Background
To solve the communication guarantee problem in the construction stage of the subway tunnel. If you use a wire network, it is not only easy to destroy and difficult to lay, but also the communication requirements and environment are changing rapidly and cannot be achieved. In this case, wireless communication is the most effective way.
However, the subway tunnel is narrow and curved, it is difficult for traditional wireless Radio Communication System means to truly solve the communication coverage. Therefore, IWAVE has formulated an integrated intelligent network solution for 4G Private Network + MESH ad hoc network cooperation coverage and carried out the effect test.
In this test, the section from Station A to Station B in the tunnel of Tianjin Metro Line 4 was selected.
Figure 1 Tianjin Metro Line 4(right)
Test Plan
Test time，11/03/2018
Testing Purposes
a) Verifying the rapid deployment capability of LTE Private Network.
b) Verifying the coverage ability of the individual Backpack soldier tunnel scene.
c) Verifying the practicality of "4G LTE Private Network + MESH Ad hoc Network cooperation coverage" to achieve full coverage.
d) Verifying the portability of inspection
Testing Device List
|
Device Name |
Quantity |
|
4G Private Network portable station (Patron-T10) |
1unit |
|
Glass Fiber Reinforced Plastic antenna |
2 |
|
Portable triangular bracket |
1 |
|
4G Private Network single soldier backpack |
1 |
|
Cluster Handset Terminal |
3 |
|
MESH Relay Station (with a shoulder clamp camera) |
3 |
Testing Network topological graph
Figure 2：Testing Network topological graph
Testing Environment Description
Testing Environment
The test site is the subway tunnel from Station A to Station B, which is under construction. The tunnel curvature of the test site is 139° and the subway turning-over radius 400m. The tunnel is more curved, and the terrain is more complicated.
Figure 3：The Green Line shows the meandering condition of station A to station B.
Figure 4-6：Photos of the construction site
Testing system construction
As shown in the figure below, the system is installed at the entrance of the construction station A tunnel, and the rapid deployment is completed. The device starts up with one click, and the total time of rapid deployment takes 10 minutes to complete.
Figure7-9：Photos of the construction site
Main technical indicators of the system
|
Frequency Band |
580Mhz |
|
Bandwidth |
10M |
|
Base Station Power |
10W*2 |
|
Single soldier backpack |
2W |
|
MESH Device Power |
200mW |
|
Base Station Antenna Gain |
6dbi |
|
Single soldier backpack Antenna Gain |
1.5dbi |
Deployment temporary of Command Dispatcher
The IWAVE 4G portable system has wired and wireless access functions. Therefore, as a mobile command dispatching station (notebook or industrial-grade tablet) of the temporary command center, it can be deployed in a safe area to carry out mobile command dispatch and view video return.
Testing Process
Solution1：4G Private Network coverage Testing
At the beginning of the test, the testers carried a 4G individual soldier handset terminal (equipped with a shoulder clip camera) and a handheld 4G private network terminal to enter and move forward from the tunnel entrance. Voice intercom and video return has been smooth in the green section of the figure below, stuck in the yellow position, and offline when it is in the red position.
The starting point of the yellow section is at the 724-ring point (from the base station position, 366meters before turning, 695 meters after turning, a total of 1.06km); the lost connection position is at the 800-ring point (from the base station position, 366 meters before turning, 820 meters after turning, a total of 1.18km). During the test, the video was smooth, and the voice was clear.
Figure11：4G Backpack single-soldier transmission Sketch map
Solution 2：4G Private Network + MESH ad hoc network cooperation coverage Testing.
We retreated a distance to the area covered by the edge of the Solution 1, find out a suitable placement point, and selected the 625-ring position (a little before the 724-ring position) to place the No. 1 MESH Relay device. See the picture right:
Then the tester carried the No. 2 MESH (equipped with a shoulder clip camera) and a handheld 4G private network handheld (connected to MESH relay through Wi-Fi) to continue testing, and the voice talkback and the video return are kept smooth all the time.
Figure12：625-ring No. 1MESH Relay Device
The communication was disconnected at the 850-ring position and the coverage distance of the single stage MESH is 338meters.
Finally, we selected add No.3 MESH device at the position of 780-ring to test the MESH cascading effect.
The tester carried the No. 3 MESH and the camera to continue the test, walked to the construction site at the end of the tunnel (about 60 meters after the 855-ring), and the video was smooth all the way.
Due to the construction ahead, the test is over. Throughout the test process, the video is smooth, and the voice and video are clear.
Figure13：780-ring No. 3 MESH Relay Device
Testing process video surveillance images
Figure14-17：Testing process video surveillance images
Testing Summary
Through the communication coverage test of the private network in the subway tunnel, the following advantages are embodied in the subway tunnel engineering application based on the scheme of the 4G Private Network + MESH ad hoc network cooperative coverage.
- System highly integrated rapid deployment
This system is highly integrated (built-in integrated power supply, core network, base station, dispatching server, and other equipment). The box adopts a three-proof structure design. There is no need to open the box, One-click boot, no need to configure and change parameters disassemble when using it, so that it can be quickly deployed in 10 minutes in the case of emergency rescue.
- Strong communication assurance capability in harsh environments
4G The private network communication system has the advantages of farther coverage, flexible matching of MESH, rapid connection of the centerless ad hoc network, multi-stage connection networking, and the unique networking design ensures the communication assurance capability in a complex environment. In this mode, the communication network can quickly move at any time, if necessary, coverage can be increased at any time.
- Strong applicability of business applications
After the deployment of the system, the network access is provided, the interface is open, and the standard WIFI and network ports are provided. It can provide wireless transmission channels for various services of subway construction. Personnel positioning, attendance checking, mobile office and other business systems can also use this network to operate.
Conclusion
In summary, this testing fully verifies that the combination networking mode of the 4G private network and the MESH ad hoc network is a very good solution, which can solve the problem of communication networks in complex subway tunnels and severe environments.
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Post time: Mar-17-2023