Performance analysis of space-frequency coding in MIMO cognitive radios

In this paper, a cognitive MIMO space-frequency coding is proposed, in which the cognitive link communicates using two transmission antennas and one receiving antenna. Cognitive MIMO systems allow the licensed spectrum to be opportunistically exploited by the cognitive user, so they enable public access to the underutilized spectral bands and therefore the overall spectral efficiency can be economically increased. While in some situations, such as high-mobility environment or channel fading rapidly, it may be difficult and costly to estimate the channel accurately for cognitive MIMO systems. To solve the problem, space-frequency coding scheme has been proposed for cognitive MIMO systems. The construction of SF codes for the cognitive MIMO system is provided.