[Ns-developers] 802.11 10Mhz Channel
Pei, Guangyu
Guangyu.Pei at boeing.com
Mon Jul 13 13:58:32 PDT 2009
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.
>
> 2009/7/13 Mathieu Lacage <mathieu.lacage at sophia.inria.fr>
>
> > hi,
> >
> > The patch overall looks good. A couple of comments:
> >
> > 1) it feels like you could move the
> WifiMacHelper::Configure* methods
> > to the WifiMac base class (that way, you could access
> > WifiMac::GetDefaultMaxPropagationDelay directly)
> > 2) maybe you could add a Standard attribute to WifiMac which is
> > similar to the YansWifiPhy::Standard attribute and does the
> same thing
> > as YansWifiPhy::SetStandard
> > 3) maybe also add a Configure80211a and Configure80211b to WifiMac.
> > Erm, I just realized that we currently have no set of 802.11b MAC
> > parameters for the 802.11b PHY contributed by gary. If you can't
> > bother with finding the right values in the spec, just add an empty
> > Configure80211b method and we will fill them in later.
> >
> > Mathieu
> >
> >
> >
> > On Thu, 2009-07-09 at 19:23 +0200, Ramon Bauza wrote:
> > > Hello,
> > >
> > > I would like to submit for code review the attached patch
> > > implementing
> > half
> > > and quarter-clocked Wifi operation using 5 and 10 Mhz
> channels spacing.
> > We
> > > would be glad to merge this new functionality in the main
> branch if
> > > ns-3 developers think it may be interesting for other people. The
> > > following
> > files
> > > have been modified (ns-3-dev):
> > >
> > > src/devices/wifi/interference-helper.cc
> > > src/devices/wifi/interference-helper.h
> > > src/devices/wifi/wifi-phy.cc
> > > src/devices/wifi/wifi-phy.h
> > > src/devices/wifi/wifi-phy-standard.h
> > > src/devices/wifi/yans-error-rate-model.cc
> > > src/devices/wifi/yans-wifi-phy.cc
> > > src/devices/wifi/yans-wifi-phy.h
> > > src/helper/nqos-wifi-mac-helper.cc
> > > src/helper/nqos-wifi-mac-helper.h
> > > src/helper/qos-wifi-mac-helper.cc
> > > src/helper/qos-wifi-mac-helper.h
> > > src/helper/wifi-helper.cc
> > > src/helper/wifi-helper.h
> > >
> > > Apart from the modifications pointed out in the previous email
> > > posted
> > some
> > > weeks ago, we have also modified some of the wifi
> helpers. In order
> > > not
> > to
> > > make the user set weird values for the MAC parameters (slot,sifs,
> > > etc)
> > from
> > > the script, we have modified the WifiMacHelper
> incorporating two new
> > > functions (Configure80211_10MhzParameters and
> > Configure80211_5MhzParameters)
> > > that allows the user to automatically select the default MAC
> > > parameters
> > for
> > > 5Mhz and 10Mhz channel spacing (we have also moved the function
> > > SetType
> > and
> > > the ObjectFactory m_mac from NqosWifiMacHelper and
> QosWifiMacHelper
> > > to WifiMacHelper).
> > >
> > > Looking forward to your comments.
> > >
> > > Best regards,
> > > Ramon Bauza.
> > >
> > > 2009/5/29 Ramon Bauza <monbauza at gmail.com>
> > >
> > > > Hello everyone,
> > > >
> > > > I am Ramon Bauza, a researcher at Miguel Hernandez
> University (Spain).
> > > > Currently, I am involved in the EU FP7 project iTETRIS
> which aims
> > > > at creating an integrated traffic and wireless
> simulation platform
> > > > that
> > will
> > > > allow evaluating traffic management strategies and communication
> > protocols
> > > > in vehicular environments. The iTETRIS project employs SUMO and
> > > > ns-3 as traffic simulation and wireless simulation
> platforms respectively.
> > > >
> > > > Our research group at UMH, it is charge of implementing the
> > > > 802.11p
> > (WAVE)
> > > > standard in ns-3. 802.11p is based on 802.11a, being the channel
> > bandwidth
> > > > and thus also the data rates the main differences between both
> > > > (802.11p
> > uses
> > > > a 10Mhz whereas 802.11a uses 20Mhz). After implementing
> 802.11p in
> > ns-3, we
> > > > will also look into and implement propagation models
> for vehicular
> > > > environments that consider LOS/NLOS visibility conditions,
> > > > vehicle-to-vehicle and vehicle-to-infraestructure
> communications,
> > > > and shadowing and multipath fading effects.
> > > >
> > > > In order to model a 10Mhz channel in ns-3, some
> > > > additions/modifications should be done (some weeks ago
> I posted a
> > > > message in the user mailing
> > list
> > > > regarding this
> > > >
> >
> http://groups.google.com/group/ns-3-users/browse_thread/thread/f27b1dd
> > cf9f1d532#
> > ).
> > > > Apart from 802.11p, I think other 802.11 standards employ 10MHz
> > channels and
> > > > thus probably the modeling of 10Mhz channels would also
> be useful
> > > > for
> > the
> > > > ns-3 community working on 802.11-related topics. In
> fact, the IEEE
> > > > Std
> > > > 802.11TM-2007 standard considers 10Mhz channel spacing
> using OFDM.
> > > > If
> > you
> > > > consider that the modeling of 10Mhz channels may be
> beneficial for
> > other
> > > > users we would be glad to merge the 10Mhz modeling in
> the main branch.
> > > >
> > > > Below, I compile the needed functions and modifications
> we plan to
> > > > introduce in ns-3 at the PHY layer for modeling a 10Mhz channel:
> > > >
> > > > + wifi-phy-standard.h
> > > >
> > > > Add WIFI_PHY_STANDARD_80211_10Mhz in the enum WifiPhyStandard
> > > >
> > > > + wifi-phy.h and wifi-phy.cc
> > > >
> > > > Declare and define the following new functions:
> > > >
> > > > static WifiMode Get3mb10Mhz (void);
> > > > static WifiMode Get4_5mb10Mhz (void);
> > > > static WifiMode Get6mb10Mhz (void);
> > > > static WifiMode Get9mb10Mhz (void);
> > > > static WifiMode Get12mb10Mhz (void);
> > > > static WifiMode Get18mb10Mhz (void);
> > > > static WifiMode Get24mb10Mhz (void);
> > > > static WifiMode Get27mb10Mhz (void);
> > > >
> > > > + yans-wifi-phy.h and yans-wifi-phy.cc
> > > >
> > > > Declare and define the void Configure80211_10Mhz
> (void) function.
> > > > Modify the void SetStandard (enum WifiPhyStandard standard)
> > > > function
> > so
> > > > that the user can also select a 10Mhz channel.
> > > >
> > > > + interference-helper.h and interference-helper.cc
> > > >
> > > > Declare and define void Configure80211_10MhzParameters (void);
> > > >
> > > > One function that should be modified is
> > > > InterferenceHelper::CalculateTxDuration (uint32_t size,
> WifiMode
> > > > payloadMode, WifiPreamble preamble) const since it assumes that
> > > > the
> > symbol
> > > > duration is always 4us (20 Mhz channel). This function should
> > > > employ a symbol duration according to the channel used
> (10Mhz or
> > > > 20Mhz). One
> > possible
> > > > solution to solve this would be to have a new variable in the
> > > > class InterferenceHelper which allows differentiating
> the channel
> > > > used. This variable could be of type WifiPhyStandard. In the
> > > > function Time InterferenceHelper::CalculateTxDuration, this new
> > > > variable would be
> > examined
> > > > and the packet txon duration will be calculated based on the
> > > > bandwidth channel.
> > > >
> > > > Please, I would like to have your comments on this in order to
> > > > proceed
> > with
> > > > the implementation.
> > > >
> > > > Thank you in advance.
> > > > Best regards,
> > > > Ramon.
> > > >
> > > >
> >
> ----------------------------------------------------------------------
> > ----
> > > > Ramon Bauza
> > > > Ubiquitous Wireless Communications Research Laboratory Uwicore,
> > > > http://www.uwicore.umh.es Signal Theory and Communications
> > > > Division University Miguel Hernández (Spain)
> > > > Tel: +34 96522 2031
> > > > Fax: +34 96665 8903
> > > >
> > > >
> >
> ----------------------------------------------------------------------
> > ------
> > > >
> >
> >
>
>
> --
> --------------------------------------------------------------
> ------------
> Ramon Bauza
> Ubiquitous Wireless Communications Research Laboratory
> Uwicore, http://www.uwicore.umh.es Signal Theory and
> Communications Division University Miguel Hernández (Spain)
> Tel: +34 96522 2031
> Fax: +34 96665 8903
> --------------------------------------------------------------
> --------------
>
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