UWB Radio Wireless Communication System Design for Railway Tunnels

Railway is an economical and comfortable mode of transportation for long distances. Safety, reliability and good quality of service are the main concern of railway industries which are maintained by railway management and communication system. There are several existing management systems like CCCS, ATCS, PTC and many more. With increasing population, demand for railway services also increases. To full fill these demands railway infrastructure has been developing continuously. By implementing latest technologies for railway communication we can make railway transportation safer, efficient, and more accessible. Ultra wideband radio communication system is amongst those very latest and rapidly growing technologies. This research work focuses on the study of UWB radio based wireless communication system for railway tunnels, whose main task is to maintain an uninterrupted data transmission between train driver to wayside controller

Ultra Wideband Preliminaries

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Comparison of Bit Error Rate and Power Spectral Density on the Ultra Wideband Impulse Radio Systems

Ultra-Wideband (UWB) is defined as a wireless transmission scheme that occupies a bandwidth of more than 25% of its center frequency. UWB Impulse Radio (UWB-IR) is a popular implementation of the UWB technology. In UWB-IR, information is encoded in baseband without any carrier modulation. Pulse shaping and baseband modulation scheme are two of the determinants on the performance of the UWB-IR. In this thesis, both temporal and spectral characteristics of the UWB-IR are examined because all radio signals exist in both the time and frequency domains. Firstly, the bit error rate (BER) performance of the UWB-IR is investigated via simulation using three modulation schemes: Pulse position modulation (PPM), on-off shift keying (OOK), and binary phase shift keying (BPSK). The results are verified for three different pulse shaping named Gaussian first derivative, Gaussian second derivative, and return-to-zero (RZ) Manchester. Secondly, the effects of the UWB-IR parameters on the power spectral density (PSD) are investigated because PSD provides information on how the power is distributed over the radio frequency (RF) spectrum and determines the interference of UWB-IR and the existing systems to each other in the spectrum. The investigated UWB-IR parameters include pulse duration, pulse repetition rate, modulation scheme, and pseudorandom codes

A Millimeter-Wave Coexistent RFIC Receiver Architecture in 0.18-µm SiGe BiCMOS for Radar and Communication Systems

Innovative circuit architectures and techniques to enhance the performance of several key BiCMOS RFIC building blocks applied in radar and wireless communication systems operating at the millimeter-wave frequencies are addressed in this dissertation. The former encapsulates the development of an advanced, low-cost and miniature millimeter-wave coexistent current mode direct conversion receiver for short-range, high-resolution radar and high data rate communication systems. A new class of broadband low power consumption active balun-LNA consisting of two common emitters amplifiers mutually coupled thru an AC stacked transformer for power saving and gain boosting. The active balun-LNA exhibits new high linearity technique using a constant gm cell transconductance independent of input-outputs variations based on equal emitters’ area ratios. A novel multi-stages active balun-LNA with innovative technique to mitigate amplitude and phase imbalances is proposed. The new multi-stages balun-LNA technique consists of distributed feed-forward averaging recycles correction for amplitude and phase errors and is insensitive to unequal paths parasitic from input to outputs. The distributed averaging recycles correction technique resolves the amplitude and phase errors residuals in a multi-iterative process. The new multi-stages balun-LNA averaging correction technique is frequency independent and can perform amplitude and phase calibrations without relying on passive lumped elements for compensation. The multi-stage balun-LNA exhibits excellent performance from 10 to 50 GHz with amplitude and phase mismatches less than 0.7 dB and 2.86º, respectively. Furthermore, the new multi-stages balun-LNA operates in current mode and shows high linearity with low power consumption. The unique balun-LNA design can operates well into mm-wave regions and is an integral block of the mm-wave radar and communication systems. The integration of several RFIC blocks constitutes the broadband millimeter-wave coexistent current mode direct conversion receiver architecture operating from 22- 44 GHz. The system and architectural level analysis provide a unique understanding into the receiver characteristics and design trade-offs. The RF front-end is based on the broadband multi-stages active balun-LNA coupled into a fully balanced passive mixer with an all-pass in-phase/quadrature phase generator. The trans-impedance amplifier converts the input signal current into a voltage gain at the outputs. Simultaneously, the high power input signal current is channelized into an anti-aliasing filter with 20 dB rejection for out of band interferers. In addition, the dissertation demonstrates a wide dynamic range system with small die area, cost effective and very low power consumption

A Millimeter-Wave Coexistent RFIC Receiver Architecture in 0.18-µm SiGe BiCMOS for Radar and Communication Systems

Innovative circuit architectures and techniques to enhance the performance of several key BiCMOS RFIC building blocks applied in radar and wireless communication systems operating at the millimeter-wave frequencies are addressed in this dissertation. The former encapsulates the development of an advanced, low-cost and miniature millimeter-wave coexistent current mode direct conversion receiver for short-range, high-resolution radar and high data rate communication systems. A new class of broadband low power consumption active balun-LNA consisting of two common emitters amplifiers mutually coupled thru an AC stacked transformer for power saving and gain boosting. The active balun-LNA exhibits new high linearity technique using a constant gm cell transconductance independent of input-outputs variations based on equal emitters’ area ratios. A novel multi-stages active balun-LNA with innovative technique to mitigate amplitude and phase imbalances is proposed. The new multi-stages balun-LNA technique consists of distributed feed-forward averaging recycles correction for amplitude and phase errors and is insensitive to unequal paths parasitic from input to outputs. The distributed averaging recycles correction technique resolves the amplitude and phase errors residuals in a multi-iterative process. The new multi-stages balun-LNA averaging correction technique is frequency independent and can perform amplitude and phase calibrations without relying on passive lumped elements for compensation. The multi-stage balun-LNA exhibits excellent performance from 10 to 50 GHz with amplitude and phase mismatches less than 0.7 dB and 2.86º, respectively. Furthermore, the new multi-stages balun-LNA operates in current mode and shows high linearity with low power consumption. The unique balun-LNA design can operates well into mm-wave regions and is an integral block of the mm-wave radar and communication systems. The integration of several RFIC blocks constitutes the broadband millimeter-wave coexistent current mode direct conversion receiver architecture operating from 22- 44 GHz. The system and architectural level analysis provide a unique understanding into the receiver characteristics and design trade-offs. The RF front-end is based on the broadband multi-stages active balun-LNA coupled into a fully balanced passive mixer with an all-pass in-phase/quadrature phase generator. The trans-impedance amplifier converts the input signal current into a voltage gain at the outputs. Simultaneously, the high power input signal current is channelized into an anti-aliasing filter with 20 dB rejection for out of band interferers. In addition, the dissertation demonstrates a wide dynamic range system with small die area, cost effective and very low power consumption

Channel Sounding for the Masses: Low Complexity GNU 802.11b Channel Impulse Response Estimation

New techniques in cross-layer wireless networks are building demand for ubiquitous channel sounding, that is, the capability to measure channel impulse response (CIR) with any standard wireless network and node. Towards that goal, we present a software-defined IEEE 802.11b receiver and CIR estimation system with little additional computational complexity compared to 802.11b reception alone. The system implementation, using the universal software radio peripheral (USRP) and GNU Radio, is described and compared to previous work. By overcoming computational limitations and performing direct-sequence spread-spectrum (DS-SS) matched filtering on the USRP, we enable high-quality yet inexpensive CIR estimation. We validate the channel sounder and present a drive test campaign which measures hundreds of channels between WiFi access points and an in-vehicle receiver in urban and suburban areas

Performance analysis of ultra wide band indoor channel

This thesis report is submitted in partial fulfillment of the requirements for the degree of Bachelor of Science in Computer Science and Engineering, 2008.Cataloged from PDF version of thesis report.Includes bibliographical references (page 41).Research on wireless communication system has been pursued for many years, but there is a renewed interest in ultra-wideband (UWB) technology for communication within short range, because of its huge bandwidth and low radiated power level. This emerging technology provides extremely high data rate in short ranges but in more secured approach. In order to build systems that realize all the potential of UWB, it is first required to understand UWB propagation and the channel properties arise from the propagation. In this research, the properties of UWB channel for indoor industrial environment was evaluated. A few indoor channel models have been studied so far for different environments but not for indoor industrial environment and various data rates are obtained according to wireless channel environments. Therefore, an accurate channel model is required to determine the maximum achievable data rate. In this thesis, we have proposed a channel model for indoor industrial environment considering the scattering coefficient along with the other multipath gain coefficient. This thesis addresses scattering effect while modeling UWB channel. Here, the performance of UWB channel model is analyzed following the parameters, such as power delay profile and the temporal dispersion properties which are also investigated in this paper.Kazi Afrina YasmeenA. K. M. WahiduzzamanMD. Ahamed ImtiazB. Computer Science and Engineerin

Interference Suppression Performance of Automotive UWB Radars Using Pseudo Random Sequences

Ultra wideband (UWB) automotive radars have attracted attention from the viewpoint of reducing traffic accidents. The performance of automotive radars may be degraded by interference from nearby radars using the same frequency. In this study, a scenario where two cars pass each other on a road was considered. Considering the utilization of cross-polarization, the desired-to-undesired signal power ratio (DUR) was found to vary approximately from -10 to 30 dB. Different pseudo random sequences were employed for spectrum spreading the different radar signals to mitigate the interference effects. This paper evaluates the interference suppression provided by maximum length sequence (MLS) and Gold sequence (GS) through numerical simulations of the radar’s performance in terms of probability of false alarm and probability of detection. It was found that MLS and GS yielded nearly the same performance when the DUR is -10 dB (worst case); for example when fixing the probability of false alarm to 0.0001, the probabilities of detection were 0.964 and 0.946 respectively. The GS are more advantageous than MLS due to larger number of different sequences having the same length in GS than in MLS