Reduced Ecological Footprints of Modern Facilities Introducing the Implementation of Advanced Wireless Technologies, and Human Resources’ Benefits

The necessity of lowering the mean power consumption of various facilities, due to the lack of their enormous future energy needs, led to an ongoing advance of various technologies. These technologies have been oriented towards the concept of a Reduced Ecological Footprint. Massive structures (such as building complexes and hospitals) have been redesigned and upgraded;many interior designs have been dramatically altered while new electronic devices are constantly being produced in order to revolutionize a long term perspective towards a “Green Planet” while they exhibit astonishing signal processing. Consequently, an enormous technology already exists which needs to be properly combined to a proposed methodology and to new ideas relevant to systems’ administration through automatic wireless control. This paper intends to reduce the gap between design and realization of the aforementioned research. Consequently, the primary contribution of this research is the proposal of a complete design protocol with minimized defects relevant to Reduced Ecological Footprints of Facilities (REFF) along with its beneficial advantages relevant to providing a healthy and productive work environment. This protocol consists of four main parts which are 1) the main key points-guidelines, 2) its objectives, 3) the know-how methodology for implementation in existing installations and 4) the description of the imminent benefits in workforce/human resources.

Enhanced PAPR in OFDM without Deteriorating BER Performance

Orthogonal frequency division multiplexing (OFDM) is vastly used in wireless networks. Its superiority relies on the fact that information can be split in large amount of frequencies. Each frequency is called information subcarrier. OFDM exhibits excellent annotation in channel fades and interferers as only a few subcarriers can be affected and consequently a small part of the original data stream can be lost. Orthogonality between frequencies ensures better spectrum management and obviates the danger of intersymbol interference. However, an essential problem exists. OFDM systems have high peak to average power ratio. This implies large fluctuations in signal power, ending up in increasing complexity of ADCs and DACs. Also, power amplifiers must work in a larger linear dynamic region. In this paper we present two new techniques for reducing Peak to Average Power Ratio (PAPR), that can be added in any OFDM system and we compare them with other existing schemes.

Turbo Codes―A New PCCC Design

Coding techniques have always been a major area of scientific interest. Due to this interest, many coding schemes were invented. Eventually, their implementation in various systems contributed in the evolvement of Wireless Communications. A breakthrough was definitely Turbo coding. Particularly, the concept of joining two or more convolutional encoders in parallel (PCCC) or in serial (SCCC), along with the iterative decoding technique, literally raised the expectations of the anticipated BER performance. In fact, Concatenated Convolutional Codes clearly outperform convolutional codes. Moreover, various systems, either under development or either for future use, will have high standards. The previous systems should present exceptional tolerance of noise effects and consequently a low overall number of received errors. For this purpose a new PCCC design was developed. The system’s performance analysis, using an AWGN channel, showed better results for various iterations compared to other schemes such as typical PCCC, SCCC and finally a Convolutional encoder with a Viterbi decoder.

Measurements of Balun and Gap Effects in a Dipole Antenna

In the present paper, design and analysis of a 2.4 GHz printed dipole antenna for wireless communication applications are presented. Measurements on return loss and radiation pattern of this antenna configuration are included in this investigation. The printed dipole is combined with the feeding structure of a microstrip via-hole balun and is fabricated on an FR-4 printed-circuit-board substrate. Two inevitable discontinuities are introduced by this antenna architecture in the form of right-angle bends in the microstrip feed line and in the dipole’s gap, respectively. The impact of mitering these bends in the reflection coefficient, resonance bandwidth and radiation pattern of antenna has been investigated by means of simulation and experiment.

Envelope Correlation Parameter Measurements in a MIMO Antenna Array Configuration

In a 2 × 2 MIMO antenna array system envelope correlation coefficient “ρ” shows the influence of different propagation paths of the RF signals that reach the antenna elements. The approximated value of this coefficient is based on a simple closed-form equation and also varies from 0 to 1. Quite perfect performance for MIMO applications is achieved when this parameter approximates to zero. In this paper, we evaluate an antenna diversity MIMO system by measuring the envelope correlation coefficient. The corresponding results in our antenna array configurations show that the measured “ρ” has very small values and approximates to zero. This observation indicates quite perfect behavior and performance of our MIMO antenna array system.

A/D Restrictions (Errors) in Ultra-Wideband Impulse Radios

Ultra-Wideband Impulse Radio (UWB-IR) technologies, although are relatively easy in transmission but they present difficulties in reception, in fact the reception of such waveform is a quite complicated matter. The main reason is that in fully digital receiver the received waveform must be sampled at a rate of several GHz. This paper focuses on the impact of the Analog to Digital (A/D) conversion stage that is used to sample the received waveform. More specifically we focus on the impact of the two main parameters that affect the performance of the Software Defined Radio (SDR) system. These parameters are the bit resolution and the time jittering. The influence of these parameters is deeply examined.

Development and Experimental Measurements of a Tunable Antenna

Modern telecommunication systems need to be equipped with antennas that are precisely tuned to more than one frequency in order to allow operation in several bands. Antenna precise tuning to the desired frequency is very important for system performance. In this paper the operating frequency of a PIFA antenna is adjusted using a varactor. This configuration has the advantage of continuous tuning, thus correcting any frequency deviation due to environmental or other changes. The PIFA antenna’s tuning ranges from 860 MHz to 1025 MHz. Also, the geometry of the antenna is studied through simulations and the effect of the varactor is tested experimentally.

Geometry Aspects and Experimental Results of a Printed Dipole Antenna

Detail experimental measurements of a 2.4 GHz printed dipole antenna for wireless communication systems is presented and discussed. A group of printed dipoles with integrated balun have been designed and constructed on a dielectric substrate. This paper is based on modifications of the known printed dipole architecture. The corresponding printed dipole antennas have differences on their forms that are provided by two essential geometry parameters. The first parameter l is related to the bend on microstrip line that feeds the dipole and the second w corresponds to the form of the dipole’s gap. The impact of these parameters on reflection coefficient and radiation pattern of antenna has been investigated. The corresponding measured results indicate that the return loss and radiation pattern of a printed dipole antenna are independent of the w parameter. Instead, variations in the value of the l parameter in the dipole’s structure affect the form of the corresponding return loss. These observations are very important and provide interesting considerations on affecting design and construction of antenna elements at frequency range of 2.4 GHz.

Design and Analysis of a Multiple-Input Receiver for Mimo Wireless Applications

In this article, we present multiple-input receiver architecture for MIMO (Multiple-Input Multiple-Output) wireless communication applications. The proposed implementation is provided by a defined number of identical receiver units that are fed by a RF modulated signal on specific carrier frequency, power strength and initial phase. These units carry out the corresponding amplification, filtering and demodulation procedures. Details on design and implementation of this Printed-Circuit-Board are introduced and further discussed. Experimental results are also presented, allowing the validation of investigation on the performance of the current receiver architecture. Besides, these measurements indicate that the proposed device, combining with a suitable antenna array, provides a versatile receiver platform for baseband signal processing. The incoming RF modulated signals have frequencies on the range of 2.4 GHz, several phases, magnitudes and modulation modes. From these, it seems that the proposed receiver implementation supports MIMO communication and multiple port channel characterization applications at 2.4 GHz ISM (Industrial, Scientific and Medical) band.

Design and Measurements of Ultra-Wideband Antenna

This paper describes the design, realization and experimental measurements of an antenna element to operate at ultra-wideband (UWB) spectrum. The type of this antenna is a circular disk monopole (CDM), with two notches opposite to each other at two sides of the disk. The feed of the antenna is a coplanar waveguide (CPW). The effect of the presence of the notches is studied through simulations and tested experimentally.

Reducing Peak-to-Average Power Ratio of a Turbo Coded OFDM

Peak to Average Power Ratio (PAPR) is defined as the instantaneous power (maximum value) to the average power ratio. PAPR is considered to be a major problem in OFDM systems. This problem can cause radical unexpected behavior of the signal fluctuation. This fluctuation is constituted by a large number of power states. The enormous number of these states leads to an additional complexity of ADCs and DACs. This research addresses the previous problem in OFDM systems utilizing Turbo Codes. μLaCP technique is employed for the purpose of decreasing PAPR. Moreover, our OFDM system was simulated in the presence of an AWGN channel with four types of codes (without the presence of ADCs and DACs). These were constituted of PCCC (typical and new), SCCC, and Convolutional Codes. Our Turbo Coded OFDM exhibited unchanged BER performance before and after the use of μLaCP technique. This was accomplished by modifying our previous PAPR reduction technique without sacrificing greatly its attributes.

Turbo Coded OFDM with Large Number of Subcarriers

Wireless communication systems have greatly advanced during the last years. A significant contributor in these systems’ performance has been Orthogonal Frequency Division Multiplexing (OFDM). Since its invention, it is considered to be a technological leap. This leap in splitting an information stream in multiple frequency carriers has been adapted by various scientists working on the development of wireless systems. Moreover, as OFDM presented excellent tolerance of channel fading and noise signals, the evolvement in terms of speed and reliability was consequent, because only a small stream of information is lost due to noise effects. OFDM along with the knowledge that Turbo codes is another excellent scheme of reducing BER, has triggered us to expand our research. So, we experimented in simulation level not only in joining OFDM with Turbo Codes but even in finding a better Turbo scheme compared to a typical PCCC, SCCC and a Convolutional encoder with Viterbi decoder. As the last goal has already been accomplished, in this paper is presented the new OFDM system consisted of our Turbo scheme. The analysis of the previous system took into consideration the effects of an AWGN channel. Also, this noise analysis was conducted using a simulation platform with specific attributes such as transmitting and receiving fixed number of subcarriers (2048 carriers after IFFT block) while using different types of convolutional concatenated codes, such as PCCC (Parallel), SCCC (Serial) and the new PCCC scheme. The results clearly show not only the improvement in the BER performance of the Turbo Coded OFDM systems (compared to others consisted of Viterbi decoders) but the overall superiority of the proposed design.

Rainfall Measurements Due to Radio Frequency Signal Attenuation at 2 GHz

In this paper we present an experimental validated system for measuring rainfall due to radio frequency (RF) signal attenuation at 2 GHz. Measurements took place in Ioannina, NW Greece, starting in April 2015 and lasting for twelve months. The primary acquired extensive results have shown reliable and accurate measurements for rainfall amounts smaller than 1 mm for 5 min periods. The very important innovation is that this paper presents significant earth-to-earth measurements due to rainfall attenuation (at 2 GHz) in order to act as a map for future investigation and as a prior knowledge for the behavior of other systems operating at frequencies around S-band.