with the ignition key at dierentpositions to test dierent modes of operations. It was shown that this particular link hada clear low pass characteristics with severe voltage attenuation without any signicantdierence caused by the dierent modes of operation. The severe characteristics of thelink did result into a fault connement mode of the CAN based PLC modems wheretheir communication capabilities were inhibited, which shows that at least with thisparticular link, reliable communication was not possible with the equipment at hand.Short EMC measurements were also carried out regarding the radiated emissions. Theresults showed that the PLC technology implemented in the existing wiring architecturecould be a possible cause of EMC problems if no counter actions are been taken intoaccount.Some of the economical aspects were also investigated, but most of the results were leftas hypothetical assumptions. A detailed cost saving analysis was nevertheless made onthe EATS-wire harness where the savings were estimated to be 1e. It is the hope thatthese calculations could be used as a sounding board for future PLC wire harness costanalysis.

In today’s constantly changing market place most organizations need to reorganize. Reorganization carries risks that could jeopardize the organization's well-being and profitability. To minimize these risks, companies need a tool to help them analyze how the reorganization will affect the business before they make major changes. Such tool has now been developed by researchers at KTH. The tool needs to be validated on a complex organization to ensure that it works. The validation is based on hypotheses from the theory underpinning the framework of the tool. Three similar complex organizations have been modeled using the framework to see if the results are expected. Of the thirteen hypotheses that were tested, eleven were accepted and two rejected. Thus, this thesis finds that the tool is validated.

Vehicular communication is currently seen as a key technology for enabling safer and more comfortable driving. In the general effort to reduce the number of casualties and improve the traffic flow despite an increasing number of vehicles, this field has a promising future. IEEE 802.11p has been chosen as the standard for the Physical Layer (PHY) design for wireless vehicular communication. However, the channels encountered in such situations pose several challenges for reliable communications. Time and frequency selectivity caused by dispersive environments and high mobility lead to doubly-selective channels. The systems are expected to conduct proper operation, in spite of these disturbances. In this thesis, we focus on the design of receivers working on the PHY layer, with an emphasis on limited complexity. This poses high constraints on the algorithms, which already have to cope with the limited amount of information provided by the training sequences. The solutions considered all involve joint channel estimation and decoding, characterized by the use of an iterative structure. Such structures allow the channel estimation to benefit from the knowledge brought by the decoder, which ultimately decreases the error rate. Following a previous work, we use algorithms based on Minimum Mean Square Error (MMSE) or Maximum A Posteriori (MAP) estimation. These receivers were modified to operate on full frames instead of individual subcarriers, and various improvements were studied. We provide a detailed analysis of the complexity of the proposed designs, along with an evaluation of their decoding performance. The trade-offs between these two parameters are also discussed. A part of these analyses isused in [10]. Finally, we give an insight into some considerations which may arise when implementing the algorithms on testbeds.

This master thesis project has been conducted as a collaboration between Svenska Kraftnät and the Royal Institute of Technology.   High demands are being put on all components in a transmission system to be available for operation, making the allowed component down-time the limiting factor in the maintenance budget for Svenska Kraftnät and other transmission system operators. By conducting condition measurements that can be performed on-line, excessive down-times could be avoided in a step towards an as efficient maintenance strategy as possible. The approach of this thesis work has been to perform a case study for a population of transmission grid circuit breakers, creating a model of the CBs’ lifetime which has then been simulated with the aim of studying the benefit of periodic on-line condition measurements for power system components. The main potential benefit examined is the decrease in total downtime for the component population, in relation to the respective components’ criticality. The conclusions of this thesis project are summarized below. -Replacing the periodic off-line preventive maintenance with on-line condition measurements for the most critical circuit breakers in a power transmission system, significantly diminishes the weighted overall down-time for all circuit breakers in the system. - It is most preferable to use frequent intervals for condition measurements for a large part of the circuit breaker population. - A maintenance strategy based on condition measurements is best motivated in cases where the randomness of circuit breaker condition deterioration is high, the failure rate is high, or condition measurements have low uncertainty, and least motivated in cases where the conditions are the opposite. - Severe transient effects in average age of the component population may appear in response to any changes in maintenance strategy (or the lack of it), having a harsh impact for power system owners. / Detta examensarbetes svenska sammanfattning vänder sig främst till personer på Svenska Kraftnät och på andra svenska elnätsföretag samt övriga aktörer inom branschen med intresse för frågor om underhållsstrategier. Examensarbetet har utförts i samarbete mellan Svenska Kraftnät och Kungliga Tekniska högskolan. Med de höga krav på tillgänglighet som ställs på komponenter i transmissionsnät idag är det viktigt att ha en så effektiv underhållsstrategi som möjligt. Av den anledningen är det intressant att undersöka nyttan av att styra en större del av underhållsresurserna till de mest kritiska komponenterna i nätet.   För Svenska Kraftnät utgörs den begränsande faktorn av tiden ur drift som tillåts på komponentnivå för förebyggande underhåll. Med tillståndsmätningar som kan utföras på komponenter i drift kan denna tid minskas.   Syftet med examensarbetet har varit att undersöka nyttan av regelbundna tillståndsmätningar som kan utföras i drift för kritiska komponenter i transmissionsnät. Den potentiella nyttan som huvudsakligen studerats är en minskad total tid ur drift för komponentpopulationen, i förhållande till komponenternas respektive viktighet.   Tillvägagångssättet som använts i undersökningen har varit att utföra en fallstudie för kraftbrytarna i ett transmissionsnät gällande tillståndsmätningar. En modell skapades för brytarnas levnad, som sedan simulerades i syftet att iaktta påverkan av: -intervallet med vilket mätningar utförs på kritiska brytare, - andelen av den totala mängden brytare som anses vara kritiska på den totala viktade tiden ur drift.   Genom att utföra en känslighetsanalys för resultaten av simuleringarna kunde vilka faktorer som är kritiska för beslutsfattande gällande regelbundna tillståndsmätningar identifieras. Rekommendationerna från projektet består i huvudsak av ett antal punkter som skulle behöva undersökas av nätoperatörer för att resultaten från studien ska vara fullt applicerbara.   Inledningsvis behöver de mest kritiska komponenterna i nätet identifieras för att klargöra var underhållsresurser bör riktas i första hand. För att sedan tillståndsmätningar ska bli aktuella behöver specifika mätmetoder och deras förmåga att återspegla komponenters tillstånd undersökas. Utöver dessa punkter är det även rimligt att undersöka om det är lämpligt att helt utesluta komponenter från förebyggande underhållsåtgärder som utförs ur drift. Följande slutsatser kunde nås inom ramen för examensarbetet, sammanfattade i punktform. - Att ersätta det regelbundna förebyggande underhållet där komponenterna är ur drift med tillståndsmätningar som utförs i drift för de mest kritiska kraftbrytarna i ett transmissionsnät, kan den totala viktade tiden ur drift för alla brytare i systemet minskas markant. -Exkluderas tiden ur drift för det förebyggande underhållet i den totala tiden ur drift för brytarna, framgår det att det är mest fördelaktigt att använda frekventa intervall mellan tillståndsmätningar för en stor andel av den totala mängden brytare, oavsett om resultaten viktas mot kriticiteten hos brytarna eller inte. -En underhållsstrategi baserad på tillståndsmätningar är bäst motiverad för fall där slumpmässigheten hos degraderingen av brytartillståndet är hög, felfrekvensen är hög, tillståndsmätningarna har låg osäkerhet eller där tiden ur drift för avhjälpande underhållsåtgärder är hög i förhållande till förebyggande underhållsåtgärder. -En underhållsstrategi baserad på tillståndsmätningar är mindre motiverad eller omotiverad för fall där slumpmässigheten av brytartillståndet är låg, felfrekvensen är låg eller där tillståndsmätningarna har hög osäkerhet. - Påtagliga transienter i komponentpopulationens medelålder kan uppstå som följd av förändringar i underhållsstrategi (eller avsaknaden av förändring). Dessa transienter kan leda till haveritoppar, samt därmed även toppar för kostnaderna för avhjälpande underhåll, med stark påverkan för elnätsägare.

While modern communication networks have provided ease of connectivity and accessibility to vast resources, its operational and management task has become complex. Today’s communication networks consist of network devices from various vendors, which produce enormous amount of operational data in the form of SNMP traps, syslog messages, NetFlow caches, etc. It has become increasingly difficult for operational and fault management applications to utilize all the necessary information from the vast pool of information of varying formats. This report presents a prototype called Network Search System (NSS) that aims at easing the development of these applications by providing a simple, uniform interface to obtain network information that require no knowledge of location of the information. NSS abstracts the information collection and generalization processes by providing a query interface to the management applications to retrieve intended information. The report presents several use cases implemented using the system to demonstrate its functionality. It also presents performance evaluations, which point out the crucial bottlenecks in the system and are subject for further improvement of the system.

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In networked control systems, dynamical systems are stabilized by actions of remotely placed controllers. This involves communication between plants and controllers over wireless channel(s). The communication channel(s) are subjected to interfering signals, caused by some external radio devices in the neighborhood or by the other wireless components within the same networked control system. Interference in the communication channel is a major problem which drastically affects performance of the dynamical systems that are to be controlled over the wireless channels. This thesis in particular focuses on such a problem; it aims to improve stabilizability of linear systems by managing interference in the wireless channels. We propose an idea of using dedicated sensor nodes in a networked control system whose sole purpose is to manage interferences. Such a dedicated sensor node is termed as a relay node in this thesis, as it relays its received information to the other components in networked control system. We assume first order linear time invariant plants with arbitrary distributed initial state and model all the communication links as white Gaussian channels. We study two related setups. In the first setup, we study the remote stabilization of a first order linear plant over a wireless channel in which the communication between the plant’s sensor (state encoder) and controller is disturbed by an independent interference signal. The relay node observes this interference information and sends it to the state encoder and the controller, which then utilize this information to mitigate interference. In the second setup, we consider two separate plants that communicate with two separate controllers using a shared spectrum. Due to the common communication medium, the signals transmitted by the state encoders of the two plants interfere with each other. In this setup, the relay node observes the signals transmitted by the encoders of both plants. It then assists by communicating its observations to the two controllers. The fundamental difference between the two setups is that in the former, the interference is independent of the signal transmitted by the encoder, whereas in the later, the interference becomes correlated with the signals transmitted by the encoders of the two plants. In both setups, we use delay-free linear sensing and control schemes. By employing these schemes, we derive sufficient conditions for mean square stability. We show that the achievable stability region significantly enlarges with the relay assisted interference cancelation schemes.

Creating vehicle platoons is a way to reduce congestion, lower fuel consumption and to make roads safer. Making these platoons is possible thanks to inter-vehicle communications, communication between vehicles and infrastructure as well as equipping the vehicles with advanced sensors. In these platoons the vehicles are driven autonomously and the distance between them can be greatly reduced compared to human driving. In November 2012 three teams from the Swedish universities KTH, CTH and LiTH have gathered at Stora Holm, a test track near Göteborg, to demonstrate platooning and to perform a set of predefined maneuvers. Using inter-vehicle communications the teams must be able to autonomously create a gap to the preceding vehicle, close the gap, change reference vehicle during a lane switch as well as other scenarios. The KTH team consists of five full time master thesis students and a few part time PhD-students. The goal of this thesis is to create a simulation environment for platooning, where the team can test their respective parts in an easy fashion and for developing code directly in this environment. The idea is that every team member should be able to copy-paste their work in to this environment without having to make changes to how the system works to see that things are behaving as intended. To create this simulation environment PreScan has been used. PreScan is designed to be a development environment for intelligent transport systems. During this thesis it has proven to be a good platform to both recreate the Stora Holm track used for the demonstration and to try controlling strategies, logic, different algorithms for sorting and other parts of the project. The PreScan environment has not been implemented with any hardware-in-the-loop simulation but for the software many parts after the WIFI communications have been thoroughly tested before it was implemented in the real trucks.