Power Control in Opportunistic Spectrum Access Cognitive Radio with Sensing Information at Transmitter

In an opportunistic spectrum access based cognitive radio network, it is usually assumed that the secondary user (SU) will transmit at peak power when it detects that the primary user (PU) is absent while it will not transmit when the PU is detected to be present. However, when the PU is detected to be inactive, the PU may not definitely be inactive as it may be a case of miss-detection. If it is a miss-detection, the SU´s data rate for that particular data frame will be reduced due to interference from the PU. In this paper, power allocation strategies are designed for each data frame based on the spectrum sensing information (SSI) gathered during the sensing period. Using the SSI, the miss-detection probability for a data frame is taken into consideration when maximizing the average data rate and minimizing the outage probability of the SU. The probability of detecting the PU is required to be above a targeted threshold and the SU is required to satisfy its long-term transmit power budget. Our results showed that the transmit power of the SU should be a function of the SSI in order to maximize the average data rate and minimize the outage probability of the SU.