Hi @Sumit,

5G NEXT-GEN RADIO (NR) uses Quasi-Cyclic LDPC (QC-LDPC).

TO increase the BER performance you need to increase the SNR, lower the code rate, increase LDPC decoder iterations and use large transport block size. I am not sure what parameters you are using, but see if this helps. This should improve the BER performance.

% Parameters

trBlkSize = 3000;           % Larger transport block

modulation = 'QPSK';        % Robust modulation

targetCodeRate = 1/3;       % Lower code rate (more redundancy)

N = trBlkSize / targetCodeRate;  % Number of bits after rate matching

% Transmit: generate random transport block

trBlk = randi([0 1], trBlkSize, 1);

% Step 1: CRC + Code block segmentation

cbSegOut = nrCodeBlockSegmentLDPC(trBlk, trBlkSize);

% Step 2: LDPC Encoding

numCBs = length(cbSegOut);

ldpcEncOut = cell(numCBs,1);

for i = 1:numCBs

ldpcEncOut{i} = nrLDPCEncode(cbSegOut{i});

end

% Step 3: Rate Matching

rmOut = cell(numCBs,1);

for i = 1:numCBs

rmOut{i} = nrRateMatchLDPC(ldpcEncOut{i}, trBlkSize, modulation, N, i-1);

end

txBits = vertcat(rmOut{:});

% Step 4: BPSK Modulation & Channel Simulation

txSymbols = 1 - 2 * txBits;                     % BPSK mapping

rxSymbols = txSymbols + 0.2 * randn(size(txSymbols));  % AWGN channel (lower noise)

rxLLR = -2 * rxSymbols;                         % LLR for BPSK

% Step 5: Rate Recovery

rxCBs = cell(numCBs,1);

for i = 1:numCBs

rxCBs{i} = nrRateRecoverLDPC(rxLLR, trBlkSize, modulation, N, i-1);

end

% Step 6: LDPC Decoding with more iterations

decCBs = cell(numCBs,1);

for i = 1:numCBs

decCBs{i} = nrLDPCDecode(rxCBs{i}, 50);  % Increased to 50 iterations

end

% Step 7: Desegmentation and CRC check

[rxTrBlk, blkErr] = nrCodeBlockDesegmentLDPC(decCBs, trBlkSize);

fprintf('Block error: %d\n', blkErr);

% Step 8: Bit Error Rate

numErrors = sum(rxTrBlk ~= trBlk);

ber = numErrors / trBlkSize;

fprintf('Bit error rate: %.4f\n', ber);

Hello @Madhan,

Thanks for replying. This will be helpful for me.

Actually, I am implementing 64 QAM OFDM Index Modulation for 5G NR using LDPC code over Rayleigh channel. Could you help me for the same. I can share you my code for your reference.