中文摘要：

在协同自适应解码转发中继系统中，该文针对 Nakagami-m 衰落信道，研究了基于多天线低复杂度的机会式传输策略的物理层安全性能。为充分利用天线分集增益提升系统安全性能，发送节点均采用发送天线选择策略，接收节点均采用最大比合并策略。推导了系统安全中断概率的闭合表达式，并进一步提供了渐近性能分析，得到了系统的安全分集阶数。仿真结果验证了理论分析的正确性，并揭示了各系统参数对机会式传输方案的安全性能的影响。结果表明，通过增加合法节点的天线数和增大合法信道的Nakagami衰落信道参数可显著提升系统安全性能。

英文摘要：

The physical layer security performances of low-complexity opportunistic transmission strategy based on multiple antenna are investigated for cooperative adaptive decode-and-forward relaying system in Nakagami-m fading channels. To fully utilize the antenna diversity gain to improve the system security performance, the transmitting nodes apply the transmit antenna selection strategy, and the receiving nodes apply the maximal ratio combining strategy. The closed-form expressions of secrecy outage probability are derived, the asymptotic analysis of secrecy performance is further provided, and the secrecy diversity order are also obtained. Simulation results verify the correctness of theoretical analysis and identify the effects of several system parameters on the secrecy performance of the opportunistic transmission strategy. It is shown that the system secrecy performance can be greatly improved by increasing the number of antennas at the legitimate nodes and increasing the Nakagami fading channel parameters of legitimate channels.