TELECOMMUNICATIONS RESEARCH GROUP

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The growth of telecommunications over the past one hundred years has had a major influence on the development of society. Telecommunications will continue to play an increasingly important role in nearly every human endeavor in all nations of the earth. The Dallas/Fort Worth Metroplex is one of the leading areas of the nation in the development, production, and application of telecommunications. Most of the major global corporations active in the field have large facilities in the DFW area. The Electrical Engineering Department at the University of Texas at Arlington (UTA) has been a key resource to Metroplex corporations and has provided undergraduate and graduate education of engineers in the telecommunications area as well as conducting important research and development in support of the new technologies utilized by these corporations.

A mission of the Electrical Engineering Department is to establish and nurture a national resource for education and research in the field of telecommunications. A primary goal is to provide continuing and advanced education in all aspects of telecommunications and associated technologies to students and experienced engineers presently employed in the industry. In addition to offering traditional courses in communications, information theory and coding, the EE Department offers courses in digital and cellular radio, advanced wireless propagation and communications, networks, data communications, satellite communications, fiber optic communications, and simulation of telecommunication systems. A wide range of research programs, both general and application-oriented, is being conducted in all areas of telecommunications, many with support of local industry.

Courses are presented by the EE Department faculty, many of whom have had outstanding industrial research careers, as well by the adjunct members of the faculty who are nationally known leaders from the local industry.

AREAS OF RESEARCH :

Modulation Methods for Wireless Systems

Wireless Propagation Modeling

Antennas for Wireless Systems

Dynamic Channel Allocation for Wireless Systems

Microwave Systems and Devices

 

CURRENT COMPLETED PROJECTS INCLUDE:

Effect of BS Power and Soft Handoff on the Outage and Capacity of an SIR-based Power-controlled CDMA System

        In the forward link of an signal-to-interference ratio (SIR)-based fast power-controlled CDMA system, the fraction of base station (BS) power allocated to a mobile station (MS) is considered a key factor affecting system performance. By using our proposed macro-diversity non-orthogonality factor, we have established a unified analytical method to characterize the distribution of the fraction of BS power allocated to an MS in either the non-soft handoff mode or the soft handoff mode. By using that distribution and limiting the maximum fraction of the BS power available to an MS, a closed form expression of the capacity at a certain outage probability is obtained. The effects of system parameters, such as the available Rake fingers, the soft handoff threshold, the unbalance of the BS power, and the power control error, on the capacity are investigated from the point of view of limitation on the fraction of the BS power allocated to an MS. Simulation results show that soft handoff does not always improve capacity and the capacity gain may result depending on the choice of the system parameters.

Interference Cancellation Enhancement through Generalized Widely Linear Equalization in PAM/QAM Systems

Recently, it has been shown that widely linear equalization provides a significant advantage over conventional linear MMSE type equalizers in PAM systems corrupted by inter-symbol-interference (ISI) and co-channel interference (CCI). We propose a generalized widely linear equalization (GWLE) scheme that applies to both PAM and QAM systems with single or multiple antennas. In the proposed implementation, the receiver first separates the in-phase (I) and quadrature (Q) parts the complex baseband received signal collected from each antenna, then jointly filters the two branches. After the filtering step, a decision device jointly detects the I-Q parts of the QAM symbol taking into account the residual correlation between the I-Q branches; For PAM, the decision devise takes a conventional form. We derive infinite length filter settings for WL-LE and WL-DFE configurations and analyze the performance when the signal is corrupted by multiple (PAM/QAM) interferers and white noise. In frequency selective Rayleigh fading channels, the interference cancelation (IC) gain is shown to be dependent mainly on the rank (r) of interference correlation matrix (ICM). In a multiple antenna system with $N$ antennas, and I-Q split, the WL receiver collects 2N copies of signal and interference. For both
PAM and QAM signaling, assuming that the DFE feedback path is error free, we show that the WL receiver exhibits full IC capability (that is complete interference removal) when the ICM is rank deficient i.e. when: r < 2N. This condition implies that a WL-DFE receiver
can reject up to 2N-1 PAM interferers or any combination of M1 PAM and M2 QAM interferers satisfying the constraint: M1+2M2 < 2N. These results are shown to be applicable to a WL-LE in case of PAM signaling. However, when the wanted signal has QAM, and when
interference has PAM components, we show that the WL-LE offers a limited gain in frequency selective channels. Simulations confirmed that the proposed methods outperform conventional multi-antenna receivers in systems that use a combination of PAM and QAM signaling schemes.

PSK Systems in the Presence of Slow Fading, Imperfect Carrier Phase and AWGN

Using Fourier series expansion and associated Legendre functions, the average bit error rate probability (BEP) of the binary and quaternary PSK on a single channel with slow fading characteristics, phase recovery error and AWGN has been evaluated. The detection loss and phase precision for both BPSK and QPSK have been calculated. The series expressions of the average BEP are found to be convergent with reasonable number of terms. The accuracy of the results is verified by computer simulation. The main contribution relies on the integral definition of the associated Legendre functions, which leads to BEP expressions involving associated Legendre functions of the first and second kind.

 

OTHER USEFUL LINKS:

UTA Dissertation/Thesis Template (Latex) IEEE Transactions Paper Template (MS Word) IEEE Conference Paper Template (MS Word) IEEE Transactions Paper Template (Latex - Style) IEEE Transactions Paper Template (Latex - Bibliography) IEEE Conference Paper Template (Latex)

Last updated 10/09/2008
For comments and/or revisions, send email to liang@uta.edu