Search results

Over-the-air multi-probe setups provide an efficient way to characterize the performance of today’s advanced wireless communication systems. In this paper the measurement uncertainty of such a setup using a car as a test object is characterized through three experiments: measurement system analysis, channel sounder measurements, and probe coupling measurements. Four issues were in focus for the an

Abstract in UndeterminedIn this paper, we present and evaluate the performance of a dynamic dual-link wideband multiple-input-multiple-output ( MIMO) channel sounder. The channel sounder can simultaneously measure two wideband dual-polarized links, each with a MIMO matrix size of 30 x 30 and 30 x 32. Multi-link MIMO systems, including multiuser and cooperative MIMO, are essential parts of future h

We deal with the construction of optimal channel shortening, also known as combined linear Viterbi detection, algorithms for ISI and MIMO channels. In the case of MIMO channel shortening, the tree structure to represent MIMO signals is replaced by a trellis. The optimization is performed from an information theoretical perspective and the achievable information rates of the shortened models are de

In this paper a number of low-complexity channel estimator structures tailored to the needs of LTE terminals have been investigated. The focus has been on the algorithms exhibiting reduced complexity while providing an acceptable level of performance. To design these estimators other factors such as interoperability with another OFDM-based standard, DVB-H, in a multi-standard environment have been

A general coupling-based model framework for wideband multiple-input multiple-output (MIMO) channels is presented in this paper. Under this framework, the channel state information (CSI) tensor can be expressed by the product of a coupling tensor, a complex Gaussian tensor and three unitary matrices. The unitary matrices can be either eigenbases or steering matrices in different domains. The coupl

This paper describes a named entity recognition (NER) system for short text messages (SMS) running on a mobile platform. Most NER systems deal with text that is structured, formal, well written, with a good grammatical structure, and few spelling errors. SMS text messages lack these qualities and have instead a short-handed and mixed language studded with emoticons, which makes NER a challenge on

Abstract in Undeterminedhis survey deals with computational complexity of column generation problems arising in the design of survivable communication networks. Such problems are often modeled as linear programs based on noncompact multicommodity flow network formulations. These formulations involve an exponential number of path-flow variables, and therefore require column generation to be solved

In this work we present a fully integrated Radio-Fiber interface implemented in 65nm CMOS, intended for remote antenna units (RAUs) in distributed antenna systems. To relax the requirements on the optical components, an intermediate frequency (IF) signal (100MHz) is transmitted over the multi-mode fiber, which is then up-converted to 2.2GHz inside the RAU. Local Oscillator (LO) signals to the mixe

This paper presents a multimode soft-output multiple-input multiple-output (MIMO) signal detector that is efficient in hardware cost and energy consumption. The detector is capable of dealing with spatial-multiplexing (SM),break space-division-multiple-access (SDMA), and spatial-diversity (SD) signals of 4 ✕ 4 antenna and 64-QAM modulation. Implementation-friendly algorithms, which reuse most of t

In this work a low power 5th order chebyshev active-RC low pass filter that meets Rel-8 LTE receiver requirements has been designed with programmable bandwidth and overshoot. Designed for a homodyne LTE receiver, filter bandwidths from 700kHz to 10MHz are supported. The bandwidth of the operational amplifiers is improved using a novel phase enhancement technique. The filter was implemented in 65nm

This paper presents a front-end architecture for fully integrated 60 GHz phased array receivers. It employs LO-path beamforming using a phase controlled phase-locked loop (PC-PLL). To demonstrate the architecture a circuit is implemented featuring a two stage low noise amplifier, two cascaded active mixers, and a PC-PLL. The receiver downconverts the 60 GHz signal in two steps, using LO signals fr

In this paper, we present a novel approach for the design of rate-maximizing channel shortening detectors with soft feedback side information for frequency-selective channels. The detector is a soft-input soft-output detector and constitutes one of the components of an iterative receiver. The design optimization is performed from an information-theoretic perspective where we maximize the achievabl

Abstract in UndeterminedIn order to create a successful software product and assure its quality, it is not enough to fulfill the functional requirements, it is also crucial to find the right balance among competing quality requirements (QR). An extended, previously piloted, interview study was performed to identify specific challenges associated with the selection, tradeoff, and management of QR i

Large market-driven software companies face new challenges in requirements engineering and management that emerged due to their recent extensive growth. At the same time, the pressure generated by competitors’ and users’ expectations demands being more competitive, creative and flexible to more quickly respond to a rapidly changing market situation. In the pursuit of staying competitive in this co

Laplace motion is a Levy process built upon Laplace distributions. Non Gaussian stochastic fields that are integrals with respect to this process are considered and methods for their model fitting are discussed. The proposed procedures allow for inference about the parameters of the underlying Laplace distributions. A fit of dependence structure is also addressed. The importance of a convenient pa

A new version of the stream cipher Grain-128 is proposed. The new version, Grain-128a, is strengthened against all known attacks and observations on the original Grain-128, and has built-in support for optional authentication. The changes are modest, keeping the basic structure of Grain-128. This gives a high confidence in Grain-128a and allows for easy updating of existing implementations.

The design and layout of a two stage SiGe E-band power amplifier using a stacked transformer for output power combination is presented. In EM-simulations with ADS Momentum, at E-band frequencies, the power combiner consisting of two individual single turn transformers performs significantly better than a single 2:1 transformer with two turns on the secondary side. Imbalances in the stacked transfo