Wireless Network Technology and Characteristics

Wireless network technology and characteristics

Wireless networks are widely used in many areas of social life because of its flexibility, scalability, mobility and other advantages, it can be said that at this stage of people's daily life has been unable to leave the wireless network system. Below I have searched for you to organize the wireless network technology and characteristics, welcome to read, I hope to help you!

Wireless network technology and features Part 1

First, the classification of wireless networks

1. Wireless personal area network

Wireless personal area network (or wireless personal area network). It is where electronic devices belonging to personal use are connected by wireless technology at the individual's workplace, and the range of the entire network is about 10 meters.

2. Wireless LAN

Wireless LAN is the use of wireless communication technology in a certain local range of the establishment of the network is a combination of computer networks and wireless communication technology, it is a wireless multi-access channel as a transmission medium, to provide the traditional wired LAN functions, enabling users to truly realize anytime, anywhere, at will broadband network access.


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3. Wireless Metropolitan Area Network

Wireless Metropolitan Area Network refers to the user in a certain urban area between a number of places to establish a wireless connection, do not have to spend a lot of money laying fiber optic cables, cables and external leased lines. In addition, WMAN can be used as a backup network when the leased lines of the cable network broadband are not intact.The use of WMAN is to transmit data through radio waves, infrared light waves. Although we are currently using a variety of different technologies, such as Multiplexed Multipoint Distributed Service (MMDS) and Local Multipoint Distributed Service (LMDS), the IEEE 802.16 technical staff responsible for setting standards for wireless access to broadband over the Internet are still developing specifications to standardize these technologies.

4. Wireless Wide Area Networks

Wireless Wide Area Networks (WANs) are wireless networking technologies that are established by users over a remote public or private subscriber network. It can cover a large geographic area, primarily through the use of a number of antennae base stations or satellite systems maintained by the wireless service provider. The current wireless network technology is known as the second generation system (which we commonly refer to as 2G). Second generation systems (2G) include Global System for Mobile Communications (GSM), Cellular Digital Packet Data (CDPD) and Code Division Multiple Access (CDMA). Efforts are underway to transition from second-generation (2G) networks to third-generation (3G) technologies.

Second, the characteristics of wireless networks

1. More flexible

Wireless networks can more easily take care of wired networks can not be taken into account in the place, and set up is very convenient. For often need to change the network cabling structure and users need to move a wider range of computers, the use of wireless LAN can overcome the inconvenience caused by cable limitations, for the time constraints, the need for rapid establishment of communications and the use of wired network setup inconvenient, costly or time-consuming situation can be the use of wireless LAN.

2. Speed is only a hundred megabytes, but it's easier to use

Gigabit wired networks have long been in the mainstream of backbone networks, but in the real world of home or small office applications, hundred megabytes of wired networks are still the absolute mainstream. So from a practical point of view, the current wireless network has been able to provide close to the speed of the wired network. Although this speed guarantee is more demanding on the distance requirements, but the convenience and performance of the contradiction between the entire current network technology, are required to break through.

3. Security has been able to protect common applications

Wireless products now offer multiple security protections. It supports 64/128/152-bit WEP data encryption, as well as WPA, IEEE 802.1X, TKIP, AES and other encryption and security mechanisms. It also supports SSID broadcast control, MAC address-based access control, coupled with strong firewall features to effectively prevent intrusion and provide strong security for wireless communications.

4. The price is higher than wired, but acceptable

For the average home user and small office user, the main comparison for wireless is the 100Gb wired home network. Again, the inputs can be categorized into two types of inputs to form a small home wireless network with four computers, for example. Formation of Ad-Hoc peer-to-peer network, do not need to invest in wireless AP, only need to buy a wireless network card. To already have a laptop computer integrated with two wireless cards, for example, but also need to buy two cards for other computers. While some 11M products can be picked up for $60-80, 54M products still cost more than $100.

If you're building an Infrastructure-centric wireless network, a wireless AP is a necessity. As the market for simple SOHO-grade wireless APs has been eliminated, a wireless router that combines a wireless AP and a broadband router has become a must-have.

Three mainstream technologies and features of wireless networks

1. Wireless broadband

Wi-Fi is commonly referred to as wireless broadband, that is, IEEE 802.11b alias, which is a short-range wireless transmission technology, capable of supporting Internet access within a geographic range of several hundred meters. range to support Internet access a radio signal. With the development of network technology and the emergence of standards such as IEEE 802.11a and IEEE 802.11g, the IEEE 802.11 standard has been collectively referred to as wireless broadband (i.e., Wi-Fi). In practical terms, to use wireless broadband (Wi-Fi), users must first have a client device that is compatible with Wi-Fi.

Wireless network technology and features Part 2

1. Introduction

Communication networks with the rapid development of INTERNET, from the traditional wiring network to the development of a wireless network, as one of the wireless network wireless local area network (WLAN) (Wireless Local Area Network) to meet the dream of people to realize the mobile office. As one of the wireless networks, WLAN (WirelessLocalArea Network) can satisfy people's dream of realizing mobile office and create a colorful and free sky for us.

2. The concept of WLAN

WLAN is the use of wireless communication technology in a certain local range of the establishment of the network, is a combination of computer networks and wireless communication technology products, it is a wireless multi-access channel as a transmission medium, to provide the traditional wired LAN (LocalAreaNetwork). It uses a wireless multi-access channel as the transmission medium, and provides traditional wired LAN (Local Area Network) functions, enabling users to truly realize broadband network access at anytime, anywhere, and at will.

3. Characteristics of WLAN

WLAN began as an extension of wired LANs, and groups, enterprises, and institutions have widely adopted WLAN technology to build their office networks. But with the further development of the application, WLAN is gradually from the traditional sense of the local area network technology to become a "public **** wireless LAN", become the international Internet INTERNET broadband access means. WLAN has easy to install, easy to expand, easy to manage, easy to maintain, high mobility, confidentiality, anti-interference and other characteristics. WLANs are easy to install, easy to expand, easy to manage, easy to maintain, highly mobile, secure, and resistant to interference.

4. WLAN standards

Because WLAN is based on computer networks and wireless communication technology, in the computer network structure, the logical link control (LLC) layer and its application layer above the different physical layer requirements can be the same, or different, so the WLAN standard is mainly for the physical layer and media access control layer. For the physical layer and medium access control (MAC) layer, it involves technical specifications and technical standards for the range of radio frequencies used, air interface communication protocols, and so on.

4.1 IEEE802.11X

(1) IEEE802.11

In 1990, the IEEE802 Standardization Committee established the IEEE802.11 Working Group on WLAN Standards. IEEE802.11 (alias: Wi-Fi (WirelessFidelity) wireless fidelity) is in June 1997 by a large number of local area networks as well as computer experts to validate the adoption of the standard, the standard defines the physical layer and media access control (MAC) specifications. The physical layer defines the signal characteristics and modulation for data transmission, defines two RF transmission methods and one infrared transmission method, and the RF transmission standards are frequency hopping spread spectrum and direct sequence spread spectrum, operating in the 2.4000 to 2.4835 GHz band.

IEEE802.11 is a wireless LAN standard initially developed by IEEE, mainly used to solve the office LAN and campus network in the user and the user terminal wireless access, the business is mainly limited to data access, the rate can only reach a maximum of 2Mbps. due to it in the rate and the transmission distance can not satisfy people's needs, so the IEEE802.11 standard by the The IEEE802.11b standard has been replaced by the IEEE802.11b standard.

(2) IEEE802.11b

In September 1999, IEEE802.11b was formally approved, the standard specifies that WLANs operate in the 2.4-2.4835GHz band, with data rates up to 11Mbps, and transmission distances of 50-150 feet. The standard is a supplement to IEEE 802.11, using compensated coding keying modulation, point-to-point mode and basic mode of operation of the two modes, the data transmission rate can be based on the actual situation in the 11 Mbps, 5.5 Mbps, 2 Mbps, 1 Mbps between the different rates of automatic switching, which changed the design of the WLAN situation, expanding the application areas of the WLAN. The IEEE 802.11 standard for WLANs has been developed and implemented.

IEEE802.11b has become the dominant WLAN standard, adopted by most vendors, with products widely used in offices, homes, hotels, train stations, airports, and many other applications. However, due to the emergence of many new standards for WLANs, IEEE802.11a and IEEE802.11g have attracted a lot of attention in the industry.

(3) IEEE802.11a

In 1999, the IEEE802.11a standard development was completed, the standard specifies that the WLAN operating frequency band in the 5.15-8.825GHz, the data transmission rate of 54Mbps/72Mbps (Turbo), the transmission distance The transmission distance is controlled at 10-100 meters. The standard is also a supplement to IEEE 802.11, expanding the physical layer of the standard, using orthogonal frequency division multiplexing (OFDM) unique spread spectrum technology, QFSK modulation, can provide 25Mbps wireless ATM interface and 10Mbps Ethernet wireless frame structure interface, support for a variety of services, such as voice, data, and images, etc., a sector can be accessed by multiple users, each user can take multiple user terminals. One sector can access multiple users, and each user can take multiple user terminals.

The IEEE802.11a standard is the successor to the IEEE802.11b standard, which was designed to replace the 802.11b standard. However, a license is not required to work in the 2.4GHz band, which is a dedicated band for industry, education, and healthcare, and is publicly available, and a license is required to work in the 5.15-8.825GHz band. Some companies still have not expressed `support for the 802.11a standard, and some are more optimistic about the latest hybrid standard, 802.11g.

(4) IEEE802.11g

Currently, the IEEE is introducing the latest version of the IEEE802.11g certification standard, the standard proposed to have the IEEE802.11a transmission rate, security better than the IEEE802.11b, the use of two modulation methods, including 802.11a used in OFDM and IEEE802.11b used in the CCK, to do with the 802.11a and 802.11b compatible.

Although 802.11a is more suitable for enterprises, WLAN operators are very likely to choose 802.11g in order to take into account existing 802.11b equipment investments.

(5) IEEE802.11i

The IEEE802.11i standard is a combination of IEEE802.1x user port authentication and device authentication, modification and integration of the WLAN MAC layer, defining a strict encryption format and authentication mechanism to improve WLAN security. The new revision of the IEEE 802.11i standard includes two main elements: Wi-Fi Protected Access (WPA) technology and Robust Secure Networking (RSN). The Wi-Fi Alliance plans to adopt the 802.11i standard as the second version of WPA, with implementation beginning in early 2004.

The IEEE802.11i standard is very important in WLAN network construction, and data security is a top priority for WLAN device manufacturers and WLAN network operators.

(6) IEEE802.11e/f/h

The IEEE802.11e standard proposes improvements to the WLAN MAC layer protocol to support multimedia transmissions in order to support the Quality of Service (QoS) mechanism for all WLAN radio broadcast interfaces.

IEEE802.11f, which defines communication between access nodes, supports the IEEE802.11 Interoperability Protocol for Access Points (IAPP).

IEEE802.11h for spectrum management techniques for 802.11a.

4. 2HIPERLAN

The Broadband Radio Access Networks (BRAN) group of the European Telecommunications Standards Institute (ETSI) has embarked on the development of a pan-European standard for Hiper (High Performance Radio) access, and has already introduced HiperLAN1 and HiperLAN2. HiperLAN1 was launched with a low data rate and was not taken seriously. In 2000, the HIPERLAN2 standard was completed, and the maximum data rate of the HIPERLAN2 standard can reach 54 Mbit/s. The HIPERLAN2 standard defines in detail the detection function and conversion signaling of WLANs, which can be used to support a lot of The HIPERLAN2 standard defines in detail WLAN detection functions and conversion signaling to support a number of wireless networks, supporting dynamic frequency selection, wireless signaling element conversion, link adaptation, multibeam antennas, and power control. The standard also gives some definitions in terms of WLAN performance, security, and quality of service QOS.

HiperLAN1 corresponds to 1EEE802.11b, HiperLAN2 has the same physical layer as 1EEE082.11a, they can use the same components, and, HiperLAN2 emphasizes on the integration with 3G.The HIPERLAN2 standard is also the more complete WLAN protocol available.

4.3HomeRF

The HomeRF Working Group was established in 1997 under the leadership of the U.S. Home RF Council, with the primary task of building interoperable voice and data communications networks for home users, and introduced HomeRF version 2.0 in August 2001, which integrates voice and data transmission technologies. data transmission technology, working in the 10GHz frequency band, data transmission rates up to 10Mbps, in the security of the WLAN is mainly considered access control and encryption technology.

HomeRF is a synthesis and enhancement of existing wireless communication standards: for data communication, it uses the TCP/IP transmission protocol from the IEEE802.11 specification; for voice communication, it uses the Digital Enhanced Cordless Communications standard.

In addition to the IEEE802.11 committee, the European Telecommunication Standardization Association, and the U.S. Home Radio Frequency Board, the Wireless LAN Alliance, WLANA (WirelessLAN Association), a nonprofit organization established by wireless LAN vendors, consisting of WLANA is a non-profit organization established by wireless LAN vendors, consisting of 3Com, Aironet, Cisco, Intersil, Lucent, Nokia, Symbol and ZTE, etc. Its main work is to verify the compatibility of similar products from different vendors and to train users of WLAN products. 4.4 China's WLAN Specification

The Ministry of Information Industry of the People's Republic of China (MII) is in the process of formulating the industry standards for WLANs, including the General Technical Requirements for Public Wireless LANs (GTRPWLANs) and the Test Specification for Public Wireless LANs (PWLANs). The technical system involved in this standard includes IEEE802.11X series (IEEE802.11, 802.11a, IEEE802.11b, IEEE802.11g, IEEE802.11h, IEEE802.11i) and HIPERLAN2. The Communication Measurement Center of the Ministry of Information Industry undertook the formulation of the relevant standards and The Ministry of Information Industry's Communications Metrology Center has undertaken the formulation of the relevant standards and conducted a large number of tests in conjunction with equipment manufacturers and domestic operators. Meanwhile, the Communications Metrology Center of the Ministry of Information Industry and ZTE Corporation have jointly built a test platform for WLAN, which provides a full range of evaluations of WLAN system equipment in terms of its performance indicators, compatibility and safety and reliability.

In addition, the "China Broadband Wireless IP Standard Working Group (www.chinabwips.org)" approved by the Ministry of Information Industry Science and Technology (MIIST) is working on standardization of mobile wireless IP access, IP mobility, mobile IP security, and mobile IP services. In May 2003, China promulgated two national standards for WLAN drafted by China Broadband Wireless IP Standard Working Group: "Specific Requirements for Local Area Networks (LANs) and Metropolitan Area Networks (MANs) for Telecommunication and Information Exchange between Information Technology Systems (ITS) Part 11: Specification of Media Access (MAC) and Physical Layer for Wireless LANs (PHY)" and "Specification for Telecommunication between Information Technology Systems (ITS) Part 11: Specification of Media Access (MAC) and PHY Layer for Wireless LANs (WLAN)". Part 11: Wireless LAN Media Access (MAC) and Physical (PHY) Layer Specification: Extended Specification for Higher-Speed Physical Layer in 2.4GHz Band", Specific Requirements for Information Technology Inter-System Telecommunication and Information Exchange Local Area Networks (LANs) and Metropolitan Area Networks (MANs). These two national standards are based on ISO/IEC8802.11 and ISO/IEC8802.11b, and the release of the two national standards will standardize the application of WLAN products in China.

5. WLAN Network Architecture

Generally, there are two types of WLAN networks: peer-to-peer and infrastructure networks.

Peer-to-peer network: consists of a group of computers with wireless interface cards. These computers are directly connected to each other in a peer-to-peer fashion with the same group name, ESSID, and password, and communicate point-to-point and point-to-multipoint within the WLAN's coverage area.

Infrastructure network: In the infrastructure network, wireless terminals with wireless interface cards take wireless access point AP as the center, and connect wireless LAN and wired network through wireless bridge AB, wireless access gateway AG, wireless access controller AC and wireless access server AS, etc., which can set up many kinds of complex wireless LAN access network to realize wireless mobile office access. Access.

6. WLAN applications

As a wireless extension of the wired network, WLAN can be widely used in the living community, amusement parks, hotels, airports, stations and other recreational areas to achieve tourism and leisure access to the Internet; it can be applied to government office buildings, campuses, enterprises and institutions to achieve mobile office, convenient meetings and classes; it can be applied to health care, financial and securities, etc., to achieve mobile office. In addition, it can be used in medical, financial securities and other aspects, to realize the doctor in the road to the patient in the online diagnosis, to realize the financial securities outdoor online trading.

For environments that are difficult to wire, such as old buildings, desert areas, etc., and for environments that are subject to frequent changes, such as various exhibition buildings; for the temporary need for broadband access, mobile workstations, etc., the establishment of a WLAN is the ideal choice.

6.1 Sales Industry Applications

For large supermarkets, the circulation of goods is very large, and the daily work of receiving goods, including order processing, delivery orders, warehousing, etc., requires that the data be entered into the database at the site of different locations. Warehouse management and warehousing, moving more items, data in the change, at present, a lot of practice is to manually do a good job of recording, and then enter the data into the database, which is time-consuming and error-prone, the use of WLAN, you can easily solve the above two problems in the supermarket in all corners of the pick-up area, in the delivery area, the shelves, in the warehouse in the use of WLAN, you can deal with a variety of documents on-site.

6.2 Logistics Industry Applications

With China's accession to the WTO, the various ports, storage areas of the digitalization of logistics operations put forward high requirements. A logistics company generally have a network processing center, but also some offices are located in more remote places, for those transport vehicles, loading and unloading container unit, such as the working conditions, goods statistics, etc., the need to timely data entry and transmission to the central computer room. Deploying WLAN is an essential infrastructure for modernizing the logistics industry.

6.3 Application in Power Industry

How to conduct telemetry, remote control, and telemodulation of remote substations is an old problem in the power system, and WLAN can monitor and record the operation of the substation to provide real-time monitoring data to the central monitoring room, and can also transmit the control commands from the central server room to each substation. WLAN can monitor and record the operation of substations to provide real-time monitoring data to the central monitoring room, and also transmit control commands from the central room to each substation. This is a potential application for WLANs in power systems that are distributed to thousands of homes, but cannot be fully detected and controlled by wired networks.

6.4 Service Industry Applications

Due to the mobile terminalization and miniaturization of PCs, a traveler has to deal with emails in a timely manner when entering the lobby of a hotel, which is essential for Internet WLAN access in hotel lobbies; in-room Internet WLAN access is also needed, especially in higher star-rated hotels. The higher the star rating of the hotel, the guest may be lying on the bed to access the Internet, guests hope that wireless Internet access everywhere, due to the mobility of WLAN, convenience and other characteristics, but also by some large and medium-sized hotels favor.

In airports and stations is a waiting time for travelers to wait for a flight, this time to open the laptop to go on the Internet, why not happy thing, at present, in North America and Europe, most of the airports and stations, are deployed in the WLAN, in our country, but also in the gradual implementation and construction.

6.5 Education Industry Applications

WLANs allow teachers and students to interact with each other from time to time for teaching and learning. Students can use mobile terminals to ask questions and submit assignments to teachers in teachers, dormitories, and libraries; teachers can give tutoring lessons to students from time to time. Students can use WLAN to access the campus network from any part of the campus, and WLAN can be an auxiliary means of multimedia teaching.

6.6 Securities Industry Applications

With WLAN, the stock market has a vegetable market-like popularity and activity. Originally, many speculators use the stock machine to watch the market, but now do not have to, WLAN allows you to realize real-time watch the market, when the transaction. The WLAN allows you to see the market in real time and trade on the fly. You don't have to go to the stock market to pay for a big account.

6.7 Showroom Applications

Some large-scale exhibitions in the exhibition hall, generally have WLAN, service providers, exhibitors, customers walk into the hall at any time to access the Internet. The WLANs are also a great way to make your business more profitable.

6.8 Small and Medium-sized Office/Home Office Applications

WLANs allow people to access the Internet, send and receive emails, and connect to the Internet anytime, anywhere in a small or medium-sized office or at home, at the same cost as wired networks.

6.9 Office applications between enterprise office buildings

For some medium to large enterprises, there is a main office building, there are other subsidiary office buildings, building to building, department to department need to communicate with each other, if you take the Jian Jian limited network, you need to pay the expensive monthly fees and maintenance fees, and WLAN does not need, and does not require comprehensive cabling, as well as the ability to realize the limited network. WLAN is not required, and does not require integrated wiring, as well as the ability to realize the functions of the limited network.

7. WLAN security

WLAN applications, for home users, public **** scenarios do not require a high level of security users, the use of VLAN (VirtualLocalAreaNetworks) isolation, MAC address filtering, service area authentication ID (ESSID), MAC address filtering, service area authentication ID (ESSID), password access control, and wireless static encryption protocol WEP (Wired Equivalent Privacy) can meet their security needs. However, for users with high security requirements in public **** scenarios, there are still security risks, and it is necessary to introduce some security mechanisms in the wired network into WLAN, implement complex encryption and decryption algorithms in the wireless access point AP (Access Point), and through the wireless access controller AC, utilize PPPoE or DHCP+WEB authentication for the second time for users to carry out Legal authentication, real-time monitoring of the user's service flow. This aspect of the WLAN security strategy needs to be practiced and further explored and improved.

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