AdHoc wireless network routing protocol design analysis and requirements

The specific design of AdHoc wireless network routing protocols will be the focus of this article. The introduction of routing protocols, network topologies, and other related technologies gives you a better understanding.

1. AdHoc wireless network routing protocol design requirements

A key issue in AdHoc Network Design is the development of a routing protocol that can provide high-quality and efficient communication between two nodes. The mobility of network nodes keeps the network topology changing. The traditional internet-based routing protocols cannot adapt to these features. Therefore, a routing protocol dedicated to AdHoc networks is required, based on the AdHoc Network Structure and features described above, the designed routing protocol must meet the following conditions:

(1) It is necessary to have the ability to quickly adapt to the dynamic changes of the network topology, and to avoid the occurrence of routing loops as much as possible, providing a convenient and simple network node location method.

(2) You must use limited bandwidth resources efficiently to reduce unnecessary overhead as much as possible.

(3) The number of intermediate transfers for multi-hop communication is also limited. Generally, the number should not exceed 3.

(4) The launch time and data volume must be minimized to save limited work energy.

(5) When possible, make the designed Routing Protocol Secure and reduce the possibility of attacks.

2. AdHoc wireless network routing protocol analysis

At present, the MANET team of IETF is focusing on AdHoc Network Routing Protocols, and has put forward many protocol drafts, such as DSR, Oscar, ZRP, and other routing protocols. In addition, professional researchers also published a large number of articles on AdHoc Network Routing Protocols, and proposed many AdHoc Network routing protocols, such as DSDV and WRP. According to the routing trigger principle, the current routing protocols can be roughly divided into a prior routing protocol, a reactive routing protocol and a hybrid routing protocol.

(1) Prior Routing Protocol

The predicate routing protocol is also known as the table-driven routing protocol. Each node maintains a route table containing route information arriving at the node, and updates the route table at any time based on changes in the network topology, therefore, the route table can accurately reflect the network topology. Once the source node sends a message, it can immediately obtain the route to the target node, this type of routing protocol is usually used to adapt to AdHoc wireless network requirements by modifying the existing wired routing protocol, such as by modifying the routing information protocol (RIP) the obtained target node sequence distance vector protocol (DSDV ). Therefore, the delay of this routing protocol is small, but the Protocol requires a large number of routing control packet routing, the Protocol overhead is large. Common prior routing protocols include DSDV, HSR, GSR, and WRP.

DSDV avoids the generation of routing loops by setting serial numbers for each route. It uses time-driven and event-driven technologies to control the transmission of Route tables, that is, each mobile node retains a route table locally, the information includes all valid sink points, route hops, and serial numbers of the destination route. The serial numbers of the destination route are used to distinguish between the new and old routes to avoid loop generation. Each node periodically transmits the local route table to a neighboring node, or when its route table changes, it also transmits its route information to the neighboring node, when no node moves, large data packets with long intervals (including multiple data units) are used for Route updates. After the neighboring node receives information about the modified route table, first, compare the size of the serial number of the source K destination route. A route with a large serial number will be used, while a route with a small serial number will be eliminated, the optimal standard routing (such as the shortest path) is used ).

HSR (HierarchicalStateRouting) is a routing protocol used for hierarchical networks. An advanced node stores the location information of all its child nodes, the logical sequence address is allocated to the node along the path from the highest root node to the lowest leaf node. You can use the sequence address for node addressing.

GSR is a global state routing protocol. It works in a similar way as DSDV. It uses a link state routing algorithm, but avoids the flooding of routing packets, it includes a nearby node table, network topology table, next hop route table, and distance table.

According to the particularity of AdHoc wireless network routing protocols, a variety of Adhoc Network Routing Protocols have been proposed in recent years. WRP is a distance-vector routing protocol. Each node maintains a distance table, route table, link overhead table, and packet retransmission table, generate your own SST using the Shortest Path of the adjacent node, and then pass the update information to the adjacent node. When the network route table does not change, the receiving node must return an idle message to indicate the connection. Otherwise, modify the distance table to find a better path. This algorithm is characterized by checking the robustness of all adjacent nodes to eliminate loops when any neighboring node changes are detected, with fast convergence.

(2) reactive routing protocol

The reactive routing protocol, also known as the on-demand routing or on-demand routing, is a Routing Method for Finding routes when needed. The node does not need to maintain timely and accurate routing information. It initiates a route query process only when data needs to be sent. Compared with the prior routing protocol, the reactive routing protocol has a low overhead, but the latency of datagram transmission is large, which is not suitable for real-time applications. Commonly used reactive routing protocols include ovv, DSR, and TORA.

AdhocOndemandDistanceVectorRouting Protocol: the source node broadcasts a route request message before sending data, and the nearby node broadcasts the message again after receiving the message, until the request message arrives at the target node or the intermediate node that knows the route of the target node, the target node or intermediate node returns a response message along the original path, after receiving the response, the source node will know the route to the target node.

The DSR protocol is called the Dynamic Source Routing Protocol and is a source routing protocol. The packet header of each group contains the entire source-destination routing information. It uses the routing Cache Technology to store source route information. When a new route is learned, the content of the route cache is modified. This protocol includes two aspects: route discovery and route maintenance.

The TORA protocol is a source-class initialization on-demand routing selection protocol. It adopts a link inversion distributed algorithm and is highly adaptive, efficient, and scalable, it is suitable for highly dynamic mobile and multi-hop wireless networks. Its main characteristic is that the control message is located at a small part of nodes closest to the topology change, therefore, the node only retains the route information of the neighboring point. In this algorithm, routes are not necessarily optimal. Therefore, sub-optimal routes are often used to reduce the overhead of route discovery.
TORA consists of three basic modules: Route creation, route maintenance, and route deletion.

(3) Hybrid Routing Protocol

Adhoc wireless networks cannot completely solve the routing problem simply by using a prior or reactive routing protocol. Therefore, many scholars have proposed a Hybrid Routing Protocol that combines the advantages of a prior and reactive routing protocol, for example, ZRP protocol. ZRP is a combination of a prior and reactive routing protocol. All nodes in the network have a self-centered virtual zone. The number of nodes in the zone is related to the configured zone radius, therefore, zones overlap, which is different from group routing. A prior routing algorithm is used in the zone, and the central node uses the region routing protocol IARP to maintain a route table for other members in the zone, use on-demand routes for nodes outside the region, and use the interval routing protocol IERP to establish temporary routes.

However, the implementation of Hybrid Routing also faces many difficulties, such as the selection and maintenance of the family, the rational selection of prior and reactive routing protocols, and the high traffic of network work.

3. Summary and prospects

This article first describes the structure and features of AdHoc wireless network routing, puts forward the conditions to be met when designing AdHoc Network protocols, and analyzes the existing routing protocols in detail. However, in the AdHoc Network, the routing function is executed by the mobile host, so the router location is mobile. the AdHoc Network's limited working energy cannot provide complex routing functions; the dynamic variation of the network topology makes it possible that the optimal routing protocol may be interrupted or not optimal. These problems make the routing algorithms in the Adhoc Network a hot topic of current research.

In recent years, more and more researchers have begun to pay attention to the application of mobile proxy technology. Some scholars have put forward theories such as the topology structure of Mobile Networks Based on Mobile proxy technology and the realization of Dynamic Routing Algorithms of wired networks. Mobile proxy technology is characterized by mobility and autonomy. Therefore, it is suitable for mobile networks. The research on Adhoc wireless network routing protocols based on mobile proxy technology will become the focus of Adhoc wireless network routing technology research in the future.

1. Details about the structure and features of AdHoc Wireless Network Routing
2. Solutions to common faults in Wireless Networks
3. Broadband Wireless Network Learning notes
4. Discussion on the Development Trend of Wireless Network Access Technology
5. Development Trend of wireless network convergence applications