Investigating Commuting Time Patterns of Residents Living in Affordable Housing: A Case Study in Nanjing, China

The phenomenon of affordable housing emerges in Chinese cities to meet low-income residents’ living needs in the city. Because affordable housing projects tend to be located far away from the city centre, their residents tend to face long commuting times to go to work. Although several studies have analysed commuting travel times, none have considered the commuting pattern of residents living in these affordable housing projects. This study employs a decision tree classifier to examine the commuting time patterns of affordable housing residents, fusing the data from the 2010 Nanjing Household Travel Survey and supplementary data collected through Google maps. Results show that attributes of the built environment and distance to work are the factors mostly influencing commuting time patterns of affordable housing residents in Nanjing. The availability of a subway service, job type, household car ownership, job location, travel mode choice, and departure time have logical but varying effects on commuting trip duration. These results provide a better understanding of these residents’ commuting patterns and provide urban planners insights about the effects of their affordable housing policies on travel behaviour.</p

Optimum receiver design and performance analysis for wireless communication

The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file.Title from title screen of research.pdf file viewed on (July 19, 2006)Includes bibliographical references.Vita.Thesis (Ph. D.) University of Missouri-Columbia 2005.Dissertations, Academic -- University of Missouri--Columbia -- Electrical and computer engineering.This dissertation is devoted to the optimum receiver design and theoretical performance analysis of wireless communication systems operated over fading channels, and this objective is incarnated by means of design, analysis and simulation of a broad range of wireless communication systems under various practical system configurations. A statistical discrete-time system model is proposed for wireless communication systems, and it provides a generic analysis and simulation framework for the design and evaluation of wireless communication systems. Based on the statistical properties of the discrete-time model, we next develop a multiuser channel estimation algorithm for quasi-synchronous CDMA systems operated over doubly selective Rayleigh fadings, and an optimum diversity receiver is proposed for systems with channel estimation error. Theoretical performance analyses are carried out to investigate the effects of channel estimation error, doubly selective fading, receiver timing phase offset, and co-channel interference on system performance. The theoretical performance expressions presented in this dissertation provide a set of analytical tools for communication system design and evaluation. In addition, all of the analytical results presented in this dissertation are rigorously verified through extensive numerical simulations, and excellent agreements are observed between the simulation results and theoretical expressions

Performance Analysis of Wireless Systems with Doubly Selective Rayleigh Fading

Theoretical error performances of wireless communication systems suffering from both doubly selective (time varying and frequency selective) Rayleigh fading and sampler timing offset are analyzed in this paper. Single-input-single-output systems with doubly selective fading channels are equivalently represented as discrete-time single-input-multiple-output (SIMO) systems with correlated frequency-flat fading channels, with the correlation information being determined by the combined effects of sampler timing phase, maximum Doppler spread, and power delay profile of the physical fading. Based on the equivalent SIMO system representation, closed-form error-probability expressions are derived as tight lower bounds for linearly modulated systems with fractionally spaced equalizers. The information on the sampler timing offset and the statistical properties of the physical channel fading, along with the effects of the fractionally spaced equalizer, are incorporated in the error-probability expressions. Simulation results show that the new analytical results can accurately predict the error performances of maximum-likelihood sequence estimation and maximum a posteriori equalizers for practical wireless communication systems in a wide range of signal-to-noise ratio. Moreover, some interesting observations about receiver oversampling and system timing phase sensitivity are obtained based on the new analytical results

Optimal Diversity Combining Based on Linear Estimation of Rician Fading Channels

Optimal receiver diversity combining employing linear channel estimation is examined. Based on the statistical properties of pilot-assisted least-squares (LS) and minimum mean square error (MMSE) channel estimation, an optimal diversity receiver for wireless systems employing practical linear channel estimation on Rician fading channels is proposed. Exact analytical expressions for the symbol error rates of LS and MMSE channel estimation aided optimal diversity combining are derived. It is shown that an MPSK wireless system with MMSE channel estimation has the same SER when the MMSE channel estimation is replaced by LS estimation. This is an interesting counter-example to the common perception that channel estimation with smaller mean square error leads to smaller SER. Extensive simulation results validate the theoretical results

Estimation of Channel Transfer Function and Carrier Frequency Offset for OFDM Systems with Phase Noise

The joint estimation of carrier frequency offset (CFO) and channel transfer function (CTF) for orthogonal frequency-division multiplexing (OFDM) systems with phase noise is discussed in this paper. A CFO estimation algorithm is developed by exploring the time-frequency structure of specially designed training symbols, and it provides a very accurate estimation of the CFO in the presence of both unknown frequency-selective fading and phase noise. Based on the estimated CFO, phase noise and frequency-selective fading are jointly estimated by employing the maximum a posteriori (MAP) criterion. Specifically, the fading channel is estimated in the form of the frequency-domain CTF. The estimation of the CTF eliminates the requirement of a priori knowledge of channel length, and it is simpler compared with the time-domain channel impulse response (CIR) estimation methods used in the literature. Theoretical analysis with the Cramer-Rao lower bound (CRLB) demonstrates that the proposed CFO and CTF estimation algorithms can achieve near-optimum performance

Doppler Spread Estimation for Broadband Wireless OFDM Systems

In this paper, we present a new Doppler spread estimation algorithm for broadband wireless orthogonal frequency division multiplexing (OFDM) systems with time-varying and frequency-selective Rayleigh fading. The algorithm is developed by analyzing the statistical properties of the power of received signals in the time domain, thus it excludes the influence of inter- carrier interference introduced by channel variation within one OFDM symbol. The operation of the algorithm doesn\u27t require the knowledge of fading coefficients, transmitted data symbols, or signal-to-noise ratio (SNR). It works well under time-selective and frequency-selective Rayleigh fading channel with SNR as low as 0 dB. Moreover, unlike existing algorithms, the proposed algorithm takes into considerations of the discrete-time channel inter-tap correlation, as the case in practical systems. Simulation results demonstrate that this new algorithm can accurately estimate a wide range of Doppler spread with low estimation latency and high computational efficiency

Signals and Systems

Signals and Systems is a core Electrical Engineering undergraduate course. This course covers the topics of signal and system analysis, with an emphasis on the analysis of linear time-invariant systems. The materials presented in this course are designed for a 15-week course for junior or senior level students. The open access materials for this course include: Course outline and guides: a detailed guideline that provides a week-by-week teaching schedule for a 15-week semester. Lecture notes: a complete set of lecture notes with detailed explanations and a large number of examples that cover all the contents that are offered in this course. Homeworks: 14 homework assignments with solution manuals. The solution manual is available to verified university instructors upon request. Lab manual: the lab manual contains a 4-section tutorial on how to use Matlab, the engineering programming language, and detailed procedures of 8 labs throughout the semester.https://scholarworks.uark.edu/oer/1004/thumbnail.jp

Channel Estimation for OFDM Systems in the Presence of Carrier Frequency Offset and Phase Noise

Channel estimation for orthogonal frequency division multiplexing (OFDM) system at the presence of carrier frequency offset (CFO) and phase noise is discussed in this paper. A CFO estimation algorithm is developed by exploiting the time-frequency structure of training symbols, and it provides a very accurate estimation of CFO at the presence of both unknown frequency selective fading and phase noise. Based on the estimated CFO, the phase noise and frequency selective fading are jointly estimated by employing the maximum a posteriori (MAP) criterion. Specifically, the fading channel is estimated in the form of frequency domain channel transfer function (CTF). The estimation of CTF eliminates the requirement of the priori knowledge of channel length, and it is simpler compared to the time domain channel impulse response (CIR) estimation method in the literature. Theoretical analysis with Cramer-Rao lower bound demonstrates that the joint phase noise and CTF estimation can achieve near optimum performance