How to detect if system is connected to ad hoc or infrastructure wifi?

Question

I am working on an application that checks, before enabling a download, that the connection is reliable (basically the connection should be an infrastructure wifi and not data pack) But in case the user is either

1. using an ad hoc network, or
2. mobile device's internet connection as WAP

and then connecting and starting the download on desktop, it is still undesired. Is there a way to detect if some wifi connection is actually not from ad hoc or using phone's WAP?

Answer 1

You can detect...

1. ...the Ad-Hoc Network by checking if you actually can access a server on the internet - usually, Ad-Hoc does not include fully connectivity so if you have network but no internet access, a download won't work

2. ...the usage of a phone access point by measuring the round-trip time of a request - they are usually quite high on mobile broadband.

   long start = System.nanoTime();
   HttpGet requestForTest = new HttpGet("http://m.google.com");
   try {
       new DefaultHttpClient().execute(requestForTest); // can last...
   } 
   catch (Exception e) {
   }
   long rtt = System.nanoTime() - start;
   // ... evaluate the rtt
   

   This table may be relevant for the evaluation (source)

   Generation | Data rate      | Latency
   2G         | 100–400 Kbit/s | 300–1000 ms
   3G         | 0.5–5 Mbit/s   | 100–500 ms
   4G         | 1–50 Mbit/s    | < 100 ms
   

Apart from those two options: why do you specifically ban Ad-Hoc or mobile broadband? Shouldn't you either

• ban nothing and let the user decide if they want to wait for ages

or

• ban ALL slow connections, i.e. monitoring the transfer rate for a couple of seconds and cancel the download automatically if it is too small