This thesis reports on an investigation of various system architectures and receiver structures for cellular communications systems which discriminate users by direct sequence code division multiple access (DSCDMA). Attention is focussed on the downlink of such a spread spectrum system and the influence of a number of design parameters is considered. The objective of the…
With the emergence of nonlinear dynamical systems analysis over recent years it has become clear that conventional time domain and frequency domain approaches to speech synthesis may be far from optimal. Using state space reconstructions of the time domain speech signal it is, at least in theory, possible to investigate a number of invariant geometrical…
The demand for mobile communication systems with high data rates has dramatically increased in recent years. New methods are necessary in order to satisfy this huge communications demand, exploiting the limited resources such as bandwidth and power as efficient as possible. MIMO systems with multiple an- tenna elements at both link ends are an efficient…
Since their inception, energy dissipation has been a critical issue for mobile computing systems. Although a large research investment in low-energy circuit design and hardware level energy management has led to more energy-efficient architectures, even then, there is a growing realization that the contribution to energy conservation should be more rigorously considered at higher levels…
With the advent of spectrally efficient wireless communication systems employing modulation schemes with varying amplitude of the communication signal, linearisation techniques for nonlinear microwave power amplifiers have gained significant interest. The availability of fast and cheap digital processing technology makes digital pre-distortion an attractive candidate as a means for power amplifier linearisation since it promises…
This thesis introduces the rank-order model and investigates its use in several image restoration problems. More commonly used as filters, the rank-order operators are here employed as predictors. A Laplacian excitation sequence is chosen to complete the model. Images are generated with the model and compared with those formed with an AR model. A multidimensional…
Blind channel identication and equalisation are the processes by which a channel impulse response can be identified and proper equaliser filter coeffcients can be obtained, without knowledge of the transmitted signal. Techniques that exploit cyclostationarity can reveal information about systems which are nonminimum phase, nonminimum phase channels cannot be identied using only second-order statistics (SOS…
This thesis introduces TLM as a new method for modelling medical ultrasound wave propagation. Basic TLM theory is presented and how TLM is related to Huygens principle is discussed. Two dimensional TLM modelling is explained in detail and one dimensional and three dimensional TLM modelling are explained. Implementing TLM in single CPU computers and parallel…
The problem of signal separation is a very broad and fundamental one. A powerful paradigm within which signal separation can be achieved is the assumption that the signals/sources are statistically independent of one another. This is known as Independent Component Analysis (ICA). In this thesis, the theoretical aspects and derivation of ICA are examined, from…
Broadband communications over the local telephone loop has become feasible nowadays by means of Digital Subscriber Line (DSL) technologies. Asymmetric DSL and one proposal for Very high bit rate DSL adopt Discrete Multitone (DMT) as modulation scheme. In this thesis we develop new equalization and echo cancellation structures for DMT-based receivers. Our main motivation is…
