Performance Troubleshooting
Verifying the Test Networking and Configuration
Verify the test networking, configuration, and tool parameter settings to ensure that they are consistent with the preset configurations. Pay attention to basic configurations that affect performance.
Check the basic WLAN configurations, including the radio type, operating frequency bandwidth, and number of spatial streams supported by APs. Table 19-28 lists the PHY features of some indoor APs.
Item |
AP7060DN |
AP6050DN |
AP5030DN |
AP7030DE |
AP6010DN |
|---|---|---|---|---|---|
Number of spatial streams |
8 |
4 |
3 |
3 |
2 |
5G-radio type |
802.11ax |
802.11ac Wave 2 |
802.11ac |
802.11ac |
802.11n |
5G-radio maximum bandwidth |
160 MHz |
160 MHz |
80 MHz |
80 MHz |
40 MHz |
Radio Type
The radio type indicates the radio mode of an AP. The 802.11ax radio provides higher-order modulation and coding scheme (MCS), significantly improving service data transmission efficiency.
By default, an AP runs with its latest radio type. To query the specific radio type of APs, run the display radio all command on the AC. Type in the command output indicates the radio type.
<AC> display radio all CH/BW:Channel/Bandwidth CE:Current EIRP (dBm) ME:Max EIRP (dBm) CU:Channel utilization ------------------------------------------------------------------------------ AP ID Name RfID Band Type Status CH/BW CE/ME STA CU ------------------------------------------------------------------------------ 1 60de-4474-9640 1 5G an on 56/80M 25/25 0 3% ------------------------------------------------------------------------------ Total:1
Operating Frequency Bandwidth
The operating frequency bandwidth is the bandwidth of the frequency band on which an AP works. A larger value indicates a stronger air interface capability and a higher rate. The value can be 20 MHz, 40 MHz, 80 MHz, or 160 MHz. The default value is 20 MHz.
To query the operating frequency bandwidth of an AP, run the display radio all command on the AC. BW in the command output indicates the operating frequency bandwidth.
<AC> display radio all CH/BW:Channel/Bandwidth CE:Current EIRP (dBm) ME:Max EIRP (dBm) CU:Channel utilization ------------------------------------------------------------------------------ AP ID Name RfID Band Type Status CH/BW CE/ME STA CU ------------------------------------------------------------------------------ 1 60de-4474-9640 1 5G an on 56/80M 25/25 0 3% ------------------------------------------------------------------------------ Total:1
Number of Spatial Streams
By default, the maximum of spatial streams are configured for an AP.
Verifying the STA Capability
High communication performance requires that both the AP and STA have high capabilities. Therefore, the STA capability needs to be verified so as to obtain the optimal performance.
The performance of the AP and STA can be obtained as follows:
- AP performance: APs support the maximum rate by default.
- STA performance: After a STA goes online, you can query its basic capabilities on the AC, including:
- Radio type
- Frequency bandwidth
- Number of spatial streams
- GI
On the AC, run the following command to query the basic capabilities of the STA:
<AC6605> display station sta-mac b878-2eb4-2689 ------------------------------------------------------------------------------ ... Station's radio mode : 11n ... Station's HT Mode : HT20 Station's MCS value : 9 Station's NSS value : 2 Station's Short GI : nonsupport ... ------------------------------------------------------------------------------
In the preceding information:
- Station's radio mode: radio type supported by the STA
- Station's HT mode: frequency band supported by the STA
- Station's MCS value: MCS value for spatial streams. With the 802.11n standard, 0 to 7 indicate a single spatial stream, 8 to 15 indicate dual spatial streams, and 16 to 23 indicate three spatial streams.
- Station's NSS value: number of spatial streams
- Station's Short GI: whether the STA supports short GI
Verifying the Wired Network Quality and Server Capability
In addition to the air interface, the performance test environment involves the wired network, which accommodates the intermediate cables, devices on the service flow path (such as switches), and devices exchanging service data (such as PCs and servers). Meet the following requirements to ensure that the wired network will not become a performance test bottleneck in the test environment:
- For devices exchanging service data:
- For a transmitter, bandwidth of data reaching the radio is no less than air interface bandwidth.
- For a receiver, bandwidth is no less than data bandwidth sent from the radio.
- Cables and devices along the service path must also meet similar bandwidth requirements.
Verify the performance of the wired network as follows: Assuming that the service path is a complete data traffic path, exclude the air interface and then perform a service flow test for wired links (with the same test PC and server). For example, when the test result reaches 1 Gbit/s in 802.11ac, it can be considered that the wired link will not become a bottleneck in the air interface test.
Troubleshooting Air Interface Quality Issues
The air interface environment is affected by factors including the received signal strength indicator (RSSI), signal-to-noise ratio (SNR), and channel independence of different TX+RX antenna combinations in the MIMO system.
In most cases, higher RSSI and SNR values indicate better performance. When the MIMO system works, higher channel independence indicates better performance.
Air interface quality affects the WLAN communication system, which is represented by the link setup rate, MCS statistics, RSSI, and channel utilization.
Interference Check
It is recommended that the test environment interference be checked before a test. Signals on the same or neighboring channel as the channel under test are considered as interference signals.
Try to perform the test in a place without any signals. If no such an environment is available, ensure that no signals exist on the channel under test and the RSSI on channels other than neighboring channels is lower than –95 dBm.
Check interference as follows:
- For Wi-Fi interference signals: Install the inSSIDer software on a laptop that supports 2.4 GHz and 5 GHz bands or install the CloudCampus APP on a dual-band mobile phone to check for Wi-Fi interference signals.
- For non-Wi-Fi interference signals: Use a WiFi Spy network adapter or a handheld spectrum analyzer to check for non-Wi-Fi interference signals.
PHY Rate Check
After a STA goes online, run the display station all command on the AC to check PHY rates. In the command output, Rx/Tx indicates the uplink/downlink PHY rates on the air interface. Note that the Rx/Tx values obtained when traffic is transmitted can reflect the actual performance.
<AC> display station all Rf/WLAN: Radio ID/WLAN ID Rx/Tx: link receive rate/link transmit rate(Mbps) ---------------------------------------------------------------------------------------------------- STA MAC AP ID Ap name Rf/WLAN Band Type Rx/Tx RSSI VLAN IP address SSID ---------------------------------------------------------------------------------------------------- 14cf-9208-9abf 0 1047-8007-6f80 0/2 2.4G 11n 215/208 -26 10 10.10.10.253 tap1 ---------------------------------------------------------------------------------------------------- Total: 1 2.4G: 1 5G: 0
To obtain the extremum single-user performance of the air interface, ensure that actual PHY rates are the same as the theoretical PHY rates in What Are PHY Rates on the Air Interface?.
If the theoretical rate cannot be reached, check environmental interference and adjust the relative antenna positions of the AP and STA.
MCS Statistics Check
MCS statistics include the packet transmit and receive rates of an AP. You can run the display wifi radio-statistics-sdk radio radio-id command in the diagnostic view to query the MSC value of each packet in the receive/transmit direction.
To ensure data accuracy, run the reset wifi radio-statistics sdk radio radio-id command in the diagnostic view to clear historical statistics before checking MCS statistics. Run the display wifi radio-statistics-sdk radio radio-id command to query MCS statistics after traffic is transmitted for a period of time.
<Huawei> system-view [Huawei] diagnose [Huawei-diagnose] display wifi radio-statistics-sdk radio 1 ... Rx MCS STATS: mcs 0- mcs 4 STATS: 0, 0, 0, 0, 0, mcs 5- mcs 9 STATS: 0, 0, 37, 0, 17595, Tx MCS STATS: mcs 0- mcs 4 STATS: 0, 0, 0, 0, 0, mcs 5- mcs 9 STATS: 16, 10, 16, 381, 48989,
The optimal situation is that 95% of MCSs are the highest-order MCSs. To adjust the environment, check environmental interference and adjust the relative antenna positions of the AP and STA.
Signal Strength Check
A high RSSI value is a guarantee for the highest air interface rate. The recommended RSSI ranges from –45 dBm to –30 dBm.
- The downlink RSSI refers to the RSSI of signals received by the STA and can be obtained using inSSIDer or Wifi Analyzer on the STA.
- The uplink RSSI refers to the RSSI of signals received by the AP from the STA and can be obtained by running the display station all command on the AC.
<AC> display station all Rf/WLAN: Radio ID/WLAN ID Rx/Tx: link receive rate/link transmit rate(Mbps) ---------------------------------------------------------------------------------------------------- STA MAC AP ID Ap name Rf/WLAN Band Type Rx/Tx RSSI VLAN IP address SSID ---------------------------------------------------------------------------------------------------- 14cf-9208-9abf 0 1047-8007-6f80 0/2 2.4G 11n 215/208 -26 10 10.10.10.253 tap1 ---------------------------------------------------------------------------------------------------- Total: 1 2.4G: 1 5G: 0
If the RSSI does not meet the preceding requirement, shorten the distance between the AP and STA (3 m or less can achieve a high RSSI in indoor scenarios) and increase the AP transmit power (APs use the maximum transmit power by default).
Channel Utilization Check
Channel utilization can be checked to detect interference on the channel to be tested. Run the following command on the AC to check channel utilization:
<AC> display ap traffic statistics wireless ap-id 1 radio 1 ----------------------------------------------------------------------- ... Wireless channel utilization(%) :0 ... -----------------------------------------------------------------------
When the DUT is not working, channel utilization should be 0. If a non-zero value is displayed, interference exists on the current channel.
Additionally, a professional Fluke USB network adapter can be used to check channel utilization.