## 2 Related Works
### Wireless Mesh Networks  
As mentioned previously, wireless mesh networks are the appropriate networking technology for connection-oriented network composition. In particular, wireless mesh networks have the characteristics of self-composition and self-recovery and have the advantage that they can communicate with other paths even if the original path is disconnected [14]. Hence, with reduced cost and time in composing network deployment considering infrastructure-based wireless mesh networks, the network function orchestration system is shown to be appropriate.  
However, in the status quo of mesh network composition, since the amount of information exchange for routing increases according to network size, there is a trend of overhead drastically increasing. In particular, in order to compose dynamic networks that are characteristic of mesh networks, every termination needs to be recognized and searched in the form. Hence, in order to reduce this overhead, research for developing wireless mesh network routing is currently active.  
Routing research in wireless networks has been actively pursued, focusing on mobile ad hoc networks, routing protocols including dynamic source routing (DSR), ad hoc on-demand distance vector routing protocol (AODV) and optimized link state routing protocol (OLSR) have been developed [15; 16]. In particular, the IEEE 802.11s wireless mesh networks standard uses the hybrid wireless mesh routing protocol (HWMP) [13]. This routing protocol has a structure that combines AODV and tree-based routing and conducts double-layered routing. However, the above methods all require a large amount of time, or have the disadvantage of incurring more overhead with routing table update process.  
Thus, this paper composes flexible networks by reducing network overhead, applying Better Approach to Mobile Ad hoc Networking (BATMAN) routing protocol. This method implements routing based on the information of nearby nodes, in contrast to the original mesh network routing method, which needs to recognize the information of all nodes.  
BATMAN  
BATMAN, invented by the Freifunk community, is a multi-hop routing protocol for mobile ad hoc mesh networks [17]. This protocol was invented to overcome the limitations of the OLSR protocol and to replace it.  
This protocol implements routing in double-layered fashion instead of triple-layered, enabling communication between terminals without an IP. From this point of view, it has the advantage that it is easy to connect with non-mesh terminals.  
The BATMAN protocol does not have a routing table for each node, unlike the original protocol and also has information regarding nearby nodes; therefore, it does not suffer from onerous overhead during the routing table update procedure.  
This protocol's operation process is as follows. Each node broadcasts the originator message (OGM) and notifies nearby nodes of the existence of a note. The nodes that receive the message broadcast the OGM message again. The OGM has a size of 52 bytes in a small packet, including the message's start address, the address where the packet has been delivered, TTL and the sequence number. Ultimately, each note, through OGM, can update the optimum node among the nearby nodes, know the optimum path between terminals and obtain information regarding link functions. Through the above procedure, without incurring excessive routing overhead, providing an optimum path is possible; and since table correction becomes faster owing to the terminal's move, a much more flexible mobile mesh network can be constituted.