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The existing wireless communication technologies in wireless blind spot coverage have challenges in non-line-of-sight scenarios in coal mines. In order to solve the above problems, a solution approach is proposed to introduce intelligent reflecting surface (IRS) into the wireless communication system in coal mines to achieve blind compensation of wireless signal coverage. This paper analyzes the causes of wireless coverage blind spots in coal mines, including closed mine environments characteristics, common non-line-of-sight scenarios, and safety constraints on transmission power and antenna settings. However, traditional wireless coverage blind spot solutions for underground coal mines have limitations in hardware deployment, maintenance costs, and technical implementation. They cannot truly meet safe and efficient communication needs of specific mining scenarios. IRS has significant performance advantages in achieving coverage blind compensation due to its low cost, low power consumption, easy deployment, and scalability. This paper introduces IRS technology from three aspects: hardware structure, auxiliary channel model and typical application scenarios (precise positioning, signal and energy simultaneous transmission, UAV communication, edge computing and physical layer security). This paper proposes the use of IRS technology to optimize underground wireless blind spot coverage. By deploying IRS reasonably in coal mines, it reduces the absorption and scattering of main signal components by walls, and utilizes the adjustable reflection characteristics of IRS to optimize signal propagation. It significantly improves signal strength and coverage range. The future research directions of IRS technology in underground wireless communication in coal mines are pointed out. The directions include energy management of IRS-aided coverage and blind compensation systems, IRS-aided underground communication based on artificial intelligence, application of new IRS technology, and flexible deployment of IRS.

Most of the existing communication networks except 5G exist in the form of independent private networks. The performance of 5G wireless communication in bandwidth, delay, number of terminal connections, and reliability has been greatly improved. Accordingly, there are new changes in network architecture and networking mode. The private network scheme is no longer a single independent private network scheme. There are also hybrid private networks and virtual private networks. This paper introduces the key technologies of 5G private network, such as network slicing, mobile edge computing, 5G LAN, time-sensitive network and so on. This paper proposes three kinds of 5G private network schemes, namely virtual private network, hybrid private network and independent private network. The virtual private network has the characteristics of wide service scope, high flexibility, low cost, and short construction cycle. It is used for various applications which have wide coverage, have access terminals not fixed in time and space, and have certain service quality requirements and certain degree of data isolation requirements. The hybrid private network has short transmission path, high security, and low end-to-end delay. It can carry out a variety of flexible independent services, but privacy is weak. The independent private network provides a physical exclusive 5G private network to meet the needs of industrial users for high bandwidth, low delay, high security and high-reliability data transmission. This paper puts forward the general principles of 5G private network scheme selection in terms of safety, availability and reliability. This paper also proposes the special requirements of 5G private network in coal mine in terms of dispatching function, integration demand, independent operation and maintenance and intrinsic safety. The selection of 5G special network scheme for coal mine is proposed. In the early stage of intelligent construction of coal mine or there is no strict requirements on data confidentiality, system use convenience, system function expansion in the coal mine, the virtual private network or hybrid private network scheme can be selected. Otherwise, the independent private network scheme can be selected. It is pointed out that relatively more hybrid private network and virtual private network schemes are adopeted in coal mines at present. The hybrid private network and virtual private network will have some advantages in the future. With the gradual establishment of small core network ecology, the independent private network scheme will be recognized by more users. In a certain period in the future, the independent private network, virtual private network and hybrid private network schemes will give full play to their respective advantages. They serve the intelligent construction of coal mines in different periods and with different requirements.

Mine unmanned vehicles are needed to reduce the number of coal mine underground operating personnel and to build safe, efficient, green and intelligent mines. The characteristics of mine unmanned vehicles are summarized as following points. The positions of underground operating personnel in coal mine are comprehensively identified. All mine vehicles are controlled. Mine track transportation equipment only needs one-dimensional positioning. The lighting condition is poor. The wireless transmission attenuation is large. There is no satellite signal. The electromagnetic environment is complex. The characteristics also include electrical explosion-proof, humid environment and water spray and dust. This paper analyzes the technical characteristics of mine vehicle positioning, such as ultrasonic positioning, laser position, radio positioning(including RFID, ZigBee, UWB, WiFi6, 5G), inertial navigation, simultaneous localization and mapping(SLAM), odometer and so on. This study puts forward a joint positioning method of mine vehicle, which is based on UWB and supplemented by inertial navigation, odometer and SLAM. This paper analyzes the technical characteristics of obstacle identification and distance measurement of mine unmanned vehicle, such as laser radar, millimeter wave radar, infrared camera, visible light camera, visible light binocular vision camera and so on. This study puts forward a multi-information fusion method of obstacle identification and distance measurement of mine unmanned vehicle. The method is mainly based on laser radar, supplemented by millimeter wave radar, infrared camera, visible light camera, visible light binocular vision camera and ultrasonic radar. When the road condition is complex and the automatic driving can not make decisions, the mine unmanned vehicle needs to automatically switch to the ground remote control mode. In view of the above situation, it is pointed out that the mine unmanned vehicle ground remote control technology based on 5G is the preferred scheme. However, the mine 5G wireless communication system has the problems of small wireless coverage radius and high cost. Therefore, it is suggested to study the application of WiFi7 in the mine vehicle ground remote control.

Integrated localization and wireless communication(ILWC) is a new information technology based on hardware resources and software information sharing to realize the coordination of location and communication functions. This paper briefly introduces the research progress of wireless communication technology and localization technology, and reveals that ILWC technology is the inevitable result of the bearer services expansion of wireless communication system. This study summarizes the definition and connotation of ILWC technology in different research. The core idea of ILWC is defined as 'hardware integration and software sharing'. The research progress of ILWC technology is summarized according to the two stages of equipment reuse and deep fusion. Combined with the particularity of the scene of the coal mine, the concept of ILWC in the coal mine is put forward. Based on the sharing of time, space, spectrum, computing and other resources, the technology is the fusion technology of communication function and localization function with an automatic scene perception and dynamic and adaptive resource allocation mechanism. The adaptability of underground ILWC in roadway, central substation, underground parking lot, coal working face and other scenes is discussed. It is pointed out that the challenges faced by underground ILWC are the complexity of underground wireless channel, unbalanced deployment of base stations and precise recognition of complex underground scene.

The mine wireless communication system has the advantages of wide communication coverage, convenient connection, good mobility, easy to establish, simple setup and maintenance, etc. It plays an irreplaceable role in in the construction of mine intelligence. The whole mine wireless communication system mainly include WiFi(IEEE 802.11b/g/n/ac), 3G, 4G, 5G and WiFi6(IEEE 802.11ax) system. 3G system is gradually replaced. 4G and WiFi system are gradually reduced. 5G and WiFi6 system are at the initial stage, and will gradually become the mainstream. The 4G, 5G and WiFi/WiFi6 systems are analyzed from the aspects of technical points, main functions and applications. And the advantages and disadvantages of each system are pointed out in this paper. ① The main disadvantage of the mine 4G wireless communication system is that the bandwidth and real-time indicators cannot meet the needs of application scenarios such as high-definition intelligent video and remote control. ② The problems of 5G in practical use are listed as following points. In the case of multiple systems and multiple antennas, there is a security problem of wireless transmission signals. 5G base stations are mainly explosion-proof and intrinsically safe types, which are large in quality and volume. There are problems of inconvenient to use and limited in use. 5G terminal ecology is lacked. The communication modules are expensive and power consumption is high. It does not have the conditions for large-scale industrial applications. There are few practical application cases, and the application scenarios need to be further explored. ③ WiFi6 wireless communication system has high latency, relatively low mobility and reliability. The mobile phone terminal is not mature enough, which affects the quality of voice calls. Based on the above analysis, it is pointed out that the demand of intelligent mine for wireless communication system is the demand of large bandwidth, low latency, high reliability, multi-access, multi-system, multi-interface, and position information. Finally, this study points out the development trend of mine wireless communication system. The trend includes system fusion (wireless communication and wired communication fusion, wireless communication internal fusion, wireless communication system and other system fusion). It also includes communication and positioning integration, equipment intrinsic safety, terminal module low power consumption and protocol interface standardization.

The paper analyzed WIA-PA communication protocols and conformance testing, and designed conformance testing platform for WIA-PA wireless communication according to WIA-PA communication protocols. It elaborated process of forward testing and reverse testing by a test case. The actual test results indicate that the conformance testing platform can detect whether the device meets WIA-PA standard protocol, and provide reliable assurance for application of WIA-PA equipment in actual industrial field.

The paper introduced scheme selection, system composition and function characteristics of mine-used TD-SCDMA wireless communication system in details, and expounded application of mine-used TD-SCDMA wireless communication system in Lushuidong Coal Mine. The application results show that the system has stable and reliable performance, large capacity, good effect of calls, large base station coverage, and can meet needs of mobile communication in coal mine underground.

In view of problem of difficult monitoring to mine mobile equipments, the paper proposed a wireless broadband transmission system for mine mobile equipments based on wired/wireless hybrid network platform. It gave architecture of the system, researched key technologies of theory of wireless signal transmission in mine complex tunnel, mobile equipments oriented wireless roaming switch and mine long distance multi-hop chain transmission, introduced core equipments of the system, including mine-used wireless switchboard, mine-used wireless relay equipment, mine-used wireless terminal and mine-used intelligent integrated access gateway. And it discussed application mode of the system in wireless video monitoring system of endless rope winch.

According to the needs of wireless communication of working face of coal mine, the paper analyzed advantages and disadvantages of existing wired and wireless communication technologies used in working face, proposed a design scheme of full coverage wireless communication system of working face of coal mine based on WMN and ZigBee technology, and introduced designs of comprehensive base station and WiFi gateway. The test results show that the system can meet the needs of wireless transmission of different information of data, voice, video, so as to achieve full coverage of wireless signal of working face.

For the problem that most existing wireless data monitoring schemes are based on professional fields, have different data requirements, processing methods , safety standards, and high cost of development and application, the paper proposed a design scheme of universal wireless data monitoring model, and introduced overall design of the model and implementation of key technologies. The model uses STC89C52RC as master chip; adopts universal integrated wireless transmission module to transmit and receive data through radio frequency chip nRF24L01; bus module uses RS232 serial data communication method. The test results show that the power of data monitoring module of scene node and the regional dataset module are 8.58 mW and 29.7 mW, transceiver distance of the model is longer than 30 m, which is able to complete reliable and stable wireless data communication.

For problem of duplication of network deployment of common WiFi communication system and personnel positioning system which both adopt independent network deployment, the paper proposed a design scheme of integrated mine-used wireless communication and personnel positioning system combining WiFi with RFID. The system realizes functions of wireless communication and personnel positioning through integrated base station, achieves integrated transmission of voice, data and image. The practical application results show that the integrated base station can complete mobile communication and card reading function which reduces investment, and the system is easy to maintain and manage.