使用 bsxfun 进行卷积，而不是 Matlab 中的循环

Question

我想用bsxfun替换for循环来计算Matlab中的卷积。以下是脚本：

for Rx = 1:Num_Rx
    for Tx= 1:Num_Tx
        Received(Rx,:)=Received(Rx,:)+conv(squeeze(channel(Rx,Tx,:))', Transmitted(Tx,:));
    end
end
% Received is a Num_Rx by N matrix, Transmitted is a Num_Tx by N matrix and channel is a 3D matrix with dimension Num_Rx, Num_Tx, N.

当我将代码更改为：

Received = bsxfun(@plus, Received, bsxfun(@conv, permute(squeeze(channel), [3 1 2]), Transmitted));

错误出来了，说"输入数组的两个非一维必须匹配"。

如何更正此行？多谢！

Answer 1

为什么要

用bsxfun替换循环？ 如果卷积中涉及的大小不是特别小，那么卷积将占用大部分开销，并且循环和此调用的某些矢量化版本之间的差异将很小。

如果你能负担得起临时存储并且它不会过多地弄乱你的数字，那么你有一个选择，那就是使用 FFT 来做这个卷积。 那看起来像

 Transmitted = reshape(Transmitted, [1 Num_Tx size(Transmitted, 2)]);
 N = size(Transmitted, 3) + size(channel, 3) - 1;
 Received = ifft(fft(channel, N, 3).*fft(Transmitted, N, 3), N, 3);
 Received = squeeze(sum(Received, 2));