Mesh will bring significant changes to broadband wireless applications

At present, wireless network technology has received more and more attention. Among them, a new broadband wireless network structure-Wireless Mesh Network (WMN) is becoming a hot topic in wireless network research. WMN is a special form of mobile AdHoc networks (MANET). It is a new structure of broadband wireless networks. It is regarded as the convergence of Wireless LAN and AdHoc networks, and has both advantages. Standards for wireless Mesh networks are described in the 802.11 s, 802.15.1/2/3/4, 802.16d, and other standards. At present, the International Organization for Standardization (ISO), especially IEEE, is working with academia to promote the standardization of wireless Mesh networks. Mesh networking technology should be introduced into standards such as 802.20 and 802.15.5.

The topology of a network built using WMN technology is grid-like. There are two types of nodes in WMN: a wireless Mesh router and a wireless Mesh terminal user. The network trunk is connected by a network-structured router.

WMN has two typical implementation modes: infrastructure Mesh mode and end user Mesh mode. In the infrastructure Mesh mode, a wireless loop can be formed between an Internet Access Point (IAP) and an end user. In the end user Mesh mode, end users form a point-to-point network through wireless channel connection. The terminal device can run independently without other infrastructure. It can support mobile terminals to move at a high speed and quickly form a broadband network.

The differences between WMN and mobile AdHoc networks are mainly manifested in two aspects: first, the networking mode is different. Mobile AdHoc networks are flat, while WMN is hierarchical and hierarchical. Multiple small Ad-Hoc networks are formed within each layer. Different layers are connected through wireless connection, it combines centralized control management with free dynamic networking. Second, they solve different problems. The mobile AdHoc Network is designed to implement peer-to-peer communication between users' mobile devices. For example, the network can be quickly deployed in the case of an emergency. WMN focuses on providing wireless access for user terminals, for example, wireless broadband access with 3G and WiMAX users.

A key issue in WMN design is the development of a routing protocol that provides high-quality and efficient communication between two nodes. Because of the changing network topology structure due to the mobility of its network nodes, the traditional In-ternet Routing Protocol cannot adapt to these features. Therefore, a dedicated routing protocol is required for wireless Mesh networks. When designing a routing protocol, consider the following:

Select a proper path algorithm. When selecting a path, you should not only consider the minimum number of hops, but also consider factors such as network connection quality and round-trip latency.

Make sure that the connection fails fault tolerance. One of the goals of WMN is to ensure the robustness of the network when the connection fails. If a connection fails, the routing protocol must quickly select another path to avoid service interruption.

Achieve network load balancing. Another purpose of using WMN is to share resources with users. When a part of WMN suffers data congestion, the path with low traffic should be selected for the new data.

It can meet the needs of different types of nodes at the same time. When designing the WMN routing protocol, we must fully consider the differences between routers and end users to meet their needs.

If you only want to improve the performance of a certain layer of protocols, the effect is not obvious. At present, the development trend of WMN is cross-layer design, that is, to consider the impact of multiple layers at the same time. The cross-layer design requirement of WMN breaks the strict hierarchy constraint in the traditional OSI/RM reference model, and aims at the different states and requirements of related modules/protocols at each layer, overall network performance is optimized using the dependency and impact between layers. Specifically, the cross-layer design aims to make full and reasonable use of existing network resources to maximize the total throughput of the system, minimize the total transmission power, and optimize QoS.

WMN technology can be applied to the "Last Mile" of military command communication networks, wireless MAN networks, wireless sensor networks, wireless LAN and other networks ". At the same time, the construction of WMN involves mobile communication, computer networks, microelectronics technology and other fields, attracting the attention of a wide range of operators, equipment suppliers and wireless value-added business integrators. However, the WMN technology is still facing some challenges.

From the wireless technology point of view, the application requirements of cooperative communications between mobile user nodes and shared spectrum resources will bring about the convergence and interoperability between different wireless technologies; from the perspective of the standardization of WMN technology, there are still many uncertainties about whether to consider integrating other existing wireless network technology standards into WMN technology. From the perspective of application, this technology has not been widely recognized by all sectors of society. In the future, the main research direction of WMN technology is to solve the challenge. In the future, WMN will surely bring significant changes to wireless broadband applications.

Related Articles]

• Mesh finds development opportunities along with "Wireless City"
  

• Wireless Mesh networks are three barriers away from large-scale applications
  

• Tempe Arizona uses wireless wi-fi mesh fixed and mobile broadband services