基于宽带信道状态信息的密钥生成策略
Secret key generation strategy based on broadband channel state information

对于宽带通信系统，大量的频点信息可以作为随机源生成密钥，从而增强通信系统的安全性。然而环境中散射径的数目是有限的，导致不同频点存在着相关性。在限定总发送功率的条件下，针对不同频点的功率分配策略会对密钥的安全性能产生影响。该文以密钥生成速率作为密钥安全性的衡量，建立了功率分配模型以实现密钥生成速率的最大化，并利用Lagrange乘数法进行求解。为降低计算复杂度，提出了一种次优的功率分配方法，并与最优的序列二次规划（sequential quadratic programming，SQP）求解算法进行对比，数值结果表明：次优功率分配策略下得到的密钥安全性能非常接近通过SQP算法得到的最优功率分配策略的密钥安全性能。
Abstract：The channel information for a large number of frequency points in broadband communication systems can be used as a random source to generate secret keys, thereby, enhancing system security. However, there is a limited number of multipaths in the scattering and there is a correlation between different frequency points. Thus, for the condition that the total transmission power is limited, the power allocation strategy for different frequency points will affect the secret key security. A power allocation model is given with the key generation rate as a measure of the security that maximizes the key generation rate. The model is solved with the Lagrange multiplier method. A suboptimal power allocation method is given to reduce the calculation complexity that compares with the optimal solution with the sequential quadratic programming (SQP) algorithm. Numerical tests show that the security with the suboptimal power allocation strategy is quite close to the security with the SQP algorithm which is considered to be the optimal strategy.