network-scheduler.cc

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/*
 * Copyright (c) 2017 University of Padova
 *
 * SPDX-License-Identifier: GPL-2.0-only
 *
 * Author: Davide Magrin <magrinda@dei.unipd.it>
 */
 
#include "network-scheduler.h"
 
#include "network-controller.h"
#include "network-status.h"
 
#include "ns3/simulator.h"
 
namespace ns3
{
namespace lorawan
{
 
NS_LOG_COMPONENT_DEFINE("NetworkScheduler");
 
NS_OBJECT_ENSURE_REGISTERED(NetworkScheduler);
 
TypeId
NetworkScheduler::GetTypeId()
{
    static TypeId tid =
        TypeId("ns3::NetworkScheduler")
            .SetParent<Object>()
            .AddConstructor<NetworkScheduler>()
            .AddTraceSource("ReceiveWindowOpened",
                            "Trace source that is fired when a receive window opportunity happens.",
                            MakeTraceSourceAccessor(&NetworkScheduler::m_receiveWindowOpened),
                            "ns3::Packet::TracedCallback")
            .SetGroupName("lorawan");
    return tid;
}
 
NetworkScheduler::NetworkScheduler()
{
}
 
NetworkScheduler::NetworkScheduler(Ptr<NetworkStatus> status, Ptr<NetworkController> controller)
    : m_status(status),
      m_controller(controller)
{
}
 
NetworkScheduler::~NetworkScheduler()
{
}
 
void
NetworkScheduler::OnReceivedPacket(Ptr<const Packet> packet)
{
    NS_LOG_FUNCTION(packet);
 
    // Get the current packet's frame counter
    Ptr<Packet> packetCopy = packet->Copy();
    LorawanMacHeader receivedMacHdr;
    packetCopy->RemoveHeader(receivedMacHdr);
    LoraFrameHeader receivedFrameHdr;
    receivedFrameHdr.SetAsUplink();
    packetCopy->RemoveHeader(receivedFrameHdr);
 
    // Need to decide whether to schedule a receive window
    if (!m_status->GetEndDeviceStatus(packet)->HasReceiveWindowOpportunityScheduled())
    {
        // Extract the address
        LoraDeviceAddress deviceAddress = receivedFrameHdr.GetAddress();
 
        // Schedule OnReceiveWindowOpportunity event
        m_status->GetEndDeviceStatus(packet)->SetReceiveWindowOpportunity(
            Simulator::Schedule(Seconds(1),
                                &NetworkScheduler::OnReceiveWindowOpportunity,
                                this,
                                deviceAddress,
                                1)); // This will be the first receive window
    }
}
 
void
NetworkScheduler::OnReceiveWindowOpportunity(LoraDeviceAddress deviceAddress, int window)
{
    NS_LOG_FUNCTION(deviceAddress);
 
    NS_LOG_DEBUG("Opening receive window number " << window << " for device " << deviceAddress);
 
    // Check whether we can send a reply to the device, again by using
    // NetworkStatus
    Address gwAddress = m_status->GetBestGatewayForDevice(deviceAddress, window);
 
    if (gwAddress == Address() && window == 1)
    {
        NS_LOG_DEBUG("No suitable gateway found for first window.");
 
        // No suitable gateway was found, but there's still hope to find one for the
        // second window.
        // Schedule another OnReceiveWindowOpportunity event
        m_status->GetEndDeviceStatus(deviceAddress)
            ->SetReceiveWindowOpportunity(
                Simulator::Schedule(Seconds(1),
                                    &NetworkScheduler::OnReceiveWindowOpportunity,
                                    this,
                                    deviceAddress,
                                    2)); // This will be the second receive window
    }
    else if (gwAddress == Address() && window == 2)
    {
        // No suitable gateway was found and this was our last opportunity
        // Simply give up.
        NS_LOG_DEBUG("Giving up on reply: no suitable gateway was found "
                     << "on the second receive window");
 
        // Reset the reply
        // XXX Should we reset it here or keep it for the next opportunity?
        m_status->GetEndDeviceStatus(deviceAddress)->RemoveReceiveWindowOpportunity();
        m_status->GetEndDeviceStatus(deviceAddress)->InitializeReply();
    }
    else
    {
        // A gateway was found
 
        NS_LOG_DEBUG("Found available gateway with address: " << gwAddress);
 
        m_controller->BeforeSendingReply(m_status->GetEndDeviceStatus(deviceAddress));
 
        // Check whether this device needs a response by querying m_status
        bool needsReply = m_status->NeedsReply(deviceAddress);
 
        if (needsReply)
        {
            NS_LOG_INFO("A reply is needed");
 
            // Send the reply through that gateway
            m_status->SendThroughGateway(m_status->GetReplyForDevice(deviceAddress, window),
                                         gwAddress);
 
            // Reset the reply
            m_status->GetEndDeviceStatus(deviceAddress)->RemoveReceiveWindowOpportunity();
            m_status->GetEndDeviceStatus(deviceAddress)->InitializeReply();
        }
    }
}
 
} // namespace lorawan
} // namespace ns3