Configuring Train-Ground Communication (For Vehicle-Mounted APs in V200R007 or Later)
Context
Train-ground communication involves Mesh handover and client scenarios.
Mesh handover scenario: Deploy trackside APs along the railway line, which set up Mesh links with vehicle-mounted APs using the same channel. The vehicle-mounted APs on a moving train can perform link handovers, without the need to scan channels.
Mesh client scenario: Deploy trackside APs by segment (for example, only in stations) instead of along the railway line. To meet throughput or coverage efficiency requirements, you need to configure trackside APs to work in different channels. Vehicle-mounted APs scan channels of neighboring APs to perform Mesh link handovers.
Perform either of the following operations based on train-ground communication scenarios.
Procedure
- Configure the Mesh handover mode.
- Run location-based-algorithm enable [ moving-direction { backward | forward | undetermined } ]
The location-based enhanced fast link handover algorithm is enabled, and the moving direction of the vehicle-mounted AP is configured.
By default, the location-based enhanced fast link handover algorithm is disabled and the moving direction of the vehicle-mounted AP is undetermined.
After the location-based enhanced link handover algorithm is enabled, the vehicle-mounted AP will switch the active link to the nearest trackside AP that meets handover requirements.
In vehicle-ground communication scenarios, signals of a trackside AP distant from a train may be temporarily better than the trackside AP near the train due to radio environment changes. If an active link handover occurs at this time, the active link may be incorrectly switched to the distant trackside AP. To prevent incorrect handovers and improve vehicle-ground communication quality, you can use the location-based enhanced link handover algorithm. This algorithm requires that trackside APs be named in ascending or descending order of sequence numbers.
Trackside APs should be named in head-name_sequence-number format. head-name describes track line information and can be different for trackside APs on the same track. It is recommended that you set the same head-name for APs on a track to differentiate tracks. sequence-number of APs along a track must be in descending or ascending order. The sequence numbers of trackside APs can be set with unequal steps. head-name and sequence-number are separated using an underscore (_), for example, L1_001, L1_002, L1_005, L1_010.
- Run location-based-algorithm enable [ moving-direction { backward | forward | undetermined } ]
- Configure the Mesh client mode.
- (Optional) Run scan-period scan-time
The air scan period is configured.
The default air scan period is 60 ms.
A longer air scan period indicates more collected data and a more accurate data analysis result. However, if the air scan period is set too large, WLAN services are affected. You are advised to use the default value.
- (Optional) Run scan-interval scan-time
The air scan interval is configured.
By default, the air scan interval is 10000 ms.
The air scan interval ranges from 300 ms to 1000 ms.
The air scan interval also applies to radio calibration, smart roaming, WLAN location, and WIDS functions.
If the customer has high requirements on real-time data analysis, configure a small air scan interval using the scan-interval command to improve the scan frequency; however, higher scan frequency indicates much larger impact on the services.
- (Optional) Run scan-period scan-time