802.11b

[cb]

hello all,
I'm trying to use the 802.11b as phy instead of the default 802.11a in
an infrastructured wireless network. in order to do that, I just call
YansWifiPhyHelper::SetStandard("Standard", StringValue("802.11b")) on
the relevant object.

unfortunately, nothing appears to work at all. looking at the pcap
traces, associations to the AP are very problematic and with lots of
retransmissions (though associations are at last successful), and
packets are not delivered at all, since nobody answers the ARP
requests of the sending node. I found the same behavior in my own code
and in the third.cc example as well (once 802.11b is set up).

any clues on why this happens? I couldn't find any. if that can help,
here is how NqstaWifiMac in third.cc reacts with 802.11a:



2s [mac=00:00:00:00:00:09] NqstaWifiMac:Enqueue(0x807ea30, 0x808c390,
ff:ff:ff:ff:ff:ff)
Sent 1024 bytes to 10.1.2.4
2.00032s [mac=00:00:00:00:00:07] NqstaWifiMac:Receive(0x806c148,
0x808c408, 0xbf9458c0)
2.00032s [mac=00:00:00:00:00:07] NqstaWifiMac:ForwardUp(0x806c148,
0x808c408, 00:00:00:00:00:09, ff:ff:ff:ff:ff:ff)
2.00032s [mac=00:00:00:00:00:08] NqstaWifiMac:Receive(0x807dee0,
0x8089b18, 0xbf9458c0)
2.00032s [mac=00:00:00:00:00:08] NqstaWifiMac:ForwardUp(0x807dee0,
0x8089b18, 00:00:00:00:00:09, ff:ff:ff:ff:ff:ff)
2.00032s [mac=00:00:00:00:00:09] NqstaWifiMac:Receive(0x807ea30,
0x808c7c8, 0xbf9458c0)
2.00032s [mac=00:00:00:00:00:09] packet sent by us.
2.0006s [mac=00:00:00:00:00:09] NqstaWifiMac:Receive(0x807ea30,
0x808c390, 0xbf9458c0)
2.0006s [mac=00:00:00:00:00:09] NqstaWifiMac:ForwardUp(0x807ea30,
0x808c390, 00:00:00:00:00:0a, 00:00:00:00:00:09)
2.0006s [mac=00:00:00:00:00:09] NqstaWifiMac:Enqueue(0x807ea30,
0x808b940, 00:00:00:00:00:0a)
Received 1024 bytes from 10.1.3.3
... and so on ...



and this is how it works with 802.11b:

2s [mac=00:00:00:00:00:09] NqstaWifiMac:Enqueue(0x807ea20, 0x808b878,
ff:ff:ff:ff:ff:ff)
Sent 1024 bytes to 10.1.2.4
2.50065s [mac=00:00:00:00:00:08] NqstaWifiMac:Receive(0x807dee0,
0x808b8d8, 0xbf9dc960)
2.50065s [mac=00:00:00:00:00:08] NqstaWifiMac:RestartBeaconWatchdog
(0x807dee0, 24995840000ns)
2.50065s [mac=00:00:00:00:00:08] NqstaWifiMac:SetBssid(0x807dee0,
00:00:00:00:00:0a)
2.50065s [mac=00:00:00:00:00:07] NqstaWifiMac:Receive(0x806c1a8,
0x808a128, 0xbf9dc960)
2.50065s [mac=00:00:00:00:00:07] NqstaWifiMac:RestartBeaconWatchdog
(0x806c1a8, 24995840000ns)
2.50065s [mac=00:00:00:00:00:07] NqstaWifiMac:SetBssid(0x806c1a8,
00:00:00:00:00:0a)
2.50065s [mac=00:00:00:00:00:09] NqstaWifiMac:Receive(0x807ea20,
0x808d768, 0xbf9dc960)
2.50065s [mac=00:00:00:00:00:09] NqstaWifiMac:RestartBeaconWatchdog
(0x807ea20, 24995840000ns)
2.50065s [mac=00:00:00:00:00:09] NqstaWifiMac:SetBssid(0x807ea20,
00:00:00:00:00:0a)
... and so on ...



thanks for any suggestion you may have.

[Nicola Baldo]

Hi,

On Aug 5, 4:39 am, cb <cbellett...@gmail.com> wrote:
> hello all,
> I'm trying to use the 802.11b as phy instead of the default 802.11a in
> an infrastructured wireless network. in order to do that, I just call
> YansWifiPhyHelper::SetStandard("Standard", StringValue("802.11b")) on
> the relevant object.
>
> unfortunately, nothing appears to work at all. looking at the pcap
> traces, associations to the AP are very problematic and with lots of
> retransmissions (though associations are at last successful), and
> packets are not delivered at all, since nobody answers the ARP
> requests of the sending node. I found the same behavior in my own code
> and in the third.cc example as well (once 802.11b is set up).
>
> any clues on why this happens? I couldn't find any.

I don't have the code at hand to check this, but I remember that some
time ago I faced a similar problem when modifying a simulation program
to make it run with 802.11b instead of 802.11a. The issue was that the
SetStandard command did not change the value for the ACK timeout
(which should be longer in 802.11b), and STA association failed
because of this. Well, I guess I should have filed a bug report for
this issue, but at the time the only 802.11b example program in ns3
was not working, so I ended up filing bug 642 instead (http://
www.nsnam.org/bugzilla/show_bug.cgi?id=642).
Since that bug was closed, if you could check whether examples/wifi-
clear-channel-cmu exhibits the same problem you are experiencing, and
post a bug report if positive, it would be great.

Regards,

Nicola

[Tom Henderson]

I filed a bug on this issue:
http://www.nsnam.org/bugzilla/show_bug.cgi?id=655

The answer may not be a trivial fix since this attribute is trying to
set the values of other attributes.

Tom

[Gary Pei]

I took a look at the third.cc example for 802.11b. The problem is that
you have to set 802.11b standard for MAC as well to call correct
WifiMac::SetStandard (enum WifiPhyStandard standard) function.

So, here is correct way to use 802.11b for third.cc

87d86
< phy.Set ("Standard", StringValue ("802.11b") );
97,98c96
< "ActiveProbing", BooleanValue (false),
< "Standard", StringValue ("802.11b"));
---
> "ActiveProbing", BooleanValue (false));
106,107c104
< "BeaconInterval", TimeValue (Seconds (2.5)),
< "Standard", StringValue ("802.11b"));

Gary

[Michael]

Does this work with the latest dev release? I get errors about "Could
not find attribute ns3::YansWifiPhy::Standard."

Thanks!
Michael

On Aug 12, 7:50 pm, Gary Pei <guangyu....@boeing.com> wrote:
> I took a look at thethird.cc example for 802.11b. The problem is that

> > >> and in thethird.cc example as well (once 802.11b is set up).

>
> > >> any clues on why this happens? I couldn't find any.
>
> > > I don't have the code at hand to check this, but I remember that some
> > > time ago I faced a similar problem when modifying a simulation program
> > > to make it run with 802.11b instead of 802.11a. The issue was that the
> > > SetStandard command did not change the value for the ACK timeout
> > > (which should be longer in 802.11b), and STA association failed
> > > because of this. Well, I guess I should have filed a bug report for
> > > this issue, but at the time the only 802.11b example program in ns3
> > > was not working, so I ended up filing bug 642 instead (http://
> > >www.nsnam.org/bugzilla/show_bug.cgi?id=642).
> > > Since that bug was closed, if you could check whether examples/wifi-
> > > clear-channel-cmu exhibits the same problem you are experiencing, and
> > > post a bug report if positive, it would be great.
>
> > I filed a bug on this issue:http://www.nsnam.org/bugzilla/show_bug.cgi?id=655
>
> > The answer may not be a trivial fix since this attribute is trying to
> > set the values of other attributes.
>

> > Tom- Hide quoted text -
>
> - Show quoted text -

[Mathieu Lacage]

in ns-3-dev, you need to do this:

WifiHelper wifi;
...
wifi.SetStandard (WIFI_PHY_STANDARD_80211b);

Mathieu