mac-802_11e.cc

在网络仿真模拟工具下实现支持QoS的MAC层EDCF协议

	 *  Space before transmitting.
	 */
        assert(mhDefer_.defer(pri) == 0); 
	//fuer den Fall, dass medium nicht idle: CW und PS-Factor zu weisen
	if(mhBackoff_.backoff(pri) == 0) { //Mac can be still  in post-backoff
	  if(is_idle()) { 
			/*
			 * If we are already deferring, there is no
			 * need to reset the Defer timer.
			 */
			if(mhDefer_.defer(pri) == 0) {
			    rTime = ((Random::random() % getCW(LEVEL(p))) * phymib_->SlotTime);
			    mhDefer_.start(LEVEL(p), getAIFS(LEVEL(p))); // + rTime);// - phymib_->SlotTime);
				

			}			
		}
	/*
	 * If the medium is NOT IDLE, then we start
	 * the backoff timer.
	 */
		else {
		    mhBackoff_.start(LEVEL(p),getCW(LEVEL(p)), is_idle());
		}
	}  
	    
}

void
Mac802_11e::recv(Packet *p, Handler *h)
{
   	struct hdr_cmn *hdr = HDR_CMN(p);
	/*
	 * Sanity Check
	 */
	//assert(initialized());

	/*
	 *  Handle outgoing packets.
	 */
	if(hdr->direction() == hdr_cmn::DOWN) {
	    Scheduler &s = Scheduler::instance();
	    send(p, h);
	    return;
        }
	/*
	 *  Handle incoming packets.
	 *
	 *  We just received the 1st bit of a packet on the network
	 *  interface.
	 *
	 */
	/*
	 *  If the interface is currently in transmit mode, then
	 *  it probably won't even see this packet.  However, the
	 *  "air" around me is BUSY so I need to let the packet
	 *  proceed.  Just set the error flag in the common header
	 *  to that the packet gets thrown away.
	 */
	Scheduler &s = Scheduler::instance();
	if(tx_active_ && hdr->error() == 0 ) {
        		hdr->error() = 1;
	
	}

	if(rx_state_ == MAC_IDLE) {
		SET_RX_STATE(MAC_RECV);
		pktRx_ = p;

		/*
		 * Schedule the reception of this packet, in
		 * txtime seconds.
		 */
		mhRecv_.start(txtime(p));
	} else {
		/*
		 *  If the power of the incoming packet is smaller than the
		 *  power of the packet currently being received by at least
                 *  the capture threshold, then we ignore the new packet.
		 */
		if(pktRx_->txinfo_.RxPr / p->txinfo_.RxPr >= p->txinfo_.CPThresh) {
			capture(p);
		} else {
			collision(p);
		}
	}
}

void
Mac802_11e::recv_timer()
{ 

    Scheduler &s = Scheduler::instance();
	u_int32_t src; 
	hdr_cmn *ch = HDR_CMN(pktRx_);
	hdr_mac802_11 *mh = HDR_MAC802_11(pktRx_);
	u_int32_t dst = ETHER_ADDR(mh->dh_da);
	// XXX debug
	//struct cts_frame *cf = (struct cts_frame*)pktRx_->access(hdr_mac::offset_);
	//u_int32_t src = ETHER_ADDR(mh->dh_sa);
	
	u_int8_t  type = mh->dh_fc.fc_type;
	u_int8_t  subtype = mh->dh_fc.fc_subtype;

	assert(pktRx_);
	assert(rx_state_ == MAC_RECV || rx_state_ == MAC_COLL);
	
        /*
         *  If the interface is in TRANSMIT mode when this packet
         *  "arrives", then I would never have seen it and should
         *  do a silent discard without adjusting the NAV.
         */
        if(tx_active_) {
                Packet::free(pktRx_);
                goto done;
        }

	/*
	 * Handle collisions.
	 */
	if(rx_state_ == MAC_COLL) {
	    discard(pktRx_, DROP_MAC_COLLISION);
	    set_nav(usec(eifs_));
	    eifs_nav_ = eifs_;
	    goto done;
	}
	
	/*
	 * Check to see if this packet was received with enough
	 * bit errors that the current level of FEC still could not
	 * fix all of the problems - ie; after FEC, the checksum still
	 * failed.
	 */
	if( ch->error() ) {
	    Packet::free(pktRx_);
	    set_nav(usec(eifs_));
	    eifs_nav_ = eifs_;
	    goto done;
	}
	
	/*
	 * avoid Nav-reset bug:
	 * if received packet has no  errors and had no collision, but nav 
	 * was set due to an earlier collision, nav has to be reset!
	 */
         if(mhNav_.busy()) reset_eifs_nav();
	
	/*
	 * IEEE 802.11 specs, section 9.2.5.6
	 *	- update the NAV (Network Allocation Vector)
	 */
	if(dst != (u_int32_t)index_) {
	    set_nav(mh->dh_duration);
	}

        /* tap out - */
        if (tap_ && type == MAC_Type_Data &&
            MAC_Subtype_Data == subtype ) 
		tap_->tap(pktRx_);
	/*
	 * Adaptive Fidelity Algorithm Support - neighborhood infomation 
	 * collection
	 *
	 * Hacking: Before filter the packet, log the neighbor node
	 * I can hear the packet, the src is my neighbor
	 */
	if (netif_->node()->energy_model() && 
	    netif_->node()->energy_model()->adaptivefidelity()) {
		src = ETHER_ADDR(mh->dh_sa);
		netif_->node()->energy_model()->add_neighbor(src);
	}
	/*
	 * Address Filtering
	 */
	if(dst != (u_int32_t)index_ && dst != MAC_BROADCAST) {
		/*
		 *  We don't want to log this event, so we just free
		 *  the packet instead of calling the drop routine.
		 */
		discard(pktRx_, "---");
		goto done;
	}

	switch(type) {

	case MAC_Type_Management:
		discard(pktRx_, DROP_MAC_PACKET_ERROR);
		goto done;
		break;

	case MAC_Type_Control:
		switch(subtype) {
		case MAC_Subtype_RTS:
			recvRTS(pktRx_);
			break;
		case MAC_Subtype_CTS:
			recvCTS(pktRx_);
			break;
		case MAC_Subtype_ACK:
			recvACK(pktRx_);
			break;
		default:
			fprintf(stderr,"recvTimer1:Invalid MAC Control Subtype %x\n",
				subtype);
			exit(1);
		}
		break;
	case MAC_Type_Data:
		switch(subtype) {
		case MAC_Subtype_Data:
			recvDATA(pktRx_);
			break;
		default:
			fprintf(stderr, "recv_timer2:Invalid MAC Data Subtype %x\n",
				subtype);
			exit(1);
		}
		break;
	default:
		fprintf(stderr, "recv_timer3:Invalid MAC Type %x\n", subtype);
		exit(1);
	}
 done:
	pktRx_ = 0;
	rx_resume();
}


void
Mac802_11e::recvRTS(Packet *p)
{

        int pri = LEVEL(p);
	struct rts_frame *rf = (struct rts_frame*)p->access(hdr_mac::offset_);

	if(tx_state_[pri] != MAC_IDLE) {
		discard(p, DROP_MAC_BUSY);
		return;
	}

	/*
	 *  If I'm responding to someone else, discard this RTS.
	 */
	if(pktCTRL_[pri]) {
		discard(p, DROP_MAC_BUSY);
		return;
	}

	sendCTS(pri, ETHER_ADDR(rf->rf_ta), rf->rf_duration);

	/*
	 *  Stop deferring - will be reset in tx_resume().
	 */
	//	if(mhDefer_.busy()) mhDefer_.stop();

	tx_resume();

	mac_log(p);
}

/*
 * txtime()	- pluck the precomputed tx time from the packet header
 */
double
Mac802_11e::txtime(Packet *p)
 {
	 struct hdr_cmn *ch = HDR_CMN(p);
	 double t = ch->txtime();
	 if (t < 0.0) {
		 drop(p, "XXX");
 		exit(1);
	 }
	 return t;
 }

 
/*
 * txtime()	- calculate tx time for packet of size "psz" bytes 
 *		  at rate "drt" bps
 */
double
Mac802_11e::txtime(double psz, double drt)
{
	double dsz = psz - PLCP_HDR_LEN;
	int plcp_hdr = PLCP_HDR_LEN << 3;
	int datalen = (int)dsz << 3;
	
	double t = (((double)plcp_hdr)/phymib_->PLCPDataRate) + (((double)datalen)/drt);
	return(t);
}



void
Mac802_11e::recvCTS(Packet *p)
{

        int pri = LEVEL(p);
	if(tx_state_[pri] != MAC_RTS) {
		discard(p, DROP_MAC_INVALID_STATE);
		return;
	}
	assert(pktRTS_[pri]);
	Packet::free(pktRTS_[pri]); pktRTS_[pri] = 0;

	assert(pktTx_[pri]);
	// debug
	//struct hdr_mac802_11 *mh = HDR_MAC802_11(pktTx_);
	//printf("(%d):recvCTS:pktTx_-%x,mac-subtype-%d & pktCTS_:%x\n",index_,pktTx_,mh->dh_fc.fc_subtype,p);
	
	mhSend_.stop();

	/*
	 * The successful reception of this CTS packet implies
	 * that our RTS was successful.  Hence, we can reset
	 * the Short Retry Count and the CW.
	 */
	//ssrc_ = 0;
	//rst_cw();
	//	if(mhDefer_.busy()) mhDefer_.stop();

	tx_resume();

	mac_log(p);
}

void
Mac802_11e::recvDATA(Packet *p)
{

        int pri = LEVEL(p);
	struct hdr_mac802_11 *dh = HDR_MAC802_11(p);
	u_int32_t dst, src, size;

	{	struct hdr_cmn *ch = HDR_CMN(p);

		dst = ETHER_ADDR(dh->dh_da);
		src = ETHER_ADDR(dh->dh_sa);
		size = ch->size();

		/*
		 * Adjust the MAC packet size - ie; strip
		 * off the mac header
		 */
		ch->size() -= ETHER_HDR_LEN11;
		ch->num_forwards() += 1;
	}

	/*
	 *  If we sent a CTS, clean up...
	 */
	if(dst != MAC_BROADCAST) {
		if(size >= macmib_->RTSThreshold) {
			if (tx_state_[pri] == MAC_CTS) {
				assert(pktCTRL_[pri]);
				Packet::free(pktCTRL_[pri]); pktCTRL_[pri] = 0;
				mhSend_.stop();
				/*
				 * Our CTS got through.
				 */
				printf("(%d): RECVING DATA!\n",index_);
				//ssrc_ = 0;
				//rst_cw();
			}
			else {
				discard(p, DROP_MAC_BUSY);
				printf("(%d)..discard DATA\n",index_);
				return;
			}
		       
                       // from my point of view, all defers have to be canceled
		       // because we are going to send an ACK
		       // => Backoff for all others
			//			if(mhDefer_.busy()) mhDefer_.stop();
			sendACK(pri, src);
			tx_resume(); 
		}
		/*
		 *  We did not send a CTS and there's no
		 *  room to buffer an ACK.
		 */
		else {
			if(pktCTRL_[pri]) {
				discard(p, DROP_MAC_BUSY);
				return;
			}
			//			if(mhDefer_.busy()) mhDefer_.stop();
			sendACK(pri, src);
			if(mhSend_.busy() == 0){
			    tx_resume();
			}
		}
	}

	/* ============================================================
	    Make/update an entry in our sequence number cache.
	   ============================================================ */

	/* Changed by Debojyoti Dutta. This upper loop of if{}else was 
	   suggested by Joerg Diederich <[e-mail]>. 
	   Changed on 19th Oct'2000 */

        if(dst != MAC_BROADCAST) {
                if (src < (u_int32_t) cache_node_count_) {
		            Host *h = &cache_[src];

                        if(h->seqno && h->seqno == dh->dh_scontrol) {
			    discard(p, DROP_MAC_DUPLICATE);
			    return;
                        }
                        h->seqno = dh->dh_scontrol;
		    
                } else {
			static int count = 0;
			if (++count <= 10) {
				printf ("MAC_802_11e: accessing MAC cache_ array out of range (src %u, dst %u, size %d)!\n", src, dst, cache_node_count_);
				if (count == 10)
					printf ("[suppressing additional MAC cache_ warnings]\n");
			};
		};
	}
	
	/*

	 *  Pass the packet up to the link-layer.
	 *  XXX - we could schedule an event to account
	 *  for this processing delay.
	 */
	//p->incoming = 1;
	// XXXXX NOTE: use of incoming flag has been depracated; In order to track direction of pkt flow, direction_ in hdr_cmn is used instead. see packet.h for details. 
	uptarget_->recv(p, (Handler*) 0);
}


void
Mac802_11e::recvACK(Packet *p)
{

        int pri = LEVEL(p);
	struct hdr_cmn *ch = HDR_CMN(p);
	if(tx_state_[pri] != MAC_SEND) {
	    discard(p, DROP_MAC_INVALID_STATE);
	return;
	}
	//printf("(%d)...................recving ACK:%x\n",index_,p);
	
	mhSend_.stop();
	
	/*
	 * The successful reception of this ACK packet implies
	 * that our DATA transmission was successful.  Hence,
	 * we can reset the Short/Long Retry Count and the CW.
	 */
	if((u_int32_t) ch->size() <= macmib_->RTSThreshold)
		ssrc_[pri] = 0;
	else
		slrc_[pri] = 0;

	/* succesful transmission => give throughput
	 * to Akaroa
	 */
	if(rtx_[pri]) rtx_[pri] = 0;
	sending = 0;
	CHECK_BACKOFF_TIMER();
        /*
	 * Backoff before sending again.
	 */
	if(!cfb_ || ch->size() > macmib_->RTSThreshold) {
	  assert(mhBackoff_.backoff(pri) == 0);
	  rst_cw(pri);
	  mhBackoff_.start(pri, getCW(pri), is_idle());
	  assert(pktTx_[pri]);
	  Packet::free(pktTx_[pri]); pktTx_[pri] = 0;
	  tx_resume();

	}
	else{
	  // if this is the first packet in cfb, we must take its
	  // duration into account, too.
	  if(cfb_dur == 0) {
	      cfb_dur = txtime(pktTx_[pri])
		            + sifs_
		            + txtime(ETHER_ACK_LEN, basicRate_);
	  }
	  pktRx_ = 0;
	  rx_resume();
	  assert(pktTx_[pri]);
	  Packet::free(pktTx_[pri]); pktTx_[pri] = 0;
	  cfb(pri);
	}
	mac_log(p);
}

void Mac802_11e::cfb(int pri)
{
  double timeout;
  struct hdr_mac802_11 *mh;
  
  // next packet out of queue
  //cout<<"packets in queue:"<<queue_->pri_[pri].getLen()<<"\n";
  if(queue_->pri_[pri].getLen() > 0) {
      Packet* p = queue_->pri_[pri].deque(); 
      // framing
      sendDATA(pri, p);
      hdr_cmn *ch = HDR_CMN(pktTx_[pri]);
      mh = HDR_MAC802_11(pktTx_[pri]);
      //cout<<"Mac "<<index_<<" in cfb(), pri "<<pri<<", cfb_bytes "<<cfb_bytes<<" + "<<ch->size()<<", cfb_maxbytes "<<cfb_maxbytes_<<"\n";
      if((u_int32_t)ETHER_ADDR(mh->dh_da) != MAC_BROADCAST) {
	  cfb_dur +=  sifs_ 
                      + txtime(pktTx_[pri])
		      + sifs_
                      + txtime(ETHER_ACK_LEN, basicRate_);
	  cfb_broadcast = 0;
      } else {
	      cfb_dur += sifs_ 
	              + txtime(pktTx_[pri]);
              cfb_broadcast = 1;
      }
  } else cfb_dur = txop_limit_[pri] + 1; 
 
  if(cfb_dur <= txop_limit_[pri]) {
    // send
    if((u_int32_t)ETHER_ADDR(mh->dh_da) != MAC_BROADCAST)
      timeout = txtime(pktTx_[pri])
	                    + DSSS_EDCF_MaxPropagationDelay	
			    + sifs_
			    + txtime(ETHER_ACK_LEN, basicRate_)
			    + DSSS_EDCF_MaxPropagationDelay;

    else
      timeout = txtime(pktTx_[pri]);    
    cfb_active = 1;
    mhSifs_.start(pri, sifs_);
  }
  else {
    cfb_dur = 0;
    cfb_broadcast = 0;
    assert(mhBackoff_.backoff(pri) == 0);
    rst_cw(pri);
    mhBackoff_.start(pri, getCW(pri), is_idle());
    //assert(pktTx_[pri]);
    //Packet::free(pktTx_[pri]); pktTx_[pri] = 0;
    tx_resume();
  }
}

// request parameters for each priority from the corresponding queues
double Mac802_11e::getAIFS(int pri)
{
    if(!AIFSset){
      levels = queue_->getLevels();
      for(int i = 0; i < levels; i++ ){
	slotnum = queue_->pri_[i].getAIFS();
	aifs_[i] = sifs_ + (slotnum * phymib_->SlotTime);
	txop_limit_[i] = queue_->pri_[i].getTXOPLimit();
	//	    cout<<"Mac "<<index_<<", pri: "<<i<<", txop_limit:"<<txop_limit_[i]<<"\n";
      }
      AIFSset = 1;
    }
    return aifs_[pri];
}


int Mac802_11e::getCW(int level)
{
    if(!CWset){
	levels = queue_->getLevels();
	for(int i = 0; i < levels; i++ ){
	    cw_[i] = queue_->pri_[i].getCW_MIN();
	    cwmin_[i] = queue_->pri_[i].getCW_MIN(); 
	    cwmax_[i] = queue_->pri_[i].getCW_MAX(); 
	}
	CWset = 1;
    }
    return cw_[level];
}

void
Mac802_11e::setQ(PriQ* priqueue){
    queue_ = priqueue;
}

inline void 
Mac802_11e::reset_eifs_nav() {
  if (eifs_nav_ > 0) {
    double now = Scheduler::instance().clock();
    
    assert(nav_ > now);
    assert(mhNav_.busy());
    
    mhNav_.stop();
    nav_ -= eifs_nav_;
    eifs_nav_ = 0.0;
    if (nav_ > now) {
      mhNav_.start(nav_ - now);
    } else {
      nav_ = now;
      CHECK_BACKOFF_TIMER();
    }
  }
}