In coming years, wireless networks have to serve a large number of data hungry devices due to proliferation of new devices and applications every year. Increasing number of wireless devices (users) are competing for physical layer resources, namely time, space and frequency, to download the data required for different applications. In order to serve a large number of users, the wireless network needs to either create new resources or utilize existing resources more efficiently.

We propose to create spatial resources in the channel by using massive MIMO technique in a cognitive cell. The cognitive cell coexists with the primary cell in underlay paradigm. In underlay CR network, the cognitive base station (CBS) can serve CRs if the interference to the primary users (PUs) is kept below a threshold. By using a large antenna array at CBS, cognitive cell simultaneously serves a large number of CRs, while restricting the interference to PUs below a specified threshold. In this project, we investigate how the network parameters, namely number of antennas at CBS (Mb), number of antennas at CRs (Mu), and number of PUs affect the ability of CBS to serve a large number of CRs. We consider three constraints in this study: 1) maximum interference at PU (I0), 2) minimum rate required by each SU (R0) , and 3) maximum transmit power (P0). The imperfect knowledge of the channel between CBS and PU is assumed in our approach.

Staff

• Primary Investigators: Danijela Čabrić
• Students: Shailesh Chaudhari