IEEE 802.15.6通道

Question

以下代碼來自IEEE 802.15.6無線體域網絡標準。頻道實現的數量是多少？我如何選擇它的價值？這個值與通過信道傳輸的輸入信號的長度之間的關係是什麼？

function [h, t, n_p] = uwb_hospban_chan_CM4(num_channels, body_direction) 
% Function for getting channel realizations for UWB Hospital BAN channel CM4. 
% Igor Dotlic (dotlic@nict.go.jp) March 2009. 
% Input variables 
% num_channels - number of channel realizations 
% body_direction= 1: 0 deg, 2: 90 deg, 3: 180 deg, 4: 270 deg 
% Output variables 
% h - comlex multipath amplitude responses 
% t - times of multipath arrivals (ns) 
% n_p - number of paths for each channel realization 
% Fixed model parameters 
L_mean = 400; % mean number of arrival paths 
lambda_inv= 0.50125; % mean time between arrivals (ns) 
% Model parameters that depend on body direction 
if body_direction == 1 
Gamma = 44.6346; % (ns) 
k_abs = 5.111739; 
sigma = 7.30; 
elseif body_direction == 2 
Gamma = 54.2868; % (ns) 
k_abs = 4.348859975; 
sigma = 7.08; 
elseif body_direction == 3 
Gamma = 53.4186; % (ns) 
k_abs = 3.638084447; 
sigma = 7.03; 
elseif body_direction == 4 
Gamma = 83.9635; % (ns) 
k_abs = 3.983472211; 
sigma = 7.19; 
end 
% Calculating number of paths 
n_p = poissrnd(L_mean, 1, num_channels); 
for k_chan = 1:num_channels 
n_p(k_chan) = max(n_p(k_chan), 1); 
end 
% Maximum number of paths 
n_p_max = max(n_p); 
% Allocating memory for channel realizations 
h = zeros(n_p_max, num_channels); 
t = zeros(n_p_max, num_channels); 
% Calculating path arrival times 
t_dif = exprnd(lambda_inv, num_channels, n_p_max-1); 
for k_chan = 1:num_channels 
t(2:n_p(k_chan),k_chan) = cumsum(t_dif(k_chan, 1:n_p(k_chan)-1)); 
end 
% Calculating path levels 
for k_chan = 1:num_channels 
h(1,k_chan) = exp(i*rand*2*pi)*sqrt(10^(sigma*randn/10)); 
% Paths 2 onwards 
for k_p = 2:n_p(k_chan) 
h(k_p, k_chan) = exp(i*rand*2*pi)*... 
sqrt(exp(-t(k_p,k_chan)/Gamma-k_abs)*10^(sigma*randn/10)); 
end 
% Normalizing current PDP realization (may be commented out) 
h(:,k_chan) = h(:,k_chan)/norm(h(:,k_chan)); 
end 

Answer 1

信道實現的數量是多少？我如何選擇它的價值？

看起來像這會影響您獲得的n_p的大小。在不知道你到底在做什麼的時候，很難建議你想要的值

這個值和通過信道傳輸的輸入信號的長度之間的關係是什麼？

我認爲你的輸入信號保持不變，但如果你有多個通道，那麼你在所有通道上發送輸入信號。