Multiple Input Multiple Output (MIMO) technology is widely used in modern IEEE radio access systems. There is a tendency to increase the number of antennas, which is also confirmed by the development of MIMO technology in mobile communication systems of 3GPP standards. Requirements for modern radio communication systems are constantly increasing. As the radio frequency spectrum becomes increasingly scarce, it becomes increasingly difficult to transmit large amounts of information by expanding the frequency channel bandwidth. Therefore, the use of MIMO technology to increase the spectral and energy efficiency of communication systems is relevant. In 5G systems, Massive MIMO technology is used, when using which the number of antennas is measured in tens and hundreds. The characteristics of various versions of MIMO technology implemented in the existing standards 802.11n, 802.11ac, 802.11ax, as well as in the promising standard 802.11be (6G systems) are described in detail. Technologies of directional transmission, spatial multiplexing, selection of antennas as particular cases of precoding are considered. Trends of MIMO technology development in wireless communication systems are shown.
Rateless Space-Time Block Codes for 5G Wireless Communication Systems
