Transmission Capacity of Cognitive Radio Networks with Interference Avoidance

The transmission capacity (TC) of the secondary (SR) network in cognitive radio networks (CRNs) is investigated in this paper. Mathematically, the TC of the SR network is defined as the maximum transmitter density of the SR network that satisfies the outage probability constraints of the primary (PR) network and the SR network, multiplied by the communication rate and the successful reception probability. In order to effectively control interference in CRNs to obtain a higher TC, we propose a spectrum sharing scheme with preservation regions to avoid excessive interference from the secondary users to the primary users. Closed-form expression for the TC of the SR network is derived under such a scheme. We optimize the transmitter density, the transmit power and the preservation range, which maximize the TC of the SR network. Numerical results show that our scheme outperforms traditional schemes.