[Ns-developers] Block ack Timeout

[Mirko Banchi]

Mathieu Lacage ha scritto:
> did you figure out an answer to this question ?
> 
> Mathieu
> 

WifiMac::GetDefaultCtsAckTimeout ()
{
  /* Cts_Timeout and Ack_Timeout are specified in the Annex C
     (Formal description of MAC operation, see details on the
     Trsp timer setting at page 346)
  */
  Time ctsTimeout = GetDefaultSifs ();
  ctsTimeout += GetDefaultCtsAckDelay ();
  ctsTimeout += GetDefaultMaxPropagationDelay () * Scalar (2);
  ctsTimeout += GetDefaultSlot ();
  return ctsTimeout;
}

i see the comment: how ctsTimeout value is calculated is specified in
the standard. About block ack:

1. Value for delay? For an cts or ack is 44 microseconds and for block
ack? i don't think that it could be calculated by a proportion.

2. We must add a slot time also for block ack timeout?

Sorry but i'm not familiar with this.

Thanks,

Mirko

> On Sun, 2009-05-24 at 20:00 +0200, Mirko Banchi wrote:
>> Hi all, on these days i'm completing 802.11n block ack
>> implementation...i think that within a week i'll ready to publish the
>> repository on code.nsnam.org for first feedbacks. I've a question about
>> calculation of timeout value for block ack. Method
>> ns3::MacLow::StartDataTxTimers now has also lines like these:
>>
>> ...
>> else if (m_txParams.MustWaitBlockAck ())
>>     {
>>       Time timerDelay = txDuration + GetBlockAckTimeout ();
>>       NS_ASSERT (m_blockAckTimeoutEvent.IsExpired ());
>>       m_blockAckTimeoutEvent = Simulator::Schedule (timerDelay,
>> &MacLow::BlockAckTimeout, this);
>>     }
>>   else if (m_txParams.MustWaitCompressedBlockAck ())
>>     {
>>       Time timerDelay = txDuration + GetBlockAckTimeout ();
>>       NS_ASSERT (m_blockAckTimeoutEvent.IsExpired ());
>>       m_blockAckTimeoutEvent = Simulator::Schedule (timerDelay,
>> &MacLow::BlockAckTimeout, this);
>>     }
>> ...
>>
>> The two implemented variants are basic block ack with a 128 bytes bitmap
>> and compressed block ack with a 64 bits bitmap. How we should calculate
>> timeout value for the two variants? In the standard i haven't found that .
>>
>> I've looked to method ns3::WifiMac::GetDefaultCtsAckTimeout. How should
>> be defined a similar method GetDefaultBlockAckTimeout?
>>
>> Thanks,
>> Mirko
>>
> 
> 


-- 
Mirko Banchi

e-mail:    mk.banchi at gmail.com
e-mail:    mk.banchi at virgilio.it
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