「通信工程」F-OFDM

调制的方法变了，OFDM之后，经过一个滤波器，就是F-OFDM，解调按照正常的OFDM解调。

classdef FOFDMModulator < matlab.System
    % F-OFDM Modulator
    %
    % This template includes the minimum set of functions required
    % to define a System object with discrete state.

    % Public, tunable properties
    properties 
        FFTLength               = 1024;
        NumGuardBandCarriers    = [212;212];
        CyclicPrefixLength      = 72;
        NumSymbols              = 1;
        FilterLength            = 513;
        ToneOffset              = 2.5000;
    end

    % Pre-computed constants
    properties(Access = private)
        OFDMModulator
        filterOrder
        numDataCarriers
        fnum
        filt
    end

    methods
        function obj = FOFDMModulator(varargin)
            % Support name-value pair arguments when constructing object
            setProperties(obj,nargin,varargin{:})
        end
    end

    methods(Access = protected)
        function setupImpl(obj)
            % Perform one-time calculations, such as computing constants
            obj.OFDMModulator = comm.OFDMModulator("FFTLength",obj.FFTLength,...
                "NumGuardBandCarriers",obj.NumGuardBandCarriers,...
                "CyclicPrefixLength",obj.CyclicPrefixLength,...
                "NumSymbols",obj.NumSymbols);
            obj.filterOrder     = obj.FilterLength - 1;
            obj.numDataCarriers = obj.FFTLength - sum(obj.NumGuardBandCarriers);
            
            L = obj.filterOrder;
            halfFilt = L/2;
            n = -halfFilt:halfFilt;
            
            % Sinc function prototype filter
            pb = sinc((obj.numDataCarriers+2*obj.ToneOffset).*n./obj.FFTLength);
            
            % Sinc truncation window
            w = (0.5*(1+cos(2*pi.*n/(L-1)))).^0.6;
            
            % Normalized lowpass filter coefficients
            obj.fnum = (pb.*w)/sum(pb.*w);

            obj.filt = dsp.FIRFilter('Structure', 'Direct form symmetric', ...
    'Numerator', obj.fnum);
        end

        function y = stepImpl(obj,u)
            txSigOFDM  = obj.OFDMModulator(u);
            txSigFOFDM = obj.filt([txSigOFDM; zeros(obj.filterOrder/2,1)]);
            y = txSigFOFDM(obj.filterOrder/2+(1:(obj.FFTLength + obj.CyclicPrefixLength)));
        end

        function resetImpl(obj)
            % Initialize / reset discrete-state properties
            release(obj.OFDMModulator);
            release(obj.filt);
        end

        function num = getNumInputsImpl(~)
            % Define total number of inputs for system with optional inputs
            num = 1;
            % if obj.UseOptionalInput
            %     num = 2;
            % end
        end

        function num = getNumOutputsImpl(~)
            % Define total number of outputs for system with optional
            % outputs
            num = 1;
            % if obj.UseOptionalOutput
            %     num = 2;
            % end
        end

        function out = getOutputSizeImpl(obj)
            % Return size for each output port
            out = [obj.FFTLength + obj.CyclicPrefixLength,1];
        end
    end
end