# Decentralizing Private Blockchain-IoT Network with OLSR
## 3 Background  
### Ad Hoc Network and OLSR  
In the IoT blockchain applications, the IoT devices majorly communicate over wireless infrastructure networks. In such cases, the blockchain and non-blockchain traffic is usually sent/received on infrastructures including Wi-Fi networks, cellular, or LoRa. As a result, the performance and sustainability entirely depend on a central point, such as Wi-Fi access points, cellular base stations, or LoRa gateways. That is because all the packets are routed to the central devices before arriving at the final destinations. Moreover, the communication range of the whole network is limited to the radio coverage range of the devices. On the other hand, as defined in the popular IEEE 802.11 [34], wireless communications are not merely driven as infrastructure but also ad hoc networks. Ad hoc networks can be formed by a group of nodes, which directly communicate with each other. In the opposite of the wireless infrastructure, the ad hoc network drives the data packet between nodes without the central point. Since the wireless communication range limits a wireless node, the node needs to participate in the routing activity to reach others. This can be realized with an ad hoc routing protocol. In such a case, the nodes can cooperate to expand the coverage of the network. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Topics** & **Method** & **Feature** & **References** \\ \hline General & Decentralized & Implementation & Transparent and & [17] \\  & voting & on Ethereum & immutable voting & & \\ \cline{2-5} General & Internet of & Simulation & Transparent storage & [18] \\  & blockchain & Vehicles & Simulation & Power trading on & [19] \\  & applications & & blockchain & & \\ \cline{2-5}  & Distributed & Implementation & Distributed data & [22] \\  & healthcare & on Ethereum & sharing & \\ \cline{2-5}  & & Simulation & Blockchain integrate & [23] \\  & & with edge computing & & \\ \hline Blockchain- & \multirow{3}{*}{Smart home} & Simulation & Decentralized & \multirow{3}{*}{[24]} \\  & IoT & & large-scale smart & \\  & & & home & \\ \cline{2-5}  & & Implementation & Environment monitor & \\  & & on Ethereum & with RPi3 & \\ \cline{2-5}  & Flood & Implementation & Blockchain on 3G and & [12] \\  & monitoring & on Ethereum & Wi-Fi networks & \\ \hline  & \multirow{3}{*}{Vehicle ad hoc network} & Simulation & Decentralized IoV & [27] \\  & & & with blockchain & \\ \cline{2-5}  & Vehicle ad hoc & Simulation & Blockchain manage & [28] \\  & network & vehicles group keys & & \\ \cline{2-5} Blockchain & \multirow{3}{*}{Simulation} & Blockchain-based & \multirow{3}{*}{[30]} \\  & enhanced ad & & reputation & \\ \cline{2-5} hoc network & Routing & Simulation & Blockchain-based & [29] \\  & protocol & routing protocol & & \\ \cline{2-5}  & Mesh network & Simulation & Centralized and & [25; 26] \\  & & & distributed sensor & \\  & & networks & & \\ \hline  & Sensor & Simulation & Blockchain-base trust & [31; 32] \\  & networks & & management & \\ \cline{2-5}  & improved & Blockchain & Simulation & Analysis of split and & \\ \cline{2-5} blockchain & over ad hoc & & merge problems & [33] \\ \cline{2-5} network & network & Implementation & Recovery from node & \\  & & on Ethereum & failure with OLSR & This work \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Overview of the related works and ours. The OLSR protocol is a table-driven, proactive routing protocol for ad hoc networks. An OLSR node discerns links, detects neighbors, and decides Multipoint Relays (MPR) nodes with HELLO messages before establishing the routing table. It periodically broadcasts HELLO messages with its neighbors' information to reachable nodes. Upon receiving the HELLO messages with attached parameters, the receiver divides associated links into asymmetric link (ASYM_LINK), symmetric link (SYM_LINK), and lost link (LOST_LINK). The node records the sender to their one-hop neighbor set with an asymmetric link sensed.