Which standard introduced MIMO technology to Wi-Fi?

The IEEE 802.11n standard, ratified in 2009, was the first to introduce Multiple-Input Multiple-Output (MIMO) technology into the Wi-Fi specification. MIMO utilizes multiple antennas to transmit and receive multiple data streams simultaneously over the same channel, a technique known as spatial multiplexing. This innovation dramatically increased data rates and link reliability compared to previous single-antenna (SISO) standards like 802.11b and 802.11g. Subsequent standards like 802.11ac and 802.11ax built upon and enhanced the MIMO technology introduced in 802.11n.

A. 802.11g

This standard used OFDM but was a single-input single-output (SISO) technology and did not include MIMO.

B. 802.11b

This early standard used DSSS/CCK and predates the development of MIMO for Wi-Fi.

D. 802.11ac

This standard introduced Multi-User MIMO (MU-MIMO) but did not introduce the original MIMO concept, which was part of 802.11n.

1. Juniper Networks. (n.d.). Wi-Fi Technology. Juniper Networks TechLibrary. Retrieved from juniper.net. (In sections describing different 802.11 standards, 802.11n is identified as the origin of MIMO).

2. IEEE 802.11n-2009 Standard. Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications Amendment 5: Enhancements for Higher Throughput. Introduction. (The official standard document specifies MIMO as a key technology for achieving higher throughput).