Ad Hoc Network Technology for Wireless Sensor Networks

2019-08-09 12:13:44

Ad Hoc Network Technology for Wireless Sensor Networks

Ad-Hoc network is a multi-hop temporary autonomous system. Its prototype is the ALOHA network established in 1968 in the United States and the PR (Packet Radio) network proposed in 1973. ALOHA network needs a fixed base station. Every node in the network must be directly connected with all other nodes in order to communicate with each other. It is a single-hop network. Until PR network, there was a real multi-hop network. The nodes in the network did not need to be connected directly, but could transmit information between two nodes which were far away and could not communicate directly through relay. PR network is widely used in military field. When IEEE develops 802.11 standard, it proposes to rename PR network as Ad-Hoc network, which is what we often call mobile ad hoc network today.

Self-organizing network is a self-organizing reconfigurable multi-hop wireless network without the support of predetermined infrastructure. In this network, the network topology, channel environment and service mode change dynamically with the movement of nodes. The network can quickly establish a communication platform for civil and military applications. Self-organizing network (SON) has received extensive attention since it came into being. At present, self-organizing networks have been effectively combined with 2.5G and 3G mobile communications, and large-scale broadband wireless adaptive self-organizing networks will become an important form of broadband wireless communications or future mobile communications. The wireless transceiver modules, such as SI4463 and SI4432, independently developed by Fuzhou Yilian Electronics, can be self-organizing networks and play an important role in self-organizing network communication.

For mobile ad hoc networks, on the one hand, the packet switching mechanism in the computer network is used for network information exchange, rather than the circuit switching mechanism in the telephone switching network; on the other hand, the user terminal is a portable mobile terminal, such as notebook, PDA and so on, and the user can be in a mobile or static state at any time. Each user terminal in wireless ad hoc network has two functions: router and host. As a host, the terminal can run various user-oriented applications; as a router, the terminal needs to run the corresponding routing protocol. This distributed control and centralized network structure can maintain the remaining communication capacity after some communication networks are destroyed, and has strong robustness and survivability.

As a distributed network, MANET is an autonomous, multi-hop network. The whole network has no fixed infrastructure. It can provide communication between terminals without using or inconvenient using existing network infrastructure (such as base station and AP). Because of the limited transmission power and wireless coverage of the terminal, if two terminals with a long distance want to communicate, they must use other nodes for packet forwarding. Thus, a wireless multi-hop network is formed between the nodes.

Mobile terminals in the network have the functions of routing and packet forwarding, and can form arbitrary network topology through wireless connections. Mobile ad hoc networks can work independently as separate networks, and can also access existing networks, such as the Internet and cellular networks, in the form of end-to-end subnetworks.