Introduction to OFDM and MIMO-OFDM
1.1 OFDM History
In recent years Orthogonal Frequency-Division Multiplexing (OFDM) [1–4] has emerged as a successful air-interface technique. In the context of wired environments, OFDM techniques are also known as Discrete Multi-Tone (DMT)  transmissions and are employed in the American National Standards Institute’s (ANSI’s) Asymmetric Digital Subscriber Line (ADSL) , High-bit-rate Digital Subscriber Line (HDSL) , and Very-high-speed Digital Subscriber Line (VDSL)  standards as well as in the European Telecommunication Standard Institute’s (ETSI’s)  VDSL applications. In wireless scenarios, OFDM has been advocated by many European standards, such as Digital Audio Broadcasting (DAB) , Digital Video Broadcasting for Terrestrial television (DVB-T) , Digital Video Broadcasting for Handheld terminals (DVB-H) , Wireless Local Area Networks (WLANs)  and Broadband Radio Access Networks (BRANs) . Furthermore, OFDM has been ratified as a standard or has been considered as a candidate standard by a number of standardization groups of the Institute of Electrical and Electronics Engineers (IEEE), such as the IEEE 802.11  and the IEEE 802.16  standard families.
The concept of parallel transmission of data over dispersive channels was first mentioned as early as 1957 in the pioneering contribution of Doelz et al. , while the first OFDM schemes date back to the 1960s, which were proposed by Chang  ...