Project background and requirements
Comprehensive pipe gallery is the underground urban pipeline comprehensive corridor. That is to build a tunnel space under the city, which integrates various engineering pipelines such as power, communication, gas, heat supply, water supply and drainage, etc., and has a special inspection port, lifting port and monitoring system. It is an important infrastructure and "lifeline" to ensure the operation of the city. It is the implementation of unified planning, design, construction and maintenance, built in the city underground for the laying of municipal public utilities.
According to the different types of pipeline entering the gallery, the pipeline gallery can be divided into gas tank, power tank, water tank, heat tank and vacuum garbage tank.
The cross section of pipe gallery is as follows:
As shown in the figure above, every 200m of the pipe gallery is set as a fire zone, and each fire zone is separated by fire door; each fire zone is provided with 1 feeding port, 1 exhaust outlet, 1 air inlet, 1 sump and 1 information gathering box; 1 self used cable transformer room is set every 1000 m, and the feeding port and transformer room share the same cabin, which is located above the pipe gallery.
The utility tunnel provides WLAN wireless full coverage. Considering the fusion access of multiple terminals, it needs to provide signal coverage of 2.4GHz and 5GHz at the same time. After WLAN is fully covered, it provides wireless network support for the inspection of the whole pipe gallery, and realizes the information management in the inspection process.
Introduction of wireless WLAN signal coverage in Utility Tunnel
As shown in the section above, a firewall is set up every 200m in the whole pipe gallery. Since 2.4GHz and 5.8GHz work in the microwave frequency band, the characteristics of these two bands are linear transmission (the signal arrives directly or through reflection). Assuming that the range of 200m is not linear transmission, the signal can also reach through the reflected signal on the wall. Since a firewall will be set every 200m, in order to ensure high-quality signal coverage and terminal cabin positioning, it is considered to place an antenna integrated base station equipment in five cabins every 200m to complete the coverage of the whole network.
Since there is one equipment room every 200m inside the pipe gallery, there are optical fiber access points and access switches. The device can be very convenient access to the internal network. The four cabins are also reserved with pipelines for each other, which is convenient for construction.
Introduction of wireless terminal fast roaming switching
The design of the system supports the fast roaming and switching of the wireless terminal. When the wireless terminal works in different cabins, it can quickly connect to the base station equipment in the cabin.
Description of coverage base station configuration:
1. The same SSID is used for the same radio frequency coverage, which makes it easy for handheld terminal devices to roam and switch between base station devices.
2. Adjacent base stations adopt different channels, and the channels are staggered by more than 5 channels.
3. Base station equipment is equipped with wireless terminal fast roaming mechanism.
Schematic diagram of equipment connection topology