OMAP Wireless Connectivity AP Performance Measurement

Introduction

We would like to measure the performance of the wireless traffic when several stations are connected to the same AP.
The following figure shows the setup needed.

Preparations

In order to do this test, we need to configure the EVM wireless to be in AP mode. For assistance use the link <WLAN AP basic use-cases>.
Once the EVM is configured to AP, we need to connect the WLAN stations to the AP.
The stations will act as servers while all clients will reside on the EVM.
We need to start the Ipref server on all of the stations. For more information about the Iperf and NetPerf options, please use the link <Performance measurement setup>.
Assuming we would like to test the TCP upstream to several stations, if we are using Iperf, on each station we must invoke:

iperf.exe -s -i2

On the client side, we need to run the clients one after another so we will invoke them as daemons. For example:
using Iperf:

iperf -c 192.168.1.110 -t20 -i2 -w64k -p5001 &

using NetPerf:

netperf -H 192.168.1.110 -D 2 -l 10 -t TCP_STREAM -f m -- -m 1472 -s64k -S64k

We will wait for few seconds then invoke the second one:
using Iperf:

iperf -c 192.168.1.111 -t20 -i2 -w64k -p5001 &

using NetPerf:

netperf -H 192.168.1.111 -D 2 -l 10 -t TCP_STREAM -f m -- -m 1472 -s64k -S64k

Where the IP addresses (192.168.1.110 and 192.168.1.111) are the IP addresses of the different stations with the Iperf server on.
Once you done that you will be able to see the bandwidth of each client-server connection.
The output of Iperf, for example, would be similar to the following:

root@am180x-evm:~# iperf -c 192.168.0.20 -t20 -i2 -w64k --port 5001 &
------------------------------------------------------------
Client connecting to 192.168.0.20, TCP port 5001
TCP window size:   128 KByte (WARNING: requested 64.0 KByte)
------------------------------------------------------------
[  3] local 192.168.0.1 port 56651 connected with 192.168.0.20 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0- 2.0 sec  2.23 MBytes  9.34 Mbits/sec
[  3]  2.0- 4.0 sec  2.38 MBytes  9.96 Mbits/sec
[  3]  4.0- 6.0 sec  1.55 MBytes  6.49 Mbits/sec
root@am180x-evm:~# iperf -c 192.168.0.21 -t20 -i2 -w64k --port 5001 &
------------------------------------------------------------
Client connecting to 192.168.0.21, TCP port 5001
TCP window size:   128 KByte (WARNING: requested 64.0 KByte)
------------------------------------------------------------
[  3] local 192.168.0.1 port 39963 connected with 192.168.0.21 port 5001
[  3]  6.0- 8.0 sec  2.08 MBytes  8.72 Mbits/sec
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0- 2.0 sec  1.14 MBytes  4.78 Mbits/sec
[  3]  8.0-10.0 sec  1.53 MBytes  6.42 Mbits/sec
[  3]  2.0- 4.0 sec  1.51 MBytes  6.32 Mbits/sec
[  3] 10.0-12.0 sec   808 KBytes  3.31 Mbits/sec
[  3]  4.0- 6.0 sec  1.21 MBytes  5.08 Mbits/sec

Analyzing the results

If we look at the result above, we can see that the throughput in the first three lines is around 9 Mbits/sec. This is the throughput when we activated station 1 which its IP address is 192.168.0.20.
When activating the second station which its IP address is 192.168.0.21, we can see that the throughput dropped to almost half. This is of course because the traffic is divided between the two stations.

HOME