5.8GHz复杂城区街巷环境信道建模与仿真

      Measured Channel Modeling and Simulation in 5.8 GHz Complex Urban 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),并基于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)建立了精确的抽头延迟线(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)达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。进一步,提出了一种基于Copula的统计一致性仿真方法: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,并在相位继承机制下最大程度保持时间依赖结构,实现幅度分布与时间相关的解耦。所提方法生成的信道序列可同时逼近目标幅度统计与DPSD统计,在幅度一致性上K-S距离均值为0.011,DPSD一致性上DPSD NMSE均值为-18.8 dB的稳定表现,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: This paper presents a measurement-based study on channel modeling and simulation for low-antenna-height Mobile Ad Hoc Networks (MANET) in complex 5.8 GHz urban street environments. It addresses the challenges of modeling non-Gaussian tap amplitudes while simultaneously preserving Doppler correlation structures. First, a high-precision broadband system was developed to capture time-varying channel impulse responses (CIR). Using the Space-Alternating Generalized Expectation-maximization (SAGE) algorithm and Akaike Information Criterion (AIC), an accurate Tapped Delay Line (TDL) model was established. Results indicate significant statistical differences between line-of-sight (LOS) and non-line-of-sight (NLOS) conditions. Dominated by dense scattering and diffraction, NLOS exhibits a root mean square delay spread (RMS-DS) of 409 ns compared to 197 ns for LOS, while the coherence bandwidth decreases from 1.149MHz to 0.508MHz. Furthermore, a Copula-based statistically consistent simulation method is proposed. By employing a complex Gaussian reference process to carry the target Doppler Power Spectral Density (DPSD), arbitrary amplitude distributions are strictly embedded via Probability Integral Transform (PIT) and inverse distribution mapping. This approach utilizes a phase inheritance mechanism to maintain temporal structures, effectively decoupling amplitude distribution from time correlation. The generated channel sequences accurately approximate both target amplitude and DPSD statistics, achieving a mean K-S distance of 0.011 for amplitude consistency and a mean DPSD NMSE of -18.8 dB. This method reliably reproduces the statistical characteristics of complex urban channels, providing a foundation for communication system design and simulation.

         

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