WiFi definition
The full name of WiFi is Wireless Fidelity, also known as the 802.11b standard. Its biggest advantage is its high transmission speed, which can reach 11 Mbps. In addition, its effective distance is also very long, and it is also compatible with various existing 802.11 DSSS devices.
WiFi is a brand of wireless network communication technology, owned by the Wi-Fi Alliance (Wi-Fi Alliance), with the purpose of improving the interoperability between wireless network products based on the IEEE 802.11 standard.
The Wi-Fi Alliance was established in 1999, and its name was Wireless Ethernet Compatibility Alliance (WECA) at the time. It was officially renamed the Wi-Fi Alliance in October 2002.
WiFi technology development
The first version of WiFi was published in 1997, which defined the medium access control layer (MAC layer) and the physical layer.
The physical layer defines two wireless frequency modulation methods and one infrared transmission method that works on the 2.4GHz ISM frequency band, and the total data transmission rate is designed to be 2Mbit/s.
The communication between the two devices can be carried out in a free and direct (ad hoc) manner or under the coordination of the base station BS (Base Station) or the access point AP (Access Point).
Two supplementary versions were added in 1999, 802.11a defines the physical layer with a data transmission rate of 54 Mbit/s on the 5GHz ISM frequency band;
- 11b defines a physical layer with a data transmission rate of up to 11 Mbit/s on the 2.4GHz ISM frequency band.
- The ISM frequency band of 4GHz is commonly used by most countries in the world, so 802.11b has been the most widely used.
In 1999, the industry established the WiFi Alliance, which is committed to solving the production and equipment compatibility issues of products that meet the 802.11 standards.
The development of the 802.11 standard and supplementary standards is as follows: 802.11, the original standard (2Mbit/s working at 2.4GHz); 802.11a, the physical layer supplement (54Mbit/s working at 5GHz);
802.11b, physical layer supplement (11Mbit/s working at 2.4GHz);
802.11c, media access control layer bridging (MAC Layer Bridging) compliant with 802.1D;
802.11d, adjustments made in accordance with national radio regulations;
802.11e, support for QoS (Quality of Service);
Interoperability of 802.11f base stations; 802.11g, physical layer supplement (54Mbit/s working at 2.4GHz);
802.11h, adjustment of wireless coverage radius, indoor and outdoor channels (5GHz frequency band);
802.11i, security, and authentication supplement;
802.11n, the introduction of multiple inputs and output MIMO) technology is basically an extended version of 802.11a.
In addition to the above IEEE standard, there is another technology called IEEE802. 11b+, which provides a data transmission rate of 22Mbit/s on the basis of IEEE802.11b (2.4GH section) through the PBCC technology (PacketBinary Convolutional Code).
In fact, this is not an IEEE open standard, but a proprietary technology (the property right belongs to Texas Instruments).
There are also some technologies called 802.1lg+, which provide a transmission rate of 108Mbit/s on the basis of IEEE802.11g. Like 802.11b+, they are also non-standard technologies. The wireless network chip manufacturer Atheros advocates SuperG.
WiFi features
The outstanding features of WiFi technology are Wider LAN coverage, No wiring required, Healthy, and safety.
Wider LAN coverage
The coverage radius of WiFi can reach about 100 meters, which is wider than that of Bluetooth technology and can cover the entire office building; the transmission speed is fast.
WiFi technology has a very fast transmission speed, which can reach llmbps (802.11b) or 54mbps (802.11a), which is suitable for high-speed data transmission services;
No wiring required
The main advantage of WiFi is that it does not require wiring and cannot be restricted by wiring conditions, so it is very suitable for the needs of mobile office users.
Healthy and safety
The transmission power specified by IEEE802.11 cannot exceed 100 milliwatts, and the actual transmission power is about 60-70 milliwatts, while the transmitting power of mobile phones is between 200 milliwatts and 1 watt, and handheld walkie-talkies are as high as 5 watts. Compared with the latter, the radiation of WiFi products is smaller.
WiFi product application
WiFi first established itself tenaciously in notebook computers. The rapid increase in the number of notebook computers, and the gradual penetration of mobile office models have laid the tone for the further popularity of WiFi.
With the efforts of Intel, IBM, AT&T, and many other UT and telecom operators, WiFi has already had more than 10,000 public hotspots in airports, hotels, cafes, and other places around the world.
Although in the current situation, it is not realistic to hope to make money through public services, the existence of these hot spots undoubtedly played a vital role in the promotion of WiFi.
At present, places with more WiFi services are mainly in hotspots such as airports, stadiums, hotels, etc. However, from the actual effect, users’ demand for this service is not large.
Judging from the current application of WiFi technology, public access to hotspots has developed rapidly under the impetus of operators, but the number of users is small and an effective profit model is lacking, which makes WiFi present a phenomenon of false heat.
In addition, the current public access service applications, except for existing applications such as surfing the Internet and receiving emails, do not appear to have exclusive, urgent, and necessary application services for users, causing consumers to generate new user needs. Which is why it is difficult to attract a large number of user groups.
The relationship between WiFi and WiMAX, 3G
WiFi, WiMAX, and 3G are all broadband wireless technologies. Due to their respective technical characteristics, their technical focuses are different. The following compares the relationship between WiFi and WiMax, and the relationship between WiFi and 3G.
The relationship between WiFi and WiMAX
The WiFi and WiMAX do not belong to the same category.
WiFi is an interoperability organization related to the IEEE 802.11x standard for wireless local area networks, while WiMAX is an interoperability organization related to the IEEE 802.16x standard for wireless metropolitan area networks.
WiFi is mainly used as a wireless local area network, while WiMax is mainly used as a wireless metropolitan area network. There is a complementary relationship between the two and there is no substitute relationship.
Wi is suitable for indoor use in cities, while WiMAX is more suitable for outdoor use in cities. The comparison between the two is shown in the table.
Comparison of WiFi and WiMAX table | ||
| WiFi | WiMAX |
Standard | IEEE802．11a/b/g | IEEE802.．11a/d/e |
Multiple access methods | CKK、OFDM | OFDM/FDD、TDD |
Frequency band | 2.4GHz or 5GHz, do not need license | 2-1lGHz, some do not need a license |
Maximum speed | 11Mb/s or 54Mb/s | >70Mb/s |
Business | Voice and Data Voice | Data, video image |
Coverage | Microcell | Macrocell |
Mobility Stationery | Stationary, walking | Stationary, walking |
Spectrum utilization | <2.7bpa/Hz | 3.75bpa/Hz |
Maturity | Very good | Bad |
Terminal | PC card, handheld terminal, | Intelligent information equipment, PC card |
Commercial | Large-scale, worldwide scale | Products launched in 2005 |
The relationship between WiFi and 3G
From the above comparison, it can be seen that WiFi technology is more inclined to replace the wired LAN, and at the same time, it can supplement the 3G network within a certain range, and carry low-mobility high-speed data services.
Comparison of 3G and WiFi table | ||
| WiFi | 3G |
Standard | IEEE 802．11a/b/g | 3GPP、3GPP2、ITU |
Multiple access methods | CKK、OFDM | CDMA/FDD、TDD |
Frequency band | 2.4GHz or 5GHz, no license | 2GHz license |
Maximum speed | 11Mb/s or 54Mb/s | 2Mb/s |
Business | Voice and data | Voice and data |
Coverage | Microcell | Macrocell |
Mobility Stationery | Stationary, walking | Stationary, walking, vehicle |
Spectrum utilization | <2.7bps/Hz | <1.6bps/Hz |
Maturity | Very good | Good |
Terminal | PC card, handheld terminal, | Mobile phone, PDA, PC card, etc. |
Commercial | Large-scale, worldwide scale | Large-scale, worldwide scale |
Advantages of WiFi
Radio waves cover a wide range
The radio wave coverage based on Bluetooth technology is very small, with a radius of only 50 in or 15 m, while the radius of WiFi can reach 300 in or 100 m, which can also be used in the entire building.
WiFi transmission speed is very fast
Although the wireless communication quality of WiFi technology transmission is not the best, its data security performance is worse than that of Bluetooth, and the transmission quality needs to be improved, but the transmission speed is very fast, which can reach 11 Mbps.
The barriers for manufacturers to enter this field are relatively low
Manufacturers only need to set up hot spots in densely populated places such as airports, stations, coffee shops, and libraries, and connect the Internet to these places through high-speed lines. Manufacturers do not need to spend money to access network wiring, thereby saving a lot of costs.
According to the different standards used by the wireless network card, the WiFi speed is also different. Among them, IEEE 802.1 lb is up to 11 Mbps (some manufacturers can reach 22 Mbps with equipment matching), IEEE 802.1la is 54 Mbps, and IEEE 802.1lg is also 54 Mbps.
WiFi is a wireless network composed of AP (Access Point) and wireless network cards.
AP is generally called a network bridge or access point. It is used as a bridge between a traditional wired local area network and a wireless local area network.
Therefore, any PC equipped with a wireless network card can share the wired local area network through the AP, And even the resources of the wide-area network, its working principle is equivalent to a HUB or router with a built-in wireless transmitter, and the wireless network card is the CLIENT end device responsible for receiving the signal transmitted by the AP.
Wirelessb/g represents the model of the network card, which can be divided into IEEE 802.1la, IEEE 802.1lb, and IEEE 802.1lg according to its speed and technology.
WiFi stands for wireless fidelity and refers to the fully compatible IEEE 802. 11 standard IEEE 802. 1lb subset. It uses the open 2.4 GHz direct sequence spread spectrum, and the maximum data transmission rate is 11 Mbps. It can also be based on the signal The strength adjusts the transmission rate to 5.5 Mbps, 2 Mbps, and 1 Mbps bandwidth.
The transmission range without linear propagation is up to 300 m outdoors, and up to 100 m indoors when there are obstacles. It is currently the most used transmission protocol.
How to build WiFi?
The basic equipment for setting up a wireless network is a wireless network card and an AP. The wireless mode matches the existing wired architecture to share network resources. The installation cost and complexity are far lower than traditional wired networks.
If it’s just a peer-to-peer network of several computers, you don’t need an AP, just each computer is equipped with a wireless network card.
AP is the abbreviation of Access Point. It mainly acts as a bridge between wireless workstations and wired local area networks in the media access control layer MAC.
With an AP, just like the Hub of a general wired network, wireless workstations can be quickly and easily connected to the network. Especially for the use of broadband, WiFi is more advantageous. After the wired broadband network (ADSL, residential LAN, etc.) arrives at the home, connect to an AP, and then install a wireless network card in the computer.
Long-distance work
The working distance of wireless WiFi is not large. Under the condition of complete network construction, the real working distance of IEEE 802.1lb can reach more than 100 m, and it solves the problem of data error correction and error code during high-speed movement. WiFi equipment and equipment, equipment handover and security authentication with the base station have also been well resolved.
Future development of WiFi
The number of wireless APs has shown a rapid growth trend in the past two years, and the convenience and efficiency of wireless networks have enabled them to gain rapid popularity. At present, in addition to having APs in some public places, there are already precedents in foreign countries that use wireless standards to build metropolitan area networks. Therefore, WiFi’s wireless position will become increasingly strong.
WiFi is the current mainstream standard for wireless access. With the strong support of Intel, WiMAX is fully compatible with existing WiFi. Compared with the IEEE 802.11x standard of WiFi, WiMAX is the IEEE 802.16x standard used. Compared with the former, WiMAX has a longer transmission distance, wider frequency band selection, and higher access speed.
It is expected to become a mainstream standard for wireless networks in the next few years, and Intel plans to use this standard to build wireless wide-area networks in the future. This is a qualitative change compared to the current wireless local area network or wireless metropolitan area network, and existing equipment can still be supported.
The demand for mobile connections from home and small office network users is the driving force for the growth of the wireless LAN market. Although so far, developed countries such as the United States and Japan are still the regions with the most WiFi users, with the further popularization of e-commerce and mobile office, cheap WiFi will surely become the inevitable choice for users who need to connect to the Internet at any time.
Supplement to high-speed wired access technology
Wired access technologies mainly include Ethernet, xDSL, etc. As a supplement to high-speed wired access technology, WiFi technology has the advantages of mobility and low price.
WiFi technology is widely used in areas where wired access requires a wireless extension, such as temporary conference venues. Due to differences in data rate, coverage, and reliability, WiFi technology will serve as a supplement to high-speed wired access technology in broadband applications.
The key technology undoubtedly determines the complement of WiFi. Now OFDM, MIMO (multiple-input and multiple outputs), smart antennas and software radio, etc., are beginning to be applied to wireless local area networks to improve WiFi performance.
For example, IEEE 802.1ln plans to combine MIMO and OFDM to double the data rate. In addition, improvements in antennas and transmission technology have greatly increased the transmission distance of wireless local area networks, which can reach several kilometers.
Supplement to the cellular mobile communication
The secondary positioning of WiFi technology is as a supplement to cellular mobile communications. Cellular mobile communication can provide wide coverage, high mobility, and low-to-medium data transmission rates. It can make use of the characteristics of WiFi high-speed data transmission to make up for its limited data transmission rate.
WiFi cannot only use the perfect authentication and billing mechanism of the cellular mobile communication network but also combine the characteristics of the wide coverage of the cellular mobile communication network to perform multi-access switching functions. In this way, the integration of WiFi and cellular mobile communication can be realized.
WiFi is a supplement to the existing communication system
Network membership and structure of WiFi connection points
Station
The most basic part of the network.
Basic Service Set (BSS)
The most basic service unit of the network. The simplest service unit can consist of only two sites, and the sites can be dynamically associated with the basic service unit.
Distribution System (DS)
The distribution system is used to connect different basic service units. The medium used by the distribution system (Medium) is logically separate from the medium used by the basic service unit, although they may be physically the same medium, such as the same wireless frequency band.
Access Point (AP)
The access point not only has the identity of an ordinary site but also has the function of accessing the distribution system.
Extended Service Set (ESS)
It is composed of a distribution system and a basic service unit. This combination is logical, not physical. Different basic service units may be far apart geographically. The distribution system can also use a variety of technologies.
Portal
It is also a logical element. Used to connect wireless LAN with wired LAN or other networks.
There are three kinds of media, the wireless medium used by the site, the medium used by the distribution system, and the medium used by other local area networks integrated with the wireless local area network. Physically they may overlap each other.
IEEE 802.11 is only responsible for addressing the wireless medium used by the site. The addressing of distribution systems and other local area networks is outside the scope of wireless local area networks.
IEEE802.11 does not specifically define the distribution system but only defines the service that the distribution system should provide. The entire wireless local area network defines 9 services.
Five types of services belong to the tasks of the distribution system, namely: Association, Disassociation, Distribution, Integration, and Resuscitation.
Four types of services belong to the tasks of the site, namely: authentication (Authentication), end authentication (Deauthentication), privacy (Privacy), and MAC data transmission (MSDU delivery).
WiFi authentication type
Currently, the certification types announced by the WiFi Alliance are as the below showing.
WPA/WPA2: WPA/WPA2
WPA/WPA2: WPA/WPA2 is a test procedure established for single-mode, dual-mode, or dual-frequency products based on IEEE 802.11a, IEEE 802.11b, and IEEE 802. 11g. The content includes verification of communication protocols, verification of wireless network security mechanisms, and network transmission performance and compatibility testing.
WMM (WiFi Multi-Media)
When audio-visual multimedia is transmitted through a wireless network, how to verify whether the bandwidth guarantee mechanism works normally on different wireless network devices and different security settings is the purpose of WMM testing.
WMM Power Save
How to manage the standby time of wireless network devices to extend the battery life without affecting its functionality when the audio-visual multimedia is transmitted through the wireless network can be verified through the WMM Power Save test.
WPS (WiFi Protected Setup)
The certification issued in 2007 aims to allow consumers to set up wireless network devices in a simpler way and to ensure a certain degree of security. Currently, WPS allows setting up wireless network devices through Pin Input Config (PIN), Push Button Config (PBC), USB Flash Drive Config (UFD), and Near Field Communication Contactless Token Config (NFC).
ASD (Application Specific Device)
This is aimed at wireless network devices with special applications, such as DVD players, projectors, printers, etc., in addition to wireless network access points and stations.
CWG (Converged Wireless Group)
It is mainly aimed at the test program of the RF part measurement of WiFi Mobile Converged Devices.
Two systems of WiFi
WiFi can be attributed to two major systems, the AP (FAT AP) system, and the AP (FIT AP) system.
The so-called FAT AP is a traditional wireless WiFi network. There is no centralized management controller device. All APs are connected through a switch.
Each AP is responsible for RF, communication, authentication, encryption, etc., so each AP needs to be Independent configuration making it difficult to achieve overall unified management and centralized RF, access, and security policy settings.
In the new solution based on the wireless controller, all APs have lost weight (Fit AP), and each AP is only responsible for the work of RF and communication. Its function is a simple, hardware-based RF low-level sensing device.
All RF signals received by the Fit AP are encoded by 802.11, then passed through the Ethernet network and transmitted to the wireless controller through the encrypted tunnel agreement signed by different manufacturers, and then the wireless controller centrally encrypts, verifies, and encrypts the encoded stream, security control, and other higher-level tasks.
Therefore, the wireless network solution based on Fit AP and the wireless controller has the characteristics of unified management and can excellently complete tasks such as automatic RF planning, access, and security control strategies. The function comparison of the two wireless network solutions is shown in the table.
Solution | Traditional wireless solution | Based on wireless controller solution |
Technological model | Traditional way | New way, enhanced governance |
Security | Traditional encryption and authentication methods | Increase the radio frequency environment monitoring, based on the user’s location security strategy. High security |
Network governance | Distribute the configuration file for each AP | The file is configured on the wireless switch, and the AP itself has zero configuration |
User management | similar to wired, distinguishing permissions based on the wired port that AP accesses | Wireless special virtual private group mode, distinguishing permissions based on user names |
WLAN networking scale | Layer 2 roaming, suitable for small-scale networking | lower-cost Layer 2 and Layer 3 roaming, topology-independent, suitable for large-scale networking, higher cost |
QoS and value-added service capabilities | Basically no QoS, only simple data access | Certain QoS control capabilities, which can expand rich services such as voice and video |
WiFi business support capabilities
Carrying capacity of WiFi network
WiFi is a wireless network composed of AP (Access Point) and wireless network cards.
Its working principle is equivalent to a HUB or router with a built-in wireless transmitter, and the wireless network card is the CLIENT terminal device responsible for receiving the signal transmitted by the AP.
WiFi technology is aimed at transmitting data, not real-time communication such as voice, so the communication quality is not good. The call quality is better only when the network usage is low and there is no interference nearby.
The low network usage is in conflict with the general business model of service providers. The new 802.11e standard helps to solve this problem.
Another point is that WiFi base stations have a small coverage area, which means that more base stations must be built to build a network. This will cause many problems, especially in terms of costs.
In the business market, what is fashionable now is the so-called seamless mobility, Using a mobile phone or PDA with both WiFi and mobile phone transceiver functions.
Use WiFi to make calls where there is WiFi, and automatically transfer to the mobile phone network where there is no WiFi, and the call will not be interrupted. None of the dual-use mobile phones currently on the market can achieve seamless movement.
Value-added services on WiFi networks
A variety of value-added services can be carried out on the WiFi network. With the continuous changes in market demand, more services will emerge in an endless stream.
The current possible services can be roughly summarized as follows: VoIP voice services, instant messaging services, Internet browsing services, video on demand, live TV, search, MP3 downloads, Wireless video surveillance, etc.
Value-added services can be promoted and popularized, but also need good packaging, good entry points, and applicable practical applications.
If combined with RFID technology, the wireless payment system is realized through WiFi wireless network, which is more suitable for supermarkets and shopping malls. Research on the specific application of WiFi network value-added services is also a major issue facing operators, and further research and analysis are needed.
The capability requirements of the business on the network
WiFi technology provides a wireless access method, and users’ PCs, mobile phones, PDAs, and other terminals can all be connected to the broadband network in a wireless manner. But access to the network is not the final goal. What users ultimately need is to be able to use various services through convenient wireless access.
Currently, services based on broadband networks are roughly divided into voice services, data services (web browsing, etc.), and streaming media services.
Each type of service has different requirements for the bearer network: the data service’s requirement for the bearer network is mainly to ensure the transmission speed of the network, and the requirements for other aspects are not high;
The requirements for the bearer network for voice services and streaming media services include real-time network transmission Performance, network transmission speed, security, QoS guarantee, etc.
You may also be interested in the below articles.
