Thesis (MScEng (Industrial Engineering))--University of Stellenbosch, 2009. / Traceability systems are capable of both tracking and tracing parts. They offer many benefits to an organisation from assisting with recall applications to monitoring the everyday workings of a production line or supply chain. There are numerous methods able to act as traceability systems but only a few can be regarded as automatic and unique identifiers. Automatic traceability of individual entities is the future. It is already widely used by a number of leading companies throughout different business sectors and wide mass adoption is imminent. At present, they are slightly more expensive than the simpler technologies but once mass produced, the cost will come down. To completely understand how traceability systems are implemented, practical experience is required. When starting a traceability project, there are a lot of different options. The different systems offer their own set of advantages and some don’t work in certain environments. It was for this reason that The Decision Making Model was developed to assist users through the difficult initial stages of traceability implementation (i.e. choosing the system most suitable to a particular environment). This model was programmed in Excel and supplies the user with a number of questions regarding the environment the system would work in as well as the user’s requirements. The answers to these questions help the user work through the different types of traceability options to eliminate unsuitable choices. The result is an easy to use program designed with the ability to be upgraded as the technologies evolve.

<p>In this thesis, a MISO wireless communication system having even transmitter antennas and a single receiver antenna is considered, where neither the transmitter nor the receiver knows channel state information. Particularly when the number of transmitter antennas is two, a novel concept called a uniquely factorable constellation pair (UFCP) is first proposed for the systematic design of a noncoherent full diversity collaborative unitary space-time block code by normalizing two Alamouti codes. It is proved that such a unitary UFCP code assures the unique identification of both channel coefficients and transmitted signals in a noise-free case as well as full diversity for the noncoherent maximum likelihood (ML) receiver in a noise case. To further improve error performance, an optimal unitary UFCP code is designed by appropriately and uniquely factorizing a pair of energy-efficient cross quadrature amplitude modulation (QAM) constellations to maximize the coding gain subject to a transmission bit rate constraint. After a deep investigation of the fractional coding gain function, a technical approach developed in this thesis to maximizing the coding gain is to carefully design an energy scale to compress the first three largest energy points in the corner of the QAM constellations in the denominator of the objective as well as carefully design a constellation triple forming two UFCPs, with one collaborating with the other two so as to make the accumulated minimum Euclidean distance along the two transmitter antennas in the numerator of the objective as large as possible and at the same time, to avoid as many corner points of the QAM constellations with the largest energy as possible to achieve the minimum of the numerator. In other words, the optimal coding gain is attained by intelligent constellations collaboration and efficient energy compression. Another contribution of this thesis is to generalize the design for the two transmitter antennas into that of the noncoherent system with any even number of transmitter antennas. Using the Alamouti coding scheme and the Toeplitz matrix structure, a novel noncoherent nonunitary space-time block code, which is called an Alamoutibased Toeplitz space-time block code, is proposed. By the fundamentals of Galois theory and algebraic number theory, two important properties on the two Alamouti codes generated from a pair of coprime phase shift keying (PSK) constellations, i.e., the uniqueness of factorization itself and the shift-invariant uniqueness of factorization, are first revealed and rigorously proved. Then, it is further shown that it is these two kinds of the unique factorizations that enable the unique blind identification of both the channel coefficients and the transmitted signals by only processing two block received signals as well as noncoherent full diversity with a generalized likelihood ratio test (GLRT) receiver. In addition, a full diversity unitary code design is also proposed by simply applying the QR decomposition to the full diversity nonunitary Alamoutibased Toeplitz space-time block code. Computer simulations demonstrate that error performance of both optimal unitary UFCP code and Alamouti-based Toeplitz code presented in this thesis outperform those of the differential code and the SNR-efficient training code, which is the best code in current literatures for the system.</p> / Master of Applied Science (MASc)