On spectrum sensing in cognitive radio CDMA networks with beamforming

Publication date: Available online 4 September 2013
Source:Physical Communication
Author(s): Sanjay Dhar Roy , Sumit Kundu , Gianluigi Ferrari , Riccardo Raheli
In this paper, the performance of Cognitive Radio (CR) Code Division Multiple Access (CDMA) networks is analyzed in the presence of receive beamforming at the Base Stations (BSs). More precisely, we analyze, through simulations, the performance achievable by a CR user, with and without spectrum sensing, in a three-cell scenario. Uplink communications are considered. Three different schemes for spectrum sensing with beamforming are presented, together with a scheme without spectrum sensing. CR users belong to a Cognitive Radio Network (CRN) which is coexisting with a Primary Radio Network (PRN). Both CRN and PRN are CDMA-based. The CRN is assumed to utilize beamforming for its CR users. Soft Hand-Off (HO) and power control are considered in both the CRN and the PRN. The impact of beamforming on the system performance is analyzed considering various metrics. In particular, we evaluate the performance of the proposed systems in terms of outage probability, blocking probability, and average data rate of CR users. The obtained results clearly indicate that significant performance improvements can be obtained by CR users with the help of beamforming. The impact of several system parameters on the performance of the three considered spectrum sensing schemes with beamforming is analyzed. Our results, in terms of probability of outage, show that the relative improvement brought by the use of beamforming is higher in the absence of spectrum sensing (reduction of 80%) than in the presence of spectrum sensing (reduction of 42%).