两状态LMS信道中LMS系统的近似中断性能研究

Approximate Outage Performance of LMS Systems over Two-State LMS Channel

针对通用的两状态陆地移动卫星(LMS)信道模型中,每一状态的Loo分布包含无限范围内的积分且不存在闭合形式,导致性能估计难以实现的问题,基于两状态信道模型给出等增益合并分集LMS系统中断概率的闭式解。利用Taylor级数展开法将包络的概率密度函数(PDF)近似为Rice分布PDF的加权和,利用Beaulieu序列法推导独立信道随机变量和的累积分布函数和二阶矩,得出系统中断概率的闭式解。仿真结果表明,近似中断概率与理论值十分一致,具有精确性、灵活性、复杂度低的优点。

The Loo distribution includes an infinite-range integral and is unclosed-form within each state for versatile two-state land mobile satellite （LMS） channel model, which makes the performance estimation difficult. The closed-form expression of outage probability for equal gain combining diversity LMS systems is presented based on two-state channel model. Firstly, the envelope probability density function （PDF） for each state is approximated as a sum of weighted Rice’s PDFs by using Taylor series expansion algorithm. At a second stage, the cumulative distribution function and second moment of the sum of independent channel random variables are derived by applying Beaulieu series method. Finally, the closed-form of outage performance is obtained. Simulation results show that the approximated outage probability not only agrees very well with exact results over two-state LMS channel model, but also has superiority in significant accuracy, flexibility, and moderate computational complexity.