In-depth research on Ad-hoc network routing protocols

In today's diverse communication modes, wireless networks have given us many things we dream. For example, the use of Ad-hoc networks makes more technologies possible. We will study its routing protocol in detail. We all know that although wireless communication systems differ in application scenarios, costs, and the maximum access rate, they share some common characteristics, that is, infrastructure must be deployed before the network is used, such as base stations, mobile exchange centers, access points, or satellites. However, in some specific application conditions, such as on-site disaster incidents and ever-changing battlefields, people need to quickly establish a network that can communicate with each other, however, such a network that requires infrastructure cannot meet the requirements of rapid deployment ｡

An Ad-hoc network is a mobile self-organizing network without infrastructure. It is a peer-to-peer network composed of several mobile user groups that want to communicate with each other, an autonomous system directly connected via a wireless link without any fixed infrastructure or central device. In this system, all nodes can be moved randomly, and can maintain contact with other nodes, that is, each mobile node acts as both a router and a terminal at the same time. When two user terminals cannot communicate directly, communication is usually achieved by means of the routing function of other nodes ｡

The routing protocol is the basis for communication between mobile nodes in the Ad-hoc network. It also directly affects QoS and security of communication services, the Research on Routing Protocols has been highly concerned by academic circles. Internet Engineering Task Force (IETF) has set up a mobile Ad-hoc Network Working Group called MANET, its main work is to research the routing of Ad-hoc networks. Many universities and research institutions at home and abroad are also engaged in Ad-hoc Routing Research ｡

Ad-hoc networks are characterized by multi-hop, dynamic topology, and wireless link transmission. Their routing protocols differ greatly from those of traditional wired networks: distance Vector Routing Protocol (Distance Vector Routing Protocol); Link State Routing Protocol (Link State Routing Protocol, it is unable to ensure that each node can grasp the latest topology information in a timely manner, and the convergence of the routing algorithm is poor. Meanwhile, the routing loop problem exists in the traditional distance vector algorithm, routing loops must be avoided in Ad-hoc routing algorithms based on distance vectors. However, in existing protocols, the routing loop solution is often complicated ｡

Currently, the existing MANET routes include proactive, reactive, and hybrid ｡

The proactive routing protocol is also known as the table drive protocol. The typical proactive protocols include DSDV and WRP. The routing discovery policies are similar to those of traditional wired routing protocols, each node must maintain a route to all nodes in the network. The advantage of this routing protocol is that when a node needs to send data groups, as long as the route to the destination node exists, the routing latency is very small, but the active routing requires a large cost to maintain the consistency of the entire network route table, as far as possible, route Updates can reflect changes in the current topology in a timely manner. Due to rapid changes in the topology, these route updates may become outdated information, and the routing protocol is always in a non-converged state ｡

The post-camera routing protocol, also known as the on demand protocol, is different from the first-line routing. reactive routing is considered to be in a dynamically changing self-organizing network, there is no need to maintain the routes to other nodes in advance. Only when the source node has a route group to send but not to the destination node, to discover routes sent by group. The topology and route table content are created on demand, it is only a part of the overall topology information. Its advantage is that it does not require periodic route information broadcast and saves some network resources. Its disadvantage is that when data packets are sent, if there is no route to the destination node, the route discovery will lead to a large delay. Typical reactive routes include ovv and DSR ｡

From the perspective of the transmission latency of data groups, the first-line game protocol is better than the reactive routing protocol. From the perspective of the efficiency of the routing protocol, the overhead of the reactive routing protocol is less than the first-line routing protocol; from the perspective of the Efficiency of obtaining the optimal route, the routes discovered by the First Routing Protocol are superior to the reactive routing protocol, although the two protocols are unsatisfactory, the reactive routing protocol is more suitable for wireless self-organizing networks ｡

Common Hybrid Routing Protocols include CGSR and ZRP. CGSR (Cluster Head Gateway Switch Routing) the Protocol is designed based on the DSDV protocol and the Cluster routing mechanism. CGSR uses the Least Cluster Change algorithm to form a Cluster structure. Besides the first node of the Cluster, CGSR also specifies the other two types of nodes. The internal node at the beginning of a group refers to the node within the wireless communication range at the beginning of the group, A gateway node is a node that is located within the wireless communication range of multiple groups at the same time. ZRP (Zone Routing Protocol) is the first self-network routing protocol that uses the cluster structure to mix on-demand and active routing policies ｡

Nodes in an Ad-hoc network are both a host and a router, you can find and maintain routes to other nodes in the network. The Ad-hoc network routing protocol aims to establish an effective route between the source node and the target node, and send data in a timely and reliable manner ｡

Routing may also be attacked. If a route is attacked, it is likely to paralyze the network. In recent years, the security of Routing Protocols has been highly concerned by researchers, in particular, the existing Ad-hoc routing protocols are vulnerable to attacks. There are two main types of routing attacks: passive attacks and active attacks ｡

A passive attack means that a malicious node does not disrupt the execution of the routing protocol, but only obtains useful routing information by listening to the communication process of the route. Due to the openness of radio waves, it is quite difficult to detect such malicious nodes ｡

Active attacks refer to malicious nodes that prevent the establishment of routes, change the packet transmission direction, interrupt the use of routes, and use false data to defraud the network for authentication and authorization. Active attacks can be further divided external and internal attacks. External attacks refer to attacks initiated by attackers outside the network, internal attacks refer to attacks initiated by malicious nodes that have been authenticated and authorized to become members of the network ｡

The routing black hole attack is a major internal attack method. It is the optimal route for a malicious node to claim that it has the target node, in this way, malicious nodes can easily intercept all data ｡