在ns3中需要帮助 - > RandomWalk2MobilityModel

Question

我是NS3的新手;你能解释一下RandomWalk2dMobilityModel的工作原理吗？

我想模拟的环境中，用户将被赋予一个目的地，他将以随机生成的速度去那里。这可能用这个模型来设计吗？

谢谢。

static void 
CourseChange (std::string foo, Ptr<const MobilityModel> mobility) 
{ 
    Vector pos = mobility->GetPosition(); 
    Vector vel = mobility->GetVelocity(); 
    std::cout << Simulator::Now() << ", model=" << mobility << ", POS: x=" << pos.x << ", y=" << pos.y 
      << ", z=" << pos.z << "; VEL:" << vel.x << ", y=" << vel.y 
      << ", z=" << vel.z << std::endl; 
} 

int main (int argc, char *argv[]) 
{ 
    Config::SetDefault ("ns3::RandomWalk2dMobilityModel::Mode", StringValue ("Time")); 
    Config::SetDefault ("ns3::RandomWalk2dMobilityModel::Time", StringValue ("2s")); 
    Config::SetDefault ("ns3::RandomWalk2dMobilityModel::Speed", StringValue ("ns3::ConstantRandomVariable[Constant=1.0]")); 
    Config::SetDefault ("ns3::RandomWalk2dMobilityModel::Bounds", StringValue ("0|200|0|200")); 

    CommandLine cmd; 
    cmd.Parse (argc, argv); 

    NodeContainer c; 
    c.Create (100); 

    MobilityHelper mobility; 
    mobility.SetPositionAllocator ("ns3::RandomDiscPositionAllocator", 
           "X", StringValue ("100.0"), 
           "Y", StringValue ("100.0"), 
           "Rho", StringValue ("ns3::UniformRandomVariable[Min=0|Max=30]")); 
    mobility.SetMobilityModel ("ns3::RandomWalk2dMobilityModel", 
          "Mode", StringValue ("Time"), 
          "Time", StringValue ("2s"), 
          "Speed", StringValue ("ns3::ConstantRandomVariable[Constant=1.0]"), 
          "Bounds", StringValue ("0|200|0|200")); 
    mobility.InstallAll(); 
    Config::Connect ("/NodeList/*/$ns3::MobilityModel/CourseChange", 
        MakeCallback (&CourseChange)); 

Answer 1

基本上答案是不， RandomWalk2dMobilityModel用于生成随机速度随机的方向，如果你想与随机速度特定的方向，那么你必须创建模式。

我创建了一个函数来创建位置之间的移动，我通过节点id，startPosition，endPosition和当前模拟时间。该函数返回到所述两个位置

double GenerateMovementBetweenTwoPosition(Ptr<Node> node, Vector startPosition,Vector newPosition, double time) 
{ 
    float x,y; 
    Ptr<MobilityModel> mobilityModel = node->GetObject<MobilityModel>(); 
    //Vector startPosition = mobilityModel->GetPosition(); 
    double distance = sqrt(pow(startPosition.x - newPosition.x, 2) 
      + pow(startPosition.y - newPosition.y, 2) ); 
    double tagSpeed = UniformVariable().GetValue(0.7,1.3); 
    double MovementTime = distance/tagSpeed; // time is in seconds as distance in meter and 1.5 m/s 
    double distanceStep = distance/ceil(MovementTime); 
    for (int i=1; i <= (int)ceil(MovementTime); i++) 
    { 
     if (time+i >= simTime) 
      return time; 
     x = startPosition.x + (distanceStep * i/distance)*(newPosition.x - startPosition.x)+ NormalVariable (-2,2).GetValue(); //path width 
     y = startPosition.y + (distanceStep * i/distance)*(newPosition.y - startPosition.y)+ NormalVariable (-2,2).GetValue(); 
    // std::cout << "x: " << x << " y: "<< y<<std::endl; 
     Simulator::Schedule (Seconds (time+i), &MobilityModel::SetPosition, mobilityModel, 
    Vector(x, y, 0.0)); 

    } 
    return time+ceil(MovementTime); 

} 

之间移动例如节点采取的仿真时间10以仿真时间100从A点移动到B点，该运动逐渐50秒从而返回仿真时间150 然而，如果仿真时间在140秒结束，那么当仿真在轨迹中间结束时，该功能将返回140。