路径损耗，阴影，衰落（瑞利，莱斯和中头m）；信号的调制，解调和比特错误率（BER）与SNR曲线-The path loss, shadowing, fading (Rayleigh, Rice and Nakagami-m) signal modulation, demodulation and bit error rate (BER) and the SNR curve

为作业最终的仿真结果与分析 PL_free.m：free space path loss model PL_logdist.m: log-distance path loss model PL_lognorm.m: log-normal shadowing path loss model plot_PL_general.m: plot the figures itum.m: ITU M.1225 vehicular-B(120km/hr) channel model AW