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#1 2010-Jul-20 08:52:04

heming_mcgill
Member
From: McGill University, Montreal
Registered: 2010-Jun-07
Posts: 46

Buffer overflow detection

Hi,

I was wondering about the specifications for the buffers on the OFDM board... For instance, I suppose we have Ethernet buffers, but do we have any other buffers on the board that will be used during a TX or RX operation?

I was trying to send some encoded live video streaming between two OFDM WARP board running csmaMAC. I observed that large packets bursts of short duration and high intensity were sent to the board performing TX. However, on the receiving side, these packets are mostly lost or trimmed. For the same average bitrate but with more distributed packet transmission (not intense bursts), the transmission works fine and few packets are lost. The test were done for QPSK and 16-QAM.

So I suspect one of the buffers must be overflown. Is there any way to bring out some flag status signal to observe if my suspicions are correct?

Thank you,

heming

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#2 2010-Jul-20 10:17:09

murphpo
Administrator
From: Mango Communications
Registered: 2006-Jul-03
Posts: 5159

Re: Buffer overflow detection

The radio board has no buffers; its interface is raw I/Q plus real-time control. The packet loss you're seeing is most likely at the Ethernet MAC. In the latest OFDM reference design, the TEMAC has a small (enough for 4 full-MTU packets, I think) Rx FIFO. And the design only unloads packets as they're sent over the air.

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#3 2010-Jul-20 11:05:29

heming_mcgill
Member
From: McGill University, Montreal
Registered: 2010-Jun-07
Posts: 46

Re: Buffer overflow detection

Thank!

I'll access the TEMAC interrupt status registers to find out.

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