AdHoc network and wireless communication of lifting mobile communication system

Time：2020-12-30 View：

AdHoc
Ad Hoc is a mobile network without wired infrastructure. Nodes in the network are all composed of mobile hosts. Ad Hoc network was initially applied to the military field. Its research originated from the data communication project of packet wireless network in battlefield environment, which was funded by DARPA. Later, in 1983and 1994, the research on anti-destructible Adaptive Network SURAN(Survivable Adaptive Network) and Global mobile Information System GloMo(Global Information System) projects was carried out. Due to the continuous development of wireless communication and terminal technology, the Ad Hoc network has also been developed in the civil environment. If temporary communication is required in areas without wired infrastructure, you can easily build a Ad Hoc network.
In A Ad Hoc network, when two mobile hosts (hosts A and B in figure 1) are within the communication coverage of each other, they can communicate directly. However, due to the limited communication coverage of mobile hosts, if two hosts (hosts A and C in figure 1) are far away from each other to communicate, the forwarding of mobile host B between them is required. Therefore, in the Ad Hoc network, the host is also a router, which is responsible for finding routes and forwarding packets. In the Ad Hoc network, the communication range of each host is limited, so routes are generally composed of multiple hops, and data can reach the destination only through forwarding of multiple hosts. Therefore, Ad Hoc network is also called multi-hop wireless network. Its structure is shown in figure 2.
Ad Hoc network can be regarded as the intersection of mobile communication and computer network. In Ad Hoc networks, the packet switching mechanism of computer networks is used instead of the circuit switching mechanism. The host of communication is generally a mobile terminal device such as a portable computer and a personal digital assistant (PDA). Ad Hoc networks are different from mobile IP networks in Internet environments. In mobile IP networks, mobile hosts can access the network through fixed wired networks, wireless links, and dial-up lines. In Ad Hoc networks, only wireless links exist. In the mobile IP network, the mobile host can communicate through the support of wired facilities such as adjacent base stations, and both the base stations and the base stations (agents and agents) are wired networks, the traditional routing protocol of the Internet is still used. The Ad Hoc network does not have the support of these facilities. In addition, the mobile host does not have routing function in the mobile IP network, but is a common communication terminal. When a mobile host moves from one zone to another, the network topology does not change. However, the movement of a mobile host Ad Hoc the network will cause the topology to change.

Wireless communication
Packet radio network is a communication network that uses wireless channels for packet exchange, that is, the information transmitted in the network should be "packet" or "packet" as the basic unit.
A group is an information segment composed of several bits. It usually contains "header" and "body. The header contains information such as the source address, sink address, and related routes of the group. The text is the information that really needs to be transmitted.
Applicable features: packet wireless network is especially suitable for data communication with lax real-time requirements and more short messages.
Network structure: Star structure distributed structure