Add WifiBandwidthFilter automatically with SpectrumWifiPhyHelper

src/spectrum/model/spectrum-channel.cc

@@ -158,6 +158,12 @@ SpectrumChannel::AddSpectrumTransmitFilter(Ptr<SpectrumTransmitFilter> filter)
     m_filter = filter;
 }
 
+Ptr<const SpectrumTransmitFilter>
+SpectrumChannel::GetSpectrumTransmitFilter() const
+{
+    return m_filter;
+}
+
 void
 SpectrumChannel::SetPropagationDelayModel(Ptr<PropagationDelayModel> delay)
 {

src/spectrum/model/spectrum-channel.h

@@ -125,6 +125,13 @@ class SpectrumChannel : public Channel
      */
     void AddSpectrumTransmitFilter(Ptr<SpectrumTransmitFilter> filter);
 
+    /**
+     * Get the transmit filter, or first in a chain of transmit filters
+     * if more than one is present.
+     * \returns a pointer to the transmit filter.
+     */
+    Ptr<const SpectrumTransmitFilter> GetSpectrumTransmitFilter() const;
+
     /**
      * Used by attached PHY instances to transmit signals on the channel
      *

src/spectrum/model/spectrum-transmit-filter.cc

@@ -61,6 +61,12 @@ SpectrumTransmitFilter::SetNext(Ptr<SpectrumTransmitFilter> next)
     m_next = next;
 }
 
+Ptr<const SpectrumTransmitFilter>
+SpectrumTransmitFilter::GetNext() const
+{
+    return m_next;
+}
+
 bool
 SpectrumTransmitFilter::Filter(Ptr<const SpectrumSignalParameters> params,
                                Ptr<const SpectrumPhy> receiverPhy)

src/spectrum/model/spectrum-transmit-filter.h

@@ -55,6 +55,13 @@ class SpectrumTransmitFilter : public Object
      */
     void SetNext(Ptr<SpectrumTransmitFilter> next);
 
+    /**
+     * Return the next transmit filter in the chain
+     *
+     * \return next transmit filter in the chain
+     */
+    Ptr<const SpectrumTransmitFilter> GetNext() const;
+
     /**
      * Evaluate whether the signal to be scheduled on the receiving Phy should
      * instead be filtered (discarded) before being processed in this channel

src/wifi/helper/spectrum-wifi-helper.cc

@@ -28,7 +28,9 @@
 #include "ns3/names.h"
 #include "ns3/preamble-detection-model.h"
 #include "ns3/spectrum-channel.h"
+#include "ns3/spectrum-transmit-filter.h"
 #include "ns3/spectrum-wifi-phy.h"
+#include "ns3/wifi-bandwidth-filter.h"
 #include "ns3/wifi-net-device.h"
 #include "ns3/wifi-spectrum-value-helper.h"
 
@@ -53,6 +55,7 @@ void
 SpectrumWifiPhyHelper::SetChannel(const Ptr<SpectrumChannel> channel)
 {
     m_channels[WHOLE_WIFI_SPECTRUM] = channel;
+    AddWifiBandwidthFilter(channel);
 }
 
 void
@@ -60,6 +63,7 @@ SpectrumWifiPhyHelper::SetChannel(const std::string& channelName)
 {
     Ptr<SpectrumChannel> channel = Names::Find<SpectrumChannel>(channelName);
     m_channels[WHOLE_WIFI_SPECTRUM] = channel;
+    AddWifiBandwidthFilter(channel);
 }
 
 void
@@ -67,6 +71,7 @@ SpectrumWifiPhyHelper::AddChannel(const Ptr<SpectrumChannel> channel,
                                   const FrequencyRange& freqRange)
 {
     m_channels[freqRange] = channel;
+    AddWifiBandwidthFilter(channel);
 }
 
 void
@@ -74,6 +79,33 @@ SpectrumWifiPhyHelper::AddChannel(const std::string& channelName, const Frequenc
 {
     Ptr<SpectrumChannel> channel = Names::Find<SpectrumChannel>(channelName);
     AddChannel(channel, freqRange);
+    AddWifiBandwidthFilter(channel);
+}
+
+void
+SpectrumWifiPhyHelper::AddWifiBandwidthFilter(Ptr<SpectrumChannel> channel)
+{
+    Ptr<const SpectrumTransmitFilter> p = channel->GetSpectrumTransmitFilter();
+    bool found = false;
+    while (p && !found)
+    {
+        if (DynamicCast<const WifiBandwidthFilter>(p))
+        {
+            NS_LOG_DEBUG("Found existing WifiBandwidthFilter for channel " << channel);
+            found = true;
+        }
+        else
+        {
+            NS_LOG_DEBUG("Found different SpectrumTransmitFilter for channel " << channel);
+            p = p->GetNext();
+        }
+    }
+    if (!found)
+    {
+        Ptr<WifiBandwidthFilter> pWifi = CreateObject<WifiBandwidthFilter>();
+        channel->AddSpectrumTransmitFilter(pWifi);
+        NS_LOG_DEBUG("Adding WifiBandwidthFilter to channel " << channel);
+    }
 }
 
 std::vector<Ptr<WifiPhy>>

src/wifi/helper/spectrum-wifi-helper.h

@@ -33,6 +33,9 @@ class SpectrumChannel;
  * The Pcap and ASCII traces generated by the EnableAscii and EnablePcap methods defined
  * in this class correspond to PHY-level traces and come to us via WifiPhyHelper
  *
+ * This helper will install an instance of a WifiBandwidthFilter on any SpectrumChannel
+ * added to this helper (via one of the SetChannel methods), unless one has
+ * previously been installed on the channel object.
  */
 class SpectrumWifiPhyHelper : public WifiPhyHelper
 {
@@ -87,6 +90,13 @@ class SpectrumWifiPhyHelper : public WifiPhyHelper
      * This method implements the pure virtual method defined in \ref ns3::WifiPhyHelper.
      */
     std::vector<Ptr<WifiPhy>> Create(Ptr<Node> node, Ptr<WifiNetDevice> device) const override;
+    /**
+     * \param channel The channel to inspect to possibly add a WifiBandwidthFilter
+     *
+     * This method will add a WifiBandwidthFilter object to the SpectrumChannel, only if
+     * one has not yet been added.
+     */
+    void AddWifiBandwidthFilter(Ptr<SpectrumChannel> channel);
 
     std::map<FrequencyRange, Ptr<SpectrumChannel>> m_channels; ///< the spectrum channels
 };