Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: Charles G. Boncelet, Dept. of Computer & Information Sciences. Includes bibliographical references.

This dissertation is concerned with performance analysis of diversity combining schemes in frequency-hop spread spectrum communications under the worst case partial-band noise and multitone jamming. Performance of a ratio-threshold diversity combining scheme in fast frequency hop spread spectrum systems with M-ary frequency shift keying modulation (FFH/MFSK ) under partial-band noise (PBN) and band multitone jamming without and with the additive white Gaussian noise (AWGN) is analyzed. The analysis is based on exact bit error probabilities, instead of bounds on the bit error probabilities. A method to compute the bit error probability for ratio-threshold combining on jamming channel is developed. Relationship between the system performance and the system parameters, such as ratio-threshold, diversity order, and thermal noise level, is illustrated. The performances under band multitone jamming and under partial-band noise jamming are compared. For binary FSK modulation, the performance under the two types of jamming is almost the same, but for 8-ary FSK modulation, tone jamming is more effective against communications. The structure of the combiner is very simple and easy to implement. Another merit of this combiner is that its output can be directly fed to a soft-decision FEC decoder. Maximum-likelihood diversity combining for an FFH/MFSK spread spectrum system on a PBN interference channel is investigated. The structure of maximum likelihood diversity reception on a PBN channel with AWGN is derived. It is shown that signal-to-noise ratio and the noise variance at each hop have to be known to implement this optimum diversity combining. Several sub-optimum diversity combining schemes, which require the information on noise variance of each hop to operate, are also considered. The performance of the maximum-likelihood combining can be used as a standard in judging the performance of other suboptimum, but more practical diversity combining schemes. The performance of the optimum combining scheme is evaluated by simulations. It is shown that the Adaptive Gain Control (AGC) diversity combining actually achieves the optimum performance when interference is not very weak. But the performance difference between some of the known diversity combining schemes, which do not require channel information to operate, and the optimum scheme is not small when the diversity order is low. An error-correction scheme is proposed for an M-ary symmetric channel characterized by a large error probability Pe. Performance of the scheme is analyzed. The value of Pe can be close to, but smaller than, 1 – 1/M for which the channel capacity is zero. Such a large Pe may occur, for example, in a jamming environment. The coding scheme considered consists of an outer convolutional code and an inner repetition code of length m which is used for each convolutional code symbol. At the receiving end, the m inner code symbols are used to form a soft-decision metric, which is subsequently passed to a soft-decision decoder for the convolutional code. Emphasis is placed on using a binary convolutional code due to the consideration that there exist commercial codecs for such a code. New methods to generate binary metrics from M-ary (M > 2) inner code symbols are developed. For the binary symmetric channel, it is shown that the overall code rate is larger than O.6R0, where R0 is the cutoff rate of the channel. New union bounds on the bit error probability for systems with a binary convolutional code on 4-ary and 8-ary orthogonal channels are presented. Owing to the variable m which has no effect on the decoding procedure, this scheme has a clear operational advantage over some other schemes. For a BSC and a large m, a method presented for BER approximation based on the central limit theorem. / Graduate

A Gold code sequence generator suitable for use in a code division multiple access spread spectrum communication application is designed. A dual, single return shift register configuration is used to generate Gold code sequences. The code sequences are generated by the mod-2 addition of two linear maximal length pseudo-random noise codes, each of which corresponds to a sixth-order primitive polynomial. A computer model of the design is used to generate all 65 possible members of the Gold code sequence family. A tabulation of all sequences and their initial condition “keys” is provided, along with a designation as to which code sequences are balanced. The mathematical basis of maximal length sequence generation is developed, using first the matrix characterization of a shift register generator, and then switching to the alternate treatment of a shift register generator as a polynomial division engine. The link between the matrix representation and the polynomial representation via the characteristic equation, the use of the generating function, and the three mathematical properties required of polynomials which are capable of generating maximal length sequences are described. Gold’s algorithm for selecting preferred polynomial pairs is presented, as is his technique for determining the characteristic phase of a maximal length sequence. The actual Gold code generator is then designed and modeled in software. All Gold code sequences output from the generator are tabulated. The family of sequences is evaluated in terms of its randomness properties. Finally, the results of computer analysis of the auto and cross-correlation characteristics of the family is summarized.

by Tsan-Fai Ho. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves 64-68). / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Review on spread spectrum communications --- p.1 / Chapter 1.2 --- The spread spectrum techniques --- p.2 / Chapter 1.2.1 --- Direct Sequence (DS) Systems --- p.2 / Chapter 1.2.2 --- Frequency Hopping (FH) Systems --- p.2 / Chapter 1.2.3 --- Time Hopping (TH) Systems --- p.4 / Chapter 1.2.4 --- Hybrid Systems --- p.4 / Chapter 1.3 --- Existing Applications of the spread spectrum systems --- p.5 / Chapter 1.4 --- Organization of the thesis --- p.6 / Chapter 2 --- The Concept of Duality --- p.7 / Chapter 2.1 --- Multi-Carrier Systems - An Overview --- p.7 / Chapter 2.2 --- Orthogonal Frequency Division Multiplexing --- p.8 / Chapter 2.2.1 --- Bandwidth Efficiency --- p.9 / Chapter 2.2.2 --- Spectral Efficiency --- p.10 / Chapter 2.2.3 --- Effects of fading --- p.11 / Chapter 2.3 --- Applications of OFDM in multiple access --- p.13 / Chapter 2.3.1 --- ST-CDMA --- p.13 / Chapter 2.3.2 --- MC-DS-CDMA --- p.14 / Chapter 2.3.3 --- OFDM-CDMA --- p.15 / Chapter 2.4 --- Duality - Time-Frequency Interrelation --- p.16 / Chapter 3 --- Performance of Multi-Carrier CDMA System --- p.17 / Chapter 3.1 --- System Model --- p.17 / Chapter 3.2 --- Performance Analysis --- p.20 / Chapter 3.2.1 --- Gaussian Channel --- p.20 / Chapter 3.2.2 --- Fading Channel --- p.24 / Chapter 3.3 --- Performance with Pulse Shape --- p.33 / Chapter 3.4 --- Appendix --- p.34 / Chapter 4 --- Signal Design Criteria for MC-CDMA System --- p.36 / Chapter 4.1 --- Existence of Signal Distortion --- p.37 / Chapter 4.2 --- Measures of the Signal Envelope Fluctuation --- p.38 / Chapter 4.3 --- Complementary Sequences --- p.41 / Chapter 4.4 --- Crest Factors --- p.42 / Chapter 4.4.1 --- Time-limited Pulse --- p.43 / Chapter 4.4.2 --- Ideally Band-Limited Pulses --- p.43 / Chapter 4.4.3 --- Shaped Pulses --- p.45 / Chapter 4.5 --- Spectrally Efficient Complementary (SEC) Sequences --- p.48 / Chapter 4.6 --- Construction of Spectrally Efficient Complementary(SEC) Sequences --- p.50 / Chapter 4.7 --- Generalized Multiphase Spectrally Efficient Complementary Sequences --- p.55 / Chapter 5 --- Summary and Future Extensions --- p.58 / Chapter 5.1 --- Summary of the Results --- p.58 / Chapter 5.2 --- Topics for Future Research --- p.59 / Appendix / Chapter A --- Exhaustive search of MPSEC sequences --- p.61 / Chapter B --- Papers derived from this thesis --- p.63 / Bibliography --- p.64

Li, Kin Fai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 95-99). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iv / Chapter 1 --- Introduction / Motivation --- p.1 / Chapter 2 --- Literature Review --- p.7 / Chapter 2.1 --- Introduction --- p.7 / Chapter 2.2 --- Dynamic Spectrum Access Networks --- p.8 / Chapter 2.3 --- Reliability --- p.10 / Chapter 2.3.1 --- Reliability in Wireless Networks --- p.10 / Chapter 2.3.2 --- Reliability in Wireline Networks --- p.11 / Chapter 2.4 --- Capacity Planning in Wireless Mesh Networks --- p.14 / Chapter 2.4.1 --- Interference Model --- p.14 / Chapter 2.4.2 --- Link Capacity Constraint --- p.15 / Chapter 2.4.3 --- Feasible Path --- p.16 / Chapter 2.4.4 --- Optimal Capacity Allocation in DSA Net- works and Wireless Mesh Networks --- p.16 / Chapter 2.5 --- Chapter Summary --- p.18 / Chapter 3 --- Lifetime Aware Routing without Backup --- p.19 / Chapter 3.1 --- Introduction --- p.19 / Chapter 3.2 --- System Model --- p.20 / Chapter 3.3 --- Lifetime Distribution of a Path without Backup Protection --- p.22 / Chapter 3.3.1 --- Exact Lifetime Distribution --- p.23 / Chapter 3.3.2 --- The Chain Approximation --- p.24 / Chapter 3.4 --- Route Selection without Backup Protection --- p.26 / Chapter 3.4.1 --- NP-Hardness of Finding Maximum Lifetime Path --- p.26 / Chapter 3.4.2 --- The Minimum Weight Algorithm --- p.28 / Chapter 3.4.3 --- Greedy Algorithm --- p.28 / Chapter 3.4.4 --- GACA - The Greedy Algorithm using the Chain Approximation --- p.32 / Chapter 3.5 --- Simulation Results --- p.33 / Chapter 3.5.1 --- Tightness of the Chain Approximation Bound for Vulnerable Area --- p.33 / Chapter 3.5.2 --- Comparison between Greedy and GACA using Guaranteed Lifetime --- p.36 / Chapter 3.5.3 --- Factors impacting the performance of GACA --- p.37 / Chapter 3.6 --- Chapter Summary --- p.43 / Chapter 4 --- Prolonging Path Lifetime with Backup Channel --- p.44 / Chapter 4.1 --- Introduction --- p.44 / Chapter 4.2 --- Non-Shared Backup Protection --- p.45 / Chapter 4.2.1 --- Lifetime of a Path with Non-Shared Backup --- p.45 / Chapter 4.2.2 --- Route Selection for paths with Non-Shared Backup --- p.46 / Chapter 4.3 --- Shared Backup Protection --- p.47 / Chapter 4.3.1 --- Sharing of Backup Capacity --- p.48 / Chapter 4.3.2 --- Lifetime of a Path with Shared Backup --- p.48 / Chapter 4.3.3 --- Route Selection for paths with Shared Backup --- p.50 / Chapter 4.4 --- Simulation Results --- p.50 / Chapter 4.4.1 --- Tightness of Failure Probability Upper Bound for Backup Protection --- p.51 / Chapter 4.4.2 --- Comparison between the Shared Backup and Non Shared Backup schemes --- p.53 / Chapter 4.5 --- Chapter Summary --- p.54 / Chapter 5 --- Finding Capacity-Feasible Routes --- p.55 / Chapter 5.1 --- Introduction --- p.55 / Chapter 5.2 --- Constructing an Edge graph --- p.56 / Chapter 5.3 --- Checking Capacity Feasibility under each Protec- tion Scheme --- p.58 / Chapter 5.3.1 --- No Backup Protection --- p.59 / Chapter 5.3.2 --- Non-Shared Backup Protection --- p.59 / Chapter 5.3.3 --- Shared Backup Protection --- p.60 / Chapter 5.4 --- Chapter Summary --- p.62 / Chapter 6 --- Performance Evaluations and Adaptive Protec- tion --- p.63 / Chapter 6.1 --- Introduction --- p.63 / Chapter 6.2 --- Tradeoffs between Route Selection Algorithms --- p.64 / Chapter 6.3 --- Adaptive Protection --- p.66 / Chapter 6.3.1 --- Route Selection for Adaptive Protection --- p.67 / Chapter 6.3.2 --- Finding a Capacity-Feasible Path for Adaptive Protection --- p.68 / Chapter 6.4 --- Comparison between No Protection and Adaptive Protection --- p.69 / Chapter 6.5 --- Chapter Summary --- p.71 / Chapter 7 --- Restoration Capacity Planning and Channel Assignment --- p.72 / Chapter 7.1 --- Introduction --- p.72 / Chapter 7.2 --- System Model --- p.74 / Chapter 7.2.1 --- Channel Assignment Model --- p.74 / Chapter 7.2.2 --- Presence of Primary Users --- p.75 / Chapter 7.2.3 --- Link Flow Rates --- p.76 / Chapter 7.2.4 --- Problem Formulation --- p.77 / Chapter 7.3 --- Simulation Results --- p.79 / Chapter 7.3.1 --- "Comparison between ""Shared Backup"" and “No Restore Plan"" using Guarantee Percentage and Reduced Capacity" --- p.80 / Chapter 7.3.2 --- Comparison using Traffic Demand Scaling Factor g and Guarantee Fraction p --- p.81 / Chapter 7.3.3 --- Comparison between Optimal Channel Assignment and Random Channel Assignment --- p.84 / Chapter 7.4 --- Chapter Summary --- p.86 / Chapter 8 --- Conclusion and Future Works --- p.87 / Chapter A --- Proof of Theorem (3.1) in Chapter3 --- p.90 / Chapter B --- Proof of Theorem (4.1) in Chapter4 --- p.92 / Bibliography --- p.95

Thesis (Ph. D.)--University of Queensland, 2001. / Includes bibliographical references.

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Thesis (Ph.D.)--University of South Australia, 1996.

Thesis (Ph. D.)--Ohio University, November, 1992. / Title from PDF t.p.