| dc.description.abstract | In this dissertation we investigate the performance of various wireless communication systems
that feature selection of the k-th best link from a number of links. We first consider the best link
selection (i.e., k = 1) and analyze the effective throughput of a transmit antenna selection scheme
for multiple antenna systems subject to Rayleigh fading. We derive an analytical expression for
the effective throughput and closed form expressions for the effective throughput in asymptotically
high and low signal-to-noise ratio (SNR) regimes.
Next, we consider the k-th best link selection scheme over various channel models that are
widely used to characterize fading in wireless communication systems such as, Weibull, Gamma,
_ -_ and Gamma-Gamma. Assuming a large number of links, we use extreme value theory to show
that the k-th highest SNR converges uniformly in distribution to a log-gamma random variable for
a fixed k and large number of links. We derive simple closed-form asymptotic expressions for the
average throughput, effective throughput and average bit error probability of the k-th best link. The
derived results cover many practical systems of interest in radio frequency and free space optical
systems.
Furthermore, we analyze the asymptotic performance of a multiuser diversity scheme for an
interference limited secondary multiuser network of underlay cognitive radio systems. Assuming
a large number of secondary users and that the noise at each secondary user’s receiver is negligible
compared to the interference from the primary transmitter, the secondary transmitter transmits
information to the secondary user with the k-th best signal-to-interference ratio (SIR). We use
extreme value theory to show that the k-th highest SIR converges uniformly in distribution to an
inverse gamma random variable for a fixed k and large number of secondary users. We use this
result to analyze the asymptotic average throughput, effective throughput, average bit error rate
and outage probability for the k-th best secondary user under continuous power adaptation at the
secondary transmitter, which ensures satisfaction of an instantaneous interference constraint at the
primary receiver caused by the secondary transmitter.
Finally, we investigate the secrecy performance of a multiuser diversity scheme for an interference
limited wireless network with a base-station (BS), multiple legitimate users and an eavesdropper,
in the presence of a single dominant interferer. Assuming interference dominates noise
power at the eavesdropper and at each legitimate user’s receiver, the BS transmits information to
the legitimate user with the k-th best SIR. We derive a closed-form expression for the secrecy
outage probability for an arbitrary number of users and an asymptotic expression for a fixed k and
large number of users. Furthermore, we derive a closed form asymptotic expression for the ergodic
secrecy capacity of the k-th best user and show that it scales logarithmically with the number of
users. | en |
