Efficient implementation of filter bank multicarrier systems using circular fast convolution

In this paper, filter bank-based multicarrier systems using a fast convolution approach are investigated. We show that exploiting offset quadrature amplitude modulation enables us to perform FFT/IFFT-based convolution without overlapped processing, and the circular distortion can be discarded as a part of orthogonal interference terms. This property has two advantages. First, it leads to spectral efficiency enhancement in the system by removing the prototype filter transients. Second, the complexity of the system is significantly reduced as the result of using efficient FFT algorithms for convolution. The new scheme is compared with the conventional waveforms in terms of out-of-band radiation, orthogonality, spectral efficiency, and complexity. The performance of the receiver and the equalization methods are investigated and compared with other waveforms through simulations. Moreover, based on the time variant nature of the filter response of the proposed scheme, a pilot-based channel estimation technique with controlled transmit power is developed and analyzed through lower-bound derivations. The proposed transceiver is shown to be a competitive solution for future wireless networks

Circular Convolution Filter Bank Multicarrier (FBMC) System with Index Modulation

Orthogonal frequency division multiplexing with index modulation (OFDM-IM), which uses the subcarrier indices as a source of information, has attracted considerable interest recently. Motivated by the index modulation (IM) concept, we build a circular convolution filter bank multicarrier with index modulation (C-FBMC-IM) system in this paper. The advantages of the C-FBMC-IM system are investigated by comparing the interference power with the conventional C-FBMC system. As some subcarriers carry nothing but zeros, the minimum mean square error (MMSE) equalization bias power will be smaller comparing to the conventional C-FBMC system. As a result, our C-FBMC-IM system outperforms the conventional C-FBMC system. The simulation results demonstrate that both BER and spectral efficiency improvement can be achieved when we apply IM into the C-FBMC system

Generalized Fast-Convolution-based Filtered-OFDM: Techniques and Application to 5G New Radio

This paper proposes a generalized model and methods for fast-convolution (FC)-based waveform generation and processing with specific applications to fifth generation new radio (5G-NR). Following the progress of 5G-NR standardization in 3rd generation partnership project (3GPP), the main focus is on subband-filtered cyclic prefix (CP) orthogonal frequency-division multiplexing (OFDM) processing with specific emphasis on spectrally well localized transmitter processing. Subband filtering is able to suppress the interference leakage between adjacent subbands, thus supporting different numerologies for so-called bandwidth parts as well as asynchronous multiple access. The proposed generalized FC scheme effectively combines overlapped block processing with time- and frequency-domain windowing to provide highly selective subband filtering with very low intrinsic interference level. Jointly optimized multi-window designs with different allocation sizes and design parameters are compared in terms of interference levels and implementation complexity. The proposed methods are shown to clearly outperform the existing state-of-the-art windowing and filtering-based methods.Comment: To appear in IEEE Transactions on Signal Processin

Efficient Fast-Convolution-Based Waveform Processing for 5G Physical Layer

This paper investigates the application of fast-convolution (FC) filtering schemes for flexible and effective waveform generation and processing in the fifth generation (5G) systems. FC-based filtering is presented as a generic multimode waveform processing engine while, following the progress of 5G new radio standardization in the Third-Generation Partnership Project, the main focus is on efficient generation and processing of subband-filtered cyclic prefix orthogonal frequency-division multiplexing (CP-OFDM) signals. First, a matrix model for analyzing FC filter processing responses is presented and used for designing optimized multiplexing of filtered groups of CP-OFDM physical resource blocks (PRBs) in a spectrally well-localized manner, i.e., with narrow guardbands. Subband filtering is able to suppress interference leakage between adjacent subbands, thus supporting independent waveform parametrization and different numerologies for different groups of PRBs, as well as asynchronous multiuser operation in uplink. These are central ingredients in the 5G waveform developments, particularly at sub-6-GHz bands. The FC filter optimization criterion is passband error vector magnitude minimization subject to a given subband band-limitation constraint. Optimized designs with different guardband widths, PRB group sizes, and essential design parameters are compared in terms of interference levels and implementation complexity. Finally, extensive coded 5G radio link simulation results are presented to compare the proposed approach with other subband-filtered CP-OFDM schemes and time-domain windowing methods, considering cases with different numerologies or asynchronous transmissions in adjacent subbands. Also the feasibility of using independent transmitter and receiver processing for CP-OFDM spectrum control is demonstrated

MULTICARRIER TRANSMISSION TECHNIQUES

In this thesis, multicarrier transmission techniques envisioned for the fifth-generation wireless networks are studied. First, three basic techniques, namely orthogonal frequency-division multiplexing (OFDM), filter-bank multicarrier offset quadrature amplitude modulation (FBMC-OQAM), and generalized frequency-division multiplexing (GFDM) are reviewed in detail. In particular, the block-based structure and cyclic prefixing of OFDM are discussed and its bit error rate (BER) performance is analyzed. Then it is demonstrated that with offset QAM the orthogonality between subcarriers in FBMC-OQAM is preserved. Next, the roles of tail biting technique and circular convolution in GFDM are explained. An efficient implementation of GFDM is also described. Second, circular filterbank multicarrier offset QAM (CFBMC-OQAM), a technique which combines the block-based structure of GFDM and offset QAM of FBMC-OQAM, is presented. Then a precoded scheme is proposed, in which the Walsh-Hadamard (WH) transform is applied to CFBMC-OQAM system, resulting in a precoded scheme called WH-CFBMC-OQAM. The proposed system has a block-based structure and can be implemented efficiently using fast Fourier transform (FTT) and inverse FFT (IFFT). In addition, a cyclic prefix can be inserted to facilitate simple equalization at the receiver. WH-CFBMC-OQAM exploits the frequency diversity by averaging the signal-to-noise ratios (SNRs) over all subcarriers. A theoretical approximation for the bit error rate performance of WH-CFBMC-OQAM over a frequency-selective channel is derived. Under the same system configuration, simulation results demonstrate the excellent performance of the proposed scheme when compared to the performance of other techniques. Simulation also verifies that the theoretical results match perfectly with simulation results for any SNR value