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#1 2016-Feb-22 09:42:24

hany
Member
Registered: 2016-Feb-22
Posts: 3

Frame Aggregation for 802.11 Reference Design

Hello,

Regarding the reference design for 802.11, do you implement any frame aggregation mechanism like A-MSDU and A-MPDU and if not? do you have any plan to implement them?

Thanks.

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#2 2016-Feb-22 11:37:48

chunter
Administrator
From: Mango Communications
Registered: 2006-Aug-24
Posts: 1212

Re: Frame Aggregation for 802.11 Reference Design

We don't currently support any kind of frame aggregation, but it's something we'd like to build in the future. The next release of the design (1.5) will include 802.11n SISO Tx and Rx support, but no aggregation just yet.

If you don't mind, could you share how your research interests would be helped by aggregation being supported? There is always a long list of things to build into the design and having feedback from users on requested features helps us prioritize which projects to tackle next.

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#3 2016-Mar-02 12:11:50

hany
Member
Registered: 2016-Feb-22
Posts: 3

Re: Frame Aggregation for 802.11 Reference Design

Thanks for the reply. Regarding my research interest currently I am looking into incorporating a cross layer solution to optimize wireless networks performance. The cross layer solution would be to modify the contention process + aggregated frame length based on the traffic pattern. Most of the work done in this domain is either simulation or pure mathematical analysis. I am looking for a suitable hardware to test my results where I can have an access to the Wifi EDCA/DCF functionality. In my institute, we already have two WARPv3. However, from what I found in the documentation you only built DCF function and the maximum throughput is around 30Mbps which you can get in legacy Wifi without any frame aggregation.

One question, if I want to add the frame aggregation capability to the current reference design, do I have to do any modification to the FPGA? As far as I know, A-MSDU aggregation is done in software in Normal Wifi cards and in your case it should be done in CPU high module only.

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#4 2016-Mar-02 15:59:20

chunter
Administrator
From: Mango Communications
Registered: 2006-Aug-24
Posts: 1212

Re: Frame Aggregation for 802.11 Reference Design

I believe that A-MSDU encapsulation could be done in CPU_HIGH as a modification to the existing encapsulation and Tx queueing operations. From the perspective of CPU_LOW and the PHY itself, it would just look like a long data packet. The caveat is that you still have to work within the limits of the maximum packet lengths supported by the underlying design. The packet buffers are 4kB, but some of that is taken up back frame_info structs that store metadata about the transmission or reception. Realistically its closer to 3kB of usable space. By default, transmissions and receptions are soft-limited to 2kB with these lines of code in wlan_phy_util.c. This forum thread provides an in-depth discussion on the changes required to increase beyond these limits.

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