[Ns-developers] 802.11 10Mhz Channel

[Basim Javed]

hi

I am not sure about this particular implementation in code, but TXOP is an
independent parameter conceptually, from CWmin or Cwmax; so should be
treated accordingly. Maybe its some programming hack.
As per standard, I dont think that TXOP is influenced by a particular
setting of CWmin.
regards


On Fri, Jul 17, 2009 at 1:59 AM, Pei, Guangyu <Guangyu.Pei at boeing.com>wrote:

>  Hi,
> Here is what I see in DcaTxop:
>
>  98 TypeId
>  99 DcaTxop::GetTypeId (void)
> 100 {
> 101   static TypeId tid = TypeId ("ns3::DcaTxop")
> 102     .SetParent<Object> ()
> 103     .AddConstructor<DcaTxop> ()
> 104     .AddAttribute ("MinCw", "The minimum value of the contention
> window.",
> 105                    UintegerValue (15),
> 106                    MakeUintegerAccessor (&DcaTxop::SetMinCw,
> 107                                          &DcaTxop::GetMinCw),
> 108                    MakeUintegerChecker<uint32_t> ())
> 109     .AddAttribute ("MaxCw", "The maximum value of the contention
> window.",
> 110                    UintegerValue (1023),
> 111                    MakeUintegerAccessor (&DcaTxop::SetMaxCw,
> 112                                          &DcaTxop::GetMaxCw),
> 113                    MakeUintegerChecker<uint32_t> ())
> 114     .AddAttribute ("Aifsn", "The AIFSN: the default value conforms to
> simple DCA.",
> 115                    UintegerValue (2),
> 116                    MakeUintegerAccessor (&DcaTxop::SetAifsn,
> 117                                          &DcaTxop::GetAifsn),
> 118                    MakeUintegerChecker<uint32_t> ())
> 119     ;
> 120   return tid;
> 121 }
> 122
> The default value of 15 was set at line 105. Why do you think that CwWin
> has nothing to do with DcaTxop?
>
> Gary
>
>
>
>  ------------------------------
> *From:* Basim Javed [mailto:basimjaved at gmail.com]
> *Sent:* Thursday, July 16, 2009 3:17 PM
> *To:* Pei, Guangyu
> *Cc:* Nicola Baldo; ns-developers
>
> *Subject:* Re: [Ns-developers] 802.11 10Mhz Channel
>
> hi all
>
> CwMin parameter has to do nothing with DcaTxop. In QoS enabled MAC, each
> queue handles its own DcaTxop independently.
>
> regards
> B
>
> On Thu, Jul 16, 2009 at 11:23 PM, Pei, Guangyu <Guangyu.Pei at boeing.com>wrote:
>
>> It seems to me that CwMin parameter is controlled by DcaTxop. Each MAC
>> handles its own DcaTxop.  Should we add a virtual function SetCwMin may
>> be added in WifiMac class? For non-QoS MACs, it seems that each mac has
>> only one DcaTxop and it is straightforward to add one. For QoS  MAC, it
>> seems that only beacon Dca needs to be set. Does this sound ok?
>>
>> Gary
>>
>>
>> > -----Original Message-----
>> > From: Nicola Baldo [mailto:nbaldo at cttc.es]
>> > Sent: Thursday, July 16, 2009 9:03 AM
>> > To: ns-developers
>> > Subject: Re: [Ns-developers] 802.11 10Mhz Channel
>> >
>> > Also CwMin should be set to 31 (instead of 15) when using 802.11b.
>> > See IEEE Std. 802.11-2007, section 15.3.3 "DS PHY characteristics".
>> >
>> > Nicola
>> >
>> > Pei, Guangyu wrote:
>> > > Hi,
>> > >
>> > > I double-checked the standard. I believe the following
>> > settings are correct.
>> > >
>> > > +WifiMac::Configure80211b (void)
>> > > +{
>> > > +  SetSifs(MicroSeconds(10));
>> > > +  SetSlot(MicroSeconds(20));
>> > > +  SetEifsNoDifs(MicroSeconds(10+304));
>> > > +  SetPifs(MicroSeconds(10+20));
>> > > +
>> > >
>> > +SetCtsTimeout(MicroSeconds(10+304+20+GetDefaultMaxPropagationDelay().
>> > > +GetMicroSeconds ()*2));
>> > > +
>> > >
>> > +SetAckTimeout(MicroSeconds(10+304+20+GetDefaultMaxPropagationDelay().
>> > > +GetMicroSeconds ()*2)); }
>> > >
>> > > In particular, I believe 304 is the Ack Tx time = AckSize + PLCP
>> > > Preamble + PCLP Header = 8*14 + 144 + 48 = 304
>> > >
>> > > Thanks,
>> > >
>> > > Gary
>> > >
>> > >> -----Original Message-----
>> > >> From: Ramon Bauza [mailto:monbauza at gmail.com]
>> > >> Sent: Monday, July 13, 2009 3:22 AM
>> > >> To: Mathieu Lacage
>> > >> Cc: ns-developers at ISI.EDU
>> > >> Subject: Re: [Ns-developers] 802.11 10Mhz Channel
>> > >>
>> > >> Hi,
>> > >>
>> > >> Thank you for your comments. Please find the new patch modified
>> > >> accordingly to your suggestions. Now, WifiMacHelpers
>> > remain the same
>> > >> way as in ns-3-dev.
>> > >> I have also added the Configure80211b method to configure MAC
>> > >> parameters.
>> > >> However, I would like someone to review the parameters, since I am
>> > >> not very familiar with the 802.11b specification.  As Std
>> > 802.11-2007
>> > >> states (page 654), I have considered:
>> > >>
>> > >> - SlotTime = 20us
>> > >> - SIFS = 10us
>> > >>
>> > >> Ramon.
>> > >>
>> >
>>
>>
>