A new algorithm is proposed which provides a sub-optimum near-far resistant pattern for correlation with a known signal in a spread-spectrum multiple access environment with additive white gaussian noise (AWGN). Only the patterns and respective delays of the K-1 interfering users are required. The technique does not require the inversion of a cross-correlation matrix. The technique can be easily extended to as many users as desired using a simple recursion equation. The computational complexity is O(K²) for each user to be decoded. It is shown that this method provides the same results as the "one-shot" method proposed by Verdu and Lupas. Also shown is a new array architecture for implementing this new solution using delta-sigma modulation and a correlator for non-binary patterns that takes advantage of the digitized Al: signals. Simulation results are presented which show the algorithm and correlator to be implementable in VLSI technology. This approach allows processing of the received signal in real-time with a delay of O(.K) bit periods per user. A modification of the algorithm is examined which allows further reduction of complexity at the expense of reduced performance. / Graduation date: 1992

As the size and power consumption of microelectronic circuits continues to decrease, passively-powered sensors promise to come to the forefront of commercial electronics. One of the most promising technologies that could realize this goal is backscatter sensing. Backscatter sensors could harvest power from and modulate data onto an impinging carrier waveform. Currently radio frequency identification (RFID) technology passively powers itself and transmits statically stored data. However, this technology has two major weaknesses: lack of resiliency against narrowband interference and slow data rates. Both of these issues could be detrimental in sensing applications. This thesis will lay out a method for addressing both of these weaknesses through a unique application of spread spectrum encoding. Instead of spread spectrum being viewed as the multiplication of an already encoded data sequence with a periodic pseudorandom sequence, each sequence could be viewed in an aperiodic manner, where a single period of a pseudorandom sequence represents a data symbol. In this manner, backscatter sensors not only benefit from the increased resiliency that spread spectrum provides, but also can have higher data rates, since multiple bits can be encoded on a single symbol and multiple nodes can be read simultaneously, using spread spectrum multiple access techniques. In this thesis, 63-chip and 255-chip Kasami sequences, as well as 127-chip Gold sequences, will be analyzed for their use in various aperiodic direct sequence spread spectrum/multiple access system configurations (systems that have up to three nodes and use up to four different aperiodic sequences per node to represent different symbols). For each different configuration, near-"ideal" code configurations/rotations will be determined for use in the system.

Thesis (Ph. D.)--University of Missouri-Columbia, 2002. / Typescript. Vita. Includes bibliographical references (leaves 189-194). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2002. / Typescript. Vita. Includes bibliographical references (leaves 189-194). Also available on the Internet.

No description available.

No description available.

Thesis (M Eng (Research)) -- University of South Australia, 1992

Thesis (M Eng (Research)) -- University of South Australia, 1992

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Thesis (MEng (Electronic))-University of Pretoria, 2008. / Includes bibliographical references.