In the past, a large number of optical fiber networks were used in the power communication private network. Once a natural disaster occurred, it would pose a serious threat to the normal operation of the optical cable. It is likely that a large-scale interruption of the optical cable will occur. When the conditions are met, it takes a long time, which will have a serious impact on the safe operation of the power grid.
Wireless communication networking technology
Wireless communication is generally composed of wireless base stations, wireless terminals and application management servers. Currently, there are mainly four wireless communication technologies based on this technology; WEAN, WiMax, WMN, 3G and other four technologies.
1. WLAN technology
1.1 WLAN is a network established in a certain local area using wireless communication technology. It is a product of the combination of computer network and wireless communication technology. It uses wireless multiple access channels as a transmission medium to provide the function of traditional wired local area network LAN, enabling users Realize anytime, anywhere, random broadband network access. WLAN technology is also known as wi-Fi technology, and there are currently three IEEE standards.
The coverage of Wi-Fi can reach about 90m, and the transmission speed is fast. The bandwidth of 802.11b can reach 11Mbit / s, while 802.11a and 802.11g can reach 54Mbit / s. This technology can form a wireless local area network, especially in offices on the same floor can use wireless office, and its transmission rate can effectively meet the needs of broadband networking.
1.2 The WIAN networking solution is composed of AC (access control point) + AP (access point) + wireless network card + network management.
1.3 Although Wi-Fi technology has been widely used, it still has certain security risks in security. Wi-Fi uses radio frequency (RF) technology to send and receive data. Because wireless networks use radio waves to transmit data signals, they are very vulnerable to attacks from outside.
2. WiMax technology
2.1 Introduction to WiMax Technology
The standards used by WiMax are 802.16d and 802.16e, and the wireless signal transmission distance can be up to 50 kilometers. WiMax is an emerging wireless communication technology that can provide high-speed Internet-oriented connections and is suitable for static and semi-static state access to the network. Its transmission rate can reach 10M-70M, which can fully meet the needs of broadband Internet access. The 802.16e standard defines the physical layer and MAC layer in the air. 802.16e accesses the IP core network, and can also provide VIP services, supporting a point-to-multipoint structure.
WiMax is a wireless broadband access technology that provides the last mile and can replace existing wired and DSL connections. WiMax will provide wireless broadband connections in fixed, mobile, and portable formats, and will eventually be able to provide wireless broadband connections without requiring direct line-of-sight base stations.
2.2WiMax networking solution
The network structure of the WiMax system includes WiMax terminals, WiMax wireless access network, and WiMax core network, as shown in Figure 1. According to different standards and application scenarios, WiMax terminals include three types: fixed (802.16-2004), portable, and mobile (802.16e).
The WiMax access network mainly refers to the base station and needs to support functions such as wireless resource management. Sometimes, to facilitate interconnection with other networks, it also needs to include an authentication and service authorization (ASA) server. The core network is mainly used to solve user authentication, roaming and other functions and as an interface with other networks.
2.3 WiMax advantages and disadvantages
From the perspective of security, WiMax provides an encryption mechanism. It defines an encryption sublayer in the media access layer (MAC), supports 128-bit, 192-bit, and 256-bit encryption systems. By using digital certificate authentication, it ensures wireless The information transmitted within the network is securely protected.
From the perspective of maturity, WiMax is an advanced technology. It is relatively late to launch, with problems of low frequency reuse and low utilization rate. However, due to the recent completion of standardization, the large-scale promotion of this technology still needs practical tests.
From the perspective of application prospects, the technology can meet the Internet access requirements in a larger range, and the coverage can include outdoor and indoor, can cover a large area of ​​signal coverage, and even a few base stations can achieve city-wide coverage.
Because of its advanced technology and ultra-long transmission distance, WiMax has always been optimistic by the industry as the future development direction of mobile technology, providing excellent last-mile network access services.
3. WMN technical analysis
3.1 Introduction to WMN Technology
WMN, the wireless mesh network technology, is a special form of mobile AdHoc network. Its early researches all originated from the research and development of mobile AdHoc network. It is a high-capacity and high-rate distributed network, which is different from the traditional wireless network. It can be regarded as a fusion of WEAN and AdHoc networks, and takes advantage of the two. As a way to solve the "last mile" "A new network structure for bottlenecks.
WMN has unique advantages such as broadband wireless convergence connection function, effective routing and fault discovery features, and no need for wired network resources.
In actual network development, it can be combined with a variety of broadband wireless access technologies such as 802.11, 802.16, 802.20, and 3G mobile communications to form a multi-hop wireless link wireless mesh network. This wireless mesh network can effectively reduce fault interference, reduce transmitter power, extend battery life, and greatly improve frequency reuse, thereby improving network capacity, wireless network coverage, and effectively improving communication reliability.
3.2 WMN networking solution
In a network constructed using wireless mesh technology, the topology is grid-like, and the entire network is composed of the following components: intelligent access point (IAP / AP); wireless router (WR); end user / device (client ).
3.3 WMN advantages and disadvantages
From the perspective of security, the current security solutions for 802.11Mesh networks are mainly Tropos' TroposMetroMesh solution and Nortel's solution. The Tropos Metro Mesh solution uses a multi-layer security architecture to provide WEP and WPA protection to clients; data between wireless routers is encrypted with 64 / 128bit WEP or 128bit AES; and VPN is used to enhance overall security. Link layer protection is the first step in a wireless network security mechanism, but separate link layer protection cannot provide protection for sensitive data.
Nortel is also unique in security. An encrypted IPSec tunnel is established between each wireless router. In order to safely transmit all users' data services, internal signaling processing and management information, that is to say, the transmission of data between wireless routers is under IPSee protection.
From the perspective of maturity, WMN is a technology under study. In the research, it has continuously combined with the characteristics of various technologies in different aspects, and there is no mature product series to support the large-scale application of the technology.
From the perspective of application prospects, WMN, an emerging network, not only has a broad application space in wireless broadband access, but in other aspects such as combining data and image acquisition modules, it can monitor or collect data on target objects, and is widely used in environmental detection, Industry, transportation, etc.
With the continuous updating and improvement of other technologies, WMN is better integrated and complementary with it, so that it can develop its advantages and avoid its weaknesses.
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