<div dir="ltr"><br clear="all"><div><div style="font-size:12.8000001907349px">I verified the ACS(Auto Channel Select) in 2.4GHz environment.</div><div style="font-size:12.8000001907349px">Set 2 APs, one is ch.1 and one is ch.11, and then transmit a heavy traffic at each channel.</div><div style="font-size:12.8000001907349px">I'm expecting ACS should choose ch.6 for ideal channel, but it always choose ch.1 or ch.11 in any case.</div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap"><br></span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap">The hostapd debug log shows each interference factor(5 times average) is below.</span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap"> 1=0.420</span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap"> 2=0.764</span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap"> 3=0.743</span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap"> 4=0.729</span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap"> 5=0.366</span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap"> 6=0.158</span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap"> 7=0.404</span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap"> 8=0.613</span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap"> 9=0.601</span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap">10=0.585</span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap">11=0.630</span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap"><br></span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap">It works fine. ACS seems to be able to calculate the interference factor correctly. The value of ch.6 indicates the lowest.</span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap">However, acs.c tries to add adjacent channel's value. Thus eventually, those values go like as following.</span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap"> 1=1.928 (1+2+3)</span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap"> 2=2.658 (1+2+3+4)</span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap"> 3=3.024 (1+2+3+4+5)</span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap"> 4=2.762 (2+3+4+5+6)</span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap"> 5=2.402 (3+4+5+6+7)</span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap"> 6=2.272 (4+5+6+7+8)</span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap"> 7=2.143</span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap"> 8=2.362</span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap"> 9=2.834</span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap">10=2.429</span></div><div style="font-size:12.8000001907349px"><span style="color:rgb(0,0,0);font-size:11.7259998321533px;white-space:pre-wrap">11=1.816</span></div><div style="font-size:12.8000001907349px"><br></div><div style="font-size:12.8000001907349px">I tried this test couple of times, but I can see the ideal channel was always selected to ch.1 or ch.11.</div><div style="font-size:12.8000001907349px">I think it's not necessary to add adjacent value. Because radio survey data of each channel would detect the adjacent interference actually 20MHz.</div><div style="font-size:12.8000001907349px">In fact, the test result shows that ch.4 detect the interference of ch.1, similarly ch.8 detect the interference of ch.11.</div><div style="font-size:12.8000001907349px">I attached a patch file for hostapd-v2.3 .</div><div style="font-size:12.8000001907349px"><br></div><div style="font-size:12.8000001907349px">Thanks,</div><div style="font-size:12.8000001907349px">Yobi </div></div><div class="gmail_signature"><div dir="ltr">============================<div>Fumikazu Yobimoto</div></div></div>
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