To enable wireless control of factories, such that sensor measurements can be sent wirelessly to an actuator, the probability to receive data correctly must be very high and the time it takes to the deliver the data from the sensor to the actuator must be very low. Earlier, these requirements have only been met by cables, but in the fifth generation mobile network this is one of the imagined use cases and work is undergoing to create a system capable of wireless control of factories. One of the problems in this scenario is when all data in a packet cannot be sent in one transmission while ensuring the very high probability of reception of the transmission. This thesis studies this problem in detail by proposing methods to cope with the problem and evaluating these methods in a simulator. The thesis shows that splitting the data into multiple segments and transmitting each at an even higher probability of reception is a good candidate, especially when there is time for a retransmission. When there is only one transmission available, a better candidate is to send the same packet twice. Even if the first packet cannot achieve the very high probability of reception, the combination of the first and second packet might be able to. / För att möjliggöra trådlös kontroll av fabriker, till exempel trådlös sändning av data uppmätt av en sensor till ett ställdon som agerar på den emottagna signalen, så måste sannolikheten att ta emot datan korrekt vara väldigt hög och tiden det tar att leverera data från sensorn till ställdonet vara mycket kort. Tidigare har endast kablar klarat av dessa krav men i den femte generationens mobila nätverk är trådlös kontroll av fabriker ett av användningsområdena och arbete pågår för att skapa ett system som klarar av det. Ett av problemen i detta användningsområde är när all data i ett paket inte kan skickas i en sändning och klara av den väldigt höga sannolikheten för mottagning. Denna uppsats studerar detta problem i detalj och föreslår metoder för att hantera problemet samt utvärderar dessa metoder i en simulator. Uppsatsen visar att delning av ett paket i flera segment och sändning av varje segment med en ännu högre sannolikhet för mottagning är en bra kandidat, speciellt när det finns tid för en omsändning. När det endast finns tid för en sändning verkar det bättre att skicka samma paket två gånger. Även om det första paketet inte kan uppnå den höga sannolikheten för mottagning så kan kanske kombinationen av det första och andra paketet göra det.

The last ten years have seen significant advances of multiuser MIMO (MU-MIMO) in wireless communication. MU-MIMO is now being introduced in several new generation wireless standards (e.g.,LTE-Advanced, 802.16m). The number of users is increasing with more and more applications. At the same time, high transmission data rate and communication reliability are required. Furthermore, there is a growing concern about green communication which relates to the effects of  the radiation emitted from wireless devices onthe human body. Therefore, the future MU-MIMO systems have to satisfy three main requirements: i) serving many autonomous users in the same time-frequency resource, ii) having high data rate and communication reliability, and iii) less energy consumption/radiation. These are seemingly contradictory requirements since the more users are served, the more interference the systems will suffer, or the more data rate is transmitted, the more power is required. MU-MIMO with very large antenna arrays seems to meet above demands and hence, it can be considered as a promising technology for next generation wireless systems. With very large antenna arrays (we mean arrays comprising say a hundred of antennas), the channel vectors are nearly-orthogonal and hence, multiuser interference can be significantly reduced. As a result, many users can be simultaneously served with high data rate. In particular, with coherent processing, transmit power can be reduced dramatically owing to array gain. In this thesis, we focus on the performance bounds of MU-MIMO with very large antenna arrays. We study the fundamental limits on the system performance when using large antenna arrays under practical constraints such as low complexity processing, imperfect channel state information, intercell interference, and finite-dimensional channels.

More and more sensitive information is communicated digitally and with thatcomes the demand for security and privacy on the services being used. An accurateQoS metric for these services are of interest both for the customer and theservice provider. This thesis has investigated the impact of different parameterson the perceived voice quality for encrypted VoIP using a PESQ score as referencevalue. Based on this investigation a parametric prediction model has been developedwhich outputs a R-value, comparable to that of the widely used E-modelfrom ITU. This thesis can further be seen as a template for how to construct modelsof other equipments or codecs than those evaluated here since they effect theresult but are hard to parametrise. The results of the investigation are consistent with previous studies regarding theimpact of packet loss, the impact of jitter is shown to be significant over 40 ms.The results from three different packetizers are presented which illustrates theneed to take such aspects into consideration when constructing a model to predictvoice quality. The model derived from the investigation performs well withno mean error and a standard deviation of the error of a mere 1:45 R-value unitswhen validated in conditions to be expected in GSM networks. When validatedagainst an emulated 3G network the standard deviation is even lower.v

Wireless sensor networks (WSNs) are used in all kinds of different sectors ranging from agriculture, environment, healthcare and the military. Embedded systems such as sensor nodes are low-power and consist of low memory, which creates a challenge for its security. One of WSN’s worst enemies is interference radio jamming attacks. They are easy to construct and execute, but hard to detect and identify. In this thesis, we tackle the problems of detecting, but most importantly identifying, and distinguishing the most commonly used interference radio jamming attacks. Presenting SpeckSense++, a firmware that makes it possible for low-power embedded systems to detect, identify and distinguish interference radio jamming attacks and unintentional interference such as Bluetooth and WiFi to a certain degree. Showing an accuracy of 96 to 90 % for proactive jammers, 89% for reactive, and 92 to 85 % for unintentional interference.

Abstract The basic responsibility for a purchasing department is to secure all the goods and services needed for an organization. In general, the department is, trying to become a a major part of the  organization and its functions are becoming increasingly automated. In this work, the communication between the purchasing department and its suppliers is examined. The study was conducted at Sweden, the largest employer in the county with 7,500 employees at the time of the study. The purpose of the thesis is to investigate whether the communication in the purchasing process in healthcare has changed during corona pandemic.  The data was collected via four interviews, with both the purchasing department's staff and two suppliers. The interview was conducted via physical meetings with the purchasing department, but also via phone. In order to succeed in work, it was important to know what questions needed to be asked in order to get optimal answers during the interviews. Data collection provided the basis for the case study because the collected information came from people who have knowledge in the research area, which made it easier to reason and give concrete answers to the research questions. The results of the study show that certain mistakes can occur in the communication between the purchasing department and the suppliers. The mistakes can reflect negativity on the overall communication and makes it more difficult for the actors to understand each other. However, under the pandemic, communication became much better because both parties became more willing to help each other out during the difficult situation. The good relationship between the parties allowed them to avoid problems regarding the purchasing process during the pandemic. Keywords: Purchasing, external communication, internal communication, procurement, Pandemic.

Workshop Mensch-Computer-Vernetzung

This master thesis presents the design and implementation of a super heterodyne 5.8 GHz receiver system for wireless transmission of phase alternating line (PAL) composite video signals. The system is implemented using surface and hole mounted devices on four separate printed circuit board (PCB) stages. These stages include a 5.8 GHz radio front-end, a 480 MHz intermediate frequency (IF) stage, a local oscillator (LO) block and frequency demodulation circuit for frequency modulation (FM) signals. Each receiver stage is interconnected using sub-miniature version A (SMA) connectors. The radio front-end PCB consists of a low-noise amplifier (LNA), a 5.8 GHz distributed element pre-select filter and a passive double-balanced mixer. This mixer uses seven discrete injection frequencies at 5260-5380 MHz that are provided by the LO block using a programmable phase-locked loop (PLL) frequency synthesizer device. The IF stage uses an automatic gain control (AGC) feedback loop with a dynamic range of 60 dB. This AGC loop is implemented using a directional coupler, a detector device, a tuning circuit and a variable gain amplifier/attenuator (VGA). The IF at 480 MHz is selected with a 25 MHz surface acoustic wave (SAW) filter. The IF is demodulated to a PAL composite video format using a PLL FM discriminator device intended for direct-broadcast satellite (DBS) signals. This device is fitted to a separate demodulation stage in conjunction with a picture adjustment circuit and a FM de-emphasis network. The output of the demodulator stage is a 75 Ω PAL composite video signal.

A common trend, in general as well as in the field of combat vehicles, is the rapidly increasing demand for data network capacity and even more in transferred data. To handle this increased demand, different countries with their armed forces and equipment manufacturers evaluate methods to increase the data transmission capacity in combat vehicles. The different types of transmitted data are of different criticality and have different security demands. An easy solution to this is to have separated networks for each type of traffic, but that is quite expensive and uses a lot of hardware. This thesis focuses on a different solution, with a shared network for all types of data transmissions. This is done by evaluating different types of data networks and add-on protocols and then testing the networks practically with varying transmission rates. In the thesis, all the practical testing is done with data networks according to the Ethernet standard, which is the standard evaluated with a throughput that is high enough for the use case. Ethernet as a standard is not suitable for critical data traffic and therefore add-on protocols for Ethernet to optimize the system for critical data traffic are tested. With these optimizations made, Ethernet can be considered more suitable for critical traffic, but this depends entirely on the system requirements.

Internet users may not get the service quality promised by theirproviders, and also may not know what service they can receive.When users experience poor Internet connection performance, itis not easy to identify the source of the problem. We developCheesePi, a distributed measurement system that measures theInternet connection experience of home users based on some net-work performance attributes (e.g. latency, packet loss rate, andWiFi signal quality). The CheesePi runs on a Raspberry Pi (acredit card sized computer) connected to the user’s home networkas a measurement agent. It is important to measure the networkperformance from the user’s side since it is difficult to measureeach individual’s link from the operator (provider) side. Eachmeasurement agent conducts measurement periodically withoutdisturbing the user’s Internet quality. Measurements are con-ducted during popular media events from SICS (Swedish Insti-tute of Computer Science) and student accommodations. Themeasurement results show customers with an Ethernet connectionexperienced significantly better latency and packet loss comparedto WiFi users. In most of the measurements users at SICS per-ceived better latency and packet loss compared to the users at thestudent accommodation. We also quantify how customers experi-enced lower performance when streaming from websites which donot use CDN technology compared to the websites which do useCDN, particularly during popular media events. / CheesePi

Ericsson har utvecklat ett ramverk för multimediakommunikation som heter Mario. Mario kan användas för att sätta upp video- och ljud-samtal över IP och finns fungerande på Android och iOS. Mario är en del av web browsern Bowser som finns att hämta på Google Play eller App Store. Bowser möjliggör att köra WebRTC applikationer skrivna i HTML5 och JavaScript på Android och iOS. Nu när Microsoft släpper sina nya plattformar, Windows RT, Windows 8 och Windows Phone 8 så finns ett intresse att försöka flytta detta ramverk till dessa plattformar. Vi kommer göra ett försök att porta Mario till Windows RT. Anledningen till att Windows RT valdes är för att det är den första plattformen att släppas av de tre nämnda produkterna. Plattforms APIet som används i Windows RT kallar för Windows Runtime (WinRT). Många delar av det här APIet delas med Windows Phone 8 och hela WinRT APIet exponeras i Windows 8. Det här betyder att förutsatt att koden designas på rätt sätt så borde den gå att flytta mellan Windows RT, Windows 8 och Windows Phone 8 utan problem. Windows RT är ett operativsystem utvecklat för att fungera på datorer som använder ARM-baserade processorer. För att Mario ska kunna fungera på WinRT så måste följande mål uppfyllas: De open-source bibliotek som används av Mario måste byggas på Mario. C/C++ kod måste kunna köras på Windows RT plattformen. Mario ramverket måste integreras med video- och ljudfångning i operativsystemet. Vad det gäller open-source projekt så ligger det under en sådan licens (LGPL) som gör att källkoden inte får ändras utan att hela källkoden till de projekten som använder open-source koden också släpps som open-source. Ericsson vill inte att Mario ska släppas som open-source utan vill själva ha kontroll på källkoden. Av denna anledning kommer vi utreda om det är möjligt att bygga dessa bibliotek utan att ändra i koden. I och med att Mario är skrivet i C och C++ så måste det också utredas hur vida det är möjligt att köra C/C++ kod i Windows RT. Vad det gäller video- och ljudfångning måste Windows RT APIet utredas för att se hur man använder det för just detta.