Background

Abstract

After the first demonstrations of electromagnetic waves in the year 1887 by the physicist Heinrich Hertz at the Technical University of Karlsruhe in Germany, wireless telegraphy transmission was demonstrated at the end of the nineteenth century by the radio pioneer and founder of the later company Guglielmo Marconi. Besides quite some important developments of different antenna technologies, the early ideas for multiple input multiple output (MIMO) schemes using multiple antennas trace back to Kaye and George (1970), Branderburg and Wyner (1974), and van Etten (1975), [1,2,3]. A concise survey is given in [4]. Later in 1984 and 1986, Winters and Salz considered beamforming techniques at Bell Laboratories, [5]. In 1994, Paulraj and Kailath introduced a patent on the concept of spatial multiplexing using multiple antennas. Raleigh and Cioffi investigated the transmission of multiple data streams using spatial–temporal coding, [6]. In the same year, Foschini introduced the concept of Bell Labs Layered Space-Time (BLAST), [7], which was refined and implemented later in 1999 by Golden et al. [8]. The digital cellular system GSM (Global System for Mobile Communications) put into operation around 1992 in Europe did not yet use the MIMO principle. However, later standards such as the 3.5 Generation (3.5G, UMTS advanced, IMT 2000), the 4G, and the 5G cellular systems adopt this key technology. Similar developments and standards prevailed for the wireless local area network WLAN and WIMAX IEEE 802.11.