5.8 GHz复杂城区街巷环境信道建模与仿真

      Channel modeling and simulation in 5.8 GHz complex urban street environments

      • 摘要: 为了准确反映5.8 GHz复杂城区街巷环境下低天线高度移动自组织网络(Mobile Ad Hoc Network, MANET)节点间的无线信道传播特性,同时解决信道模型各抽头幅度呈非高斯分布且需兼顾多普勒相关结构的仿真难题,本文开展了基于实测的信道建模与仿真研究。首先构建高精度宽带测量系统获取时变信道冲激响应(channel impulse response, CIR),结合空间交替广义期望最大化(space-alternating generalized expectation-maximization, SAGE)算法与赤池信息准则(Akaike Information Criterion, AIC)建立了抽头延迟线(tapped delay line, TDL)信道模型。建模结果表明,视距(line-of-sight, LoS)与非视距(non-line-of-sight, NLoS)状态下信道统计特性差异显著:NLoS受密集散射与绕射机制主导,其均方根时延扩展(root mean square delay spread, RMS-DS)为409 ns,远高于LoS的197 ns,对应的相干带宽则从1.149 MHz降至0.508 MHz。为实现模型的时变仿真,进一步提出了一种基于Copula的统计一致性信道仿真方法:以复高斯参考过程承载目标多普勒功率谱密度(Doppler power spectral density, DPSD),通过概率积分变换(probability integral transform, PIT)与逆分布映射实现任意幅度分布的严格嵌入,并通过相位继承保持时变相关性,实现幅度分布与时间相关的解耦。结果表明,该方法可同时复现目标幅度分布与DPSD特征,幅度一致性上K-S距离小于0.01,DPSD一致性上DPSD的归一化均方误差优于−18 dB,可准确再现复杂城区信道模型的统计特征,为通信系统设计提供信道模型与仿真支撑。

         

        Abstract: To accurately characterize the wireless channel propagation characteristics between nodes in a Mobile Ad Hoc Network (MANET) under low antenna height conditions within complex urban street canyon environments at 5.8 GHz, and to address the challenges in simulating channel models where tap amplitudes exhibit non-Gaussian distributions while preserving the Doppler correlation structure, this paper presents a measurement-based channel modeling and simulation study. First, a high-precision wideband measurement system is established to capture the time-varying channel impulse response (CIR). Subsequently, the tapped delay line (TDL) channel model is developed using the space-alternating generalized expectation-maximization (SAGE) algorithm in conjunction with the Akaike Information Criterion (AIC). Modeling results reveal significant differences in channel statistics between line-of-sight (LoS) and non-line-of-sight (NLoS) conditions: NLoS propagation, dominated by dense scattering and diffraction, exhibits a root mean square delay spread (RMS-DS) of 409 ns, considerably larger than the LoS value of 197 ns, while the corresponding coherence bandwidth decreases from 1.149 MHz to 0.508 MHz. To enable time-variant simulation of the model, a statistically consistent channel simulation method based on Copula theory is further proposed. This method employs a complex Gaussian reference process to carry the target Doppler power spectral density (DPSD). Through probability integral transform (pit) and inverse distribution mapping, it achieves rigorous embedding of arbitrary amplitude distributions while preserving time-varying correlation via phase inheritance, thereby decoupling amplitude distribution from temporal correlation. Results demonstrate that this approach simultaneously replicates the target amplitude distribution and DPSD characteristics, achieving a Kolmogorov-Smirnov (K-S) distance below 0.01 for amplitude consistency and a normalized mean square error (NMSE) better than 18 dB for DPSD consistency. The method accurately reproduces the statistical characteristics of complex urban channel models, providing robust channel modeling and simulation support for communication system design.

         

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