An Antenna Information Sensor Unit (AISU) is a device usually installed on top of a base station antenna. It mainly consists of GNSS antennas and sensors and is used to measure important antenna engineering parameters such as azimuth, mechanical tilt, longitude, latitude, and altitude.
Why AISU Is Required?
Accurate antenna engineering parameters are essential for network operation, maintenance, and optimization. Traditionally, these parameters were collected manually on-site, which was time-consuming, labor-intensive, and prone to human errors. Outdated or incorrect parameters can negatively affect network optimization accuracy and intelligent network analysis.
Moreover, during extreme weather conditions such as heavy storms, it becomes difficult to track antenna status changes. Using an AISU allows remote, automatic, and real-time collection of engineering parameters, improving both efficiency and accuracy of network management.
How AISU Works
The AISU uses built-in GNSS antennas and sensors for precise positioning and measurement. It automatically reports antenna parameters, including azimuth, mechanical tilt, height, longitude, and latitude. The device communicates directly with the base station and network management system (NMS), enabling real-time monitoring and updates of antenna parameters without the need for field visits. This creates a self-aware antenna system, allowing remote viewing and analysis of antenna data through the NMS.
Engineering Parameters Measured by AISU
The AISU collects data through multiple sensing methods:
- Longitude and latitude: determined using GNSS.
- Height: calculated through GNSS positioning.
- Mechanical downtilt: measured by a built-in gravity sensor.
- Azimuth: obtained from the carrier phase difference of signals received by two GNSS antenna groups, based on satellite positions.
Data Transmission Method
The AISU is deployed together with the antenna and connected to the RET port on an RRU, the AISG port on an RCU, or the AUX port on an AAU. The collected parameters are sent via optical fibers to the base station, which then reports them to the network management system (NMS). The NMS centrally manages the site’s engineering parameters, including storage, updates, and verification, ensuring the information stays current and accurate.
AISU Application Scenarios
AISUs are used in various environments such as standard installation sites, high-radiation areas, and multipath reflection locations.
Standard scenarios: When installed on towers with a clear sky view above 120°, accurate measurements can be achieved after a 4–6 hour stability test. If metallic structures like maintenance platforms are nearby, longer test times (up to 12 hours) may be needed.
- High-radiation environments: The AISU should be kept away from strong radiation sources, preferably more than 5 meters, to prevent signal interference.
- Multipath reflection scenarios: Since GNSS antennas are sensitive to reflected signals, the AISU should be at least 2 meters away from reflective objects to maintain accurate azimuth readings.