[Discuss-gnuradio] RTT time of ping based on OFDM tunnel

[Alex Zhang]

Hi all,

I did some experiments of Ping, between two USRP N210 nodes, over the OFDM link. I need to know if any other has the same performance as I did.

This OFDM link is using two frequencies,  900MHz and 1800MHz, as the SBX daughter board is used. The antenna is VERT900 which is working in  824 to 960 MHz, 1710 to 1990 MHz Quad-band .

Two computers of intel i7 (4 cores @3.4GHz) are used to run gnuradio.  

My performance is that as below:

Static ARP entries are used for both the computer. Tunnel devices are setup receptively to run ping on it.

Bandwidth = 500K, occ=400/512, average RTT time is 14ms, and packet loss of ping is 17%

Bandwidth = 1M, occ = 400/512, average RTT time is 8ms, and packet loss of ping 33%

Bandwidth = 1.2M, occ = 400/512, average RTT time is 7ms, but packte loss of ping is degraded to >90%, means the PC can not support such kind bandwidth.

If I use two intel core 2 PC, the supported bandwidth with acceptable paccket loss rate (35%) is a little higher than 500K (RTT = 20ms). With more bandwidth, the computer would be slow down significantly and the link quality is near crash.

So I need to know if any other friend have tested such experiment and what the corresponding performance is.

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Alex,

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