[Ns-developers] Handoff is attempted in Ad Hoc (Non Infrastructure) Mode too !!: A bug in ns-2.33 in mac/mac-802_11.cc

[Mayur]

I guess, there is a bug in the condition for Handoff Attempt in 
mac/mac-802_11.cc

*_Abstract:_*
    A possible bug in ns 2:

    *        Version : *ns-2.33*
    *        File: <ns-2.33>/mac/*mac-802_11.cc*
    *        Place: *Condition for Handoff Attempt in  RetransmitDATA()
      function*
    * *      *Brief: *It calls for Handoff even in Non Infrastructure
      (Ad Hoc) mode
      *

_*Details:*_

Presently the handoff is attempted after 3 number of failures. The 
snippet is shown below:

 
/*********************** Current Code Snippet ************************
>  *if (*rcount == 3 && handoff == 0)* {
>                 //start handoff process
>                 printf("Client %d: Handoff Attempted\n",index_);
>                 associated = 0;
>                 authenticated = 0;
>                 handoff = 1;
>                 ScanType_ = ACTIVE;
>                 sendPROBEREQ(MAC_BROADCAST);
>                 return;
>         }     

As observed during simulation runs, even in case of ad hoc scenarios 
(without APs) a node attempts for Handoff, viz., it configures a Probe 
Request and goes to start the Backoff timer.

The correction is trivial as shown below. We have to just include the 
condition for the existence of infra structure mode.

/****** Modification Suggested ***************************/
>  if (*infra_mode_ *&& *rcount == 3 && handoff == 0) {
>                 //start handoff process
>                 printf("Client %d: Handoff Attempted\n",index_);
>                 associated = 0;
>                 authenticated = 0;
>                 handoff = 1;
>                 ScanType_ = ACTIVE;
>                 sendPROBEREQ(MAC_BROADCAST);
>                 return;
>         }     
Suggestions and Comments are welcome, I doubt myself, as no body has so 
far dictated this simple observation.

regards,
Mayur