WiFi Basics(2) – Wi-Fi Standards

Introduction

Wi-Fi is a wireless network communication technology based on IEEE 802.11 standards. The following describes the milestone 802.11 standards.

IEEE 802.11

IEEE 802.11 is a series of standards formulated for Wi-Fi. The first version was released in 1997, which defined the access control layer and physical layer for media access. At the physical layer, the standards defined 2 radio frequency modulation modes and 1 infrared transmission mode over the 2.4 GHz Industrial, Scientific, and Medical (ISM) frequency band. The designed total data transmission rate was 2 Mbit/s.

IEEE 802.11a and IEEE 802.11b

In 1999, these 2 versions were added. 802.11a defined a physical layer with a data transmission rate up to 54 Mbit/s over the 5 GHz ISM frequency band. 802.11b defined a physical layer with a data transmission rate up to 11 Mbit/s over the 2.4 GHz ISM frequency band.

IEEE 802.11g

802.11g was passed in July 2003. Its carrier frequency is 2.4 GHz (same as that of 802.11b), and the transmission rate reaches 54 Mbit/s.
802.11g hardware is backward compatible with 802.11b hardware. Some wireless router vendors develop new standards based on 802.11g standard to meet market requirements and increase the theoretical transmission rate to 108 Mbit/s or 125 Mbit/s.

IEEE 802.11n

IEEE 802.11n was a new 802.11 standard developed by a new unit of the IEEE in January 2004. It was formally approved in September 2009. Its theoretically maximum transmission rate is 600 Mbit/s, and the transmission distance is longer.

IEEE 802.11ac

The rapid development of mobile services and high-density access poses higher requirements on the bandwidth of Wi-Fi networks. The 802.11ac standard released in 2013 introduces wider radio bandwidth (160 MHz) and higher-order modulation technology (256-QAM), with a transmission rate up to 1.73 Gbit/s, further increasing the Wi-Fi network throughput. In 2015, the 802.11ac Wave 2 standard was released, making beamforming and MU-MIMO mainstream functions and improving the system access capacity. Unfortunately, 802.11ac supports only terminals working on the 5 GHz frequency band, and compromises user experience on the 2.4 GHz frequency band.

IEEE 802.11ax

The next-generation Wi-Fi needs to solve the problem that the efficiency of a Wi-Fi network decreases when many terminals access the Wi-Fi network. In 2019, the Wi-Fi 6 (802.11ax) standard was officially released to introduce technologies such as uplink MU-MIMO, OFDMA, and 1024-QAM high-order coding. Wi-Fi 6 improves network capacity and transmission efficiency by fully utilizing spectrum resources and enabling multiple terminals to access the network. Compared with Wi-Fi 5, Wi-Fi 6 aims to increase the average throughput of users by at least four times and the number of concurrent users by more than three times in a dense user environment. Therefore, Wi-Fi 6 is also known as high-efficiency WLAN (HEW).

Specifications Comparison