## 2 Wireless MESH Networks  
The rapid development of mobile services and the significant increase in the number of mobile devices makes it necessary to provide more and more novel solutions in terms of reliability and performance of wireless network structures. MESH networks are one of the types of these structures [16; 40]. These networks constitute a wireless communication infrastructure between distributed network nodes. These nodes can be installed wherever power infrastructure is provided. These structures are frequently used in ad hoc type solutions, which are perceived as cheap and energy-saving nodes. As technology advances, they are becoming more and more miniaturized and efficient. The essence of this type of network is to provide direct, non-hierarchical communication between as many nodes as possible. Therefore, the main idea of MESH wireless networks is based on the appropriate physical topology, as various techniques can be used in the area of logical topology--switching, routing, load balancing, etc.  
Thanks to the implementation of this type of network, it is possible to set up a connection without the need to use a wired network, which enables a significant increase in network coverage. The density of nodes has a direct impact on the number of connections between them, the effect of which is an increase in reliability and distribution of load in the network. Such a solution may be particularly important in areas where it is difficult to build a wired network infrastructure; e.g., forested and mountainous terrain; environments that are temporary in nature, such as at occasional events, including concerts and sports competitions; but also in parks, buildings, and many other places.  
The infrastructure of MESH wireless networks is based on the classical grid topology (Figure 1). Obviously, it is not always possible to provide a physical infrastructure on the basis of a full mesh, because then a combination of \(n(n\!-\!1)/2\) connections is necessary, where \(n\) is the number of nodes. On the one hand, this solution can be expensive, but on the other hand it is impossible to implement; e.g., due to technological limitations such as the range of radio connections. In this case partial mesh solutions are used; they are intended to ensure the cohesion of the network in the first step, and in the second step enable possible redundancy of connections.  
Figure 1: Topologies of the mesh: (**a**) full mesh; (**b**) partial mesh.  
Figure 2 presents an example of the implementation of a wireless MESH network based on, e.g., the 802.11s standard [41; 42]. Thanks to the use of such a solution, it is possible to combine effective wireless communication between the wireless nodes, which are intermediate points (e.g., access points) and end devices connected to it.  
MESH technologies are used to create fast and redundant wireless infrastructure. Implementing them in wireless networks extends their functionality and contributes to the increase of their performance; thus, becoming a more effective transmission medium for various convergent network types as well, ensuring stable transmission of video, audio, control data, etc. In addition, their advantage in relation to traditional wireless networks is their increased resistance to failures, and the use of an appropriate number of devices allows one to balance their load by selecting the optimal routes.