【信号处理】基于k均值聚类算法实现QAM信号均衡附matlab代码

这篇博客介绍了在无线通信中，针对无线节点或移动终端成本低、体积小、低功耗的需求，提出了一种基于QAM矩形星座的K-means聚类改进算法，用以解决高阶QAM调制在功放非线性影响下的解调问题。该算法在严重失真下表现优异且复杂度低，适用于对信号质量有高要求的场景。

1 简介

在短距离无线通信中,无线节点或移动终端通常有低成本,小体积,低功耗的要求,因此无法使用复杂的预失真或补偿电路克服功放的非线性影响,这是无线节点或移动终端在上行链路中难以使用高阶QAM调制的重要原因之一.基于QAM矩形星座的特点,提出了一种K-means聚类的改进算法作为中央基站节点的高阶QAM解调算法.在发送信号受到较严重的功放非线性失真时,所提改进算法解调性能更优,算法复杂度更低.

2 部分代码

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%figurehold on% %% Set up gridmeanlist = []; % list to append mean grid value to for surface-class gridgridsize = 10000; % total grid area (no. cells)gridx = 100; % length of x-axisgridy= 100; % length of y-axisalg_frac = 1; % percentage of algal coverage at start of experiment (all initialise as light algae: class 1)non_alg_frac = gridsize-alg_frac; % residual = non-algal, assumed clean% create grid by randomly spacing 1's and 2's in a 10x10 gridalg_pixels = gridsize*(alg_frac/100) non_alg_pixels = gridsize-alg_pixelsgrid = reshape([zeros(non_alg_pixels,1) ; ones(alg_pixels,1)],gridx,gridy) ;grid(:) = grid(randperm(numel(grid))) ;for counter = 1:1:12    rand = randi(100,1); % return one pseudorandom integer between 1-100    for i = 2:1:gridx-1  %%%% NEED TO DEAL WITH EDGES BETTER!!!!        for j = 2:1:gridy-1 %%%% NEED TO DEAL WITH EDGES BETTER!!!!                                if grid(i,j) == 0   % if cell = 0, 10% chance of bloom initiation, otherwise stay clean                if rand == 1                    grid(i,j) = grid(i,j)+1;                else                    grid(i,j) = grid(i,j);                end                            elseif grid(i,j) < 10 % if cell is between 1 and 10, 40% chance of increasing in situ                if rand < 30                    grid(i,j) = grid(i,j)+1;                elseif rand > 30 && rand < 80 % 40 % chance of bloom spreading, not darkening                    rand1 = randi(8,1); % each neighbour has equal chance of being colonised                    if rand1 == 1                        grid(i,j+1) = grid(i,j+1)+1;                    elseif rand1 == 2                        grid(i,j-1) = grid(i,j-1)+1;                    elseif rand1 == 3                        grid(i+1,j+1) = grid(i+1,j+1)+1;                    elseif rand1 == 4                        grid(i+1,j-1) = grid(i+1,j-1)+1;                    elseif rand1 == 5                        grid(i+1,j) = grid(i+1,j)+1;                    elseif rand1 == 6                        grid(i-1,j) = grid(i-1,j)+1;                    elseif rand1 == 7                        grid(i-1,j-1) = grid(i-1,j-1)+1                    elseif rand1 == 8                        grid(i-1,j+1) = grid(i,j+1)+1                    end            elseif grid(i,j) == 10 % if cell value is 10 bloom can only grow by spreading                if i < gridx && j < gridy && i >1 && j >1                    if rand1 == 1                        grid(i,j+1) = grid(i,j+1)+1;                    elseif rand1 == 2                        grid(i,j-1) = grid(i,j-1)+1;                    elseif rand1 == 3                        grid(i+1,j+1) = grid(i+1,j+1)+1;                    elseif rand1 == 4                        grid(i+1,j-1) = grid(i+1,j-1)+1;                    elseif rand1 == 5                        grid(i+1,j) = grid(i+1,j)+1;                    elseif rand1 == 6                        grid(i-1,j) = grid(i-1,j)+1;                    elseif rand1 == 7                        grid(i-1,j-1) = grid(i-1,j-1)+1;                    elseif rand1 == 8                        grid(i-1,j+1) = grid(i,j+1)+1;                    end                else                    grid(i,j) = grid(i,j);                end                end            end        end    end                    meanlist(counter) = mean2(grid);    surf(grid);    view(2);    cbar = colorbar;    cbar.Limits=[0,10];    caxis([0,10]);    drawnow    pause(0.1)            % calls to SNICAR should go in here: populate second grid with albedos        end