Sub-optimal Ultra-wide Band Receivers

Ultra-wide Band (UWB) has sparked a lot of interest lately from the industry and academia. The growing capacity of the wireless industry is requires a new communication system that satisfies the high data rate which does not interfere with existing RF systems. UWB promises to be this new technology. UWB also promises low power, low cost and flexibility. The UWB Channel opens up a huge new wireless channel with Giga Hertz Capacities as well as the highest spatial capacities measured in bits per hertz per square meter. When properly implemented UWB channel can share spectrum with traditional radio systems without causing harmful interference. In this thesis we studied and compared several reduced complexity sub-optimal Ultra-Wide Band receivers. These receivers include auto correlation receiver, the square value detector and the absolute value detector are studied. We consider OOK and PPM modulation schemes. We examine these schemes and the receivers on Gaussian and UWB indoor channels. We compare the performance with optimal receivers. A transmitter receiver system using 0.1us pulses implemented using existing hardware. A packet consisting of 24 bits were transmitted and the received signal could be verified in real time using a vector signal analyzer. The results show sub-optimal receivers provide a better trade off between robust, complexity and performance

An enhanced pulse position modulation (PPM) in ultra-wideband (UWB) systems

Simplicity, transmission rate, and bit error rate (BER) performance are three major concerns for ultra-wideband (UWB) systems. The main advantage of existing pulse-position modulation (PPM) schemes is simplicity, but their BER performance is poorer than that of an on-off-keying (OOK) modulation scheme, and their transmission rate is lower than that of an OOK scheme. In this research project, I will explore a novel PPM scheme, which can maintain the simplicity of the PPM schemes as well as achieve a BER performance and a transmission rate similar to the OOK scheme. During the research, I will thoroughly investigate the relationship between pulse position allocation and the BER performance and the transmission rate of UWB systems through computer simulations and theoretical analysis, and develop a whole set of design rules for the novel PPM scheme

Pulse shape design for ultra wide band communications

Ultra Wideband (UWB) technology is promising for high-speed short-range communication applications due to its large bandwidth, high data rate, low power requirement and short-range characteristics. Instead of exploring new unused frequency band, the UWB communication follows the overlay principle. The great potential of UWB lies in the fact that it can co-exist with the already licensed spectrum users and can still pave the way for a wide range of applications. Pulse shape design is a key technique in the UWB system. This thesis concentrates on pulse shaping techniques for UWB communication system. -- This thesis first summarizes the main pulse shaping schemes, and then describes the design of a pulse shaping method based on combining Gaussian derivative pulses for impulse based UWB systems. New pulse shapes are created to satisfy the Federal Communications Commission (FCC) spectral mask by this method. Since the objective function of the received signal-to-noise ratio (SNR) optimization is affected by different factors, multiple parameters are also designed to try to achieve the best received SNR. The performance of new pulses and other frequently used UWB pulses are compared through theoretical calculations and simulations coded in MATLAB. -- The main contributions of this thesis include the new determined way of combining certain numbers of Gaussian derivative pulses to create a single pulse that not only conforms to the FCC spectral mask, but also effectively exploits the permitted frequency spectrum, as well as the development of an end-to-end UWB signal transmission simulation chain that can use Time Hopping Pulse Position Modulation (TH-PPM) modulation and Time Hopping Binary Phase Shift Keying (TH-BPSK) modulation through an Additive White Gaussian Noise (AWGN) channel and the IEEE 802.15.3a standard channel model. -- Comparisons have been done of the overall performance of the systems using different pulses in various scenarios such as: single link system use AWGN channel and IEEE standard channel and multiuser system using AWGN channel and IEEE standard channel. In order to exploit the temporal diversity of the multi-path IEEE channel to improve performance of the decision process, a perfect RAKE receiver simulation model is used in the simulation chain. The theoretical calculation and simulation results indicate that the proposed pulses outperform other pulses to different extents under different situations. Discussions on the implementation issues of the pulse shaper are also provided in this thesis. -- The work reported here could act as a starting point from which improvements and extensions can be made and incorporated

COMPLEX PULSE FORMING TEACHNIQUE USING AM DETECTOR TYPE CIRCUITRY AND THE APPLICATION OF CDMA TO RFID FOR THE SIMULTANEOUS READING OF MULTIPLE TAGS

A novel complex ultra wideband RF pulse forming technique has been implemented in this research, using the coefficients derived from discrete Fourier transform of a virtual pulse train. Incorporated in this technique is a multiple frequency communication systems designed such that transmitter receiver proximity and the fading effect of the individual frequencies make part of a corresponding modulation technique. A code division multiple access (CDMA) application to RFID to greatly reduce read time, while at the same time eliminating inter tag interference, has been investigated with the analysis of a typical cart aisle scenario. With the current rate of growth of inventory world wide there is a tremendous need for more efficient method of data gathering, data storage, and data retrieval. In this dissertation, the application of the CDMA RFID technology has been analyzed to demonstrate the potentials of integrating the RFID technology to the EPC global numbering system

Code design for TDOA UWB based positioning of multiple sources

Projece fet en col.laboració amb Université Catholique du LouvainIn this thesis we study the feasibility of obtaining acceptable variance values in TDOA UWB based positioning of multiple sources. We define the conditions a time-hopping code must satisfy to mitigate multi-user interference. We design two time-hopping code generators. We propose a TOA estimator. We show simulation results and we conclude that both generated time-hopping code and the proposed estimator reduce the TOA estimation variance and that it is possible to reach the CRB when multiple sources are transmitting. Finally, we prove that TDOA based positioning can achieve a standard deviation of the position error in the order of mm

Contribution to the Rapid Acquisition of Signals for UWB Communication Systems

Ultra Wide-band is a promising technology for future short-range wireless communications with high data rate. In generally, one of the biggest difficult tasks for researchers today is the acquisition task of signals, where they are looking through different tools for getting a good quality of transmission; the phenomenon of multipath always stands up in the front as the first problem to be faced. When we talk about the Ultra Wide Band (UWB) signals, the problem becomes more complicated due to ultrashort impulses duration used by this kind of signals that causes the generation of paths by huge numbers. In this thesis, to address the task mentioned above, the study is subdivided into two aspects. The first one is the UWB channel estimation that we have done to have information about the amplitudes and the delays of the paths. For this purpose, a maximum likelihood method is used to find the amplitudes and the delays estimate using two estimation contexts: Data Aided (DA) and Non-Data-Aided (NDA). In the second aspect, various parameters affecting the acquisition of signals are evaluated. Furthermore, several contributions in the framework of a new strategy based on an Intelligent Controlling System (ICS) are done and detailed in this thesis for the first once. This system is characterised by its flexibility through two techniques, one that allows to users to communicate even with different M-ary PPM levels at the same time. Another technique that gives the flexibility for dealing with the phenomenon of multipath, where this latter is combated through manipulating the modulation’s levels via the ICS to achieve a rapid acquisition of UWB signals

Emerging Communication Technologies (ECT) Phase 2 Report

The Emerging Communication Technology (ECT) project investigated three First Mile communication technologies in support of NASA s Second Generation Reusable Launch Vehicle (2nd Gen RLV), Orbital Space Plane, Advanced Range Technology Working Group (ARTWG) and the Advanced Spaceport Technology Working Group (ASTWG). These First Mile technologies have the purpose of interconnecting mobile users with existing Range Communication infrastructures. ECT was a continuation of the Range Information System Management (RISM) task started in 2002. RISM identified the three advance communication technologies investigated under ECT. These were Wireless Ethernet (Wi-Fi), Free Space Optics (FSO), and Ultra Wideband (UWB). Due to the report s size, it has been broken into three volumes: 1) Main Report 2) Appendices 3) UWB