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#1 2017-Jul-10 21:29:59

wckim
Member
Registered: 2017-Apr-04
Posts: 14

CTS frame generated by WARP AP

Hello, all
I received a lot of help from your previous answers.
Thank you.

These days, I'm trying to capture 'the CTS frame generated by WARP AP' or 'the CTS frame toward WARP AP' with Wireshark. And I'm using Mango_802.11_RefDes_v1.6.2 version.

But when I captured normal WARP AP's packets ('gl_dot11RTSThreshold = 2000' in 'wlan_mac_dcf.c') using Wireshark, I could not capture any CTS frames from WARP AP.

So I changed the value of gl_dot11RTSThreshold from 2000 to 500, but the AP will not be able to provide the Internet.

In these case, I have two questions.

First, How do I generate a CTS frame on a WARP AP?
Second, Why am I not able to connect to the Internet if I change the 'gl_dot11RTSThreshold' variable of the WARP AP from 2000 to 500, 800, or 1000?

Thank you.

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#2 2017-Jul-11 09:54:32

chunter
Administrator
From: Mango Communications
Registered: 2006-Aug-24
Posts: 1192

Re: CTS frame generated by WARP AP

What is the client STA in this test? The WARP AP will always generate a CTS frame in response to receiving an RTS frame, regardless of the WARP AP's setting of gl_dot11RTSThreshold. So, you need to get your client STA to send an RTS to the WARP AP. If the STA is another WARP node running our 802.11 Reference Design, you can lower its gl_dot11RTSTrheshold. If the client STA is a commercial 802.11 device, you might be able to lower its RTS threshold.

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#3 2017-Jul-12 21:12:50

wckim
Member
Registered: 2017-Apr-04
Posts: 14

Re: CTS frame generated by WARP AP

Sorry, my question was not enough.

This is a question related to the problem that RTS and CTS do not generate when using normal WARP AP and laptop STA.

When gl_dot11RTSTrheshold of WARP AP is 2000, there is no problem with internet connection, but RTS / CTS can not be captured.
So I lowered the gl_dot11RTSTrheshold of WARP AP to 500, 800, 1000 to capture RTS and CTS of WARP AP and laptop STA.
And then the internet was not connected, RTS / CTS can not be captured.
(The CTS of other AP(Not WARP) and laptop STA is well captured.)

So my question is:

First, How do I generate a RTS/CTS frame of a WARP AP and laptop STA.
Second, Why am I not able to connect to the Internet if I change the 'gl_dot11RTSThreshold' variable of the WARP AP from 2000 to 500, 800, or 1000?

Thanks.

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#4 2017-Jul-13 11:34:35

chunter
Administrator
From: Mango Communications
Registered: 2006-Aug-24
Posts: 1192

Re: CTS frame generated by WARP AP

I've just recreated your issue. This is a bug -- RTS generation appears to be broken when the underlying MPDU is an HTMF waveform (802.11n). Since we use HTMF by default, this is why you aren't able to connect to the internet when you lower gl_dot11RTSThreshold. As a short term fix, I'd suggest dropping to NONHT (802.11a/g) rates while I work up a software fix to re-establish support for HTMF with RTS/CTS. To do this, you can either modify the C code to change this line from a 1 to a 0. Or, if you are using stock bitstreams and not modifying the C, you can make the change via wlan_exp with the ht_capable argument with the AP's configure_bss method. Once I have a software fix, I'll respond to this post with the patch you can apply to your code before we get a 1.7.1 release of the design posted. Sorry for the trouble; I'll get the fix completed ASAP.

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#5 2017-Jul-14 13:40:02

chunter
Administrator
From: Mango Communications
Registered: 2006-Aug-24
Posts: 1192

Re: CTS frame generated by WARP AP

I've made the full fix in this changeset.  If you are using the 1.7.0 design, I think you should be able to just replace your wlan_mac_dcf.c with this one and adopt the fix.

We'll get this incorporated into a 1.7.1 release early next week. Thanks for finding the bug and sorry again for any trouble it caused.

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#6 2017-Jul-16 20:31:47

wckim
Member
Registered: 2017-Apr-04
Posts: 14

Re: CTS frame generated by WARP AP

Many thanks for your reply.

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