上下行鏈路速率差距很大，若能動態調節上下行通道頻寬，可優化使用者體驗，提高效率。
以下是利用NS-3模擬上下行鏈路程式碼：

#include <iostream>  
#include <fstream>  
#include <string>  
#include <cassert>  

#include "ns3/core-module.h"  
#include "ns3/network-module.h"  
#include "ns3/internet-module.h"  
#include "ns3/point-to-point-module.h"  
#include "ns3/applications-module.h"  
#include "ns3/ipv4-global-routing-helper.h"  
#include "ns3/random-variable-stream.h"
#include "ns3/random-variable-stream-helper.h"
using namespace ns3;  
using namespace std;  

NS_LOG_COMPONENT_DEFINE ("uplink-downlink-Example4");  

static void RxDrop (Ptr<const Packet> p)  //丟包 回撥函式  
{  
  NS_LOG_UNCOND ("RxDrop at " << Simulator::Now ().GetSeconds ());  
}  

int  
main (int argc, char *argv[])  
{  
    Time::SetResolution (Time::NS);//設定時間單位為納秒  
    LogComponentEnable ("uplink-downlink-Example4", LOG_LEVEL_INFO);  
    LogComponentEnable ("TcpL4Protocol", LOG_LEVEL_INFO);  
//    LogComponentEnable ("TcpSocketImpl", LOG_LEVEL_ALL);  
    LogComponentEnable ("PacketSink", LOG_LEVEL_INFO);  

//Config::SetDefault ("ns3::OnOffApplication::PacketSize", UintegerValue (1024));  
//Config::SetDefault ("ns3::OnOffApplication::DataRate", StringValue ("50Mb/s"));  
CommandLine cmd;  
cmd.Parse (argc,argv);  

NodeContainer nodes;  
nodes.Create (2);//建立2個節點 

PointToPointHelper pointToPoint;
pointToPoint.SetDeviceAttribute ("DataRate", StringValue ("100000Mbps"));
pointToPoint.SetChannelAttribute ("Delay", StringValue ("0.002ms"));
NetDeviceContainer devices;
devices = pointToPoint.Install (nodes);
InternetStackHelper stack;
stack.Install (nodes);

////////////設定丟包率 

Ptr<UniformRandomVariable> x =CreateObject<UniformRandomVariable>();
x->SetAttribute ("Min",DoubleValue(0));
x->SetAttribute ("Max",DoubleValue(1));

   // Ptr<RateErrorModel> em = CreateObjectWithAttributes<RateErrorModel> ( "RanVar",  StringValue ("ns3::ConstantRandomVariable[Constant=0.000002583]"), "ErrorRate", DoubleValue (0.00001));  
    Ptr<RateErrorModel> em_1 = CreateObjectWithAttributes<RateErrorModel> ( "RanVar", StringValue("ns3::UniformRandomVariable[Min=0.0|Max=1.0]"),"ErrorRate", DoubleValue (0.0001));
    devices.Get(0)->SetAttribute("ReceiveErrorModel", PointerValue (em_1));

    devices.Get(0)->TraceConnectWithoutContext ("PhyRxDrop", MakeCallback (&RxDrop));  

   /////////////////////////////////////////////////////////////////////////////////////////////

    Ptr<RateErrorModel> em_2 = CreateObjectWithAttributes<RateErrorModel> ( "RanVar", StringValue("ns3::UniformRandomVariable[Min=0.0|Max=1.0]"),"ErrorRate", DoubleValue (0.0001));
    devices.Get(1)->SetAttribute("ReceiveErrorModel", PointerValue (em_2));

    devices.Get(1)->TraceConnectWithoutContext ("PhyRxDrop", MakeCallback (&RxDrop));
   //////////////////////////////////////



Ipv4AddressHelper address;
address.SetBase ("10.1.1.0", "255.255.255.0");
Ipv4InterfaceContainer interfaces = address.Assign (devices);

uint16_t port_1 = 50000;  
ApplicationContainer sinkApp_1;  
Address sinkLocalAddress_1 (InetSocketAddress (Ipv4Address::GetAny (), port_1));  
PacketSinkHelper sinkHelper_1 ("ns3::TcpSocketFactory", sinkLocalAddress_1);  
sinkApp_1.Add(sinkHelper_1.Install(nodes.Get(1)));                // Packet sink 安裝在第二個節點上

sinkApp_1.Start (Seconds (0.0));  
sinkApp_1.Stop (Seconds (30.0));  

OnOffHelper clientHelper_1 ("ns3::TcpSocketFactory", Address ());  

//clientHelper.SetAttribute ("OffTime", StringValue ("ns3::ExponentialRandomVariable[Mean=0.01|Variance=0.5|Bound=0.0]")); 
clientHelper_1.SetAttribute ("OffTime", StringValue ("ns3::ConstantRandomVariable[Constant=0.0002583]"));

///注意是豎線分隔   各個不同的引數 
clientHelper_1.SetAttribute ("OnTime", StringValue ("ns3::ConstantRandomVariable[Constant=0.0001583]"));  

clientHelper_1.SetAttribute ("PacketSize", UintegerValue (1024));
clientHelper_1.SetAttribute ("DataRate", StringValue ("1Mbps"));

ApplicationContainer clientApps_1;  
//節點1>節點2  
AddressValue remoteAddress_1  
(InetSocketAddress (interfaces.GetAddress (1), port_1));  
clientHelper_1.SetAttribute("Remote",remoteAddress_1);  
clientApps_1.Add(clientHelper_1.Install(nodes.Get(0)));  


clientApps_1.Start(Seconds(1.0));  
clientApps_1.Stop (Seconds(10.0));  


   /////////////////////////////////////downlink  ////////

uint16_t port_2 = 50001;
ApplicationContainer sinkApp_2;
Address sinkLocalAddress_2 (InetSocketAddress (Ipv4Address::GetAny (), port_2));
PacketSinkHelper sinkHelper_2 ("ns3::TcpSocketFactory", sinkLocalAddress_2);
sinkApp_2.Add(sinkHelper_2.Install(nodes.Get(0)));                // Packet sink 安裝在第二個節點上

sinkApp_2.Start (Seconds (0.0));
sinkApp_2.Stop (Seconds (30.0));

OnOffHelper clientHelper_2 ("ns3::TcpSocketFactory", Address ());

//clientHelper.SetAttribute ("OffTime", StringValue ("ns3::ExponentialRandomVariable[Mean=0.01|Variance=0.5|Bound=0.0]")); 
clientHelper_2.SetAttribute ("OffTime", StringValue ("ns3::ConstantRandomVariable[Constant=0.0002583]"));

///注意是豎線分隔   各個不同的引數 
clientHelper_2.SetAttribute ("OnTime", StringValue ("ns3::ConstantRandomVariable[Constant=0.0001583]"));

clientHelper_2.SetAttribute ("PacketSize", UintegerValue (1024));
clientHelper_2.SetAttribute ("DataRate", StringValue ("100Mbps"));

ApplicationContainer clientApps_2;
//節點1>節點2  
AddressValue remoteAddress_2
(InetSocketAddress (interfaces.GetAddress (0), port_2));
clientHelper_2.SetAttribute("Remote",remoteAddress_2);
clientApps_2.Add(clientHelper_2.Install(nodes.Get(1)));


clientApps_2.Start(Seconds(1.0));
clientApps_2.Stop (Seconds(10.0));




Ipv4GlobalRoutingHelper::PopulateRoutingTables ();  
//嗅探,記錄所有節點相關的資料包  
pointToPoint.EnablePcapAll("uplink-downlink-Tcp4");  

Simulator::Run ();  
Simulator::Destroy ();  
return 0;  
}  
 

利用wireshark解析上下行鏈路的吞吐率：

其中
tcp.port==50000 是上行鏈路的接受埠的吞吐率
tcp.port==50001 是下行鏈路的接受埠的吞吐率