Secrecy Analysis of Correlated Multicast Channel with Equal Gain Combining and Cooperative Relaying

Wireless communication security is critical for next-generation high-yield systems such as 5G and 6G. Traditional multicasting protocols often lack a robust framework to ensure proper authentication and privacy, with correlation degrading signal-to-noise ratio (SNR) and reducing overall channel capacity. To increase security, equal gain combining (EGC), one of the diversity-combining techniques mitigates fading and correlation, whereas cooperative relaying chooses the relay with the highest SNR to optimize performance. This paper investigates the combined use of EGC and cooperative relaying to strengthen multicast security. Closed-form expressions for secure outage probability (SOPM) and non-zero secrecy multicast capacity (PNSMC) are derived, considering fading, correlation, and relay diversity. Results show that security improves with stronger fading, more destination antennas, and additional relays, and is adversely affected by increased signal correlation and a higher number of eavesdroppers.