Sebastian Kozlowski

Time-Modulated Reconfigurable Antenna Based on Integrated S-PIN Diodes for mm-Wave Communication Systems

This paper concerns the study of the mm-wave reconfigurable antennas based on S-PIN diodes suitable for using in mm-wave communication systems. The investigated antennas were designed, fabricated, and subjected to the measurements in both steady and transient states. One selected antenna was incorporated into a wireless system to determine its suitability for operating in such a system as a time-modulated linear array. By means of appropriate switching of the antenna, multiple radio frequency (RF) chains were simulated in a receiver having only one RF chain. This allowed applying a combining technique for improving the system performance in a presence of a strong interfering signal.

Measurements and Analysis of the Propagation Channel for Various Indoor Environments

The paper presents measurements results of the propagation channel for three types of indoor environments. Basing on these results statistical analysis and comparison of obtained data are presented. Short review of channel profile measurement techniques are also presented. The paper includes discussion of indoor channel propagation type influence on positioning systems accuracy. Measurements were part of EU VI FP RESOLUTION project, in which WUT was responsible for propagation and antennas work package.

Phased Array Antennas in MIMO Receiver

In this paper, a computer simulation of a MIMO system comprising phased array antennas (PAA) in all receiving branches is presented. In order to examine the system performance under relatively realistic conditions, a ray-tracing simulator was applied to generate a baseband channel impulse response matrix H. A bit error rate (BER) of two systems utilizing different detection methods: V-BLAST and simple matrix inversion was examined in order to determine phased array antennas applicability. Results of an attempt to determine relationship between BER and properties of particular H matrix realisation are also provided.

Computer Simulations of the Propagation Channel for Various Indoor Environments

This paper presents the results of computer simulations performed as a part of EU VI FP RESOLUTION project. Conducted research concerns propagation of radio waves inside large halls. Channel characteristics influencing on accuracy of microwave positioning system were determined by means of ray-tracing method. Various propagation scenarios, locations of transmitter and radiation patterns of transmitting antenna were taken into consideration.

Implementation and verification of cyclostationary feature detector for DVB-T signals

This study deals with implementation and verification of the cyclostationary feature detector suitable for DVB-T signals. A new decision statistic has been proposed for a multi-cycle detector. Computer simulations have shown that it outperforms decision statistics of similar complexity in terms of the probability of missed detection for fixed probability of false alarm. The detector utilising the new decision statistic has been implemented in the experimental set-up and used for detection of the digital television signal. The measurement results have been compared against the results obtained from the computer simulations.

The project and implementation of an upconverter for the DVB-T signal

DVB-T is becoming the most popular standard of terrestrial video transmission. The number of devices working in this standard is growing; therefore developing methods and measurement set-ups enabling testing entire devices as well as their sections is reasoned. In the present paper there has been shown a project and test results of a system, whichs aim was to transmit the DVB-T signal in any frequency channel in the range of 470-870 MHz. The system is supposed to be a core of automated DVB-T measurements setup and consists of the DTA-116 TV card and the constructed device, which is a low-cost alternative for the commercial solutions. The upconverter was designed, realized in PCB technique and tested experimentally.

Performance of MIMO System with Receiver Employing Phased Array Antennas

This paper presents the results of computer simulation of a MIMO system comprising phased array antennas (PAA) in all receiving branches. Values of baseband channel impulse responses were calculated by the ray-tracing simulator in order to examine the system performance under relatively realistic conditions. An applicability of PAAs was investigated by means of comparison of a bit error rate (BER) of two MIMO systems working in the same environment. Receiver of the first one employed PAAs, while receiver of the latter one was provided with simple omnidirectional radiators. Additionally, each receiver was assumed to utilize two different detection methods: V-BLAST and simple matrix inversion.

SDR implementation of the receiver of adaptive communication system: SDR Implementation of an Adaptive Rx

The paper presents software implementation of a receiver forming a part of an adaptive communication system. The system is intended for communication with a satellite placed in a low Earth orbit (LEO). The ability of adaptation is believed to increase the total amount of data transmitted from the satellite to the ground station. Depending on the signal-to-noise ratio (SNR) of the received signal, adaptive transmission is realized using different transmission modes, i.e., different modulation schemes (BPSK, QPSK, 8-PSK, and 16-APSK) and different convolutional code rates (1/2, 2/3, 3/4, 5/6, and 7/8). The receiver consists of a software-defined radio (SDR) module (National Instruments USRP-2920) and a multithread reception software running on Windows operating system. In order to increase the speed of signal processing, the software takes advantage of single instruction multiple data instructions supported by x86 processor architecture.

SDR implementation of the receiver of adaptive communication system

The paper presents description of software implementation of the receiver of adaptive communication system. The system is foreseen to be used to communicate with a satellite placed in low Earth orbit (LEO), in order to increase amount of data transmitted from the satellite to the ground station. Depending on signal to noise ratio (SNR) of the received signal adaptive transmission using different modulation schemes (BPSK, QPSK, 8PSK, 16APSK) and different convolutional code rate (1/2, 2/3, 3/4, 5/6, 7/8) is realized.