Determining the WiFi Link Speed

[alastair1008]

I am writing a program that does one thing, it finds out the current link speed of the wifi connection and reports it to the user in real time. the problem I am having is that it does not seem to be able to find out the current link speed, only the max link speed of the device (300 Mbps). the reason I am writing this is that I have a problem where, periodically the link speed will drop drastically (down to 1-2 Mbps) and I want to be able to see when that happens. with this code it will simply give me the maximum speed that the adapter supports, not the current link speed of the connection.

private void update(object state)
{

    System.Net.NetworkInformation.NetworkInterface[] nics = null;
    nics = System.Net.NetworkInformation.NetworkInterface.GetAllNetworkInterfaces();
    long speed = 0;
    string adapter = "";
    foreach (System.Net.NetworkInformation.NetworkInterface net in nics)
    {
        if (net.Name.Contains("Wireless") || net.Name.Contains("WiFi") || net.Name.Contains("802.11") || net.Name.Contains("Wi-Fi"))
        {
            speed = net.Speed;
            adapter = net.Name;
            break;
        }
    }
    string temp;
    if (speed == 0)
    {
        temp = "There is currently no Wi-Fi connection";
    }
    else
    {
        temp = "Current Wi-Fi Speed: " + (speed / 1000000) + "Mbps on " + adapter + ". " + System.DateTime.Now;
    }
    if (label1.InvokeRequired)
    {
        SetTextCallback d = new SetTextCallback(update);
        label1.Invoke(d, new object[] { temp });
    }
    else
    {
        label1.Text = temp;
    }
}

this method is called periodically by this code

System.Timers.Timer timer = new System.Timers.Timer(200);
timer.Elapsed += new System.Timers.ElapsedEventHandler(update);
timer.Enabled = true;

right now the problem is that I only returns the maximum link speed supported by the device, not the current link speed.
I am not trying to determine internet speed, just the link speed of the 802.11n connection at a given moment.
the info I am trying to get is the same info that I can get by checking the network connection properties inside windows.