cpmmodelc.nc

tinyos-2.x.rar

    double prr = prr_estimate_from_snr(SNR);
    double coin = RandomUniform();
    if ( (prr >= 0) && (prr <= 1) ) {
      if (coin < prr)
	prr = 1.0;
      else
	prr = 0.0;
    }
    return prr;
  }

  bool checkReceive(receive_message_t* msg) {
    double noise = noise_hash_generation();
    receive_message_t* list = outstandingReceptionHead;
    noise = pow(10.0, noise / 10.0);
    while (list != NULL) {
      if (list != msg) {
	noise += pow(10.0, list->power / 10.0);
      }
      list = list->next;
    }
    noise = 10.0 * log(noise) / log(10.0);
    return shouldReceive(msg->power - noise);
  }
  
  double packetNoise(receive_message_t* msg) {
    double noise = noise_hash_generation();
    receive_message_t* list = outstandingReceptionHead;
    noise = pow(10.0, noise / 10.0);
    while (list != NULL) {
      if (list != msg) {
	noise += pow(10.0, list->power / 10.0);
      }
      list = list->next;
    }
    noise = 10.0 * log(noise) / log(10.0);
    return noise;
  }

  double checkPrr(receive_message_t* msg) {
    return prr_estimate_from_snr(msg->power / packetNoise(msg));
  }
  

  /* Handle a packet reception. If the packet is being acked,
     pass the corresponding receive_message_t* to the ack handler,
     otherwise free it. */
  void sim_gain_receive_handle(sim_event_t* evt) {
    receive_message_t* mine = (receive_message_t*)evt->data;
    receive_message_t* predecessor = NULL;
    receive_message_t* list = outstandingReceptionHead;

    dbg("CpmModelC", "Handling reception event @ %s.\n", sim_time_string());
    while (list != NULL) {
      if (list->next == mine) {
	predecessor = list;
      }
      list = list->next;
    }
    if (predecessor) {
      predecessor->next = mine->next;
    }
    else if (mine == outstandingReceptionHead) { // must be head
      outstandingReceptionHead = mine->next;
    }
    else {
      dbgerror("CpmModelC", "Incoming packet list structure is corrupted: entry is not the head and no entry points to it.\n");
    }
    dbg("CpmModelC,SNRLoss", "Packet from %i to %i\n", (int)mine->source, (int)sim_node());
    if (!checkReceive(mine)) {
      dbg("CpmModelC,SNRLoss", " - lost packet from %i as SNR was too low.\n", (int)mine->source);
      mine->lost = 1;
    }
    if (!mine->lost) {
      // Copy this receiver's packet signal strength to the metadata region
      // of the packet. Note that this packet is actually shared across all
      // receivers: a higher layer performs the copy.
      tossim_metadata_t* meta = (tossim_metadata_t*)(&mine->msg->metadata);
      meta->strength = mine->strength;
      
      dbg_clear("CpmModelC,SNRLoss", "  -signaling reception\n");
      signal Model.receive(mine->msg);
      if (mine->ack) {
        dbg_clear("CpmModelC", " acknowledgment requested, ");
      }
      else {
        dbg_clear("CpmModelC", " no acknowledgment requested.\n");
      }
      // If we scheduled an ack, receiving = 0 when it completes
      if (mine->ack && signal Model.shouldAck(mine->msg)) {
        dbg_clear("CpmModelC", " scheduling ack.\n");
	sim_gain_schedule_ack(mine->source, sim_time() + 1, mine);
      }
      else { // Otherwise free the receive_message_t*
	free_receive_message(mine);
      }
      // We're searching for new packets again
      receiving = 0;
    } // If the packet was lost, then we're searching for new packets again
    else {
      if (RandomUniform() < 0.001) {
	dbg("CpmModelC,SNRLoss", "Packet was technically lost, but TOSSIM introduces an ack false positive rate.\n");
	if (mine->ack && signal Model.shouldAck(mine->msg)) {
	  dbg_clear("CpmModelC", " scheduling ack.\n");
	  sim_gain_schedule_ack(mine->source, sim_time() + 1, mine);
	}
	else { // Otherwise free the receive_message_t*
	  free_receive_message(mine);
	}
      }
      else {
	free_receive_message(mine);
      }
      receiving = 0;
      dbg_clear("CpmModelC,SNRLoss", "  -packet was lost.\n");
    }
  }
   
  // Create a record that a node is receiving a packet,
  // enqueue a receive event to figure out what happens.
  void enqueue_receive_event(int source, sim_time_t endTime, message_t* msg, bool receive, double power, double reversePower) {
    sim_event_t* evt;
    receive_message_t* list;
    receive_message_t* rcv = allocate_receive_message();
    double noiseStr = packetNoise(rcv);
    rcv->source = source;
    rcv->start = sim_time();
    rcv->end = endTime;
    rcv->power = power;
    rcv->reversePower = reversePower;
    // The strength of a packet is the sum of the signal and noise. In most cases, this means
    // the signal. By sampling this here, it assumes that the packet RSSI is sampled at
    // the beginning of the packet. This is true for the CC2420, but is not true for all
    // radios. But generalizing seems like complexity for minimal gain at this point.
    rcv->strength = (int8_t)(floor(10.0 * log(pow(10.0, power/10.0) + pow(10.0, noiseStr/10.0)) / log(10.0)));
    rcv->msg = msg;
    rcv->lost = 0;
    rcv->ack = receive;
    // If I'm off, I never receive the packet, but I need to keep track of
    // it in case I turn on and someone else starts sending me a weaker
    // packet. So I don't set receiving to 1, but I keep track of
    // the signal strength.

    if (!sim_mote_is_on(sim_node())) { 
      dbg("CpmModelC", "Lost packet from %i due to %i being off\n", source, sim_node());
      rcv->lost = 1;
    }
    else if (!shouldReceive(power - noiseStr)) {
      dbg("CpmModelC,SNRLoss", "Lost packet from %i to %i due to SNR being too low (%i)\n", source, sim_node(), (int)(power - noiseStr));
      rcv->lost = 1;
    }
    else if (receiving) {
      dbg("CpmModelC,SNRLoss", "Lost packet from %i due to %i being mid-reception\n", source, sim_node());
      rcv->lost = 1;
    }
    else if (transmitting && (rcv->start < transmissionEndTime) && (transmissionEndTime <= rcv->end)) {
      dbg("CpmModelC,SNRLoss", "Lost packet from %i due to %i being mid-transmission, transmissionEndTime %llu\n", source, sim_node(), transmissionEndTime);
      rcv->lost = 1;
    }
    else {
      receiving = 1;
    }

    list = outstandingReceptionHead;
    while (list != NULL) {
      if (!shouldReceive(list->power - rcv->power)) {
	dbg("Gain,SNRLoss", "Going to lose packet from %i with signal %lf as am receiving a packet from %i with signal %lf\n", list->source, list->power, source, rcv->power);
	list->lost = 1;
      }
      list = list->next;
    }
    
    rcv->next = outstandingReceptionHead;
    outstandingReceptionHead = rcv;
    evt = allocate_receive_event(endTime, rcv);
    sim_queue_insert(evt);

  }
  
  void sim_gain_put(int dest, message_t* msg, sim_time_t endTime, bool receive, double power, double reversePower) {
    int prevNode = sim_node();
    dbg("CpmModelC", "Enqueing reception event for %i at %llu with power %lf.\n", dest, endTime, power);
    sim_set_node(dest);
    enqueue_receive_event(prevNode, endTime, msg, receive, power, reversePower);
    sim_set_node(prevNode);
  }

  command void Model.putOnAirTo(int dest, message_t* msg, bool ack, sim_time_t endTime, double power, double reversePower) {
    receive_message_t* list;
    gain_entry_t* neighborEntry = sim_gain_first(sim_node());
    requestAck = ack;
    outgoing = msg;
    transmissionEndTime = endTime;
    dbg("CpmModelC", "Node %i transmitting to %i, finishes at %llu.\n", sim_node(), dest, endTime);

    while (neighborEntry != NULL) {
      int other = neighborEntry->mote;
      sim_gain_put(other, msg, endTime, ack, power + sim_gain_value(sim_node(), other), reversePower + sim_gain_value(other, sim_node()));
      neighborEntry = sim_gain_next(neighborEntry);
    }

    list = outstandingReceptionHead;
    while (list != NULL) {    
      list->lost = 1;
      dbg("CpmModelC,SNRLoss", "Lost packet from %i because %i has outstanding reception, startTime %llu endTime %llu\n", list->source, sim_node(), list->start, list->end);
      list = list->next;
    }
  }
    

  command void Model.setPendingTransmission() {
    transmitting = TRUE;
    dbg("CpmModelC", "setPendingTransmission: transmitting %i @ %s\n", transmitting, sim_time_string());
  }

  
 default event void Model.receive(message_t* msg) {}

 sim_event_t* allocate_receive_event(sim_time_t endTime, receive_message_t* msg) {
   sim_event_t* evt = (sim_event_t*)malloc(sizeof(sim_event_t));
   evt->mote = sim_node();
   evt->time = endTime;
   evt->handle = sim_gain_receive_handle;
   evt->cleanup = sim_queue_cleanup_event;
   evt->cancelled = 0;
   evt->force = 1; // Need to keep track of air even when node is off
   evt->data = msg;
   return evt;
 }

 receive_message_t* allocate_receive_message() {
   return (receive_message_t*)malloc(sizeof(receive_message_t));
 }

 void free_receive_message(receive_message_t* msg) {
   free(msg);
 }
}