  In this paper, we study the performance of a TCP connection over cognitive
radio networks. In these networks, the network may not always be available for
transmission. Also, the packets can be lost due to wireless channel
impairments. We evaluate the throughput and packet retransmission timeout
probability of a secondary TCP connection over an ON/OFF channel. We first
assume that the ON and OFF time durations are exponential and later extend it
to more general distributions. We then consider multiple TCP connections over
the ON/OFF channel. We validate our theoretical models and the approximations
made therein via ns2 simulations.
