IEEE802_11ax.c

/************************************************************************************
 * Copyright (C) 2023                                                               *
 * TETCOS, Bangalore. India                                                         *
 *                                                                                  *
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 *                                                                                  *
 * Author: HESUOFDM@IITM                                                *
 *                                                                                  *
 * ---------------------------------------------------------------------------------*/
 
#include "main.h"
#include "IEEE802_11.h"
#include "IEEE802_11_Phy.h"
 
/**
This function is called to initialize the MIMO and OFDM parameters relevant to 
IEEE802.11ax. 
This function is called from the "fn_NetSim_WLAN_PHY_Configuration()" for HE PHY.
Initialize time parameters as per the Table 27-13—Timing-related constants IEEE Std 802.11™-2024 pdf
also initialize 802.11ax PHY header relevant parameters.
*/
void fn_NetSim_IEEE802_11ax_OFDM_MIMO_init(NETSIM_ID nDeviceId,NETSIM_ID nInterfaceId)
{
    UINT nNSTS_MAX = 8;
    UINT nNSS_MAX = 8;
    PIEEE802_11_PHY_VAR phy = IEEE802_11_PHY(nDeviceId,nInterfaceId);
 
    // Initialize Subcarrier allocation related constants According Table 27-14 and Timing related constants from Table 27-13 from IEEE Std 802.11™-2024 pdf
 
    if(phy->dChannelBandwidth == 20)
    {
        phy->PHY_TYPE.ofdmPhy_11ax.nCH_BANDWIDTH = HE_CBW20;
        phy->PHY_TYPE.ofdmPhy_11ax.nNSD = 234; // NSD Number of complex data numbers    
        phy->PHY_TYPE.ofdmPhy_11ax.nNSP = 8;     // NSP Number of pilot values
        phy->PHY_TYPE.ofdmPhy_11ax.nNST = 242; // 52 + 4
        phy->PHY_TYPE.ofdmPhy_11ax.nNSR = 122; // NSR Highest data subcarrier index
        phy->PHY_TYPE.ofdmPhy_11ax.nFFT = 256; // FFT length    
    }
    else if(phy->dChannelBandwidth == 40)
    {
        phy->PHY_TYPE.ofdmPhy_11ax.nCH_BANDWIDTH = HE_CBW40;
        phy->PHY_TYPE.ofdmPhy_11ax.nNSD = 468; // NSD Number of complex data numbers    
        phy->PHY_TYPE.ofdmPhy_11ax.nNSP = 16;     // NSP Number of pilot values
        phy->PHY_TYPE.ofdmPhy_11ax.nNST = 484; // 108 + 6
        phy->PHY_TYPE.ofdmPhy_11ax.nNSR = 244;  // NSR Highest data subcarrier index
        phy->PHY_TYPE.ofdmPhy_11ax.nFFT = 512; // FFT length
    }
    else if(phy->dChannelBandwidth == 80)
    {
        phy->PHY_TYPE.ofdmPhy_11ax.nCH_BANDWIDTH = HE_CBW80;
        phy->PHY_TYPE.ofdmPhy_11ax.nNSD = 980; // NSD Number of complex data numbers    
        phy->PHY_TYPE.ofdmPhy_11ax.nNSP = 16;     // NSP Number of pilot values
        phy->PHY_TYPE.ofdmPhy_11ax.nNST = 996; // 108 + 6
        phy->PHY_TYPE.ofdmPhy_11ax.nNSR = 500;  // NSR Highest data subcarrier index
        phy->PHY_TYPE.ofdmPhy_11ax.nFFT = 1024; // FFT length
    }
    else
    {
        phy->PHY_TYPE.ofdmPhy_11ax.nCH_BANDWIDTH = HE_CBW160;
        phy->PHY_TYPE.ofdmPhy_11ax.nNSD = 1960; // NSD Number of complex data numbers   
        phy->PHY_TYPE.ofdmPhy_11ax.nNSP = 32;     // NSP Number of pilot values
        phy->PHY_TYPE.ofdmPhy_11ax.nNST = 1992; // 108 + 6
        phy->PHY_TYPE.ofdmPhy_11ax.nNSR = 1012;  // NSR Highest data subcarrier index
        phy->PHY_TYPE.ofdmPhy_11ax.nFFT = 2048; // FFT length
    }
 
    // Assign all the timing relevent parameters
    phy->PHY_TYPE.ofdmPhy_11ax.dDeltaF_PreHE = 312500; // SubcarrierFrequencySpacing 312.5KHz (20 MHz/64) or (40 MHz/128)
    phy->PHY_TYPE.ofdmPhy_11ax.dDeltaF = phy->dChannelBandwidth/ (phy->PHY_TYPE.ofdmPhy_11ax.nFFT * 1.0);//SubcarrierFrequencySpacing 312.5KHz (20 MHz/64) or (40 MHz/128)
    phy->PHY_TYPE.ofdmPhy_11ax.dTDFT_PreHE = 3.2; //IDFT/DFT period 3.2 MicroSecs for Pre HE
    phy->PHY_TYPE.ofdmPhy_11ax.dTDFT = 12.8;  // IDFT/DFT period 3.2 MicroSecs
    phy->PHY_TYPE.ofdmPhy_11ax.dTGI_PreHE = 0.8; // 3.2/4 = 0.8 MicroSecs  Guard interval duration 0.8 = TDFT/4  
    phy->PHY_TYPE.ofdmPhy_11ax.dTGIL_LTF = 1.6; // 0.8 * 2 = 1.6 MicroSecs Double guard interval 1.6 
    phy->PHY_TYPE.ofdmPhy_11ax.dTGI1 = 0.8; // Short guard interval duration   dDFT/8 = 0.4 
    phy->PHY_TYPE.ofdmPhy_11ax.dTGI2 = 1.6;
    phy->PHY_TYPE.ofdmPhy_11ax.dTGI4 = 3.2;
 
    if(phy->nGuardInterval == 800)
        phy->PHY_TYPE.ofdmPhy_11ax.dTGI_HE_LTF = phy->PHY_TYPE.ofdmPhy_11ax.dTGI1;
    else if(phy->nGuardInterval == 1600)
        phy->PHY_TYPE.ofdmPhy_11ax.dTGI_HE_LTF = phy->PHY_TYPE.ofdmPhy_11ax.dTGI2;
    else
        phy->PHY_TYPE.ofdmPhy_11ax.dTGI_HE_LTF = phy->PHY_TYPE.ofdmPhy_11ax.dTGI4;
 
    phy->PHY_TYPE.ofdmPhy_11ax.dTSYM1 = 13.6;
    phy->PHY_TYPE.ofdmPhy_11ax.dTSYM2 = 14.4;
    phy->PHY_TYPE.ofdmPhy_11ax.dTSYM4 = 16.0;
 
    if(phy->nGuardInterval == 800)
        phy->PHY_TYPE.ofdmPhy_11ax.dTSYM = phy->PHY_TYPE.ofdmPhy_11ax.dTSYM1;
    else if(phy->nGuardInterval == 1600)
        phy->PHY_TYPE.ofdmPhy_11ax.dTSYM = phy->PHY_TYPE.ofdmPhy_11ax.dTSYM2;
    else
        phy->PHY_TYPE.ofdmPhy_11ax.dTSYM = phy->PHY_TYPE.ofdmPhy_11ax.dTSYM4;
    
    phy->PHY_TYPE.ofdmPhy_11ax.nTL_STF = 8;     // Non-HT short training sequence duration 8 = 10*TDFT/4 
    phy->PHY_TYPE.ofdmPhy_11ax.nTL_LTF = 8;     // Non-HT long training field duration 8 =2 * TDFT + TGI2 
    phy->PHY_TYPE.ofdmPhy_11ax.nTL_SIG = 4;     // Non-HT SIGNAL field duration 4 = TDFT/2 + TGI2
    phy->PHY_TYPE.ofdmPhy_11ax.nTRL_SIG = 4; 
    phy->PHY_TYPE.ofdmPhy_11ax.nTHE_SIGA = 8;   // HE-SIGA field duration 8 = TDFT/2 + TGI2
    phy->PHY_TYPE.ofdmPhy_11ax.nTHE_SIGB = 4;
    phy->PHY_TYPE.ofdmPhy_11ax.nTHE_STF_NT = 4;
    phy->PHY_TYPE.ofdmPhy_11ax.nTHE_LTF_1x = 3.2;
    phy->PHY_TYPE.ofdmPhy_11ax.nTHE_LTF_2x = 6.4; // HE long training field duration 3.2 in 1x, 6.4 in 2x
    phy->PHY_TYPE.ofdmPhy_11ax.nTHE_LTF_4x = 12.8; // HE long training field duration 3.2 in 1x, 6.4 in 2x, 12.8 in 4x
    
    if(phy->nGuardInterval == 800)
        phy->PHY_TYPE.ofdmPhy_11ax.nTHE_LTF = phy->PHY_TYPE.ofdmPhy_11ax.nTHE_LTF_1x;
    else if(phy->nGuardInterval == 1600)
        phy->PHY_TYPE.ofdmPhy_11ax.nTHE_LTF = phy->PHY_TYPE.ofdmPhy_11ax.nTHE_LTF_2x;
    else
        phy->PHY_TYPE.ofdmPhy_11ax.nTHE_LTF = phy->PHY_TYPE.ofdmPhy_11ax.nTHE_LTF_4x;
 
    
    phy->PHY_TYPE.ofdmPhy_11ax.nTHE_LTF_SYM = phy->PHY_TYPE.ofdmPhy_11ax.nTHE_LTF + phy->PHY_TYPE.ofdmPhy_11ax.dTGI_HE_LTF;
    phy->PHY_TYPE.ofdmPhy_11ax.nTSYML = 4;
    phy->PHY_TYPE.ofdmPhy_11ax.nTPE = 0; //Preamble extension duration set to 0 
 
    
    if(phy->nGuardInterval == 800)
        phy->PHY_TYPE.ofdmPhy_11ax.nGI_TYPE = HE_GI_800NS;
    else if(phy->nGuardInterval == 1600)
        phy->PHY_TYPE.ofdmPhy_11ax.nGI_TYPE = HE_GI_1600NS;
    else
        phy->PHY_TYPE.ofdmPhy_11ax.nGI_TYPE = HE_GI_3200NS;
 
 
    // STBC is disabled (0 = disabled, 1 = enabled)
    phy->PHY_TYPE.ofdmPhy_11ax.nSTBC = 0;
 
    // Set NSS (number of spatial streams) = min(TX antennas, RX antennas), max 8
    phy->NSS = min((phy->nNTX < phy->nNRX ? phy->nNTX : phy->nNRX), nNSS_MAX);
 
    // Set NSTS (number of space-time streams) = NSS if STBC is disabled
    phy->NSTS = phy->NSS;
 
    // Ensure NSTS does not exceed 8 (HE SU max)
    phy->NSTS = min(phy->NSTS, 8);
 
    // Set HE-LTF count based on NSTS and LTF mode (1x, 2x, or 4x)
    // Default: 1x LTF mode (no compression)
    switch (phy->NSTS) {
    case 1:  phy->N_HE_LTF = 1; break;  // 1 LTF for 1 stream
    case 2:  phy->N_HE_LTF = 2; break;  // 2 LTFs for 2 streams
    case 3:
    case 4:  phy->N_HE_LTF = 4; break;  // 4 LTFs for 3-4 streams
    case 5:
    case 6:  phy->N_HE_LTF = 6; break;  // 6 LTFs for 5-6 streams
    case 7:
    case 8:  phy->N_HE_LTF = 8; break;  // 8 LTFs for 7-8 streams
    default: phy->N_HE_LTF = 1; break;  // Fallback (should not happen)
    }
 
    phy->dControlFrameDataRate = fn_NetSim_IEEE802_11_HEPhy_getCtrlFrameDataRate(phy);
    phy->dBroadcastFrameDataRate= fn_NetSim_IEEE802_11_HEPhy_getCtrlFrameDataRate(phy);
}
 
/**
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This function is updated from the corresponding IEEE802_11ac.c and definitely needs correction.
A flag field may be considered to add preamble time to the transmission time.
The implementation for BCC coding and LDPC are incorrect as it is in IEEE802_11ac.c!
For BCC coding 
NSYM = mSTBC * ceil ( (8*length + 16 + 6*NES)/(mSTBC*NDBPS) )
For LDPC
NSYM = Navbits / NCBPS 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/
double fn_NetSim_IEEE802_11ax_TxTimeCalculation(NetSim_PACKET *pstruPacket, NETSIM_ID nDevId, NETSIM_ID nInterfaceId)
{
    double dTxTime = 0.0;
    double dNSYM, dTempNum = 0.0; 
    int mSTBC = 1, nNDBPS, nNCBPS;
    int nNavbits = 1;
    PIEEE802_11_PHY_VAR pstruPhy = IEEE802_11_PHY(nDevId,nInterfaceId);
    double dPacketLength = pstruPacket->pstruPhyData->dPayload;
 
    if(isIEEE802_11_CtrlPacket(pstruPacket)) // Other than WLAN control packets
    {
        nNDBPS = pstruPhy->PHY_TYPE.ofdmPhy_11ax.nNDBPS/pstruPhy->NSS;
        nNCBPS = pstruPhy->PHY_TYPE.ofdmPhy_11ax.nNCBPS/pstruPhy->NSS;
    }
    else  
    {
        nNDBPS = pstruPhy->PHY_TYPE.ofdmPhy_11ax.nNDBPS;
        nNCBPS = pstruPhy->PHY_TYPE.ofdmPhy_11ax.nNCBPS;
    }
 
 
    if(pstruPhy->PHY_TYPE.ofdmPhy_11ax.nFEC_CODING == BCC_CODING)
    {
        dTempNum =  (8 * dPacketLength) + 16 + ( 6 * pstruPhy->NESS) ;      
        if(pstruPhy->PHY_TYPE.ofdmPhy_11ax.nSTBC)
            mSTBC = 2;
 
        dTempNum = 8*dPacketLength;
        dNSYM = mSTBC* ( dTempNum/(mSTBC * nNDBPS));
        dTxTime = pstruPhy->PHY_TYPE.ofdmPhy_11ax.dTSYM * dNSYM ;
        return dTxTime; 
    }
    else
    {
        dNSYM = nNavbits * nNCBPS;
        dTxTime = pstruPhy->PHY_TYPE.ofdmPhy_11ax.dTSYM * dNSYM ;
        return dTxTime;
    }
}
 
double get_11ax_preamble_time(PIEEE802_11_PHY_VAR phy)
{
    double dTGF_HE_PREAMBLE;
    int nSignalExtension = 0;
 
    dTGF_HE_PREAMBLE = phy->PHY_TYPE.ofdmPhy_11ax.nTRL_SIG \
        + phy->PHY_TYPE.ofdmPhy_11ax.nTHE_SIGA
        + phy->PHY_TYPE.ofdmPhy_11ax.nTHE_STF_NT
        + (phy->N_HE_LTF * phy->PHY_TYPE.ofdmPhy_11ax.nTHE_LTF_SYM);
 
    return 20 + //Legacy preamble duration
        dTGF_HE_PREAMBLE + 
        //(phy->PHY_TYPE.ofdmPhy_11ax.dTSYM * phy->PHY_TYPE.ofdmPhy_11ax.nNSYM) +
        // N_MA*N_HE_LTF*THE_LTF_SYM +
        // T_PE +
        nSignalExtension;
}