| Abstract |
A transmitter with cognitive capability can sense talk between the
other transmitter-receiver pairs. When this transmitter knows full
or partial message of the others, it can choose an efficient
strategy to access the transmission medium. This is referred to as
cognitive radio channel. This work aims to investigate multi-tone
transmission over two-user cognitive radio channels where cross-talk
interference is weak. Cognitive transmitter (Tx$1$) is assumed to
have full knowledge of message that is sent by the other transmitter
(Tx$2$) to its corresponding receiver (Rx$2$). Channel capacity is
carefully analyzed for frequency-selective scenarios. Efficient
power-allocation strategies at Tx$1$ are investigated for various
wireless environments. It is shown that Tx$1$ can find an efficient
resource-accessing strategy if the channel gain of Tx$1$-Rx$1$ (the
corresponding receiver) link is larger than the channel gain of
Tx$2$-Rx$2$ link. In this case, the cognitive transmitter Tx$1$ can
offer better performance by employing equal power allocation approach.
Otherwise, it is not worthy for Tx$1$ to access transmission medium
of Tx$2$-Rx$2$ link. |