Analytic models for the performance of the forward link of 3G CDMA systems using different maximum ratio combining (MRC) RAKE finger weight assignments are presented. The spreading modulations under investigation are the balanced QPSK and the complex-spreading QPSK. The models are computationally efficient, accurate, and applicable to Root Raised Cosine (RRC) pulse shaping with any roll-off factor, variable processing gain, chip rate, and data rate for orthogonal codes, random codes, quasi-orthogonal codes, Gaussian noise, and realistic channel models. The expressions derived are then used to obtain the so-called orthogonality factor, which is commonly used in system-level simulations. Next, closed-form mathematical expressions for the variance due to infinite chips interfering in systems using arbitrary Nyquist pulses are derived. These expressions are applicable to both the forward link and the reverse link. For the latter, the existing knowledge on the accurate and efficient estimation of the performance of CDMA systems is extended by presenting closed mathematical expressions for bandlimited systems using arbitrary Nyquist pulses for both BPSK and Offset-QPSK (OQPSK) modulation. The impact of adjacent channel interference in bandlimited systems is subsequently considered. Finally, mathematical expressions for the accurate and efficient estimation of a CDMA system using RRC pulse-shaping and a RAKE receiver in the presence of multipath interference are presented.

In this paper, we consider the code division multiple access of the multiuser cooperative network system, all sources transmit signals using assigned spreading waveforms in first phase, and all relays transmit precoded signals using a common spreading waveform to help send signals to all destinations in second phase, in order to improve the performance. In this paper, we proposed the precoding strategy of relay point and the decoding strategy of destination point; at first we use the zero-forcing to eliminate the multi-user interferen- ce at the destination, and then joint design of the precoding vector at relay point and the decoding vector at destination point to achieve different optimization objectives. In this paper, we consider the power constraints to optimal the average SNR for the precoding vector and decoding vector, but the precoding vector favors the source-destination pairs with better channel quality in this condition, we also present the design of fairness, joint design of the precoding vector and the decoding vector to make the worst SNR can have the best signal-to-noise ratio after the design, and also consider the power constrain.

Several issues on the problems of the adaptive array beamforming and code-division multiple access (CDMA) multiuser detection are investigated in this dissertation. Recently, based on the decomposition of observation vector space into two orthogonal eigenspace, the eigenspace-based (ESB) and the generalized eigenspace-based (GEIB) array signal processing techniques have been widely discussed due to their superior performance over conventional techniques. At first, the purpose of this dissertation is mainly to present robust and efficient algorithms for further enhancing the performance of ESB and GEIB techniques under imperfect and practical operation environments. We also propose a method of corrected steering angles to combat the supersensitivity of eigenanalysis interference canceler (EIC) to source number overestimation and steering angle errors. We analyze the performance of several ESB multiuser detectors, including conventional direct-form detector and generalized sidelobe canceler (GSC) for synchronous CDMA system with and without desired user code mismatch. We also present a way of resolving spreading code mismatch in blind multiuser detection with subspace-based technique. Furthermore, the structure of GSC can be utilized to deal with the case of the desired user's SNR < 0 dB. Next, algorithm for adaptive H¡Û filter has demonstrated the advantage of reduction of sensitivity to modeling error (due to finite tap number) and suitability for arbitrary ambient noise over recursive least squares (RLS) algorithm. However, the computational burden of the H¡Û algorithm is enormous. In order to reduce the computational complexity, subweight partition scheme is employed to an H¡Û-based algorithm. The computation burden of the conventional adaptive H¡Û algorithm can be mitigated with slight performance degradation. The H¡Û-based algorithm is then further extended to the adaptive beamformer and blind multiuser detector. Finally, we present new diversity techniques for multiuser detection under multipath fading channels in asynchronous CDMA systems. The enhanced capacity of diversity for multipath channels can be achieved by appropriately utilizing the constraint matrix and the response vector in multiple constraint minimum variance (MCMV) algorithm. Moreover, the proposed techniques offer gratifying multiple access interference (MAI) suppression. We also incorporate the signal subspace-based projection into MCMV detector, so that the noise enhancement in the MCMV criterion can be reduced.

This thesis addresses handoff issues in a WCDMA system with space-time block coded transmit antenna diversity. Soft handoff has traditionally been used in CDMA systems because of its ability to provide an improved link performance due to the inherent macro diversity. Next generation systems will incorporate transmit diversity schemes employing several transmit antennas at the base station. These schemes have been shown to improve downlink transmission performance especially capacity and quality. This research investigates the possibility that the diversity obtained through soft handoff can be compensated for by the diversity obtained in a transmit diversity system with hard handoff. We analyze the system for two performance measures, namely, the probability of bit error and the outage probability, in order to determine whether the improvement in link performance, as a result of transmit diversity in a system with hard handoffs obviates the need for soft handoffs.

To effectively combat MAI and MI in wireless networks, we exploit complementary code technique in this thesis. Terminals in cooperative communication system are not only doing the transmission or relaying, but also involve a novel strategy "network coding" which has been investigated widely. In our work, we aim to combine network coding into the conventional cooperative communication system, but we face certain problems in it. Cooperative system has diversity at the destination, but when network coding operation involved, theoretically, it violate the rules of diversity, since the new signals transmitted by relay are no longer as same as the signals from sources. However, we discover a method to solve this problem, which is using the multiplier in relay nodes to replace the conventional network coding operation- XOR. After creating the network coding-based system, our goal is to achieve diversity in cooperative communication system. In this work, we use MRC (maximum ratio combining) for the performance analysis, which is the optimal strategy. Many math works will be shown in the following chapters.

Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains iv, 74 p. : ill. Includes abstract. Includes bibliographical references (p. 73-74).

Thesis (M.Eng.)--Memorial University of Newfoundland, 2000. / Bibliography: p. 96-104.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (p. 163-176).

Thesis (Ph. D.)--University of Missouri-Columbia, 2002. / Typescript. Vita. Includes bibliographical references (leaves 137-143). 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.