Efficient multitap equalization for FBMC‐OQAM systems

Abstract

This work provides a simple yet efficient multitap equalization structure for filter bank multicarrier systems, which is a candidate waveform for the next generation (5G) of mobile communication systems. More specifically, we analyze the system performance under medium-to high-frequency selective channels. In this scenario, the single-tap equalizer is not enough to compensate the channel effects, and then, a multitap equalizer need to be deployed. In the literature, the available equalization structures that are more efficient in aggressive scenarios are generally quite complex, whereas the less complex alternatives do not perform satisfactorily in such conditions. In this context, we propose a new multitap equalization approach in the frequency domain, aiming at reducing the computational complexity while improving the system robustness against high-frequency selectivity conditions. For a wide range of number of taps and antennas, the proposed minimum mean square error-based frequency domain equalizer presents a much reduced computational complexity, ie, less than 1% of the conventional minimum mean square error-based time domain complexity.The operation, advantages, performance, and the main differences between multitap equalization schemes against the simple one-tap equalizer for filter bank multicarrier systems are comprehensively discussed.One of the main topologies used in the fourth-generation systems has been the orthogonal frequency division multiplexing (OFDM), which has various commercial applications such as wireless networks (Wi-Fi 802.11), multiple-input-multiple-output (MIMO) systems, cellular systems (LTE), and digital television digital video broadcasting-terrestrial. 1 Moreover, OFDM system has many advantages, eg, ability to operate in frequency selective channels, robustness against multipath fading effect, easy implementation with fast Fourier transform algorithms, and trivial equalization due the favorable channel condition on each subcarrier. Because of its features, OFDM is still a candidate for the 5G. However, the OFDM system has some well-known issues that may hinder its use in 5G, such as sensibility with the frequency synchronization, 2 high levels of peak-to-average power ratio (PAPR), which require high linearity amplifiers to avoid signal saturation, and consequently, the signal distortion. 3 Therefore, new advancing research works are necessary, aiming at proposing alternatives to attend the 5G requirements. 4 An alternative method for multiplexing data via multiple carriers, similar to the OFDM, is the filter bank multicarrier (FBMC). In the FBMC scheme, multiple filters are used to transmit data in parallel, using one filter per carrier. In practice, Abbreviations: FBMC, filter bank multicarrier; OQAM, offset quadrature amplitude modulation; MTE, multitap equalization; OFDM, orthogonal frequency division multiplexing. Equally contributing authors.Trans Emerging Tel Tech. 2019;30:e3775.wileyonlinelibrary.com/journal/ett

FBMC Receiver Design and Analysis for Medium and Large Scale Antenna Systems

“…In this appendix, we derive the FSE based on a MMSEbased technique that can achieve the optimal performance. In our derivations, we take a similar approach to [47] and [48], and the exact equivalent channel after single-tap combining, the PDP or its estimate is used as the input to the MMSE equalizer.…”

Equalization methods for Filter Bank Multicarrier OQAM

“…To address this problem, an equalizer has to be included in the FBMC infrastructure. Several empirical investigations [5] recommended various approaches. Refer to for more information on relevant prior research.…”

Spectral efficiency analysis for massive MIMO orthogonal frequency division multiplexing and filter bank multicarrier in a realistic scenario using signal‐to‐noise‐and‐distortion ratio and interpolation for different modulation coding schemes

“…Multi‐carrier techniques aim to deal with frequency selective channels so that in each subcarrier the channel is seen as flat. Also, a single tap equalizer per subcarrier can mitigate the intersymbol interference (ISI) effect 11 . In the FBMC scheme, multiple filters are used to transmit data in parallel, using one filter per carrier.…”