Doctoral Dissertations


Mingxi Wang

Keywords and Phrases

Mutual information


"This dissertation proposes a new approach to maximizing data rate/throughput of practical communication system/networks through linear precoding and power allocation. First, the mutual information or capacity region is derived for finite-alphabet inputs such as phase-shift keying (PSK), pulse-amplitude modulation (PAM), and quadrature amplitude modulation (QAM) signals. This approach, without the commonly used Gaussian input assumptions, complicates the mutual information analysis and precoder design but improves performance when the designed precoders are applied to practical systems and networks. Second, several numerical optimization methods are developed for multiple-input multiple-output (MIMO) multiple access channels, dual-hop relay networks, and point-to-point MIMO systems. In MIMO multiple access channels, an iterative weighted sum rate maximization algorithm is proposed which utilizes an alternating optimization strategy and gradient descent update. In dual-hop relay networks, the structure of the optimal precoder is exploited to develop a two-step iterative algorithm based on convex optimization and optimization on the Stiefel manifold. The proposed algorithm is insensitive to initial point selection and able to achieve a near global optimal precoder solution. The gradient descent method is also used to obtain the optimal power allocation scheme which maximizes the mutual information between the source node and destination node in dual-hop relay networks. For point-to-point MIMO systems, a low complexity precoding design method is proposed, which maximizes the lower bound of the mutual information with discretized power allocation vector in a non-iterative fashion, thus reducing complexity. Finally, performances of the proposed power allocation and linear precoding schemes are evaluated in terms of both mutual information and bit error rate (BER). Numerical results show that at the same target mutual information or sum rate, the proposed approaches achieve 3-10dB gains compared to the existing methods in the medium signal-to-noise ratio region. Such significant gains are also indicated in the coded BER systems"--Abstract, page iv-v.


Xiao, Chengshan

Committee Member(s)

Zheng, Y. Rosa
Kosbar, Kurt Louis
Liu, Xiaoqing Frank
Moss, Randy Hays, 1953-


Electrical and Computer Engineering

Degree Name

Ph. D. in Electrical Engineering


Missouri University of Science and Technology

Publication Date

Summer 2012

Journal article titles appearing in thesis/dissertation

  • Linear precoding for MIMO multiple access channels with finite discrete inputs
  • On the power allocation for relay networks with finite alphabet constraint
  • Linear precoding for relay networks: a perspective on finite-alphabet inputs
  • Practical liner precoder design for finite alphabet MIMO-OFDM with experiment validation


xii, 131 pages

Note about bibliography

Includes bibliographical references.


© 2012 Mingxi Wang, All rights reserved.

Document Type

Dissertation - Open Access

File Type




Subject Headings

Computer programming
MIMO systems
Wireless communication systems

Thesis Number

T 10038

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Electronic OCLC #