Jiri Sebesta

Phase difference of arrival distance estimation for RFID tags in frequency domain

The paper gives an overview of phase based ranging techniques, focusing on the phase difference of arrival method measured in frequency domain (FD-PDoA). After a theoretical overview of distance estimation and localization, it introduces an experimental RFID front-end prototype used for FD-PDoA measurements. Proposed modular design is very flexible and allows easy replacement of any block, as well as direct access to all required low-level signals. The main part of the article is devoted to range estimation experiments in an anechoic chamber, using the developed front-end and signal processing in a PC with MATLAB. Several measurement problems are addressed, such as demodulator phase imbalance correction, wrapped phase recovery, etc. Ranging is performed with common passive EPC Gen2 RFID tags.

Relative timing characteristics of GPS timing modules for time synchronization application

This paper is focused on the measurement and evaluation of the relative timing characteristics of GPS (Global Positioning System) timing receivers for time synchronization application. I-Lotus M12M oncore timing modules optimized for the timing applications were utilized as tested timing modules. These modules represent the next generation of the low cost GPS timing receivers which expect accuracy of time synchronization to the so-called Universal Time Coordinated (UTC) in the nanoseconds. The previous generation of receivers was M12+ oncore. Measurement was realized with two M12M timing receivers to obtain their relative time error. The relative time differences between generated 1PPS (one pulse per second) output signals (between rising edges of the pulses) and also 100PPS signals were measured. Error from UTC time was not needed to know but only relative time error between generated 1PPS (100 PPS) signals by the receivers. From the viewpoint of these receivers application for precise time synchronization measured date are presented and statistically evaluated. The aim of using such timing system is a precision signal marking in different known locations.

Exploring and Measuring Possible Co-Existences between DVB-T2-Lite and LTE Systems in Ideal and Portable Fading Channels

From the point of technical innovations the development and standardization of Digital Video Broadcasting - 2 nd Generation Terrestrial (DVB-T2) and Long-Term Evolution (LTE) systems are definitely the most significant results in the last decade. These systems have a very high potential to fulfill the highest user requirements, but they can operate in the same frequency spectrum. As a result, different co-existence scenarios can occur. In this paper, we explore and measure the co-existence between DVB-T2-Lite (e.g. portable TV) and LTE multimedia services in ideal and portable fading channel models. Theoretical backgrounds of the investigated co-existence scenarios, proposal and realization of an appropriate workplace for their measuring and evaluation are presented and described. Moreover, deeper investigation of the mutual influence of the DVB-T2 system on the LTE one is also explored and graphically illustrated. The obtained results show that these co-existences could be critical for both systems from the point of providing multimedia services with a constant level of Quality of Services (QoS).

Coexistence Between DVB-T/T2 and LTE Standards in Common Frequency Bands

In the last decade, fulfilling the growing users’ expectations on the quality of provided multimedia services is one of the biggest challenges for different wireless communication systems. However, many times, different kinds of wireless systems can operate in the same (shared) frequency band. Such coexistence generally negatively affects the performance of the systems colliding. This is especially true for the widely used Digital Video Broadcasting-Terrestrial (DVB-T) or upcoming DVB-2nd Generation Terrestrial (DVB-T2) and Long-Term Evolution (LTE) standards, operating in Europe. Hence, the aim of this paper is to explore the impact of interfering mobile telecommunication services on the mobile TV services provided by LTE and DVB-T/T2 systems in the same frequency band. For the simulation of the coexistence between the LTE and DVB-T/T2 services on the physical layer level, an appropriate method is proposed and complex simulation tools are coupled. The results, presented as a dependence of modulation error ratio at the receiver input and bit error ratio at the channel decoder input on the spectral level ratio, show comparable performances for DVB-T and DVB-T2 systems. Results from simulations are verified by laboratory measurements and should help to better understand the influence of co-channel interferences from LTE mobile networks on DVB-T/T2 networks for mobile transmission scenarios.

Study of the coexistence between ZigBee and Wi-Fi IEEE 802.11b/g networks in the ISM band

The number of wirelessly connected multimedia devices and different communication standards, supported by these devices, is rapidly increasing. However, the appropriate frequency bands (licensed and unlicensed) for data transmission by these standards are very limited. The rising density of wireless networks and their coexistence in the same or adjacent radio frequency (RF) spectrum can significantly decrease the quality of provided services. This paper deals with the study of coexistence between ZigBee (IEEE 802.15.4) and Wireless Fidelity (Wi-Fi) networks, including the IEEE 802.11b/g standards, which operate in the unlicensed Industrial, Scientific and Medical (ISM) band at 2.4 GHz. Firstly, a general simulation model was developed. Secondly, to verify results from simulation by measurement, an appropriate laboratory workplace in anechoic chamber was proposed and realized. Such setup and the measurement principle are briefly described in this paper too. Impact of the IEEE 802.11b/g networks on the ZigBee and vice versa is evaluated by dependence of bit error rate (BER) and error vector magnitude (EVM) on the power imbalance between power levels of considered RF signals, respectively.

BLE device indoor localization based on RSS fingerprinting mapped by propagation modes

Nowadays, Bluetooth Low Energy (BLE) technology has a great attention in the field of wireless localization techniques, especially in the case of indoor scenarios. Study presented in this paper explores BLE localization performance in indoor scenarios based on a received signal strength (RSS). Firstly, we present a Ray-Launching based application to emulate BLE radio frequency (RF) signal propagation in the office environment. Secondly, an appropriate measurement workplace and its setup is proposed to measure RSS values. Obtained results are used to create an RSS-fingerprinting map. Furthermore, accuracy of position determination is calculated and evaluated. Results show advantage of BLE technology for indoor localization purposes (without calibration measurement). However, its performance highly depends on the number of considered BLE nodes and on applied evaluation method (e.g. number of considered sectors).

Study of the performance of RSSI based Bluetooth Smart indoor positioning

Recently, there is a high interest for appropriate systems and methods to localize the position of people and their devices in indoor environments (e.g. home, office, hospital). From technical and economical points of view, Bluetooth Low Energy (BLE) is one of the promising technologies in this field. This paper deals with the study of performances of this technology for these purposes. For the indoor localization, a received signal strength indication (RSSI) method is used. It was tested in ideal (anechoic chamber) and real (in the office) environment conditions. For the measurement campaign and evaluation of the obtained results a generic framework is proposed. Experimental results (simulation vs. measurement) show similar behaviour of the BLE technology in ideal (no signal reflection) and real (multipath propagation) transmission environments.

Doppler Radar System for Small Objects Localization

This paper addresses design of a localization system using Doppler radar. First the hardware requirements are discussed. A lot of attention is paid to logarithmic amplifier issues as it plays a key role in the final design. Then the time-frequency analysis is presented as an option for signal processing.

Symbol Detection in Avalanche Photodiode Based Optical Receiver

The paper deals with OOK (on-off keying) symbol detection in additive white Gaussian noise. In the case of avalanche photodiode (APD) based receiver the optimum threshold voltage for symbol detection varies with received signal power, avalanche multiplication gain and excess noise factor. Since the optimum threshold is complex to implement, a simpler criterion for symbol detection is usually used. Although some strategies of threshold evaluation show an inconsiderable sensitivity loss, they are often used because of their simplicity

Influence of the LTE System using Cognitive Radio Technology on the DVB-T2 System using Diversity Technique

In recent years, the development of advanced wireless communication systems has been rapidly progressing. In Europe, the 2nd Generation Terrestrial Digital Video Broadcasting (DVB-T2) and Long-Term Evolution (LTE) are the most promising techniques to provide multimedia services efficiently (in flexible quality and with high spectrum efficiency). The purpose of this work is to explore possible influences of the LTE uplink services, using cognitive radio (CR) technology, on the area which is covered by DVB-T2 services. In the case of DVB-T2, both single-input single-output (SISO) and multiple-input single-output (MISO) transmission techniques are considered. The defined coexistence scenarios are measured with an appropriate measurement testbed. The performance of the received TV signal is evaluated on its physical layer (PHY) level. The obtained results allow better understand the influence of LTE system on DVB-T2 which is using diversity technique in the same RF channel (co-channel coexistence). One of the main results is that there are the same requirements on the Forward Error Correction (FEC) decoding process in the DVB-T2 receiver, when power imbalances between TV transmitters (an both SISO and MISO modes) are considered at the interfering LTE signal. This finding was also proved by analysis of variance (ANOVA).