On the performance of DoA estimation algorithms in cognitive radio networks: -A new approach in spectrum sensing

Since the spectrum is a scarce natural resource, sensing a spectrum is an important part of Green Engineering. The cognitive radio has been proposed to meet the ever increasing demand of the radio spectrum by allocating the spectrum dynamically to allow unlicensed access on non-interfering basis. But, the conventional spectrum sensing methods are seeking for spectrum opportunities in either of three dimensions viz. time, frequency and space. However, other dimensions like `Code´ and `Angle´ need to be explored further for spectrum opportunity. This paper investigates the performance of Direction of Arrival (DoA) estimation algorithms like MUSIC, Capon and ESPRIT in cognitive radio networks. The adaptive thresholding has been proposed to improve the performance of DOA algorithms. The results show that the performance of the algorithms improves with increasing number of array elements, increasing number of snapshots and increasing signal to-noise ratio. This new approach of DoA estimation of licensed user, increases channel capacity and improves frequency reuse capability by multiplexing licensed and unlicensed users into the same channel at the same time in the same geographical area by forming the beam of unlicensed user in the direction other than the licensed users´ DoA direction.