test_ldpc.m

% 5g ldpc encoding and decoding test
% reference: 3GPP TS 38.212 section 5.3.2
% author: Xiao, Shaoning 萧少宁
% license: MIT

function pass_flag = test_ldpc(varargin)

if nargin == 0
    base_graph_index = 1;
    Z_c = 384;
elseif nargin == 1
    base_graph_index = varargin{1};
    Z_c = 384;
elseif nargin == 2
    base_graph_index = varargin{1};
    Z_c = varargin{2};
end

SNR_list = 10;

trial_number = 1;

BLER = zeros(1, length(SNR_list));

TxRx.Decoder.LDPC.Iterations = 30;
TxRx.Decoder.LDPC.Type = 'OMS';
% TxRx.Decoder.LDPC.Type = 'MPA';

if base_graph_index == 1
    load base_graph_1_check_node_list
    base_graph_check_node_list = base_graph_1_check_node_list;
    LDPC.inf_bits = 22 * Z_c;
elseif base_graph_index == 2
    load base_graph_2_check_node_list
    base_graph_check_node_list = base_graph_2_check_node_list;
    LDPC.inf_bits = 10 * Z_c;
else
    error('wrong base graph index.');
end

for SNR_list_index = 1:length(SNR_list)
    
    sigma_square = 10^(-SNR_list(SNR_list_index)/10);
    
    for trial = 1:trial_number
        
        tx_bits = randi([0, 1], LDPC.inf_bits, 1);
        
        %         [encoded_bits, LDPC.H, Z_c] = ldpc_encode(tx_bits, base_graph_index);
        [encoded_bits, LDPC.H, Z_c] = ldpc_encode_optimized(tx_bits, base_graph_index);
        
        [LDPC.par_bits, LDPC.tot_bits] = size(LDPC.H);
        
        symbols = 1 - 2 * encoded_bits;
        
        noise = randn(size(symbols));
        
        waveform = symbols + noise * sqrt(sigma_square);
        
        LLR_received = 2 * waveform / sigma_square;
        
        rx_bits = decLDPC_layered(TxRx, LDPC, LLR_received.', base_graph_check_node_list, Z_c);
        
%         f0=1./(1+exp(-2*LLR_received));
%         f1 = 1 - f0;
%         f = [f0, f1].';
%         rx_bits_prime = ldpc_decode(f0,f1, full(LDPC.H), TxRx.Decoder.LDPC.Iterations);
%         
%         ldpc_dec = comm.LDPCDecoder(LDPC.H);
%         LLR_received_extended = [zeros(2*Z_c, 1); LLR_received];
%         decoded_bits = step(ldpc_dec, LLR_received_extended);
%         
%         [rx_bits_prime, success, k] = ldpc_decode_1(f, full(LDPC.H), 2);
        rx_bits = rx_bits(:);
        
        if ~isequal(tx_bits, rx_bits)
            BLER(SNR_list_index) = BLER(SNR_list_index) + 1;
        end
        
%         if ~isequal(rx_bits_prime(1:LDPC.inf_bits), tx_bits)
%             BLER(SNR_list_index) = BLER(SNR_list_index) + 1;
%         end
%         
%         if ~isequal(double(decoded_bits), tx_bits)
%             BLER(SNR_list_index) = BLER(SNR_list_index) + 1;
%         end
        
    end
    
end

fprintf('BLER is %f\n', BLER/trial_number);

if BLER < 1e-10
    pass_flag = true;
else
    pass_flag = false;
end

end