Title page for ETD etd-07172006-130058

Type of Document Master's Thesis
Author Ghani, Sarfraz M
Author's Email Address sghani@vt.edu
URN etd-07172006-130058
Title Improving the Performance of Wireless Systems via Selective Interference Nulling and Adaptive Medium Access Control Design
Degree Master of Science
Department Electrical and Computer Engineering
Advisory Committee
Advisor Name Title
Annamalai, Annamalai Jr. Committee Chair
Reed, Jeffrey Hugh Committee Member
Zaghloul, Amir I. Committee Member
  • Cross-layer Simulation
  • Adaptive Interference Nulling
  • Diversity Combining
  • Wireless Communication
  • Smart Antenna
Date of Defense 2006-06-26
Availability unrestricted
Escalating demands for high performance wireless systems requires the confluence of smart communication methods, network protocols and ongoing advances in fabrication technologies, in order to bring smaller form factor mobile handsets to market. On par with these trends, this thesis focuses on two main areas, namely, Multiple Antenna Systems and Adaptive MAC Design to improve wireless system performance.

The first part of this research work presents a mathematical framework for characterizing the performance of cellular mobile radio systems equipped with smart antennas at the mobile handset to suppress a few dominant cochannel interferers (CCI) out of a total of L active independent but non-identically distributed Rayleigh faded CCI signals. Earlier works on this subject chose an unrealistic i.i.d assumption for the cochannel interferers. Since the CCI signals are of dissimilar signal strengths in practical operating environments, the premise of i.n.d fading statistics for the cochannel interferers is more realistic. In the subsequent section an analytical framework to investigate the benefits of a hybrid antenna array using selective interference nulling (SIN) and maximal ratio combining (MRC) in mobile radio environments is developed.

In the second part of this thesis, we explore the performance gains that can be achieved by exploiting the synergy resulting from the combination of the MAC and the physical layer of a wireless network. As in a traditional design, the physical layer is responsible for providing error protection for the transmission packets while the MAC layer allocates transmission bandwidth to the contending users. However, in the proposed scheme the MAC layer makes slot assignment decisions based on the channel state information (CSI) from the physical layer.

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