###### Abstract  
Cognitive radio inspired non-orthogonal multiple access (CR-NOMA) networks are a research focus in the wireless communication field. The secure communication of wireless networks has become a pressing issue due to the openness of the wireless channel. Multiple-antenna technology can enhance the secrecy performance in CR-NOMA networks, thus we propose a multiple-input-single-output (MISO) CR-NOMA network where the base station (BS) is equipped with multiple antennas, while others have a single antenna in the paper. The BS serves three secondary users in the presence of an eavesdropper and a primary user. We propose two transmit antenna selection (TAS) schemes, namely the space-time transmission (ST) scheme and the maximum channel capacity (MCC) scheme, respectively. Firstly, we obtain an exact closed-form expression for the secrecy outage probability (SOP) of three secondary users and the overall SOP of the networks with the two schemes, respectively. To gain further insights, the present study analyzes the asymptotic SOP performance to analyze the relationship between the network parameters and secrecy outage performance. Based on this, we propose a power allocation algorithm to further improve the secrecy outage performance of the networks. Finally, we verify the analyses with Monte Carlo simulations. The numerical and simulation results demonstrate that: (1) The MCC scheme outperforms the ST scheme on the secrecy outage performance. (2) The proposed power allocation algorithm optimizes the secrecy outage performance of the networks. (3) There exists a sole respective optimal power allocation factor for a BS different transmission power. c pacs: 12.38.Hc, 12.38.-b, 12.  
connection reliability of the CR-NOMA network surpasses that of the orthogonal multiple access (OMA) based on a CR network. These findings underscore the potential of CR-NOMA as a promising approach to improve the performance of future wireless networks in terms of connectivity and reliability. The issue of wireless network security has become a prominent research focus, as users' confidential information is vulnerable to eavesdropping in wireless network channels. Based on information security theory, physical layer security (PLS) technology has emerged as a practical solution [8; 9]. In recent studies [10; 11], the security communication concerns in CR-NOMA networks have been investigated from the PLS perspective. Specifically, the authors investigated the secrecy performance of the CR-NOMA network in the presence of multiple primary users under the PLS scenario, where secondary users were considered potential eavesdroppers [10]. Moreover, [11] investigated the secrecy outage probability (SOP) of one secondary user in CR-NOMA networks under the quality-of-service (QoS) and security constraints of the primary user. Nonetheless, a notable limitation of the aforementioned studies is that the base station (BS) is equipped with only a single antenna, thus prompting researchers to shift their focus towards multi-antenna networks and investigate various transmit antenna selection (TAS) schemes to enhance secrecy outage performance [12; 13; 14; 15; 16; 17; 18]. For example, in [12], [PERSON] et al. proposed a zero-forcing-beamforming (ZFBF) technique to enhance the secrecy performance in multiple-antenna CR-NOMA networks. In [13; 14], the SOP of secondary users in cooperative multiple-input-single-output (MISO) CR-NOMA networks were examined, with consideration given to the absence of a direct link between the secondary transmitting BS and secondary users, and the provision of a relay for cooperative signal transmission. Moreover, [PERSON] et al. proposed a space-time transmission (ST) scheme and a maximum channel capacity (MCC) scheme [15], which served as the basis for [PERSON] et al. 's study on the SOP of two secondary users in the MISO-NOMA network with STT and MCC schemes. Simulation results shown that the secrecy performance with STT and MCC schemes were substantially better than that of a single-antenna NOMA system [16].