prmsPDSCH.m

function p= prmsPDSCH(chanBW, contReg, modType, varargin)
% LTEPDSCHPRMS Returns parameter structures for LTE PDSCH simulation.
%
%   Assumes a FDD, normal cyclic prefix, full-bandwidth, single-user 
%   SISO or SIMO downlink transmission.
%% PDSCH parameters
switch chanBW
    case 1      % 1.4 MHz
        BW = 1.4e6; N = 128; cpLen0 = 10; cpLenR = 9;
        Nrb = 6; chanSRate = 1.92e6;
    case 2      % 3 MHz
        BW = 3e6; N = 256; cpLen0 = 20; cpLenR = 18;
        Nrb = 15; chanSRate = 3.84e6;
    case 3      % 5 MHz
        BW = 5e6; N = 512; cpLen0 = 40; cpLenR = 36;
        Nrb = 25; chanSRate = 7.68e6;
    case 4      % 10 MHz
        BW = 10e6; N = 1024; cpLen0 = 80; cpLenR = 72;
        Nrb = 50; chanSRate = 15.36e6;
    case 5      % 15 MHz
        BW = 15e6; N = 1536; cpLen0 = 120; cpLenR = 108;
        Nrb = 75; chanSRate = 23.04e6;
    case 6      % 20 MHz
        BW = 20e6; N = 2048; cpLen0 = 160; cpLenR = 144;
        Nrb = 100; chanSRate = 30.72e6;
end
p.BW = BW;                  % Channel bandwidth
p.N = N;                    % NFFT
p.cpLen0 = cpLen0;          % Cyclic prefix length for 1st symbol,特殊CP
p.cpLenR = cpLenR;          % Cyclic prefix length for remaining，普通CP
p.Nrb = Nrb;                % Number of resource blocks，RB的的个数，6-110
p.chanSRate = chanSRate;    % Channel sampling rate
p.contReg = contReg;
p.numTx = 1;
p.numRx = 1;
p.numLayers = 1;
p.numCodeWords = 1;

% For Normal cyclic prefix, FDD mode
p.deltaF = 15e3;    % subcarrier spacing，子载波间隔
p.Nrb_sc = 12;      % no. of subcarriers per resource block,一个RB12个子载波
p.Ndl_symb = 7;     % no. of OFDM symbols in a slot，一个slot7个OFDM符号

% Actual PDSCH bits calculation - accounting for PDCCH, PBCH, PSS, SSS
numResources = (p.Nrb*p.Nrb_sc)*(p.Ndl_symb*2);% 总个数
numCSRRE = 2*2*2 * p.Nrb;               % CSR, RE per OFDMsym/slot/subframe per RB
numContRE = (10 + 12*(p.contReg-1))*p.Nrb;
numBCHRE = 60+72+72+72;              % removing the CSR present in 1st symbol
numSSSRE=72;
numPSSRE=72;

numDataRE=zeros(3,1);
% Account for BCH, PSS, SSS and PDCCH for subframe 0
numDataRE(1)=numResources-numCSRRE-numContRE-numSSSRE - numPSSRE-numBCHRE;
% Account for PSS, SSS and PDCCH for subframe 5
numDataRE(2)=numResources-numCSRRE-numContRE-numSSSRE - numPSSRE;
% Account for PDCCH only in all other subframes
numDataRE(3)=numResources-numCSRRE-numContRE;
 
% Maximum data resources - with no extra overheads (only CSR + data)
p.numResources=numResources;
p.numCSRResources =  numCSRRE;  
p.numContRE = numContRE;
p.numBCHRE = numBCHRE;
p.numSSSRE=numSSSRE;
p.numPSSRE=numPSSRE;
p.numDataRE=numDataRE;
p.numDataResources = p.numResources - p.numCSRResources;

% Modulation types , bits per symbol, number of layers per codeword
Qm = 2 * modType;
p.Qm = Qm;
p.numLayPerCW = p.numLayers/p.numCodeWords;

% Maximum data bits - with no extra overheads (only CSR + data)
p.numDataBits = p.numDataResources*Qm*p.numLayPerCW;
numPDSCHBits =numDataRE*Qm*p.numLayPerCW;
p.numPDSCHBits = numPDSCHBits;
p.maxG = max(numPDSCHBits);