<p>The aim of the thesis is to find out the most suitable channel estimation algorithms for the existing MIMO-OFDM SDR platform. Starting with the analysis of several prevalent channel estimation algorithms, MSE performance are compared under different scenarios. As a result of the hardware independent analysis, the complexvalued matrix computations involved in the algorithms are decomposed to real FLoating-point OPerations (FLOPs). Four feasible algorithms are selected for hardware dependent discussion based on the proposed hardware architecture. The computational latency is exposed as a manner of case study.</p>

<p>Telecommunication systems are under constant development. Currently 3GPP is working on an evolution of the 3G-standard, under the name 3G Long Term Evolution (LTE). Some of the goals are higher throughput and higher peak bit rates. A crucial part to achieve the higher performance is channel dependent scheduling (CDS). CDS is to assign users when they have favorable channel conditions. Channel dependent scheduling demands accurate and timely channel quality reports. These channel quality indication (CQI) reports can possibly take up a large part of the allocated uplink. This thesis report focuses on the potential gains from channel dependent scheduling in contrast to the loss in uplink to reporting overhead.</p><p>System simulations show that the gain from channel dependent scheduling is substantial but highly cell layout dependent. The gain with frequency and time CDS, compered to CDS in time domain only, is also large, around 20\%. With a full uplink it can still be a considerable gain in downlink performance if a large overhead is used for channel quality reports. This gives a loss in uplink performance, and if the uplink gets to limited it will severely affect both uplink and downlink performance negatively.</p><p>How to schedule and transmit CQI-reports is also under consideration. A suggested technique is to transmit the CQI reports together with uplink data. With a web traffic model simulations show that a high uplink load is required to get the reports often enough. The overhead also gets unnecessary large, if the report-size only depends on the allocated capacity.</p>

The purpose of this study is to learn more about the consumers' interaction with companies over different channels. It is conducted from a consumer's point of view, but the insights gained through this study will help companies to design and build better services. In this context, the concepts of User Experience, cross-channel and Customer Experience provide a theoretical framework. The new approach in this study is to combine the three concepts, their framing and their identified design elements. This conceptual framing contains a list of design elements with a positive influence on the service experience. However, the conceptual framing provides no answers on how to apply these design elements. In the methodology part, possible approaches are discussed. The heuristic evaluation used in the two case studies is a method that takes all three concepts from the theoretical framework into account. With the first heuristic, it is possible to analyze single touchpoints like User Experience demands. The following heuristics are used within a cross-channel context. Finally, the last heuristic is responsible for the holistic perspective from Customer Experience. The case studies are then conducted to verify the applicability of the design elements with the heuristic evaluation. The findings of the study were positive and suggest that the heuristic evaluation is a suitable method to analyze a company's service offerings. Additionally, the case studies lead to results which are useful for the two companies (Migros and Nestlé). The overall conclusion of this study is that the three concepts complement each other very well. User Experience is responsible for well designed touchpoints. Cross-channel expands the perspective on ecosystems and evaluates how the touchpoints operate together. Finally, Customer Experience analyzes the whole company and its touchpoints on a heuristic perspective.

We investigate evolution of mountain channel morphology and riverbed surface roughness by conducting laboratory experiments. The experimental flume is 4m long by 0.1m wide with a working length of 2.5m. We control initial sediment size distribution, flume slope, water discharge, and sediment feed rate. Measurements include topographic profiles, flow depth, surficial grain-size distribution, sediment transport rate, and sediment size distribution. Experiments begin with a gravel bed of a broad sediment size distribution, at two initial flume slopes: 8.2% and 12.4%. Discharge is held constant until transport rates and topographic changes indicate the system is at near steady state. Coarse sand is then fed into the channel at 1,000 g/min as a means to perturb the system. Sediment feed is held constant until the perturbed bed reach steady-state conditions. The feed is subsequently ceased and measurements continue until sediment transport rates and topography stabilize. These laboratory experiments provide first-hand observations of channel systems evolving after perturbations. Transport rates decay exponentially following perturbations and remain very low when the channel bed is stabilized. The introduction of coarse sand acts to smooth the channel bed by filling in topographic lows in the 8.2% sloped channel. At a 12.4% slope, increased mobility of sand allows steady state conditions to be met with little smoothing of the bed. The sand also increases the mobility of coarser sediment that was previously stable, likely due to local surface smoothing at grain scale. The increased fraction of surface sand cover maintains increased scouring and mobilization of coarser grains. These post-perturbation mechanisms are interpreted to be responsible for topographic adjustments as the system readjusts towards new steady-state conditions. Surface sorting and transporting distributions reflect high sand fractions well after perturbations have ceased. This suggests that brief pulses of fine sediment can increase coarse sediment mobility for prolonged periods. / text

This thesis evaluates the benefits of Multiple Input Multiple Output (MIMO) techniques on the capacity of Multimode Fiber (MMF) links. Optical MMF MIMO systems take advantage of the spatial diversity present in the multiple propagating paths in multimode fibers. By using multiple lasers at the input facet of the fiber and multiple photodetectors at the output, we show that the capacity of the link is improved from the single device link, hence demonstrating the usefulness of MIMO in such optical systems. An initial simulation of butt-coupling a Vertical Cavity Surface Emitting Laser (VCSEL) to multimode fiber reveals that the placement position of the laser axis with respect to the fiber axis is critical in exciting a large number of modes. More specifically, we show that there exists a tradeoff between total power coupled into the fiber and the number of modes launched. We then consider a mathematical description of the fiber channel and use it to simulate the capacity of a 1x1, 2x2, and 3x3 MIMO links over a statistical ensemble of channel realizations. This simulation reveals that a 2x2 system is capable of approximately a 50% increase in capacity over the 1x1 case while the 3x3 system is capable of approximately an 80% increase. Moreover, we show that the choice of the placement positions on the facets of the fiber affects the channel capacity, thereby implying that an optimal device position exists. We find the optimal device geometry by an exhaustive search and compare the capacities for the optimal geometry and that of a suboptimal one. A capacity tolerance study is then developed that considers perturbations about the optimal device locations and shows that the capacity of a rotated laser plane is over 90% of the capacity of the original device locations. A second perturbation study considers lateral offsets and shows that systems with a higher number of devices show good tolerance with poorer lateral tolerances for systems with less devices. When small lasers and a large grid of possible device locations are used, an exhaustive search for the optimal device location becomes computationally infeasible. We show that the problem of searching for the optimal detector locations while holding the laser positions fixed is submodular. This property allows a greedy algorithm to select the device positions at a small fraction of the computational complexity, however, only guaranteeing that the capacity of the resulting configuration is greater than a (1 - e^-1) fraction of the optimal configuration. We use this technique to compare the exhaustive search and the greedy search for coarse grids, and then exclusively use the greedy algorithm to select a device configuration for a fine grid whereby an exhaustive search is computationally infeasible. / text

The advancements of semiconductor processing technology have led to the ability for computing platforms to operate on large amounts of data at very high clock speeds. To fully utilize this processing power the components must have data continually available for operation upon and transport to other system components. To enable this data requirement, high speed serial links have replaced slower parallel communication protocols. Serial interfaces inherently require fewer signals for communication and thus reduce the device pin count, area and cost. A serial communication interface can also be run at a higher frequency because the clock skew between channels is no longer an issue since the data transmitted on various channels is independent. Serial data transmission also comes with a set of drawbacks when signal integrity is considered. The data must propagate through a channel that induces unwanted effects onto the signals such as intersymbol interference. These channel effects must be understood and mitigated to successfully transmit data without creating bit errors upon reception at the target component. Previously developed adaptive equalization techniques have been used to filter the effects of intersymbol interference from the transmitted data in the signal. This report explores the modeling and implementation of a system comprised of a transmitter, channel, and receiver to understand how intersymbol interference can be removed through a decision-feedback equalizer realized in hardware. The equalizer design, implementation, and measurements are the main focus of this report and are based on previous works in the areas of integrated circuit testing, channel modeling, and equalizer design. Simulation results from a system modeled in Simulink are compared against the results from a hardware model implemented with an FPGA, analog to digital converter and discrete circuit elements. In both the software and hardware models, bit errors were eliminated for certain amounts of intersymbol interference when a receiver with decision-feedback equalization was used instead of a receiver without equalization. / text

A vessel-mounted ADCP study focusing on channel-scale flow patterns in Galveston Bay near the Houston Shipping Channel and Mid-Bay Island is described. Winds of 5-7 m/s at 215-230◦ from N were present during data collection. For both peak ebb and flood conditions, the tidal circulation forced flow in a direction opposing the wind, perhaps due to a large-scale flow divergence forced by Mid-Bay Island. The strongest such currents were measured closest the island. During peak flood flow, the shape of the along-channel velocity profile for the open water upwind of the channel at Mid-Bay Island indicated uniform flow, and the salinity profile indicated a well-mixed water column. The near-island along- channel velocity profile showed a near-linear trend, and the salinity profile indicated a stratified water column. This suggested that the stratification had some effect the velocity profile shape, but further research is needed to better quantify this effect. During peak ebb flow, the near-island along-channel velocities were highly variable with respect to the mean velocity, indicating an area of active turbulence. Salinity profiles collected in the open water and near-island both showed stratification, something that was not seen during flood conditions. Differences in observations between flood and ebb flows can possibly be attributed to the survey location with respect to the chain of dredge spoil islands. During flood flows Mid-Bay Island is the first of the islands, and the flows surrounding the island may part of a developing horizontal boundary layer. During ebb flows the island is last in the chain relative to the direction of flow, and therefore the surrounding flows are well back from the leading edge of a horizontal boundary layer. / text

During the synthesis of secretory and membrane proteins, polypeptides move through a universally conserved protein-conducting channel, formed by the Sec61/SecY complex that is located in the eukaryotic endoplasmic reticulum membrane or the prokaryotic plasma membrane. The channel operates in two different modes depending on its binding partners. In co-translational translocation, a pathway found in all organisms, the channel associates with a translating ribosome. In post-translational translocation, the channel cooperates with either the Sec62–Sec63 complex in eukaryotes or the SecA ATPase in bacteria. Despite tremendous progress in our understanding of protein translocation over the past decades, many questions about its mechanism remain to be answered. These include (1) how the channel maintains the membrane barrier for small molecules while transporting large proteins, (2) what is the functional implication of channel oligomerization, and (3) how the channel interacts with binding partners and polypeptide substrates during translocation. To address these questions, we developed a novel in vivo method to generate both co- and post-translation translocation intermediates in intact Escherichia coli cells, such that polypeptide chains are only partially translocated through the channel. Using this method, we first demonstrated that a translocating polypeptide itself blocks small molecules from passing through an open SecY channel. A hydrophobic pore ring surrounding the polypeptide chain is vital for maintaining the membrane barrier during translocation. Next, we examined the importance of SecY oligomerization in protein translocation. Crosslinking experiments showed that SecY molecules interact with each other in native membranes, but that this self-association is greatly decreased upon insertion of polypeptide substrates. We also showed that SecY mutants that cannot form oligomers are still functional in vivo. Collectively, our data indicate that a single copy of SecY is sufficient for protein translocation. Finally, we isolated an intact co-translational translocation intermediate from E. coli cells and analyzed its structure by cryo-electron microscopy. An initial map shows a translating ribosome containing all three tRNAs is bound to one copy of the SecY channel. Analysis of a large dataset is ongoing in order to understand the structural basis of how the channel interacts with the ribosome and translocating nascent chain.

Syfte: Studien syftar till att undersöka vilka avsikter företag kan ha med att använda sociala medier som en marknadsföringskanal. Syftet kommer brytas ner i en frågeställning. Metod: Studien har genomförts genom en kvalitativ ansats. En semi-strukturerad mall tillämpades. Kvalitativa ansatsen var genom att intervjua tio olika företag som närvara på sociala medier. Teori: Denna studie innehåller följande teorier – viral marknadsföring, AIDA-modellen, och linjära kommunikationsmodellen. Empirin: Här presenteras informanternas svar kortfattat. Intervjumallen men utförliga frågor och svar framgår som bilaga. Slutsats: Genom att analysera den insamlade data har vi lyckats besvara studiens syfte som syftar till att undersöka vilka avsikter företag kan ha med att använda sociala medier som en marknadsföringskanal. Företag vill skapa en dialog med sina kunder och stärka kundrelationen. De vill ständigt vara tillgängliga för sina kunder och få feedback för att växa och åtgärd sina brister. Den största nackdelen med sociala medier enligt studiens involverade företag är den hastiga spridningseffekten av negativ information. / Purpose: The purpose of this study is to investigate and discover the intention(s) behind company’s use of social media as a marketing channel. The purpose will be divided into a research question. Method: The study is of a qualitative type and a semi-structured model was applied. The data was gathered by interviewing ten different companies, all of which using social media in some way. Theory: The study is comprised of the following theories: Viral marketing, the AIDA-model and the linear communication model. Empirics: The answers from the interviews are briefly presented in this section. The questions given during the interviews and the answers are presented as an attachment. Conclusion: Through analyzing the gathered data, we have been able to answer the purpose of this study with the goal of discovering what intentions a company might have when deciding to use social media as a marketing channel. Companies want to create a dialog with their customers and strengthen their relationship with them. They want to be available constantly and receive feedback in order to grow and attend to whatever flaws they may have. According to the companies interviewed, the greatest disadvantage with social media is the ability to rapidly spread negative information.

The glycine receptor (GlyR) is a ligand-gated ion channel and member of the nicotinic acetylcholine receptor superfamily. Glycine and the partial agonist taurine are both believed to be the endogenous ligands of the receptor. Partial agonists have lower efficacies than full agonists, eliciting submaximal responses even at saturating concentrations. Recent evidence suggests that efficacy at these receptors is determined by conformational changes that occur early in the process of receptor activation. We previously identified a mutation of the aspartate-97 residue to arginine (D97R), which produces a spontaneously active mutant with behavior that mimics the effects of saturating glycine concentrations on wildtype (WT) GlyR. This D97 residue is hypothesized to form an electrostatic interaction with arginine-119 on an adjacent subunit to stabilize a closed channel closed state. We found that the disruption of this bond converts taurine into a full agonist and greatly increases the efficacies of other [beta]-amino acid partial agonists. Our findings suggest that the determination of efficacy in the GlyR involves the disruption of an inter-subunit electrostatic interaction soon after binding. We next investigated whether the taurine efficacy could be enhanced by ethanol, a well-studied positive allosteric modulator of receptor function. Whole-cell recordings of WT GlyRs demonstrated that alcohol could potentiate the effect of low concentrations of taurine, but did not increase the efficacy of a saturating concentration. Therefore we sought to understand the mechanism by which alcohol enhances the GlyR, because ethanol's actions at inhibitory receptors in the brain are thought to produce many of the physiological effects associated with its use. We examined the effects of 3 [mu]M glycine ± 50 or 200 mM ethanol on outside-out patches expressing WT [alpha]1 GlyR, to determine the effects of alcohol at the single-channel level. Alcohol enhanced GlyR function in a very specific manner. It had minimal effects on open and closed dwell times. Instead, ethanol potentiated GlyR function almost exclusively by increasing burst durations and increasing the number of channel openings per burst, without affecting the percentage of open time within bursts. Kinetic modeling suggests that ethanol increases burst durations by decreasing the rate of glycine unbinding. / text