The inefficient divergence handling is one of the processing bottlenecks in today's Graphical Processing Units (GPUs) with single-instruction multiple thread (SIMT) architecture. The radio ray-tracing algorithms are frequently accelerated by such architectures. Intersecting scene objects while traversing acceleration structures with rays concurrently by multiple threads typically gives divergent flow patterns. The problem is usually hidden by the programmer's view of independent threads. A loop optimization technique having the potential to increase efficiency of the core architectural blocks while processing embedded divergences has been investigated. An optimization of concurrent loops was proposed, allowing better alignment of thread flows via iteration scheduling. Processing speedups can generally be observed in the total running time if kernels are compute-bound, as demonstrated by several examples. The studied iteration scheduling policies do not impose alterations to the core SIMT concept and design, thus preserving the benefits of data level parallelism while speeding up tasks such as radio coverage computation.
COBISS.SI-ID: 28013351
In this paper, we propose a new indirect method for constructing the radio frequency layer of radio environment map (RF-REM) called self-tuning method (STM). The proposed STM takes into account the characteristics of the operating environment and performs estimation of the transmitter parameters, i.e. its location, antenna diagram, antenna azimuth, transmit power, as well the parameters of the propagation model to obtain the best match between the available measurements and the predicted signal levels. We compare STM to several most often considered existing methods using different numbers of randomly distributed measurements. The analysis shows the robustness of the STM to various spatial distributions of measurements and its fast convergence and low residual root mean square error compared to the inverse distance weighted (IDW) method, the inverse distance square weighted method (IDW2), the Kriging method, and the location estimation-based method (LIvE).
COBISS.SI-ID: 28420647
In this paper we propose a framework for dynamic composition of communication services which is well suited for facilitating research and prototyping on real experimental infrastructures of remotely configurable embedded devices. By using the concept of composeability, our framework supports modular component development for various networking functions, therefore promoting code re-use. The framework has been implemented in the LOG-a-TEC sensor network testbed where it will support validation and performance evaluation of new radio environment characterization and radio localization procedures.
COBISS.SI-ID: 28254247
This paper addresses a user-centric approach to network and user traffic modelling that has been validated and used in the process of introducing, optimizing and planning new services at the Slovenian national telecom operator and service provider, Telekom Slovenije d.d. The proposed approach is based on the end-users and their user-group profiles that are founded on the real measurements from the observed telecommunication network consisting of more than thousand MSANs and more than 300 thousand subscribers. The proposed approach has been successfully validated showing that for the observed period the modelled link load deviates less than 5% from the measurements. Furthermore, in the presented case study the proposed approach is used successfully in the process of introducing and optimisation of Fast Channel Change service.
COBISS.SI-ID: 28767783
The paper, which is a result of past scientific research and high-profile publications, was prepared in cooperation with State Key Laboratory of Rail Traffic Control and Safety, Jiaotong University, Bejing, China and Universidad Politécnica de Madrid, Spain. The importance of the radio wave propagation characteristics in curved tunnels for designing reliable communications in subway systems is emphasized in the paper. The extensive propagation measurements conducted in two typical types of subway tunnels with different radii of curvature and different configurations (frequency, polarizaton) are presented. The results provide the insight into the large-scale fading characteristics in real curved subway tunnels at various frequencies. The qualitative analysis and corresponding findings are useful for the link budget, channel modeling, and validation for simulators of various wireless communication systems deployed in real curved tunnels, realizing the intelligent transportation system in subway and railway systems.
COBISS.SI-ID: 28657191