The IEEE 802.11 Standard
The development of standards for wireless local area networks by the IEEE began in the late 1980s, following the opening of the three ISM radio bands for license-free use by the Federal Communications Commission (FCC) in 1985, ultimately culminating in 1997 with the approval and publication of the 802.11 standard. Since then, the initial standard has undergone many revisions and extensions, establishing itself as a dominant player in the wireless network domain, with the 802.11b extension being the first standard to hit the market, known as WiFi.
A brief overview of the evolution of the 802.11 standard:
- 802.11 (original): Introduced in 1997, this version included two spread spectrum methods for transmission in the 2.4GHz frequency band. It supported both ad-hoc networks and infrastructure networks. The first method operated with Frequency Hopping Spread Spectrum (FHSS) and supported a transmission rate of 1Mbps, while the second method used Direct Sequence Spread Spectrum (DSSS) and supported a transmission rate of up to 2Mbps. It also included an infrared variation.
- 802.11a: Presented in 1999, this standard was designed for WLAN, supporting high data rates up to 54Mbps using Orthogonal Frequency Division Multiplexing (OFDM) in the 5GHz frequency band.
- 802.11b: Also introduced in 1999, this standard pushed speeds to 11Mbps (1, 2, 5.5, 11Mbps) using Direct Sequence Spread Spectrum (DSSS) in the 2.4GHz frequency band. It maintained compatibility with the original 802.11 standard.
- 802.11g: Using OFDM modulation, this standard achieved data rates up to 54Mbps in the 2.4GHz frequency band while remaining backward compatible with 802.11b.
- 802.11n: Finalized in October 2009, this standard introduced Multiple Input Multiple Output (MIMO) communication, allowing for simultaneous transmission through multiple antennas. It aimed for high throughput, at least 100Mbps, utilizing a doubled bandwidth (40MHz instead of the previous 20MHz) and operating in both the 2.4GHz and 5GHz frequency bands.
- 802.11ac: Approved in January 2014, this standard operates in the 5GHz band, promising speeds of at least 1Gbps with actual transmission rates approaching at least 500Mbps. It represents the evolution of the 802.11n standard, expanding its features with MIMO techniques, wider bandwidth (up to 160MHz), and up to 256 QAM channels.
The 802.11ac standard is expected to bring significant changes to the world of VANETs (Vehicular Ad-Hoc Networks), although it is still in its early stages.
