Distributed cooperative admission and power control for Device-to-Device links with QoS protection in cognitive heterogeneous network

In this paper, we propose two distributed admission and power control (DAPC) algorithms for Device-to-Device (D2D) communication which share uplink resources with cellular system through cognitive radio techniques in underlay mode. In the presence of quality of service (QoS) protection (both for admitted D2D link (DL) and cellular link (CL)) and transmit power limit, the DAPC-Capacity algorithm is proposed with preference for the D2D system capacity, and the DAPC-Number algorithm is proposed with preference for the number of admitted DLs. Both the two algorithms try to determine if the new coming DL can be admitted in the system, and optimize powers of DLs to maximize the D2D system capacity. In proposed algorithms, each DL uses gradient descent method to update its transmit power, and the new coming DL and admitted DLs use different formulas to calculate gradients. In calculation of gradients, DLs cooperate with each other and only need to exchange “price” messages which indicate the effect of interference. Through the numerical results, we demonstrate the satisfying performance of proposed algorithms compared to traditional centralized algorithm.