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AP8030(V2R6) station access Failure in Some Areas

Publication Date:  2016-12-31 Views:  111 Downloads:  0
Issue Description

Customer feedback that during a match, STAs of wifi 2.4 GHz in some areas could not connect to the WLAN or the service traffic was low, while all 5 GHz STAs were working properly. When no match is held, STAs in all areas can properly connect to the WLAN.
The following figure shows test points Suite-E-1 and Suite-E-2:

The following table lists test data during a match and during non-match days.

 

Area

One Day Before the Match

2.4 GHz Throughput (Mbit/s)

2 Hours Before the Match

2.4 GHz Throughput (Mbit/s)

Suite-E-1

13.78

12.12

1.66

1.18

Suite-E-2

21.78

15.88

1.3

1.63

At 2 hours before the match, 2.4 GHz STAs could hardly connect to the WLAN, and some APs had only five or six users associated.
By analyzing logs, it was found that severe interference existed on 2.4 GHz channels. The interference source, however, could not be determined.
The test on the match was intended to find out the interference source and provide a Wi-Fi optimization solution.

 

Handling Process

When a match was held, the WLAN was monitored and analyzed using tools such as mobile phones with Speedtest installed and the professional Fluke Wi-Fi tester.Test tools below:
Speedtest: used to test the radio link throughput, indicating WLAN performance.
Fluke Wi-Fi Tester: a professional wireless spectrum scanning tool, which can display the channel usage (Wi-Fi/non-Wi-Fi), indicating interference on each channel. The higher channel usage indicates a shorter distance from the interference source.

1.Monitor the 2.4 GHz throughput at 4 hours before, 2 hours before, during, and 1 hour after the match. The throughput at 4 hours before the match was higher than 10 Mbit/s, It greatly dropped to the half of the normal value at 2 hours before the match when only some users were entering the stadium. During the match, the throughput was nearly zero. The 2.4 GHz traffic throughput started to recover about 30 minutes after the match. The following table lists test data.

Time Segment

Throughput Tested Using Speedtest

Downlink/Uplink (Mbit/s)

Channel Usage Tested Using Fluke

4 hours before the match

10.03/15.68

All frequency bands: low

2 hours before the match

5.25/1.99

Some frequency bands: high

2 hours before the match

0.54/0.01

All frequency bands: high

During the match

0.02/0.09

All frequency bands: high

1 hour after the match

6.87/6.67

Some frequency bands: low

2. At 4 hours before the match, use the professional Fluke Wi-Fi Tester to test channel usage. It was found that the 2.4 GHz usage was low, and the Wi-Fi and non-Wi-Fi interference were small.

At 2 hours before the match, the 2.4 GHz throughput decreased, and the non-Wi-Fi interference on channels increased.At 2 hours before the match, the 2.4 GHz throughput decreased, and the non-Wi-Fi interference on channels increased.

3. After customer's approval, reserve 2.4 GHz test signals on one AP and disable 2.4 GHz signals on all other APs. The test result shows that the throughput was still low and non-Wi-Fi interference was still high (as shown in the gray column directed by a red arrow).

4.Check for interference sources in the entire stadium. Severe non-Wi-Fi interference existed on all channels next to the TV studio near the podium.

Surrounding the location of the interference source, select typical test points for the 2.4 GHz throughput test, as shown in the following figure.

The throughput test result is described in the following table:

 

Area

Throughput Tested Using Speedtest (2.4 GHz)

Downlink (Mbit/s)

Uplink (Mbit/s)

Suite-E

0.54

0.01

TestPoint A

0.53

1.55

TestPoint B

0.02

0.09

TestPoint C

0.16

0.17

The traffic throughput on each test point was low.
After confirmation, it was found that FreeSpeak II wireless intercom system was deployed in the TV studio and overlapped with the 2.4 GHz frequency band. This device wireless intercom system caused noise interference to 2.4 GHz WLAN signals. In addition, its clients were distributed in the stadium and communicated with the wireless intercom system through the base station in the TV studio, affecting WLAN signals in a wide area.
To ensure the FreeSpeak II voice service during the match, disable the 2.4 GHz frequency band of the WLAN after obtaining approval of the customer. Currently, nearly all WLAN STAs support the 5 GHz frequency band. According to the onsite test, the video service is smooth. The following table lists the throughput test result using Speedtest about 5GHz.
 

Area

Throughput Tested Using Speedtest (5 GHz)

Downlink (Mbit/s)

Uplink (Mbit/s)

Suite

6.36

7.04

TestPoint A

8.44

6.01

TestPoint B

7.11

9.21

TestPoint C

5.27

6.66

The throughput on each point meets users' requirements for web page browsing, mobile app, and mobile video services on mobile phones.

 

Root Cause
The FreeSpeak II wireless intercom system in the TV studio caused interference to 2.4 GHz WLAN signals.
It is confirmed that FreeSpeak II uses the 2.400-2.483 MHz frequency band, containing all 2.4 GHz WLAN channels.
Solution
To ensure the voice service during the match, disable the 2.4 GHz frequency band of the WLAN and use only 5 GHz signals.
Suggestions
when face to the issue of signal interference, try to scan by professional instrument (just as Fluke Wi-Fi Tester: a professional wireless spectrum scanning tool).then we can provide the dependable report to customer ASAP.

END