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Fat AP and Cloud AP V200R008C00 CLI-based Configuration Guide

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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
Terminal Location

Terminal Location

Basic Concepts

As shown in Figure 21-1, the terminal location system includes at least three RUs, one central AP, and one location server. Functions of each component are as follows:

  • RU: The RUs collect wireless signals. The RUs periodically switch channels to collect strength information about terminal signals in the surrounding environment on each channel and report the collected information to the location server.
  • central AP: The central AP delivers terminal location configurations to the RUs. In addition, the central AP also classifies and filters the information received from the RUs based on the device type (such as authorized terminals and rogue APs).
  • Location server: The location server functions as the location server and display terminal in the location system. The location server computes the signal transmission model according to locations of RUs and obstacles, and calculates locations of terminals, rogue APs, or Wi-Fi interference sources based on the RSSI information collected by each RU. The display terminal draws maps and displays locations of the devices on the map.
Figure 21-1  Typical networking for the terminal location system

Implementation Principles

Terminal location technology locates terminals as follows:

  1. RUs collect strength information about radio signals and forwards the information to the location server.

    1. The RUs periodically switch channels to collect frames sent from terminals in the surrounding environment on each channel and record frame information including RSSI information, timestamp, data rate, and channel information. RSSIs are essential in determining whether a terminal is near or far from the RUs.
    2. The RUs encapsulate the collected radio signal information into UDP packets and report collected data to the central AP. Then, the central AP reports the data to the location server. When the network between the RUs and the location server is not reachable, the RUs report data to the central AP first. The central AP then filters information about terminals and rogue APs before reporting the data to the location server.
  2. The central AP reports the information received from RUs to the location server.

    As shown in Figure 21-2, after receiving information from the RUs, the central AP processes the information as follows:
    1. Determine whether the data received from the RUs is location data. If not, the data is processed in other ways.
    2. If the central AP receives the location data, the central AP processes the data in the following way: if the data is about terminal locations, the central AP reports the data directly to the location server; if the data is about authorized RU locations, the central AP discards the data; if the data is about rogue AP locations, the central AP reports the data to the location server.
    Figure 21-2  Processing location information

  3. The location server computes the location information.

    The location process involves the offline phase and online phase.
    1. Offline phase: The location server divides the whole network into multiple equal area grids, computes the signal transmission model according to environment features (indoor/outdoor and obstacle features), calculates the theoretical differences among RSSIs of a STA in the grid to all RUs based on the imported RU location information, and stores the data into the database.
    2. Online phase: At least three RUs report terminal information to the location server after receiving the terminal information. The location server compares the information received from the RUs with the information in the database to obtain the location of the terminal.
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Updated: 2019-01-11

Document ID: EDOC1000176006

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