In 2020, 5GtoB will accelerate significantly, and vertical industries will gradually become important users of 5G, and they will be deeply involved in the verification of 5G network capabilities to examine whether 5G meets the needs of the industry. In the test, due to factors such as inconsistent business requirements, single test scenarios, and failure to consider the capabilities of equipment manufacturers, industry users have different perceptions of 5G network capabilities. This article conducts a quantitative and qualitative analysis of the 5G coverage, business requirements and network planning of underground mines, and provides a certain reference for 5G network planning in coal mines.

1. Data analysis of 5G coverage test in underground coal mine

1) Underground test in Xinyuan Coal Mine
In the test of Xinyuan Coal Mine of Shanxi Huayang New Materials Group, a 2.6GHz four-channel leather station was deployed, with a single channel transmitting power of 21.7dBm (150mW), and the function of turning on the uplink and downlink time slots (time slot ratio DL: UL = 1: 3) The wrong frequency networking scheme is adopted underground, that is, adjacent base stations are opened with 80MHz bandwidth carrier.
In the process of testing the coverage of fully mechanized mining face, the shearer was about 90 meters away from the antenna and passed the position of the shearer. The signal quickly decayed due to obstruction. At a distance of 108 meters from the antenna, the uplink rate fluctuates around 24 Mbps.
During the test of the auxiliary transportation roadway, the terrain changed a lot at a distance of 330 meters from the antenna, and the signal decayed rapidly. At 390 meters, the uplink rate fluctuated about 20 Mbps.

2) Pang Pang Ta mine underground test
Shanxi Coking Coal Pangpangta Mine deployed four-channel leather station equipment in the 3.5GHz frequency band, with one antenna connected to each two channels, two antennas back to back, output power per channel 250mW, and 100MHz carrier enabled. Coverage tests were carried out on the pedestrian inclined shaft and the fully mechanized mining face.
In the pedestrian inclined shaft test, at a distance of 200 meters from the antenna, the upload rate was 33.2 Mbps; at 250 meters, the upload rate dropped to about 15.5 Mbps. The coverage radius of a single station is greater than 200 meters.
In the fully mechanized mining face, the base stations are installed on both sides of the working face, covering the middle of the fully mechanized mining face, and the base station antenna is suspended under the hydraulic roof. At a distance of 180 meters from the antenna, the uplink rate is about 30.1 Mbps.

2. Mine 5G business requirements

Why should mine 5G applications emphasize the uplink edge rate? The answer is business needs.
The coverage of the wireless network is planned based on business requirements. So, what business can 5G do in the mine? According to the "5G+ Coal Mine Intelligence White Paper" released in October 2020, underground operations can be roughly divided into information collection, video surveillance, communication, and remote control. Information collection services are mainly upstream small packet services and are not sensitive to delay; video surveillance requires a large uplink bandwidth for the network. Taking 4K cameras as an example, the bandwidth requirements are about 15-20Mbps, and the delay sensitivity is medium; personnel communication services, The requirements for network uplink and downlink are the same. If it is a video call, the network demand is about 4-8Mbps; for remote control services, the network requires large uplink bandwidth, low downlink delay, and uplink back to the scene video or radar and other sensor data According to the video resolution and the number of images to be returned, the bandwidth requirement is about 20-30Mbps. The downlink transmission equipment control signal requires little bandwidth, but it is highly sensitive to delay. Generally, the delay is less than 50 milliseconds. It is the remote control of vehicles such as rubber tires, and the delay is further reduced to 20ms.

3. Mine network planning based on business needs
Based on business requirements, combined with specific mine scenarios, the planning of underground 5G networks can be simply divided into two categories, namely: coverage-limited scenarios and capacity-constrained scenarios.
Typical scenarios with limited coverage, such as auxiliary transportation lanes and main transportation lanes. This type of area 5G mainly completes services such as video surveillance, mobile device data backhaul, and communications, with fewer equipment and small business volume. In this scenario, when the edge rate meets the business requirements, the farther the site coverage is, the better, and the distance between the sites can be as large as possible to reduce network deployment costs.

4. Concluding remarks
5G is a booster that promotes the deep integration of advanced ICT technologies such as the coal industry and artificial intelligence, big data, cloud computing, etc. It is useful for changing the traditional coal production model and the image of the coal industry, enhancing the happiness and sense of acquisition of miners, and promoting the energy revolution. It has a very important meaning. It is believed that with the continuous efforts of the majority of coal companies, equipment manufacturers, operators and technical service providers, 5G will surely become the core content of coal mine digital infrastructure construction, and will effectively promote the transformation, upgrading and high-quality development of the coal industry.