## 2 Wireless Communication Technologies in Harsh Underground Mining Operations
### Mine Operational Constraints  
When going beyond the transmission of signals within the environment, local environment characteristics inherent to the mining operations need to be considered. These determine requirements for the actual physical setup and maintenance of a network and its components and the possible usage, which is highly dependent on the setup within the environment. Mining environments do have an enormous variety depending on the naturally formed ore body and its properties that determine the mining method and used equipment [1]. Mining methods can be classified in various ways. The most relevant for the installation and maintenance of a communication infrastructure are the following factors:  
* Repetitive use of areas
* Change of geometry/consistency of roof
* Movement of production/extraction point
* Geometry for signal transmission on a global scale  
Mining layouts that support repetitive and focused usage of the same underground areas with minor change in geometry favour installations of communication infrastructure. Typical examples are most stoping layouts and also caving layouts, where there is a production level with transport drifts connected to draw points that are used excessively and over long periods of time [9; 21]. An illustrated layout is shown in Figure 2. Example of a typical stoping layout [21].  
Networks can be installed for automation purposes and/or local data transfer and tracing. In these layouts, automation and teleoperation can be more advanced due to the repetitive nature of tasks and the ability to maintain network infrastructure.  
In orebodies that are mined, it is more challenging to maintain infrastructure in dynamic, constantly moving or expanding layouts because it needs to be located near the extraction point and/or the travel routes of mobile equipment. An exemplary layout for this would be the pillar layout as seen in Figure 3, where there is a lot of interaction of different pieces of mobile equipment at the face and in some cases also a change of the floor due to benching. The extraction point moves constantly or with every drill and blast cycle, which makes it very difficult, tedious and costly to maintain infrastructure that needs to be close to the face.  
Additionally, it is critical to consider the sensitivity of devices to blasting impacts, as they may even affect blasting safety. For example, regional or state-wide formulary legislation between the radiated power and a minimum distance to blasting devices and detonators must be taken into account (regional German law: [22] USA, Indiana state law [23]. However, the vast majority of the technologies discussed in this paper only require the minimum distance to be maintained for any radiative power level, which is usually one meter.  
Figure 3: Example of a typical room and pillar layout [11]. Reprinted/adapted with permission from Ref. [11]. 2023, Epiroc Deutschland GmbH.  
Figure 2: Example of a typical stoping layout [21]. Reprinted/adapted with permission from Ref. [21]. 2023, Epiroc Deutschland GmbH.  
Furthermore, established and long-running processes with no changes in used machine type, procedures, etc., are not necessarily time-dependent in their use case, resulting in networks with constant requirements and longer lifecycles than public networks. However, it can be assumed and is probably also feasible that a network can be expanded, updated, or modified with new use cases added in the operation.