Professional Mobile Radio (PMR) also known as Private Mobile Radio or Land Mobile Radio (LMR) are radio systems conceived for public safety or professional event organizers. They are designed to provide a reliable and robust communication system independent from conventional public networks. In France, for instance, the national police is equipped with a PMR network, namely ACROPOL, that blankets the entire country and allows both voice and low data rate services. The object of this thesis is the North-American standard Project P25. It is a standard defined by the Telecommunications Industry Association (TIA) and is currently used by many radio communication systems in North-America. This report presents the results of a Matlab/C simulation designed to provide performances information on P25 physical layer. This knowledge is exploited to verify that the standard requirements are met. The final purpose of this thesis is the integration of Project 25 Layer 1 on a real radio platform. Thus, this report gauges the performances of all the modulators defined in the TIA standard for both Project 25 phase 1 and phase 2. Several tests are presented, they were realized in different conditions, that is with different channel models, propagation models as well as with or without any fading, in static and dynamic conditions. From this simulation, the Bit Error Rates vs Eb/N0 results have been extracted and are presented. The complete Forward Error Correction part has also been implemented and the correction capability of all the encoders and decoders has been verified, yielding the BER vs Eb/N0 plots. The resistance to an interferer has been evaluated, in several cases, with an interferer in the same channel or in an adjacent channel. The second part of this report presents the integration of the physical layer on a radio device. This was done to validate that both physical and MAC layers were compliant to the standard. This has been realized by interfacing the radio platform with Matlab via an Ethernet link and using UDP protocol.  Furthermore, at the end of the thesis some conclusions are drawn and future possible studies are detailed.

We have different kinds of signal processing everywhere around us in our everyday life, in our cellphones, when we are listening to music, watching TV etc. This makes signal processing a very interesting and important technical area, where the demand of skilled engineers sets the limit of what is possible. Working with signal processing requires in-depth knowledge in areas such as mathematics, physics, electronics, and other related areas. For this, it has traditionally been demanded by a talented developer to also master the advanced programming languages such as C / C + + and Assembler. This has begun to change; today there are several companies that offer graphical development environments for signal processing, environments where programming skills are not needed anymore, and the focus can be on signal processing instead. The goal with this project is to build a corresponding graphical development environment to reach an understanding of what is required of these systems, and also to grasp what opportunities that are available within graphic programming. Inspiration for the work has partly arise from some of the tools available on the market, and partly from previous theses that have been written about graphic programming. The challenge lies in creating a program that can execute signal diagrams in real time from given signal blocks, and be able to handle feedback loops in an efficient way and to do so at the lowest "cost" in terms of clock cycles as possible. This should also be compared against to code, compile and run a complete signal diagram directly. To increase the usability it should also be possibility to externally manage in real time the parameters of the signal diagram during execution. The interface is a separate program, which is to some extent similar to Matlab Simulink, where a signal diagram is drawn up graphically by connecting wires between different signal blocks. This signal scheme is then executed in an additional program that serves as a runtime environment. In this report, the term "signal engine" is used for this program. Signal engine is equivalent to the program that should have been run directly into a standalone DSP (Digital Signal Processor) if a more classic design had been selected, but now runs as a separate process in Windows.

Two hop relay based networks consist of three network nodes: source,relay station, and destination in which relay station assists the sourceto communicate reliably and efficiently with the destination. Moreover,these networks provide cost efficient solution for achieving highdata rate via cooperative communication between relays with singleantennas. In two hop relay based networks, communication from a source todestination takes place over two phases, i.e , in first phase from sourceto relay station and in second phase from relay station to the destination.Therefore, it is essential to formulate transmission strategies,i.e, TDMA, SDMA, Hybrid TDMA-SDMA and multicast in terms ofresource allocation, beamforming over two phases so that interferenceis taken into account and high data rates are achieved. In this thesis,some relay selection methods have been proposed to optimize thenetwork performance. Different proposed transmission strategies arecompared in different scenario settings in order to analyse and decidethe best strategy in each setting. Based upon simulation results it is recommended to use adaptivetime split ratio between the two phases. Brute force relay selection givesthe optimal relay assignment but Hungarian assignment algorithm alsoperforms pretty close to brute force performance. SDMA with cooperativerelays connection with multiple antennas at the relays performsmuch better than the other transmission strategies. However, multicaststrategy performs much better if second phase channel knowledge is notavailable at the base station.

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.

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.

The concept of interference alignment has recently become one of the importanttools to analyze the capacity of many multiuser communication networks,e.g. K-user interference channel, wireless X networks, multi hop interferencenetworks, etc. The idea is to consolidate the interference into smallerdimensions of signal space at each receiver and use the remaining dimensionsto transmit the desired signals. Furthermore, most progress in understandingof the wireless networks capacity has been made on the single hop schemes andmulti-hop multi-cast networks. However, there has not been as much progressin multi-hop multi-flow networks where all messages are not required by alldestination nodes. One of the basic problems in this area, is the capacity of2 × 2 × 2 interference channel. It is proved that the upper bound value of 2degrees of freedom (DoF) for this channel can be achieved using the so called“aligned interference neutralization” method.In the proposed interference alignment schemes for network problems whichwe mentioned in the above, including 2 × 2 × 2 interference channel, there aresome theoretical assumptions which seem to be difficult to apply in practice,e.g. high transmit power, asymptotic symbol extension of the channel, globaland perfect channel state information (CSI), etc. Among these assumptionsthe availability of CSI specially at transmitter, is crucial for performing theinterference alignment technique. The CSI at transmitter (CSIT) is usuallyavailable through feedback from receiver and it is used to estimate the currentchannel state, given that the channel coherence-time is long enough. However,it has been shown recently that the delayed CSIT, which is assumed to be independentof current channel state, still can be used to increase DoF of somespecific network settings.In this work, we consider the 2 × 2 × 2 interference channel where twosource nodes communicate with corresponding destination nodes via two relaynodes. We investigated the degrees of freedom of 2×2×2 interference channelwith delayed CSIT and we derived the upper bound on the degrees of freedomof the channel under this condition. Furthermore, we showed that this upperbound can be achieved using interference alignment technique. We also showedthat this completely out-of-date information of the channel can still be usefulto achieve higher rate compared to the situation where no CSIT is availableat the source nodes. Moreover, we observed that using relay nodes in interferencechannel can improve DoF compared to one hop interference channelwhere transmitters and receivers directly communicate with each other.

As a promising technology, wireless sensor networks have a wide range of applications. However, the development of wireless sensor networks is stillin face of multiple challenges. Among these challenges, the privacy issue is acritical parameter involved in providing secure and reliable services and attracts much attention from researchers and engineers. In the last decade, alarge number of privacy solutions for wireless sensor networks have been proposed. However, most of them are taken as additional secure functionality blocks rather than being integrated in the original sensor network designs. In this thesis project, we will focus on the privacy assessment of a parallel distributed detection network, which represents a simplied physical-layer of wireless sensor networks. The security threat is assumed to come from a passive eavesdropper. Four privacy leakage criteria are proposed to evaluate the privacy issue of the distributed detection network in dierent scenarios. As references, the privacy leakages are evaluated by dierent criteria when the distributed detection system is optimized in the perspectives of Bayesian detection theory and information theory without considering the presence of the eavesdropper. Then, we propose the corresponding privacy-concerned distributed detection systems. Comparisons to the optimal detection systems are performed and they reveal the trade-off between privacy leakage suppression and detection performance degradation.

Demand for high data rates is increasing rapidly for future wireless systems.This trend is due to the increase in the number of mobile subscribers that need bandwidth hungry multimedia applications anywhere, anytime. Fourth generation cellular systems like IMT-advanced are being developed to meet these requirements. The unreliable nature of the wireless medium is one of the main hinderance in providing high data rates. Cooperative communication in cellular networks is emerging as a new paradigm to deal with the channel impairments. User cooperation via fixed relays in cellular systems form multiple access relay channels (MARCs) and provide an effective and cost efficient solution to achieve spatial diversity gains. Network resources can be utilized efficiently by using network coding at cooperating nodes. A lot of research work has focused on highlighting the gains achieved by using network coding in MARCs. However, there are certain areas that are not fully explored yet. For instance, the kind of the detection scheme used at the base station receiver and its impact on the link performance has not been addressed. In most cases, the outage probability has been used as a performance measure of MARCs. However, it is well known that the outage probability gives information about the signal availability, but it does not give the complete picture about the reliability of the link and the achieved quality of service. This thesis work looks at the link performance, in terms of symbol error probability, of multiple access relay channels that employ network coding at the relay node. Different types of detection schemes are considered and their performance is compared under different link conditions. Analytical expressions for the average symbol error probability of the cooperating users are derived. Focusing on the uplink of cellular systems, certain rules are devised on how to group users at relay node to ensure mutual benefit for the cooperating users. As a way of improving the link performance of multiple access relay channels and their robustness, the thesis considers constellation selection for the different branches. This method takes advantage of the redundancy between the transmitted symbols created by network coding and the augmented signal space obtained at the base station receiver. The obtained results show that, with a proper selection of the constellation sets, the link performance of MARCs can be improved. The thesis further looks at the interaction between the channel coding schemes of the cooperating users and network coding. It is shown that joint channel-network coding in MARCs can be seen as a product code. This new representation provides considerable flexibility in selecting efficient decoding algorithms at the base station receiver and gives the possibility to use more powerful network coding schemes for MARCs. / QC 20101118 / Sino-Swedish Cooperative Program: IMT-Advanced and Beyond

Background: When we use our phone to make a purchase, booking, or simply contact someone, we expect a quick response to acknowledge that our request has been sent and received. Today’s traffic requests are higher than ever, and will most likely continue to grow. This puts pressure on the communication platforms to keep up with the demand and continue to perform and deliver the requests within short time frames. Twilio and 46elks are two communication platforms that offer an SMS gateway service, and this thesis will take a deeper look at how they perform when implemented on an ASP.NET Core 6 web application.  Objectives: The goal of this thesis is to evaluate if there are any disparities or similarities between the two communication platform’s SMS gateway services regarding performance. The performance quality attributes are focused on time behaviour, CPU utilization, and RAM usage. Method: Comparing two communication platforms by using a quasi-experiment. A web application was developed with ASP.NET Core 6 to handle incoming SMS bookings. With the provided data from the SMS, it created and stored the booking. Once done, a confirmation SMS was delivered to the Sender. The performance quality attributes were stored and collected for evaluation of each incoming SMS during the experiments. Results: Overall, Twilio had a longer time behaviour and higher RAM usage compared to 46elks, but Twilio had a lower CPU utilization compared to 46elks. Conclusions: The time behaviour and CPU utilization between the two communication platforms were significant different. Interesting findings were that when injecting a higher workload on the web application, the performance improved in two quality attributes, RAM usage and time behaviour, for both communication platforms.

Wireless networks are an iconic technology of today’s modern era, theyare present in our daily activities as can be exemplified by cellular communications,wi-fi, bluetooth, and others. Vector measurements play an importantrole in the design, simulation, and testing of wireless networks and are usedto characterize key devices operating in the radio interface, such as amplifiers,filters, and mixers.Accurate characterization is the key for improving the capacity and efficiencyof wireless networks. As the demand for network capacity continuouslyincreases, the accuracy of vector measurements must also improve. Further,it is anticipated that such trends will continue in the years to come. Consequently,the wireless industry needs to include nonlinear behavior in theircharacterization and analysis, to assess and guaranty the operation of the devices,and to comply to the specifications from governmental regulations. Incontrast to linear behavior, nonlinear behavior presents an additional bandwidthrequirement because the signal bandwidth grows when it passes throughnonlinear devices. In this thesis, vector measurements for devices operatingin wireless networks are studied, emphasizing a synthetic approach for theinstrumentation. This approach enables the use of digital post-processing algorithms,which enhances the measurement accuracy and/or speed and canovercome hardware impairments. This thesis presents the design of a vectorialmeasurement system for wireless devices considering the aforementionedtrends and requirements. It also explores the advantages of the proposedapproach, describes its limitations, and discusses the digital signal processingalgorithms used to reach its final functionality. Finally, measurement resultsof the proposed setup are presented, analyzed and compared to those of modernindustrial instruments. / <p>QC 20130204</p>