gateway-lorawan-mac.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 "gateway-lorawan-mac.h"
 
#include "lora-net-device.h"
#include "lora-phy.h"
#include "lora-tag.h"
#include "lorawan-mac-header.h"
 
namespace ns3
{
namespace lorawan
{
 
NS_LOG_COMPONENT_DEFINE("GatewayLorawanMac");
 
NS_OBJECT_ENSURE_REGISTERED(GatewayLorawanMac);
 
TypeId
GatewayLorawanMac::GetTypeId()
{
    static TypeId tid = TypeId("ns3::GatewayLorawanMac")
                            .SetParent<LorawanMac>()
                            .AddConstructor<GatewayLorawanMac>()
                            .SetGroupName("lorawan");
    return tid;
}
 
GatewayLorawanMac::GatewayLorawanMac()
{
    NS_LOG_FUNCTION(this);
}
 
GatewayLorawanMac::~GatewayLorawanMac()
{
    NS_LOG_FUNCTION(this);
}
 
void
GatewayLorawanMac::Send(Ptr<Packet> packet)
{
    NS_LOG_FUNCTION(this << packet);
 
    // Get data rate to send this packet with
    LoraTag tag;
    packet->RemovePacketTag(tag);
    uint8_t dataRate = tag.GetDataRate();
    uint32_t frequencyHz = tag.GetFrequency();
    NS_LOG_DEBUG("DR: " << unsigned(dataRate));
    NS_LOG_DEBUG("SF: " << unsigned(GetSfFromDataRate(dataRate)));
    NS_LOG_DEBUG("BW: " << GetBandwidthFromDataRate(dataRate));
    NS_LOG_DEBUG("Freq: " << frequencyHz << " Hz");
    packet->AddPacketTag(tag);
 
    // Make sure we can transmit this packet
    if (GetWaitTime(frequencyHz).IsStrictlyPositive())
    {
        // We cannot send now!
        NS_LOG_WARN("Trying to send a packet but Duty Cycle won't allow it. Aborting.");
        return;
    }
 
    auto sf = GetSfFromDataRate(dataRate);
    auto bw = GetBandwidthFromDataRate(dataRate);
    // see SX1272/73 Datasheet, Section 4.1.1.6, Rev. 4, Jan. 2019
    auto ldro = bool((sf == 11 || sf == 12) && bw == 125'000);
 
    LoraTxParameters params;
    params.spreadingFactor = sf;
    params.bandwidthHz = bw;
    params.codingRate = CodingRate::CR_4_5;
    params.lowDataRateOptimize = ldro;
    params.preambleLenSymb = 8;
    params.implicitHeader = false;
    params.crcEnabled = true;
 
    // Get the duration
    Time duration = LoraPhy::GetTimeOnAir(packet->GetSize(), params);
 
    NS_LOG_DEBUG("Duration: " << duration.As(Time::S));
 
    // Find the channel with the desired frequency
    double sendingPower = m_channelHelper->GetTxPowerForChannel(frequencyHz);
 
    // Add the event to the channelHelper to keep track of duty cycle
    m_channelHelper->AddEvent(duration, frequencyHz);
 
    // Send the packet to the PHY layer to send it on the channel
    m_phy->Send(packet, frequencyHz, IQPolarity::DOWN, params, sendingPower);
 
    m_sentNewPacket(packet);
}
 
bool
GatewayLorawanMac::IsTransmitting()
{
    return m_phy->IsTransmitting();
}
 
Time
GatewayLorawanMac::GetWaitTime(uint32_t frequencyHz)
{
    NS_LOG_FUNCTION_NOARGS();
    return m_channelHelper->GetWaitTime(frequencyHz);
}
 
void
GatewayLorawanMac::TxFinished(Ptr<const Packet> packet)
{
    NS_LOG_FUNCTION(this << packet);
}
 
void
GatewayLorawanMac::Receive(Ptr<const Packet> packet)
{
    NS_LOG_FUNCTION(this << packet);
 
    // Make a copy of the packet to work on
    Ptr<Packet> packetCopy = packet->Copy();
 
    // Only forward the packet if it's uplink
    LorawanMacHeader macHdr;
    packetCopy->PeekHeader(macHdr);
 
    if (macHdr.IsUplink())
    {
        NS_LOG_DEBUG("Received packet: " << packet);
        // Pass the packet up to the NetDevice
        if (!m_receiveCallback.IsNull())
        {
            m_receiveCallback(packetCopy);
        }
        m_receivedPacket(packet);
    }
    else
    {
        NS_LOG_DEBUG("Not forwarding downlink message to NetDevice");
    }
}
 
void
GatewayLorawanMac::FailedReception(Ptr<const Packet> packet)
{
    NS_LOG_FUNCTION(this << packet);
}
 
} // namespace lorawan
} // namespace ns3