A reliability-controllable secure transmission strategy for cooperative cognitive vehicular networks under Gaussian channel error estimation

Cognitive radio (CR) and cooperative communication (CC) represent two potent technologies designed to alleviate spectrum scarcity and improve the throughput of vehicular networks, while their integration has introduced multifaceted security concerns. This work explores the tradeoff between reliability and physical layer security (PLS) within the underlay cooperative cognitive vehicular networks (CCVNs). In CCVNs, a secondary vehicle communicates with the destination vehicle via a decode-and-forward (DF) relay, and an eavesdropper with imperfect channel state information (ipCSI) is present in the process. We adopt a more realistic system model considering Gaussian channel error estimation. Based on this model, we design a reliability-controllable secure transmission strategy and derive closed-form expressions for key performance indicators, including transmission delay, security, reliability, and throughput. These expressions are obtained by leveraging the computed cumulative distribution function (CDF) of the instantaneous equivalent signal-to-noise ratio (SNR). Furthermore, we optimize key parameters to maximize the secrecy throughput while meeting reliability constraints. Results from numerical calculations and simulation experiments highlight the significant improvement in reliability offered by the proposed strategy over conventional methods.