# Multilayered Network Model for Mobile Network Infrastructure Disruption
## 3 Proposal of Multilayered Network Model for Mobile Network Infrastructure Disruption
### Inter-Layer Communication  
In this section, the inter-layer communication will be described. We assume that all layers operate independently. The WSN network requires the existence of communication based on IPv6, which enables WSN nodes to reach the Access Point. The best solution to this is ZigBee with 6 LoWPAN or RPL protocol mentioned in Section 3.2. The MNM approach is using a system of gateways, called WSN gateways. The WSN sensors are therefore divided into two types: WSN sensor node and WSN gateway sensors. In the network disruption scenario, WSN gateway sensors will serve as a gateway for urgent data to the higher layers. The ordinary WSN sensor nodes will use IEEE 802.15.4 ZigBee communication technology to communicate with other sensors or WSN gateway sensors. On the other hand, beside ZigBee standard, WSN gateway sensors will also use IEEE 802.11 Wi-Fi. Therefore, WSN gateway sensors need to implement a dual protocol stack that is depicted in Figure 3.  
Based on the dual protocol stack, WSN gateway sensors will be able to communicate with WSN sensor nodes as well as MANET nodes. This scenario is depicted in Figure 4, where the source WSN sensor node is unable to send urgent data to AP_1 because of the disrupted link. However, urgent data can be delivered through the another WSN gateway sensor and MANET layer nodes to the functional AP_2. Figure 4: The example of communication between WSN sensor nodes, WSN gateway sensors and MANET layer nodes. Figure 3: The example of dual protocol stack used in WSN gateway sensors. At the Data Link OSI layer, WSN sensor nodes use ZigBee, while WSN gateway sensors use both ZigBee and Wi-Fi. On the Network layer, WSN sensor nodes will use IPv6 routing protocol such as 6 LoWPAN.In this paper, higher layers are not considered, which is highlighted by dotted parts in Figure 3. However, in terms of energy consumption, light protocols should be used, such as the UDP transport protocol on the Transport layer. UDP protocol is lighter than TCP and is useful for energy-constrained WSN sensors and WSN gateway sensors. Examples of protocols used in higher layers include Constrained Application Protocol (CoAP) for constrained RESTful Environment running over UDP with lightweight Efficient XML Interchange (EXI) protocol which is a counterpart of XML. Since MANET nodes are not strict energy-constrained and MANET network is an independent network, it is possible to use the TCP transport protocol. However, if critical data are transported in disruption scenario, used protocol in the transport layer has to be UDP. Therefore, the Transport layer of MANET nodes has to be flexible. To use the WSN gateway system and optimize energy consumption, the routing protocol used in WSN should be cluster-based or use sink-mobility, where elected cluster-head or sink node will act as a gateway to higher MNM layers. The appropriate routing protocols will be described closely in Section 4.1. The only used communication technology in MANET layer of MNM will be IEEE 802.11 Wi-Fi standard. From the WSN layer point of view, only the WSN gateway sensors are able to send urgent data to the MANET layer. On the other hand, all MANET nodes are able to receive those data. To maintain the integrity of these two layers, it is recommended for the MANET network to use the routing protocol based on IPv6 addressing. This will ensure that the MANET node will be able to deliver critical data to the access point within the 5G network and will also not require reverse conversion between IPv4 and IPv6. The third layer of the DRONET network uses IEEE 802.11 Wi-Fi standard to connect to nodes of the MANET layer. Based on Wi-Fi standard is possible for UAV of DRONET layer to search for MANET nodes from the air and establish communication. However, the MANET network can be quite large in terms of several nodes and spread over a large area. In order to cover the MANET network with the UAV, it is necessary to perform an area exploration and identify the network topology.