[ns] doubt in hcca patch to ns2

[Sandeep]

Hello all,
I am working on a project on 802.11E schedulers. I am trying to 
implement WFQ scheduler with some minor modifications, using the ns2HCCA 
patch for NS-2.27.

However, I am facing the following problems:

1. Where (in the code) does a CAP start mechanism take place. There is a 
startCAP(void) function in mac-802_11e.cc file, but it is called twice. 
Once, when we specify start-hcca in the TCL  script and second time when 
we pass the TSPEC parameters in the TCL script.
Is this function called only when the QAP starts a CAP?

2. How does the patch ensure that the TXOP list that is created is being 
followed fully. Consider the offline TXOP list that is created. Suppose 
it contains the TXOP times for the stations 1,2,5,6. How does the patch 
ensure that first only station 1 will access the channel, and then 
stations 2, 5, 6 ... and so on. How is this being ensured?

3. How do the stations get access to the channel i.e. how does the 
channel access switch mechanism take place. E.g. Suppose at time t 
station 1 is accessing the channel. After time t+t1 , i want station 2 
to access the channel. How can i do that? 
I would be really grateful if anyone could explain me the working of the 
patch w.r.t the questions mentioned above. Also, any suggestion as to 
how to go about implementing the WFQ scheduler would be welcome.

Thanks in advance,
with regards,
Sandeep.