The development of mesh network is imperative. The new generation wireless mesh network aims to provide high performance and high reliability services. This paper briefly introduces the technical principle, network architecture and protocol of wireless Mesh network, analyzes its advantages, and looks forward to its future application prospect.
In recent years, wireless networks have developed by leaps and bounds. According to different applications and requirements, many new wireless communication technologies and standards have emerged, and wireless mesh network is one of the new technologies that people pay attention to. WMN is a new network technology, namely mesh network. Its topology is dynamic, and it has the functions of self-organization and self-healing, that is, it can automatically form a network without manual intervention, and each terminal can join or quit freely. When transmitting information, the information is continuously forwarded through multiple hops until the destination terminal. If this technology is applied to the networking of wireless sensors, Wi-Fi (Wireless Fidelity), WiMAX (Worldwide Interoperability for Microwave Access) and other technologies, it can expand its application scope and enhance its functions, thus forming a wireless sensor network, improving the coverage of wireless local area networks and forming a metropolitan area network. Because of its broad application prospects, people pay more and more attention to it and apply it to life and work.
Wireless mesh network is a low-power multi-hop system. They process messages by passing packets from one node to another until they reach their destination. Peer-to-peer network nodes filter out all packets, leaving only their own packets. In contrast, a mesh node receives packets to be sent to other nodes and sends them again. Each node of wireless Mesh network can be used as an access terminal, and it also has the functions of routing and information forwarding, so it has high networking freedom. Wireless mesh networks operate in a very similar way.
Private network, and provide multiple redundant communication paths from the source to the destination. If a person
Due to hardware failure or interference, the path stops working, and the mesh network will automatically change the message.
Route the packet through another path.
There are two types of nodes in WMNs: routers or clients. Among them, the routers that form the backbone of the network have little mobility, and they provide connections with other networks (such as
Internet, cellular network, IEEE802, sensor network) connecting gateway and road and bridge functions; Clients can be fixed or mobile, and they can form their own network or the same network as the routers of mesh networks.
Wireless multi-hop. By reducing the transmission power of wireless nodes, multi-hop transmission between nodes can be realized, which can not only effectively reduce the energy consumption of nodes, but also reduce the interference between nodes, improve the spatial reusability of wireless channels, and thus improve the network capacity.
Self-organization and self-repair ability. Wireless mesh network is flexible, easy to configure and self-repairing, and the nodes are distributed in the mesh network. The network has strong expansibility and can realize multipoint-to-multipoint wireless communication.
Liquidity According to the types of nodes, the mobility of routing nodes is required to be minimum, and client nodes can move flexibly.
Access mode. Flexible and diverse, it can be networked with Internet, cellular network, sensor network, etc.
Energy consumption pattern. Generally speaking, the energy consumption of routing nodes is not strictly limited, while client nodes usually need to implement energy-saving protocols.
Compatibility and interoperability. Good compatibility with existing wireless networks and strong interoperability.
From another point of view, WMN topology and architecture analysis absorbs the advantages of star and mesh networks and is a seamless integration of them. This integration is accomplished by executing WMR (Wireless Mesh Routing) protocol on network nodes (see figure 1).
As can be seen from figure 1, in order to provide multi-reflection wireless routing function, WMR routing protocol is implemented on both access points and mobile nodes. At the same time, in order to achieve compatibility with IP, WMR is placed between MAC layer and IP layer as the middle layer protocol, which makes WMR protocol can be well implemented without making too much changes to other protocol layers. This makes WMR compatible with most existing applications (including wireless standards represented by 802. 1 1x).
Compared with traditional wireless networks, WMN has many advantages.
(1) reliability is greatly enhanced.
The grid topology adopted by WMN avoids the service convergence, central network congestion, interference and single point failure caused by centralized control mode in point-to-multipoint star structures such as 802.1/WLAN and cellular network, thus bringing additional reliability guarantee cost investment.
(2) It has a conflict protection mechanism.
WMN can identify the links that collide, and the included angle between the optional link and its own link is obtuse, which reduces the interference between links.
(3) Simplify the link design
WMN usually requires a short wireless link length, which reduces the cost (transmission distance and performance) of the antenna. On the other hand, the transmission power is reduced, which will also reduce the interference between RF signals of different systems and system self-interference, and finally simplify the wireless link design.
(4) The network coverage has been expanded.
Due to the introduction of WR and IAP, end users can access the network or contact other nodes anywhere. Compared with the traditional network, the access point range is greatly enhanced, the spectrum utilization rate is improved, and the system capacity is increased.
(5) Flexible networking and convenient maintenance.
Due to the networking characteristics of WMN network itself, as long as a small number of wireless devices such as WR are added where necessary, existing facilities can be used to form a wireless broadband access network. The routing characteristics of WMN network make the link interruption or local expansion and upgrading not affect the operation of the whole network, thus improving the flexibility and feasibility of the network, which is more powerful and perfect than the traditional network.
Mesh networks have broad application prospects in many fields such as families, enterprises and public places.
(1) family
An important use of wireless mesh network is to establish a home wireless network. Home wireless Mesh network can connect desktop PC, notebook computer, HDTV, DVD player, game machine and other consumer electronic devices without complicated wiring and installation process. In the home wireless Mesh network, various household appliances are not only online users, but also provide access services for other devices as part of the network infrastructure. When the number of household appliances increases, this networking mode can provide greater capacity and wider coverage. Another advantage of wireless Mesh network in home applications is that it can support applications with high bandwidth concentration, such as high-definition video.
(2) Enterprises
At present, most wireless communication systems in enterprises use traditional cellular telephone wireless links to provide users with point-to-point and point-to-multipoint transmission. Wireless Mesh network is different, it allows network users to enjoy bandwidth, eliminates the bottleneck of current single-hop network, and can realize the dynamic balance of network load. Adding or adjusting an AP in a wireless mesh network is also easier, more flexible in configuration and lower in installation and use cost than wired AP. Especially for those enterprises that need to move access points frequently, the flexible multi-hop structure and configuration of wireless Mesh network will be very beneficial to the adjustment and upgrade of network topology.
(3) School
Campus wireless network is very similar to large enterprises, but it also has its own different characteristics. First, the campus WLAN is large in scale, which not only has a large geographical scope and many users, but also has a large amount of communication, because students use multimedia more than ordinary enterprise users; Second, the network coverage requirements are high, and the network must be able to realize seamless roaming between indoor, outdoor, auditorium, dormitory, library and public places; Third, load balancing is very important. Because students often concentrate on activities, when students use the network in a certain place at the same time, communication congestion may occur.
The traditional way to solve these problems is to install high-density APS indoors, but the number of APS installed outdoors is very small. However, due to the great changes in the user demand of campus network, it may be necessary to add new APS or adjust the deployment position of APS frequently, which will bring great cost increase. However, using wireless Mesh network is not only easy to upgrade and adjust the network structure, but also can realize seamless roaming outdoors and indoors.
(4) Hospital
Wireless mesh network also provides an ideal networking scheme for public places such as hospitals. Due to the dense and complex structure of hospital buildings, some areas must be protected from electromagnetic radiation, so it is one of the most difficult areas to install wireless networks. Hospital network has the characteristics of difficult wiring and high requirements for network robustness. Wireless mesh network is an ideal solution to these problems. If we want to adjust the hospital wireless network topology, we only need to move the existing Mesh nodes or install new Mesh nodes. The process is very simple, and it is very convenient to install new grid nodes. The robustness and high bandwidth of wireless grid also make it more suitable for hospital deployment.
(5) Tourism and leisure places
Wireless Mesh network is very suitable for remote places where wiring is difficult or uneconomical, but it needs to provide users with broadband wireless internet access, such as tourist places, resorts, motels and so on. Wireless mesh networks can provide broadband services for these places at the lowest cost.
(6) Rapid deployment and temporary installation
For those places that need rapid deployment or temporary installation, such as exhibitions, trade fairs or disaster relief, wireless Mesh network is undoubtedly the most economical and effective networking method. For example, it is necessary to temporarily hold a meeting or exhibition in a certain place for a few days, and networking with wireless Mesh network can minimize the cost.
WMN not only has broad application prospects in many fields, such as families, enterprises, public places, etc., but also can monitor or collect data on target objects in other aspects, such as combining data and image acquisition modules, which are widely used in environmental detection, industry, transportation and other fields. With the continuous updating and improvement of other technologies, WMN can better integrate and supplement them and give full play to their respective advantages.