# Wireless Mesh Networking: An IoT-Oriented Perspective Survey on Relevant Technologies
## 4 Mesh in Bluetooth/BLE Networks
### Applications  
The SIG Bluetooth Mesh standard is still relatively recent and solutions employing this standard are under development. Despite that, the use of mesh networks based on BLE devices is of great interest and has applications in different fields. In the following, some examples are provided.  
One of the most relevant applications of BLE technology is localization: in this context, the use of a mesh network allows to cover larger areas and to connect multiple subnetworks. In [46], the authors propose a BLE-based location tracking system to monitor livestock behavior collecting useful information about animals health and welfare. In the proposed approach, BLE nodes are used for continuous tracking of cows in a barn through a self-organizing multi-hop mesh network which collects the data. This data is processed with an advanced tracking algorithm that copes with signal fading and body shadowing. The mesh network is implemented using a BLE 4.1-based open source implementation of a mesh network, denoted as FruityMesh. Concerning localization, in [47] the authors present a localization system able to support real-time communications between interactive nodes (through the joint adoption of mesh topology and broadcast options useful for beacon solutions). More in detail, the proposed development is composed by beacon devices (namely, smartphones) able to form a mesh network. This allows to show that smartphones are able to detect, at specific locations, those users of interest, while this information is ready to be forwarded to the collector through relay devices. This kind of solution presents the advantage of being able to manage the communication entirely through the BLE Mesh network, while end users are not required to look for a mobile connection for reaching services in the backend system.  
Another relevant application scenario for BLE mesh is the Smart City context. The work described in [48] presents a novel approach to implement smart city-oriented services based on SIG BLE mesh standard specifications. Experimental results show that collected information can be forwarded among BLE nodes even in the presence of an already existing Metropolitan Area Network (MAN). The focus of [49] is on Proximity Services (ProSe), which can be classified into two categories: public safety communication and social discovery. The authors present the implementation of a multi-hop BLE mesh in which a proactive routing mechanism with Received Signal Strength Indicator (RSSI) link-quality assistance is proposed. Then, a ProSe development framework, denoted as BLE Mesh is presented, with the aim to provide significant benefits for application developers, framework maintenance professionals, and end users to build ProSe apps easily and quickly.  
The last topics in which the usage of the BLE for building mesh networks is emerging as a relevant solution is the Industry 4.0 and the industrial monitoring scenario. In [41], the problem of real-time industrial environments monitoring is addressed with a multi-hop mesh BLE topology. In [50], authors propose a Fog Computing-based architecture designed for Industrial Cyber-Physical System (ICPS) and aimed at supporting low-latency distributed applications (oriented to the Industry 4.0 paradigm) which normally offload processing and traffic resource consumption from high-level systems (e.g., the Cloud).