基于Simulink单载波链路射频波束成形仿真

function [startOffset,M] = dmgPacketDetect(x,varargin) %dmgPacketDetect DMG packet detection for SC PHY using STF field % % STARTOFFSET = dmgPacketDetect(X) returns the offset from the % start of the input waveform to the start of the detected preamble using % auto-correlation. The dmgPacketDetect() only detect DMG SC packet % type. % % STARTOFFSET is an integer scalar indicating the location of the start % of a detected packet as the offset from the start of the matrix X. If % no packet is detected an empty value is returned. % % X is the received time-domain signal. It is an Ns-by-1 matrix of real % or complex samples, where Ns represents the number of time domain % samples. % % STARTOFFSET = dmgPacketDetect(..., OFFSET) specifies the offset to % begin the auto-correlation process from the start of the matrix X. The % STARTOFFSET is relative to the input OFFSET when specified. It is an % integer scalar greater than or equal to zero. When unspecified a value % of 0 is used. % % STARTOFFSET = dmgPacketDetect(...,OFFSET,THRESHOLD) specifies the % threshold which the decision statistic must meet or exceed to detect a % packet. THRESHOLD is a real scalar greater than 0 and less than or % equal to 1. When unspecified a value of 0.03 is used. % % [STARTOFFSET,M] = dmgPacketDetect(...) returns the decision % statistics of the packet detection algorithm of matrix X. When % THRESHOLD is set to 1, the decision statistics of the complete waveform % will be returned and STARTOFFSET will be empty. % % M is a real vector of size N-by-1, representing the decision statistics % based on auto-correlation of the input waveform. The length of N % depends on the starting location of the auto-correlation process till % the successful detection of a packet. % % Example 1: % % Detect a received 802.11ad SC packet without channel impairments % % cfgDMG = wlanDMGConfig('MCS',1); % Create packet configuration % % % Generate transmit waveform % txWaveform = wlanWaveformGenerator([1;0;0;1],cfgDMG); % % % Delay the signal by appending zeros at the start % rxWaveform = [zeros(20,1);txWaveform]; % % startOffset = dmgPacketDetect(rxWaveform,0,0.99); % disp(startOffset) % % Example 2: % % Return the decision statistics of the input waveform. The waveform % % consists of five WLAN packets. The decision statistics shows five % % peaks. Each peak corresponds to the detection of a single packet. % % cfgDMG = wlanDMGConfig('MCS',1); % Create packet configuration % txWaveform = wlanWaveformGenerator([1;0;0;1],cfgDMG, ... % 'NumPackets',5,'IdleTime',20e-6); % [~,M] = dmgPacketDetect(txWaveform,0,1); % figure; % plot(M); % axis([0 length(M) 0 1.2]); % Copyright 2017-2018 The MathWorks, Inc. %#codegen narginchk(1,3); nargoutchk(0,2); % Check if M is requested if nargout==2 M = []; end validateattributes(x, {'double'}, {'2d','finite'}, mfilename, 'signal input'); startOffset = []; if isempty(x) return; end if nargin == 1 threshold = 0.03; % Default value offset = 0; % Default value elseif nargin == 2 threshold = 0.03; validateattributes(varargin{1}, {'double'}, {'integer','scalar','>=',0}, mfilename, 'offset'); offset = varargin{1}; else validateattributes(varargin{1}, {'double'}, {'integer','scalar','>=',0}, mfilename, 'offset'); validateattributes(varargin{2}, {'double'}, {'real','scalar','>',0,'<=',1}, mfilename, 'threshold'); offset = varargin{1}; threshold = varargin{2}; end % Validate Offset value coder.internal.errorIf(offset>size(x,1)-1, 'wlan:shared:InvalidOffsetValue'); symbolLength = 128; % Length of single repetition of Golay sequence for SC PHY numRepetitions = 17; % Number of repetition of Golay sequence in the preamble of SC PHY lenLSTF = symbolLength*numRepetitions; % Length of STF field lenHalfLSTF = lenLSTF/2; % Length of 1/2 STF field inpLength = (size(x,1)-offset); % Append zeros to make the input equal to multiple of STF/2 if inpLength<=lenHalfLSTF numPadSamples = lenLSTF-inpLength; else numPadSamples = lenHalfLSTF*ceil(inpLength/lenHalfLSTF)-inpLength; end padSamples = zeros(numPadSamples,size(x,2)); % Process the input waveform in blocks of STF length. The processing % blocks are offset by half the STF length. numBlocks = (inpLength+numPadSamples)/lenHalfLSTF; if nargout==2 % Define decision statistics vector DS = coder.nullcopy(zeros(size(x,1)+length(padSamples)-offset-2*symbolLength+1,1)); if numBlocks > 2 for n=1:numBlocks-2 % Update buffer buffer = x((n-1)*lenHalfLSTF+(1:lenLSTF)+offset,:); [startOffset,out] = correlateSamples(buffer,symbolLength,threshold); DS((n-1)*lenHalfLSTF+1:lenHalfLSTF*n,1) = out(1:lenHalfLSTF); if ~(isempty(startOffset)) % Packet detected startOffset = startOffset+(n-1)*lenHalfLSTF; DS((n-1)*lenHalfLSTF+(1:length(out)),1) = out; % Resize decision statistics M = DS(1:(n-1)*lenHalfLSTF+length(out)); return; end end % Process last block of data blkOffset = lenHalfLSTF*(numBlocks-2); buffer = [x(blkOffset+1+offset:end,:);padSamples]; [startOffset,out] = correlateSamples(buffer,symbolLength,threshold); if ~(isempty(startOffset)) startOffset = startOffset+blkOffset; % Packet detected end DS(blkOffset+1:end,1)= out; M = DS(1:end-length(padSamples)); else buffer = [x(offset+1:end,:);padSamples]; [startOffset,out] = correlateSamples(buffer,symbolLength,threshold); M = out; end else if numBlocks > 2 for n=1:numBlocks-2 buffer = x((n-1)*lenHalfLSTF+(1:lenLSTF)+offset,:); % Update buffer startOffset = correlateSamples(buffer,symbolLength,threshold); if ~(isempty(startOffset)) startOffset = startOffset+(n-1)*lenHalfLSTF; % Packet detected return; end end % Process last block of data blkOffset = lenHalfLSTF*(numBlocks-2); buffer = [x(blkOffset+1+offset:end,:);padSamples]; startOffset = correlateSamples(buffer,symbolLength,threshold); if ~(isempty(startOffset)) startOffset = startOffset+blkOffset; % Packet detected end else buffer = [x(offset+1:end,:);padSamples]; startOffset = correlateSamples(buffer,symbolLength,threshold); end end end function [packetStart,Mn] = correlateSamples(rxSig,symbolLength,threshold) % Estimate the start offset of the preamble of the receive WLAN packet, % using auto-correlation method [1]. % [1] OFDM Wireless LANs: A Theoretical and Practical Guide 1st Edition % by Juha Heiskala (Author),John Terry Ph.D. ISBN-13:978-0672321573 pNoise = eps; % Adding noise to avoid the divide by zero weights = ones(symbolLength,1); packetStart = []; % Initialize output % Shift data for correlation rxDelayed = rxSig(symbolLength+1:end,:); % Delayed samples rx = rxSig(1:end-symbolLength,:); % Actual samples % Sum output on multiple receive antennas C = sum(filter(weights,1,(conj(rxDelayed).*rx)),2); CS = C(symbolLength:end)./symbolLength; % Sum output on multiple receive antennas P = sum(filter(weights,1,abs(rxDelayed).^2./symbolLength),2); PS = P(symbolLength:end)+pNoise; Mn = abs(CS).^2./PS.^2; N = Mn > threshold; % The scalingFactor is used to scale the length of continuous region of % correlation samples above the threshold. scalingFactor = 5; if (sum(N) >= symbolLength*scalingFactor) % Convert mxArray to a known data type. Needed for codeGen startOnes = patternMatch([N(1)~=1 N.'],[0 1]); endOnes = patternMatch([N.' N(end)~=1],[1 0]); lengthOnes = endOnes - startOnes + 1; i