Boluda-Ruiz Rubén, García-Zambrana Antonio, Castillo-Vázquez Carmen, Castillo-Vázquez Beatriz
Opt Express. 2014 Jun 30;22(13):16629-44. doi: 10.1364/OE.22.016629.
In this paper, a novel adaptive cooperative protocol with multiple relays using detect-and-forward (DF) over atmospheric turbulence channels with pointing errors is proposed. The adaptive DF cooperative protocol here analyzed is based on the selection of the optical path, source-destination or different source-relay links, with a greater value of fading gain or irradiance, maintaining a high diversity order. Closed-form asymptotic bit error-rate (BER) expressions are obtained for a cooperative free-space optical (FSO) communication system with Nr relays, when the irradiance of the transmitted optical beam is susceptible to either a wide range of turbulence conditions, following a gamma-gamma distribution of parameters α and β, or pointing errors, following a misalignment fading model where the effect of beam width, detector size and jitter variance is considered. A greater robustness for different link distances and pointing errors is corroborated by the obtained results if compared with similar cooperative schemes or equivalent multiple-input multiple-output (MIMO) systems. Simulation results are further demonstrated to confirm the accuracy and usefulness of the derived results.
本文提出了一种新颖的自适应协作协议，该协议在存在指向误差的大气湍流信道上使用检测转发（DF）方式，通过多个中继进行通信。这里分析的自适应DF协作协议基于光路、源 - 目的端或不同源 - 中继链路的选择，选择衰落增益或辐照度较大的链路，以保持较高的分集阶数。对于具有Nr个中继的协作自由空间光（FSO）通信系统，当发射光束的辐照度易受多种湍流条件影响（遵循参数为α和β的伽马 - 伽马分布）或指向误差影响（遵循考虑了光束宽度、探测器尺寸和抖动方差影响的失准衰落模型）时，获得了闭式渐近误码率（BER）表达式。与类似的协作方案或等效的多输入多输出（MIMO）系统相比，所得结果证实了该协议对于不同链路距离和指向误差具有更高的鲁棒性。仿真结果进一步证明了所得结果的准确性和实用性。
