  We study the file transfer problem in opportunistic spectrum access (OSA)
model, which has been widely studied in throughput-oriented applications for
max-throughput strategies and in delay-related works that commonly assume
identical channel rates and fixed file sizes. Our work explicitly considers
minimizing the file transfer time for a given file in a set of
heterogeneous-rate Bernoulli channels, showing that max-throughput policy
doesn't minimize file transfer time in general. We formulate a mathematical
framework for static extend to dynamic policies by mapping our file transfer
problem to a stochastic shortest path problem. We analyze the performance of
our proposed static and dynamic optimal policies over the max-throughput
policy. We propose a mixed-integer programming formulation as an efficient
alternative way to obtain the dynamic optimal policy and show a huge reduction
in computation time. Then, we propose a heuristic policy that takes into
account the performance-complexity tradeoff and consider the online
implementation with unknown channel parameters. Furthermore, we present
numerical simulations to support our analytical results and discuss the effect
of switching delay on different policies. Finally, we extend the file transfer
problem to Markovian channels and demonstrate the impact of the correlation of
each channel.
