Empirical Analysis of Chirp and Multitones Performances with a UWB Software Defined Radar: Range, Distance and Doppler

In this study, a protocol for an unbiased analysis of radar signals' performance. Using a novel UWB software-defined radar, range profile, Doppler profile and detection range are evaluated for both Linear Frequency Modulated pulse and Multitones. The radar was prototyped and is comparable in overall performance to software defined radar test-beds found in the literature. The measured performance was in agreement with the simulations

Mimo and OFDM in Wireless Communication

In day to day life the need of usage of bandwidth has become very expensive. There should be a solution which will give us the maximum usage of bandwidth with less cost and maximum efficiency. The solution is to implement MIMO and OFDM in wireless communication. The combination of MIMO and OFDM with 802.11n wireless LAN implemented on FPGA gives the better performance in terms of speed. This paper includes necessity of MIMO and OFDM in wireless communication and the model designed using MIMO and OFDM in MATLAB simulink and implemented on FPGA

Performance of a Software Defined Radio based Non-Coherent OFDM Wireless Link

With improved technological successions, wireless communication applications have been incessantly evolving. Owing to the challenges posed by the multipath wireless channel, radio design prototypes have become elemental in all wireless systems before deployment. Further, different signal processing requirements of the applications, demand a highly versatile and reconfigurable radio such as Software Defined Radio (SDR) as a crucial device in the design phase. In this paper, two such SDR modules are used to develop an Orthogonal Frequency Division Multiplexing (OFDM) wireless link, the technology triumphant ever since 4G. In particular, a non-coherent end-to-end OFDM wireless link is developed in the Ultra High Frequency (UHF) band at a carrier frequency of 470 MHz. The transmitter includes Barker sequences as frame headers and pilot symbols for channel estimation. At the receiver, pulse alignment using Max energy method, frame synchronization using sliding correlator approach and carrier offset correction using Moose algorithm are incorporated. In addition, wireless channel is estimated using Least Square (LS) based pilot aided channel estimation approach with denoising threshold and link performance is analyzed using average Bit Error Rate (BER), in different pilot symbol scenarios. In a typical laboratory environment, the results of BER versus receiver gain show that with 4 pilot symbols out of 128 carriers, at a gain of 20 dB, BER is 0.160922, which is reduced to 0.136884 with 16 pilot symbols. The developed link helps OFDM researchers to mitigate different challenges posed by the wireless environment and thereby strengthen OFDM technology

Performance of a Software Defined Radio based Non-Coherent OFDM Wireless Link

With improved technological successions, wireless communication applications have been incessantly evolving. Owing to the challenges posed by the multipath wireless channel, radio design prototypes have become elemental in all wireless systems before deployment. Further, different signal processing requirements of the applications, demand a highly versatile and reconfigurable radio such as Software Defined Radio (SDR) as a crucial device in the design phase. In this paper, two such SDR modules are used to develop an Orthogonal Frequency Division Multiplexing (OFDM) wireless link, the technology triumphant ever since 4G. In particular, a non-coherent end-to-end OFDM wireless link is developed in the Ultra High Frequency (UHF) band at a carrier frequency of 470 MHz. The transmitter includes Barker sequences as frame headers and pilot symbols for channel estimation. At the receiver, pulse alignment using Max energy method, frame synchronization using sliding correlator approach and carrier offset correction using Moose algorithm are incorporated. In addition, wireless channel is estimated using Least Square (LS) based pilot aided channel estimation approach with denoising threshold and link performance is analyzed using average Bit Error Rate (BER), in different pilot symbol scenarios. In a typical laboratory environment, the results of BER versus receiver gain show that with 4 pilot symbols out of 128 carriers, at a gain of 20 dB, BER is 0.160922, which is reduced to 0.136884 with 16 pilot symbols. The developed link helps OFDM researchers to mitigate different challenges posed by the wireless environment and thereby strengthen OFDM technology

Architectures and Algorithms for the Signal Processing of Advanced MIMO Radar Systems

This thesis focuses on the research, development and implementation of novel concepts, architectures, demonstrator systems and algorithms for the signal processing of advanced Multiple Input Multiple Output (MIMO) radar systems. The key concept is to address compact system, which have high resolutions and are able to perform a fast radar signal processing, three-dimensional (3D), and four-dimensional (4D) beamforming for radar image generation and target estimation. The idea is to obtain a complete sensing of range, Azimuth and elevation (additionally Doppler as the fourth dimension) from the targets in the radar captures. The radar technology investigated, aims at addressing sev- eral civil and military applications, such as surveillance and detection of targets, both air and ground based, and situational awareness, both in cars and in flying platforms, from helicopters, to Unmanned Aerial Vehicles (UAV) and air-taxis. Several major topics have been targeted. The development of complete systems and innovative FPGA, ARM and software based digital architectures for 3D imaging MIMO radars, which operate in both Time Division Multiplexing (TDM) and Frequency Divi- sion Multiplexing (FDM) modes, with Frequency Modulated Continuous Wave (FMCW) and Orthogonal Frequency Division Multiplexing (OFDM) signals, respectively. The de- velopment of real-time radar signal processing, beamforming and Direction-Of-Arrival (DOA) algorithms for target detection, with particular focus on FFT based, hardware implementable techniques. The study and implementation of advanced system concepts, parametrisation and simulation of next generation real-time digital radars (e.g. OFDM based). The design and development of novel constant envelope orthogonal waveforms for real-time 3D OFDM MIMO radar systems. The MIMO architectures presented in this thesis are a collection of system concepts, de- sign and simulations, as well as complete radar demonstrators systems, with indoor and outdoor measurements. Several of the results shown, come in the form of radar images which have been captured in field-test, in different scenarios, which aid in showing the proper functionality of the systems. The research activities for this thesis, have been carried out on the premises of Air- bus, based in Munich (Germany), as part of a Ph.D. candidate joint program between Airbus and the Polytechnic Department of Engineering and Architecture (Dipartimento Politecnico di Ingegneria e Architettura), of the University of Udine, based in Udine (Italy).Questa tesi si concentra sulla ricerca, lo sviluppo e l\u2019implementazione di nuovi concetti, architetture, sistemi dimostrativi e algoritmi per l\u2019elaborazione dei segnali in sistemi radar avanzati, basati su tecnologia Multiple Input Multiple Output (MIMO). Il con- cetto chiave `e quello di ottenere sistemi compatti, dalle elevate risoluzioni e in grado di eseguire un\u2019elaborazione del segnale radar veloce, un beam-forming tri-dimensionale (3D) e quadri-dimensionale (4D) per la generazione di immagini radar e la stima delle informazioni dei bersagli, detti target. L\u2019idea `e di ottenere una stima completa, che includa la distanza, l\u2019Azimuth e l\u2019elevazione (addizionalmente Doppler come quarta di- mensione) dai target nelle acquisizioni radar. La tecnologia radar indagata ha lo scopo di affrontare diverse applicazioni civili e militari, come la sorveglianza e la rilevazione di targets, sia a livello aereo che a terra, e la consapevolezza situazionale, sia nelle auto che nelle piattaforme di volo, dagli elicotteri, ai Unmanned Aerial Vehicels (UAV) e taxi volanti (air-taxis). Le tematiche affrontante sono molte. Lo sviluppo di sistemi completi e di architetture digitali innovative, basate su tecnologia FPGA, ARM e software, per radar 3D MIMO, che operano in modalit`a Multiplexing Time Division Multiplexing (TDM) e Multiplexing Frequency Diversion (FDM), con segnali di tipo FMCW (Frequency Modulated Contin- uous Wave) e Orthogonal Frequency Division Multiplexing (OFDM), rispettivamente. Lo sviluppo di tecniche di elaborazione del segnale radar in tempo reale, algoritmi di beam-forming e di stima della direzione di arrivo, Direction-Of-Arrival (DOA), dei seg- nali radar, per il rilevamento dei target, con particolare attenzione a processi basati su trasformate di Fourier (FFT). Lo studio e l\u2019implementazione di concetti di sistema avan- zati, parametrizzazione e simulazione di radar digitali di prossima generazione, capaci di operare in tempo reale (ad esempio basati su architetture OFDM). Progettazione e sviluppo di nuove forme d\u2019onda ortogonali ad inviluppo costante per sistemi radar 3D di tipo OFDM MIMO, operanti in tempo reale. Le attivit`a di ricerca di questa tesi sono state svolte presso la compagnia Airbus, con sede a Monaco di Baviera (Germania), nell\u2019ambito di un programma di dottorato, svoltosi in maniera congiunta tra Airbus ed il Dipartimento Politecnico di Ingegneria e Architettura dell\u2019Universit`a di Udine, con sede a Udine

A high speed image transmission system for ultra-wideband wireless links

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.Includes bibliographical references (p. 97-98).Ultra-wideband (UWB) communication is an emerging technology that offers short range, high data rate wireless transmission, with low power consumption and low consumer cost. Operating in the 3.1 GHz - 10.6 GHz frequency band with bandwidth above 500 MHz, it is an overlay technology that can co-exist with other narrowband services in the same frequency range, thus alleviating the problem of over-crowded spectrum. In particular, pulse-based UWB technologies allows for building of ultra-low power, medium- to long-range transceivers, at the expense of data transmission rate. This thesis presents a pulse-based, non-coherent UWB wireless image transmission platform. The system features a one-way wireless link. On the transmitter side, a host PC processes the images into transmittable packets in MATLAB, and sends them to the UWB radio through an interfacing FPGA module. On the receiver side, the UWB receiver radio receivers the packets, decodes the bits, and passes them back to the receiver host PC through another interfacing FPGA module. The receiver host PC collects the decoded bits and reconstructs the original image in MATLAB. The unidirectional wireless channel is complemented by a feedback path, provided through internet connection between the two host PCs. To improve usability, graphical user interfaces are setup on both host PCs. The overall system transmits 120 x 160 uncompressed bitmap images. It achieves a maximum payload data rate of 8 Mb/s.(cont.) It is able to transmit data reliably, with above 95% packet reception rate and below 2 x 10-5 bit error rate, for distances up to 16 meters. At 16 meters, the system has a maximum transmission data rate of 2.67 Mbps.by Helen He Liang.M.Eng

Wideband Channel Sounding Techniques for Dynamic Spectrum Access Networks

In recent years, cognitive radio has drawn extensive research attention due to its ability to improve the efficiency of spectrum usage by allowing dynamic spectrum resource sharing between primary and secondary users. The concept of cognitive radio was first presented by Joseph Mitola III and Gerald Q. Maguire, Jr., in which either network or wireless node itself changes particular transmission and reception parameters to execute its tasks efficiently without interfering with the primary users [1]. Such a transceiving mechanism and network environment is called the dynamic spectrum access (DSA) network. The Federal Communications Commission (FCC) allows any type of transmission in unlicensed bands at any time as long as their transmit power level obeys specific FCC regulations. Performing channel sounding as a secondary user in such an environment becomes a challenge due to the rapidly changing network environment and also the limited transmission power. Moreover, to obtain the long term behavior of the channel in the DSA network is impractical with conventional channel sounders due to frequent changes in frequency, transmission bandwidth, and power. Conventional channel sounding techniques need to be adapted accordingly to be operated in the DSA networks. In this dissertation, two novel channel sounding system frameworks are proposed. The Multicarrier Direct Sequence Swept Time-Delay Cross Correlation (MC-DS-STDCC) channel sounding technique is designed for the DSA networks aiming to perform channel sounding across a large bandwidth with minimal interference. It is based on the STDCC channel sounder and Multicarrier Direct Sequence Code Division Multiple Access (MC-DS-CDMA) technique. The STDCC technique, defined by Parsons [2], was first employed by Cox in the measurement of 910 MHz band [3{6]. The MC-DS-CDMA technique enables the channel sounder to be operated at different center frequencies with low transmit power. Hence, interference awareness and frequency agility are achieved. The OFDM-based channel sounder is an alternative to the MC-DS-STDCC technique. It utilizes user data as the sounding signal such that the interference is minimized during the course of transmission. Furthermore, the OFDM-based channel sounder requires lower sampling rate than the MC-DS-STDCC system since no spreading is necessary

Poissonian communications : free space optical data transfer at the few-photon level

Communicating information at the few photon level typically requires some complexity in the transmitter or receiver in order to operate in the presence of noise. This in turn incurs expense in the necessary spatial volume and power consumption of the system. In this work we present a self-synchronised free-space optical communications system based on simple, compact and low power consumption semiconductor devices. A temporal encoding method, implemented using a gallium nitride micro-LED source and a silicon single photon avalanche photo-detector (SPAD) demonstrates data transmission at rates up to 100 kb/s for 8.25 pW received power, corresponding to 27 photons per bit. Furthermore, the signals can be decoded in the presence of both constant and modulated background noise at levels significantly exceeding the signal power. The systems low power consumption and modest electronics requirements are demonstrated employing it as a communications channel between two nano-satellite simulator systems