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Clustering is a key concept of existing MIMO channel models, such as the COST 2100 model. Parameter based clustering has been studied for a while, but how parameter based clusters relate to the physical environment is not well known yet. A measurement based ray launching tool is developed and used for studying clustering and its relation to physical scatterers. By using estimated angles and delays
The problem of burst losses in OBS networks has an impact on the service quality perceived by end users. In order to guarantee certain level of Service Quality (QoS) in terms of burst losses, wavelength resources have to be dimensioned properly. In this paper, we address the problem of the Virtual Topology (VT) design that concerns the establishment of explicit routing paths and the allocation of
This article presents an architecture of a Digital Front-End Receiver (DFE-Rx) for the next-generation mobile terminals. A main focus is placed in flexibility, scalability and concurrency. The architecture is capable of detecting, synchronizing and reporting carrier-frequency offset, of multiple concurrent radio standards. The proposed receiver is fabricated in a 65nm CMOS low power high-VT cell t
When developing applications for end-user nodes in distributed systems, it is not unusual to find that the business logic part of the solution is relatively inexpensive to develop. The resource intense parts of the solution are more likely to be those of presenting the functionality provided by the node to the end-user, and of connecting the node with the rest of the system. By considering systems
Abstract— Context: Software product lines (SPL) are used in industry to achieve more efficient software development. To test a SPL is complex and costly and often becomes a bottleneck in the product line organization. Objective: This research aims to develop and evaluate strategies for improving system test selection in a SPL. Method: Initially industrial practices and research in both SPL testing
Pervasive middleware systems are important for enabling the configuration and coordination of the services provided by devices in pervasive environments. PalCom is an example of such a system that aims to enable interaction among pervasive services over heterogeneous networks. In this paper we discuss the need for providing networking-media independent messaging among pervasive devices, and identi
Massive MIMO is considered a key technology for the future wireless communication systems. The promising properties in terms of higher spectral and transmit-energy efficiency are brought by the large number of antennas at the base station (BS). As the number of antennas increases, the aperture of the BS antenna array may become much larger, as compared to today's antenna arrays. In this case, mobi
This study is concerned with a specific rerouting strategy in telecommunication networks named Elastic Robust Rerouting (ERR), introduced first in [8]. We recall main points on this strategy, provide mathematical formulation and discuss in details a solution method. The second question studied in this paper is concerned with its distributed version and some related implementation issues. We report
We present a method to compute, quickly and efficiently, the mutual information achieved by an IID (independent identically distributed) complex Gaussian input on a block Rayleigh-faded channel. The method accommodates both scalar and MIMO (multiple-input multiple-output) settings. Operationally, the mutual information thus computed represents the highest spectral efficiency that can be attained u
In this paper we propose a novel trellis based soft-input soft-output MIMO detector with significantly reduced search space. The performance of the detector is measured by evaluating the ultimate communication rate that is achievable for a system employing the novel detector; this limit corresponds to a mutual information that can be determined by standard methods. We also derive an expression tha
Spatially-Coupled LDPC (SC-LDPC) codes have been recently shown to be very efficient for transmissions over nonergodic channels, in particular over block-fading channels [1]. In fact, it is possible to design a SC-LDPC code with any given code diversity [2]. In this work, we investigate the performance of SC-LDPC codes over block-fading channels, assuming a mismatch (or offset) between the first b
We introduce a mixed-integer optimization model for two-layer IP-over-Flexgrid networks, and present a cost study performed using the CPLEX package for the introduced model. The study concerns a generic German network with 12 nodes and 20 links in the optical layer, and a set of six IP traffic matrices with increasing demand volumes. The optimization assumes a hot-standby mechanism in the optical
We present a model for estimating the final keep/cancel decision point, on a per-feature basis, for scope inclusion in a future release. The Basic Lost Opportunity Estimation Model (BLOEM), based on data from a company that uses an agile-inspired software development model, supports feature selection when the time-dependent business value estimates change as the requirements analysis progresses. T
Measurement results of an analog channel decoder in 65 nm CMOS are presented. We target ultra compact and low power applications with low to medium throughput requirements. The decoding core is designed for (7,5)(8) convolutional codes and takes 0.104 mm(2) on silicon. The degrading effects of analog imperfections are investigated and the presented results allow power, performance and throughput t
Industry--academia collaboration is critical for empirical research to exist. However, there are many obstacles in the collaboration process. This paper reports on the experiences gained by the author, in a 2-year collaboration project on software testing which involved on-site work by the researcher in the industry premises. Based on notes, minutes of meetings, and progress reports, the project h
Reference attribute grammars (RAGs) is a powerful formalism for developing modular extensible compilers and program analysis tools. This paper presents JavaRAG, an implementation of RAGs as a Java library that is independent of the abstract syntax tree structure. This makes it possible to extend legacy compilers implemented in Java with RAG computations. We have evaluated the approach by integrati
