Re: 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@...>
>         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@...>
>         >
>         > > 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/f27b1ddcf9f1d532#).
>         > > 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
> ----------------------------------------------------------------------------