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Knowledge Base

Determination and avoidance radar signal trigger AP6510DN V200R005 DFS mechanism

Publication Date:  2019-07-10  |   Views:  398  |   Downloads:  4  |   Author:  SU1001046399  |   Document ID:  EKB1000064348

Contents

Issue Description

The scene with S12708 equipped with plate AC as controller, AP6510DN is equipped with a narrow beam directional antenna to realize high-density coverage. AC and AP are using the V200R005 version, layer-3 networking, tunnel mode forwarding, fixed channel and power. Check the actual channel before configure.

<MER-HW1-CoreSW-1>dis actual channel-power ap 314 r 1
  --------------------------------------------------------
   RADIO  CHANNEL POWER-LEVEL POWER(dBm) CHANNEL-BANDWIDTH
  --------------------------------------------------------
   314/1  124     10          13         20MHz
  --------------------------------------------------------
<MER-HW1-CoreSW-1>dis actual channel-power ap 315 r 1
  --------------------------------------------------------
   RADIO  CHANNEL POWER-LEVEL POWER(dBm) CHANNEL-BANDWIDTH
  --------------------------------------------------------
   315/1  124     10          13         20MHz
  --------------------------------------------------------
<MER-HW1-CoreSW-1>dis actual channel-power ap 316 r 1
  --------------------------------------------------------
   RADIO  CHANNEL POWER-LEVEL POWER(dBm) CHANNEL-BANDWIDTH
  --------------------------------------------------------
   316/1  140     10          13         20MHz
  --------------------------------------------------------

Which is different from configuration,

[MER-HW1-CoreSW-1-wlan-radio-314/1]dis th
#
  radio-profile id 2
  channel 20MHz 124
  power-level 10
  service-set id 202 wlan 1
  service-set id 2 wlan 2
#
return
[MER-HW1-CoreSW-1-wlan-radio-315/1]dis th
#
  radio-profile id 2
  channel 20MHz 128
  power-level 10
  service-set id 202 wlan 1
  service-set id 2 wlan 2
#
return
[MER-HW1-CoreSW-1-wlan-radio-316/1]dis th
#
radio-profile id 2
  channel 20MHz 132
  power-level 10
  service-set id 202 wlan 1
  service-set id 2 wlan 2
#
Return

Commit the configuration,

[MER-HW1-CoreSW-1-wlan-view]commit ap 314
Warning: Committing configuration may cause service interruption, continue?

[Y/N]:y
[MER-HW1-CoreSW-1-wlan-view]commit ap 315
Warning: Committing configuration may cause service interruption, continue?

[Y/N]:y
[MER-HW1-CoreSW-1-wlan-view]commit ap 316
Warning: Committing configuration may cause service interruption, continue?

[Y/N]:y

Then check the real time channel again,

[MER-HW1-CoreSW-1-wlan-view]dis actual channel-power ap 314 r 1
  --------------------------------------------------------
   RADIO  CHANNEL POWER-LEVEL POWER(dBm) CHANNEL-BANDWIDTH
--------------------------------------------------------
   314/1  124     10          13         20MHz
  --------------------------------------------------------
[MER-HW1-CoreSW-1-wlan-view]dis actual channel-power ap 315 r 1
  --------------------------------------------------------
   RADIO  CHANNEL POWER-LEVEL POWER(dBm) CHANNEL-BANDWIDTH
  --------------------------------------------------------
   315/1  124     10          13         20MHz
  --------------------------------------------------------
[MER-HW1-CoreSW-1-wlan-view]dis actual channel-power ap 316 r 1
  --------------------------------------------------------
   RADIO  CHANNEL POWER-LEVEL POWER(dBm) CHANNEL-BANDWIDTH
  --------------------------------------------------------
   316/1  140     10          13         20MHz
  --------------------------------------------------------

Doesn't work, restart the AP still abnormal, RF files have been already set to fix channel / power

[MER-HW1-CoreSW-1-wlan-radio-prof-2.4G]dis th
#
  channel-mode fixed
  power-mode fixed
  wmm-profile id 1
#
return
[MER-HW1-CoreSW-1-wlan-radio-prof-5G]dis th
#
  channel-mode fixed
  power-mode fixed
  wmm-profile id 2
#
return

Alarm Information

R&D analysis found the channel setting commit successful, radar signal trigger DFS mechanism, here is the log:

#Sep 22 2014 21:39:45 MER-HW1-CoreSW-1

WLAN/4/RADIO_CHANNEL_CHANGE_NOTIFY:OID 1.3.6.1.4.1.2011.6.139.3.24.1.1

Channel of radio is changed. (APID=315, APID=315, RadioID=1, Channel=124,

APMAC=[xx.xx.xx.xx.ad.40 (hex)], CauseId=2, CauseStr=In DFS, PreChannel=128)
#Sep 22 2014 21:39:47 MER-HW1-CoreSW-1

WLAN/4/RADIO_CHANNEL_CHANGE_NOTIFY:OID 1.3.6.1.4.1.2011.6.139.3.24.1.1

Channel of radio is changed. (APID=316, APID=316, RadioID=1, Channel=140,

APMAC=[xx.xx.xx.xx.af.00 (hex)], CauseId=2, CauseStr=In DFS, PreChannel=132)

Handling Process

After recognizing the problem, delivery team observed the radar signal on field, and avoid the radar channel in the network planning. After this change, no more channel switching.

Root Cause

DFS,Dynamic Frequency Selection is a kind of channel switching mechanism in order to avoid the influence on the radar and other public security radio signal, it's also the basic condition fot WLAN products pass the CE certification, which is the chip level algorithm, has higher priority than the configuration and software version. Deploying WLAN projects in the European Union, part of the outdoor AP 5G channels may conflict with local radar signal, trigger mechanism of DFS, the channel is forced to switch, inconsistent with the network planning, which brings a series of problems such as the same frequency interference.

Solution

In addition to find problems in high density WLAN scene, HUAWEI engineers also found such situation in some partner-deliver project , the case with auto channel adaptive, which is more covert. With the advice of HUAWEI engineer , partner engineer analysised the signal environment, and limit the options of auto channel adaptive.

Suggestions

DFS is very common in the EU and other developed countries, therefore according to the signal environment area, built optional channel list and make it a part of the network planning training can avoid such problems happening again.