Advanced Groupband Data Modem Using Orthogonally Multiplexed QAM Technique

Filter Bank Multicarrier for Massive MIMO

“…Those who have cited [7], have only acknowledged its existence without presenting much details, e.g., [13] and [15]. However, the cosine modulated filter banks that have been widely studied within the signal processing community, [17], are basically a reinvention of Chang's filter bank, formulated in discrete-time.…”

Multiuser MIMO-OFDM for Next-Generation Wireless Systems

“…Around the same era, Keasler et al [47] invented a high-speed OFDM modem for employment in switched networks, such as the telephone network. Hirosaki designed a subchannelbased equalizer for an orthogonally multiplexed QAM system in 1980 [46] and later introduced the DFT-based implementation of OFDM systems [53], based on which a so-called groupband data modem was developed [54]. Cimini, Jr. [48] and Kalet [55] investigated the performance of OFDM modems in mobile communication channels.…”

Per tone equalization for DMT-based systems

“…Combining (9) with (1) then results in (10) This least squares problem (for a particular choice of ) is then solved for each tone , for instance by a QR decomposition [13] of the compound matrix . The resulting signal, ISI-ICI and noise energy for tone can then be found, respectively, as (11) (12) (13) The SNR of tone becomes .…”

“…A groupband data modem based on the orthogonally multiplexed QAM technique, using per channel equalizers [9] is proposed in [10]. These equalizers also work in the frequency domain, but they are double sampling with respect to the symbol rate and there is no cyclic prefix involved in the system.…”