Full Analysis of Wireless LAN protocols and basic terms (1)

Although the structure and principles of a wireless network are roughly the same as those of a wired network, there is still a big difference between the wireless Internet and the wired Internet in terms of terminal devices and network performance. Compared with wired networks, wireless data networks have many disadvantages, such as limited bandwidth, high latency, poor connection stability, and difficult availability prediction. However, due to their strong mobility, these shortcomings will not affect the development of wireless networks. This article will bring you some basic concepts about wireless networks. Understanding these basic concepts is of great significance for more in-depth use of wireless networks.

I. Basic wireless network protocols

The wireless protocol is also mentioned in IEEE.

Knowledge gas station 1: "IEEE"

This is the largest professional society in the United States, which was merged by AIEE (American Institute of Electrical Engineering) and IRE (American Institute of radio engineers) in January 1, 1963. IEEE is a non-profit scientific and technological society with over 175 members from nearly 0.36 million countries around the world. The organization is a leading authority in fields such as space, computer, telecommunications, biomedicine, electric power, and consumer electronics. Its standards include: electrical and electronic equipment, test methods, original devices, symbols, definitions, and test methods.

OK. With the above basics, I will go back and learn about the standard wireless network protocols, including IEEE802.11b, 802.11a, and 802.11g. We can also see the supported protocol standards in the wireless network product description. Different supported protocol standards have different functions and speeds.

1. IEEE802.11b Protocol

IEEE802.11b is an 11 Mb/s wireless standard that provides complete network services for laptop or desktop users. The wireless network frequency of this protocol is 2.4 GHz. The maximum transmission rate can reach 11 Mbps, enabling automatic switching between 1 Mbps, 2 Mbps, 5.5Mbps, and 11 Mbps; theoretically, the maximum indoor transmission distance can reach 100 meters, and the outdoor distance can reach 300 meters. Currently, 802.11b is also called Wi-Fi. Evaluation: the implementation of such standards was earlier. Currently, many wireless products on the market only support this protocol. A significant feature of such products is the "high quality and low price". Although the supported speed can only reach 11 Mbps, its affordable price can greatly lower the threshold for users of wireless networks. This type of product is already a transitional "product ".

2. IEEE802.11a protocol

This protocol is a follow-up standard that has been widely used in office, home, hotel, airport, and many other occasions for 802.11b wireless network standards. It operates at 5 GHz, with a maximum transmission rate of 54 Mbps and a transmission layer of 25 Mbps. Provides 25 Mbps wireless ATM interface and 10 Mbps Ethernet Wireless Frame Structure interface. The transmission distance is 10 meters ~ 100 meters in length; OFDM orthogonal frequency division multiplexing (multiplexing) modulation technology can support the transmission of speech, data, and images, but note that this Protocol is not compatible with 802.11b protocol.

Comment: The 802.11a protocol has little interference due to its fast transmission speed and 5 GHz operating frequency. wireless products using this protocol can also be widely used in Wireless LAN. However, it is not very popular in the market because it is expensive and incompatible.

3. IEEE802.11g Protocol

IEEE802.11g can be regarded as a high-speed version of IEEE802.11b. Like 802.11b, IEEE802.11g also works in the GHz band. However, to achieve the transmission speed of 54 Mbit/s, IEEE802.11g adopts OFDM orthogonal frequency division multiplexing (OFDM) modulation method different from IEEE802.11b. It supports the transmission rate of 54Mbps. IEEE802.11g is compatible with IEEE802.11b, but it is also not compatible with 802.11a. Comment: with people's requirements on wireless LAN data transmission, wireless products supporting 802.11g protocol standards have become the mainstream in the market; moreover, its enhanced version of 802.11g + has already risen to the wireless era of ipvm.

Knowledge gas station 2: "Wi-Fi"

It is a set of universal certification for wireless network products based on IEEE 802.11 series standards implemented by WECA, also known as "Wi-Fi Alliance", which is a WECA organization for WEGA Wireless LAN standardization. It is incorrect to call Wireless LAN "Wi-Fi ).

Knowledge gas station 3: "working frequency band"

This is a range of wireless network frequencies. A relatively simple understanding is that mobile phones used by ordinary users must also work within a certain frequency range, generally between 800 GHz and GHz ).