73 lines
2.4 KiB
Matlab
73 lines
2.4 KiB
Matlab
function [len_CP] = Generate_CP(channel_response,N_windows,N_level,min_len_CP)
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% 产生CP长度的函数
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% 在该方法中，假设将要发送的OFDM符号的数量等于H_bs中窗的数目。
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% 输入channel_response 信道响应；N_windows 需要划窗的个数；N_level 量化等级；
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% min_len_CP，最小CP取决于最大延迟拓展，有最小CP值>最大延迟拓展
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% 输出CP的长度向量，其长度等于窗的个数
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% 子载波个数
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N_carriers = length(channel_response);
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% 窗的长度
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Len_windows = N_carriers / N_windows;
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% 对信道增益进行降序排序并记录索引
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[channel_gain, sorted_indices] = sort(abs(channel_response), 'descend');%
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G_max = max(channel_gain);
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G_min = min(channel_gain);
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% 距离水平
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D_L = (G_max-G_min)/N_level;
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% 计算每个子载波对应的等级
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level_k = zeros(1,N_carriers);
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for i = 1:N_carriers
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% 边界值处理
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if channel_gain(i) <= G_min
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level_k(i) = 1;
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elseif channel_gain(i) >= G_max
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level_k(i) = N_level;
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% 根据式(3)的变形，可以得到权重等级
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else
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level_k(i) = ceil((channel_gain(i) - G_min)/D_L);
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end
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end
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% 根据式(2)计算子载波权值
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weight_k = 2*level_k-1;
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% 对每个窗进行计算，获得该窗下对应的CP长度
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weight_matrix = zeros(N_windows,Len_windows);
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choose_matrix = zeros(N_windows,Len_windows);
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len_CP = zeros(1,N_windows);
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for i = 1:N_windows
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weight_matrix(i,:) = weight_k((i-1)*Len_windows+1:i*Len_windows);% 将权重向量转变为权重矩阵，其中每一行为每一个窗的权重
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current_CP = weight_matrix(i,1);% 临时变量，用于权重相加
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choose_matrix(i,1) = current_CP;% 选择矩阵，记录相加权重的值
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for j = 2:Len_windows
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% 累加权重，进行判断
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if current_CP <= min_len_CP
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current_CP = current_CP + weight_matrix(i,j);
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choose_matrix(i,j) = weight_matrix(i,j);
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% 边界条件处理
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if j == Len_windows
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if current_CP <= min_len_CP % 仍未满足条件
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len_CP(i) = min_len_CP;
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break;
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else
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len_CP(i) = current_CP;% 满足条件
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break;
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end
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end
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% current_CP > min_len_CP，直接赋值
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else
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len_CP(i) = current_CP;
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break;
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end
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end
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end
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end |