RTS_CTS.c

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/************************************************************************************
* Copyright (C) 2021                                                                *
* TETCOS, Bangalore. India                                                          *
*                                                                                   *
* Tetcos owns the intellectual property rights in the Product and its content.      *
* The copying, redistribution, reselling or publication of any or all of the        *
* Product or its content without express prior written consent of Tetcos is         *
* prohibited. Ownership and / or any other right relating to the software and all   *
* intellectual property rights therein shall remain at all times with Tetcos.       *
*                                                                                   *
* This source code is licensed per the NetSim license agreement.                    *
*                                                                                   *
* No portion of this source code may be used as the basis for a derivative work,    *
* or used, for any purpose other than its intended use per the NetSim license       *
* agreement.                                                                        *
*                                                                                   *
* This source code and the algorithms contained within it are confidential trade    *
* secrets of TETCOS and may not be used as the basis for any other software,        *
* hardware, product or service.                                                     *
*                                                                                   *
* Author:    Shashi Kant Suman                                                      *
*                                                                                   *
* ----------------------------------------------------------------------------------*/
#include "main.h"
#include "IEEE802_11.h"
#include "IEEE802_11_Phy.h"
#include "IEEE802_11_MAC_Frame.h"
 
static double get_RTS_CTS_Time(PIEEE802_11_MAC_VAR mac, PIEEE802_11_PHY_VAR phy)
{
    mac;
    return ceil(2 * (double)phy->plmeCharacteristics.aSIFSTime
        + get_preamble_time(phy)
        + ((getCTSSize() * 8) / phy->dControlFrameDataRate));
}
 
double calculate_RTS_duration(NETSIM_ID txId,
                              NETSIM_ID txIf,
                              NetSim_PACKET* packet)
{
    NETSIM_ID rxId = packet->nReceiverId;
    NETSIM_ID rxIf = fn_NetSim_Stack_GetConnectedInterface(txId, txIf, rxId);
 
    PIEEE802_11_PHY_VAR phy = IEEE802_11_PHY(txId, txIf);
    fn_NetSim_IEEE802_11_SetDataRate(txId, txIf, rxId, rxIf, packet, pstruEventDetails->dEventTime);
    double packetTime = fn_NetSim_IEEE802_11_CalculateTransmissionTime(packet->pstruMacData->dPayload +
                                                                       getMacOverhead(phy,
                                                                                      packet->pstruMacData->dPayload),
                                                                       txId,
                                                                       txIf);
    double ctsTime = (getCTSSize() * 8.0) / phy->dControlFrameDataRate;
    double ackTime = (getAckSize(phy) * 8.0) / phy->dControlFrameDataRate;
    double rtsTime = (getRTSSize()*8.0) / phy->dBroadcastFrameDataRate;
 
    return ceil(get_preamble_time(phy) +
        rtsTime +
        phy->plmeCharacteristics.aSIFSTime +
        get_preamble_time(phy) +
        ctsTime +
        phy->plmeCharacteristics.aSIFSTime +
        get_preamble_time(phy) +
        packetTime +
        phy->plmeCharacteristics.aSIFSTime +
        get_preamble_time(phy) +
        ackTime);
}
 
double calculate_CTS_duration(NETSIM_ID d,
                              NETSIM_ID i,
                              double rtsduration)
{
    PIEEE802_11_PHY_VAR phy = IEEE802_11_PHY(d, i);
    double rtsTime = (getRTSSize() * 8.0) / phy->dControlFrameDataRate;
    return ceil(rtsduration -
        (phy->plmeCharacteristics.aSIFSTime +
            get_preamble_time(phy) +
            rtsTime));
}
 
static bool decide_RTS_CTS_Mechanism()
{
    double d=0;
    NetSim_PACKET* p=IEEE802_11_CURR_MAC->currentProcessingPacket;
    
    if (isBroadcastPacket(p) || isMulticastPacket(p))
        return false; //Broadcast or multicast packet
 
    if (isIEEE802_11_CtrlPacket(p))
        return false; //No RTS CTS for IEEE802.11 control packet
    while(p)
    {
        d+=p->pstruMacData->dPayload;
        p=p->pstruNextPacket;
    }
    return (d >= IEEE802_11_CURR_MAC->dot11RTSThreshold);
}
 
void fn_NetSim_IEEE802_11_RTS_CTS_Init()
{
    PIEEE802_11_MAC_VAR mac = IEEE802_11_CURR_MAC;
 
    if(!decide_RTS_CTS_Mechanism())
        return; //NO RTS-CTS
 
    mac->waitingforCTS=mac->currentProcessingPacket;
    double  d = calculate_RTS_duration(pstruEventDetails->nDeviceId,
                                       pstruEventDetails->nInterfaceId,
                                       mac->currentProcessingPacket);
    mac->currentProcessingPacket = fn_NetSim_IEEE802_11_CreateRTSPacket(mac->waitingforCTS, d);
 
    mac->metrics.nRTSSentCount++;
 
    //Update the packet processing time
    mac->dPacketProcessingEndTime += get_RTS_CTS_Time(mac,IEEE802_11_CURR_PHY);
 
}
 
void fn_NetSim_IEEE802_11_RTS_CTS_ProcessRTS()
{
    pstruEventDetails->dEventTime += IEEE802_11_CURR_PHY->SIFS;
    pstruEventDetails->nSubEventType = SEND_CTS;
    pstruEventDetails->nEventType = MAC_OUT_EVENT;
    fnpAddEvent(pstruEventDetails);
    IEEE802_11_Change_Mac_State(IEEE802_11_CURR_MAC,IEEE802_11_MACSTATE_TXing_CTS);
 
    IEEE802_11_CURR_MAC->metrics.nRTSReceivedCount++;
}
 
void fn_NetSim_IEEE802_11_RTS_CTS_SendCTS()
{
    PIEEE802_11_MAC_VAR mac = IEEE802_11_CURR_MAC;
    if (mac->dNAV > pstruEventDetails->dEventTime)
    {
        //Virtual CS Condition
        fn_NetSim_Packet_FreePacket(pstruEventDetails->pPacket);
        return;
    }
 
    NetSim_PACKET* packet=fn_NetSim_IEEE802_11_CreateCTSPacket(pstruEventDetails->pPacket);
    //Free the RTS packet
    fn_NetSim_Packet_FreePacket(pstruEventDetails->pPacket);
 
    //Send CTS to phy
    pstruEventDetails->dPacketSize = packet->pstruMacData->dPacketSize;
    pstruEventDetails->nSubEventType = 0;
    pstruEventDetails->nEventType = PHYSICAL_OUT_EVENT;
    pstruEventDetails->pPacket = packet;
    fnpAddEvent(pstruEventDetails); 
 
    IEEE802_11_CURR_MAC->metrics.nCTSSentCount++;
}
 
void fn_NetSim_IEEE802_11_RTS_CTS_AddCTSTimeOut(NetSim_PACKET* packet,NETSIM_ID devId,NETSIM_ID devIf)
{
    ptrIEEE802_11_HDR hdr = packet->pstruMacData->Packet_MACProtocol;
 
    NetSim_EVENTDETAILS pevent;
    PIEEE802_11_PHY_VAR phy = IEEE802_11_PHY(devId,devIf);
    PIEEE802_11_MAC_VAR mac = IEEE802_11_MAC(devId, hdr->sendInterfaceId);
    double ctstime;
 
    ctstime = ceil(packet->pstruPhyData->dStartTime
        + phy->plmeCharacteristics.aSIFSTime
        + get_preamble_time(phy)
        + ((getCTSSize() * 8)/phy->dControlFrameDataRate));
 
    pevent.dEventTime=ctstime+2;
    pevent.dPacketSize=0;
    pevent.nDeviceId=devId;
    pevent.nDeviceType=DEVICE_TYPE(devId);
    pevent.nEventType=TIMER_EVENT;
    pevent.nInterfaceId= hdr->sendInterfaceId;
    pevent.nPacketId=packet->nPacketId;
    pevent.nProtocolId=MAC_PROTOCOL_IEEE802_11;
    if(packet->pstruAppData)
    {
        pevent.nSegmentId=packet->pstruAppData->nSegmentId;
        pevent.nApplicationId=packet->pstruAppData->nApplicationId;
    }
    else
    {
        pevent.nSegmentId=0;
        pevent.nApplicationId=0;
    }
    pevent.nSubEventType=CTS_TIMEOUT;
    pevent.pPacket=NULL;
    pevent.szOtherDetails=NULL;
    mac->EVENTID.ctsTimeout = fnpAddEvent(&pevent);
}
 
void fn_NetSim_IEEE802_11_RTS_CTS_CTSTimeOut()
{
    PIEEE802_11_MAC_VAR mac = IEEE802_11_CURR_MAC;
    IEEE802_11_Change_Mac_State(mac, IEEE802_11_MACSTATE_MAC_IDLE);
    if (fn_NetSim_IEEE802_11_CSMACA_CheckRetryLimit(mac, 1))
    {
        mac->nRetryCount++;
        fn_NetSim_IEEE802_11_CSMACA_IncreaseCW(mac);
        fn_NetSim_IEEE802_11_CSMACA_Init();
    }
    else
    {
        if (mac->waitingforCTS)
        {
            NetSim_PACKET* pstruPacket = mac->waitingforCTS;
 
            if (pstruPacket->DropNotification)
                pstruPacket->DropNotification(pstruPacket);
            fn_NetSim_Packet_FreePacket(mac->currentProcessingPacket);
            fn_NetSim_Packet_FreePacket(mac->waitingforCTS);
            mac->currentProcessingPacket = NULL;
            mac->waitingforCTS = NULL;
        }
        mac->nRetryCount = 0;
        fn_NetSim_IEEE802_11_CSMACA_Init();
    }
}
 
void fn_NetSim_IEEE802_11_RTS_CTS_ProcessCTS()
{
    PIEEE802_11_MAC_VAR mac=IEEE802_11_CURR_MAC;
    fnDeleteEvent(mac->EVENTID.ctsTimeout);
    fn_NetSim_Packet_FreePacket(mac->currentProcessingPacket);
    mac->currentProcessingPacket=mac->waitingforCTS;
    mac->waitingforCTS=NULL;
    mac->metrics.nCTSReceivedCount++;
    //Free CTS packet
    fn_NetSim_Packet_FreePacket(pstruEventDetails->pPacket);
    pstruEventDetails->pPacket=NULL;
    
    pstruEventDetails->dEventTime += IEEE802_11_CURR_PHY->SIFS;
    pstruEventDetails->nSubEventType = SEND_MPDU;
    pstruEventDetails->nEventType = MAC_OUT_EVENT;
    if(mac->currentProcessingPacket->pstruAppData)
    {
        pstruEventDetails->nApplicationId = mac->currentProcessingPacket->pstruAppData->nApplicationId;
        pstruEventDetails->nSegmentId = mac->currentProcessingPacket->pstruAppData->nSegmentId;
    }
    else
    {
        pstruEventDetails->nApplicationId = 0;
        pstruEventDetails->nSegmentId = 0;
    }
    pstruEventDetails->nPacketId = mac->currentProcessingPacket->nPacketId;
    fnpAddEvent(pstruEventDetails);
    IEEE802_11_Change_Mac_State(IEEE802_11_CURR_MAC,IEEE802_11_MACSTATE_TXing_MPDU);
}