Analysis of Simulated and Measured Indoor Channels for mm-Wave Beamforming Applications

Ray tracing- (RT-) assisted beamforming, where beams are directly steered to dominant paths tracked by ray tracing simulations, is a promising beamforming strategy, since it avoids the time-consuming exhaustive beam searching adopted in conventional beam steering strategies. The performance of RT-assisted beamforming depends directly on how accurate the spatial profiles of the radio environment can be predicted by the RT simulation. In this paper, we investigate how ray tracing-assisted beamforming performs in both poorly furnished and richly furnished indoor environments. Single-user beamforming performance was investigated using both single beam and multiple beams, with two different power allocation schemes applied to multibeamforming. Channel measurements were performed at 28–30 GHz using a vector network analyzer equipped with a biconical antenna as the transmit antenna and a rotated horn antenna as the receive antenna. 3D ray tracing simulations were carried out in the same replicated propagation environments. Based on measurement and ray tracing simulation data, it is shown that RT-assisted beamforming performs well both for single and multibeamforming in these two representative indoor propagation environments

Optimal sequential fingerprinting: Wald vs. Tardos

We study sequential collusion-resistant fingerprinting, where the fingerprinting code is generated in advance but accusations may be made between rounds, and show that in this setting both the dynamic Tardos scheme and schemes building upon Wald's sequential probability ratio test (SPRT) are asymptotically optimal. We further compare these two approaches to sequential fingerprinting, highlighting differences between the two schemes. Based on these differences, we argue that Wald's scheme should in general be preferred over the dynamic Tardos scheme, even though both schemes have their merits. As a side result, we derive an optimal sequential group testing method for the classical model, which can easily be generalized to different group testing models.Comment: 12 pages, 10 figure

The Iray Light Transport Simulation and Rendering System

While ray tracing has become increasingly common and path tracing is well understood by now, a major challenge lies in crafting an easy-to-use and efficient system implementing these technologies. Following a purely physically-based paradigm while still allowing for artistic workflows, the Iray light transport simulation and rendering system allows for rendering complex scenes by the push of a button and thus makes accurate light transport simulation widely available. In this document we discuss the challenges and implementation choices that follow from our primary design decisions, demonstrating that such a rendering system can be made a practical, scalable, and efficient real-world application that has been adopted by various companies across many fields and is in use by many industry professionals today

Tracing and Debugging of Lazy Functional Programs - A Comparative Evaluation of Three Systems

In this paper we compare three systems for tracing and debugging Haskell programs: Freja, the Redex Trail System and Hood. We identify the similarities and differences of these systems and we evaluate their usefulness in practice by applying them to a number of small to medium programs in which errors had deliberately been introduced

Measuring Interaction Design before Building the System: a Model-Based Approach

Early prototyping of user interfaces is an established good practice in interactive system development. However, prototypes cover only some usage scenarios, and questions dealing with number of required steps, possible interaction paths or impact of possible user errors can be answered only for the specific scenarios and only after tedious manual inspection. We present a tool (MIGTool) that transforms models of the behavior of a user interface into a graph, upon which usage scenarios can be easily specified, and used by MIGTool to compute possible interaction paths. Metrics based on possible paths, with or without user navigation errors, can then be computed. For example, when analyzing four mail applications, we show that Gmail has 3 times more shortest routes, has twice more routes that include a single user error, has routes with 13\ufewer steps, but has also optimal routes with the smallest probability to be chosen. Without MIGTool, this kind of analysis could only be done after building some prototype of the system, and then only for specific scenarios by manually tracing user actions and relative changes to the screens. With MIGTool the exploration of suitability of a design with respect to different scenarios, or comparison of different design alternatives against a single scenario, can be done with just a partial specification of the user interface behavior. This is made possible by the ability to associate scenarios steps to required user actions as defined in the model, by an efficient strategy to identify complete execution traces that users can follow, and by computing a range of diverse metrics on these results