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Signal Processing
(SP)
Society The Signal Processing Society (SP-1) caters to hardware, firmware and software engineers involved in signal processing techniques, implementation and apparatus.
For upcoming SP lectures and meetings, please visit the
calendar page.
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Organizations > IEEE Global Sig Proc Society Reference |
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Past Lectures |
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The classical theory of variable systems is based on the solutions of linear ordinary differential equations with varying coefficients. The varying coefficients are usually functions of an independent variable, so-called the time variable. The “time variable” is assumed to be a real variable for physical systems. This assumption facilitates analysis and synthesis of fixed (so-called time-invariant) systems by allowing the Laplace transform techniques to be used. However, the assumption of “real time” is shown to be inadequate for realization of time-varying systems in the transformed domain. The discussion in this presentation is based on a different point of view. Specifically, the approach consists essentially in investigating the possibility of system realization through an examination of the behavior of systems that are functions of a complex time-variable. This approach allows, in effect, a two-dimensional Laplace transform technique to be used for the time-varying systems in the same manner that the conventional frequency-domain technique is used in connection with fixed systems. The challenge is the physical interpretation of a “complex time variable” versus the “real time,” and its implications on the transformed variable, so-called the “frequency variable.”
Despite the ever-increasing civilian applications, the main drawback of GPS remains to be its high sensibility to multi-path and interference. The effect of interference on the GPS receiver is to reduce the signal-to-noise ratio (SNR) of the GPS signal such that the receiver is unable to obtain measurements from the GPS satellite. The spread-spectrum (SS) scheme, which underlies the GPS signal structure, provides a certain degree of protection against interference. However, when the interferer power becomes much stronger than the signal power, the spreading gain alone is insufficient to yield any meaningful information. This talk discusses a new technique for anti-jam Global Positioning System (GPS). A novel GPS anti-jam receiver using multi-antenna receivers is introduced which relies on the replications of the coarse/acquisition (C/A) code within a GPS symbol. The proposed receiver utilizes the inherent GPS self-coherence property to excise narrowband and broadband interferers that have different temporal structures from that of the GPS signals.
Third generation wireless communication systems were introduced to extend the data capabilities of second-generation systems by providing quality of service (QoS) management and enabling the high data rates required for high speed web access, and transmission/reception of high quality images and video. To satisfy predicted future increasing demands on even higher rate data services, additional enhancements are being incorporated into the different 3G air interface standards. The first step in evolving the 3G standards is enabling high-speed packet access in the downlink or forward link, i.e. when the terminal is receiving information from the network. The higher data rates are achieved via new features such as adaptive modulation and coding, Hybrid ARQ and fast scheduling. Other enhancements that are being considered are extending the high-speed packet access to the uplink or reverse link (when the terminal is transmitting information to the network) and smart antenna techniques. In this talk we will review the new features recently introduced or being considered for 3G air interfaces and discusses their impact on the performance of the evolving standards.
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2010-05-21 |
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Chairman
Extending
Laplace & Fourier Transforms: A Personal Perspective 
Dr. Shervin Erfani -
University of Windsor