Future wireless systems will be characterized by a large range of possible uses cases. This requires a flexible allocation of the available time-frequency resources, which is difficult in conventional orthogonal frequency division multiplexing (OFDM). Thus, modifications of OFDM, such as windowing or filtering, become necessary. Alternatively, we can employ a different modulation scheme, such as filter bank multi-carrier (FBMC). In this paper, we provide a unifying framework, discussion, and performance evaluation of FBMC and compare it with OFDM-based schemes. Our investigations are not only based on simulations, but are substantiated by real-world testbed measurements and trials, where we show that multiple antennas and channel estimation, two of the main challenges associated with FBMC, can be efficiently dealt with. In addition, we derive closed-form solutions for the signal-to-interference ratio in doubly-selective channels and show that in many practical cases, one-tap equalizers are sufficient. A downloadable MATLAB code supports reproducibility of our results.

Filter Bank Multicarrier Modulation Schemes for Future Mobile Communications

Multiple filter-banks enable QAM transmission and reception in filter-bank multi-carrier (FBMC) systems. In this paper, we propose a new method to design a set of simultaneously used base filters for QAM-FBMC by optimizing the trade-off between spectrum confinement and self-interference. The increased freedom in multiple base filter designs brings merits of a tailor-made spectrum confinement and desirable bit error performance simultaneously. Simulations results show the superiority of the proposed QAM-FBMC systems to other post-OFDM waveform candidates.

A new waveform enabling enhanced QAM-FBMC systems

A filter-bank multicarrier–quadrature amplitude modulation (FBMC-QAM) system with two prototype filters for transmitting QAM symbol is proposed, and the orthogonality conditions for the FBMC-QAM system without the intrinsic interference is derived. The proposed transmitter performs the individual filtering for the even and odd-numbered sub-carrier symbols, respectively. In order to satisfy the derived orthogonality conditions, we perform a sub-block wise reverse ordering procedure for the outputs of the odd-numbered sub-carrier filter. Also, this paper shows that the proposed FBMC-QAM system satisfies the suggested orthogonality conditions and can use the multiple-input multiple-output transmission schemes as the conventional orthogonal frequency division multiplexing (OFDM) systems. The signal-to-interference power ratio and the bit error rate (BER) for the proposed FBMC-QAM system are evaluated. Numerical results show that the proposed FBMC-QAM system has almost the same BER performance compared with the FBMC-OQAM and OFDM systems.

A New Filter-Bank Multicarrier System With Two Prototype Filters for QAM Symbols Transmission and Reception

Recently, as asynchronous heterogeneous network scenario becoming one of the key features for next generation wireless communications, superior spectrum confinement as well as higher spectral efficiency compared to cyclic prefixed orthogonal frequency division multiplexing (CP-OFDM) has been taken into consideration for future radio access technologies. In this paper, we propose a new quadrature amplitude modulation based filter-bank multi-carrier (QAM-FBMC) system that provides with an inherent spectral efficiency gain against CP-OFDM, which comes from reduction of the redundancies such as cyclic prefix (CP) and guard-band, while keeping the symbol rate same as in CP-less OFDM. We propose a new transceiver structure consisting of at least two different filter-bank bases at both transmitter and receiver sides. Practical algorithms including channel estimation and equalization to mitigate multi-path fading channel without CP are proposed. Various evaluation results show that the proposed system performs comparable to the CP-OFDM system even without CP and guard-band reduction is also available from the well-confined spectrum.

QAM-FBMC: A New Multi-Carrier System for Post-OFDM Wireless Communications

Filter Bank Multi-Carrier (FBMC) offers superior spectral properties compared to Orthogonal Frequency Division Multiplexing (OFDM), at the cost of imaginary interference, which makes the application of Multiple-Input and Multiple-Output (MIMO) more challenging. By spreading symbols in time (or frequency), we can completely eliminate the imaginary interference, so that all MIMO techniques known in OFDM can be straightforwardly applied in FBMC. The spreading process itself has low complexity because it is based on Hadamard matrices. Although spreading allows to restore complex orthogonality in FBMC within one transmission block, we observe interference from neighboring blocks. By including a guard timeslot, the signal-to-interference ratio can be further improved. Furthermore, we investigate the effect of a time-variant channel on such spreading approach. Finally, testbed measurements show the applicability of our FBMC based MIMO transmission scheme in real world environments.

Enabling Low-Complexity MIMO in FBMC-OQAM

A filter-bank multicarrier - quadrature amplitude modulation (FBMC-QAM) system with two prototype filters for transmitting QAM signal is proposed. The proposed transmitter performs separate filtering for the even-numbered sub-carrier symbols and the odd-numbered sub-carrier symbols. We derive the orthogonality conditions for a FBMC-QAM system without the intrinsic interference. In order to satisfy the suggested orthogonality conditions, we perform a kind of block interleaving for the odd-numbered sub-carrier filtering. The receiver structure is the counterpart to the transmitter. Numerical results showed that the proposed FBMC-QAM system has almost the same bit error rate (BER) performance compared to the FBMC-OQAM and the orthogonal frequency division multiplexing (OFDM) system. with the proposed FBMC-QAM, multiple-input multiple-output transmission schemes and channel estimation schemes can be utilized similarly as in OFDM.

A new filter-bank multicarrier system for QAM signal transmission and reception

In this paper, we propose a new sequence generation methodology to make a constant amplitude zero autocorrelation (CAZAC) preamble available in offset Quadrature Amplitude Modulation-based filter bank multicarrier (FBMC) synchronization. The role of the new sequence is to compensate the filtering and symbol overlap of the FBMC structure so as to finally be able to make a CAZAC preamble in time domain. To derive the new sequence, we formulate a symbol overlap model that shows the relation between the new sequence and a CAZAC preamble. On the other hand, the offset modulation format is a constraint that needs to be considered in the design of the new sequence. By using a property of this offset modulation constraint, we derive a closed-form expression of the new sequence from the symbol overlap model. In addition, we extend an advanced model to create a pseudo-CAZAC preamble that is not data-dependent, thus enabling convenience of implementation. Simulation results show the superiority of the proposed model with respect to synchronization accuracy, out-of-band radiation, and peak to average power ratio. Moreover, we verify that the proposed model is well-suited for use in the cellular environment through complexity and resource efficiency comparisons.

Synchronization Sequence Design for FBMC/OQAM Systems

The present invention relates to a transceiving method and apparatus that enable QAM signal transmission in a filter bank multi-carrier (FMBC) communication system and provides, in particular, a transceiving method and apparatus that enable quadrature amplitude modulation (QAM) signal transmission without intrinsic interference by separating filtering between a sub-carrier having an even index and a sub-carrier having an odd index, and superimposing and transmitting sub-carriers filtered by means of separation The thus-rendered present invention is a transmission method in the FBMC communication system, the method comprising the steps of: dividing at least two QAM signals into a plurality of groups; performing filtering on each of the plurality of groups; and superimposing and transmitting the QAM signal in the plurality of groups filtered on a time axis The present invention relates to a transmission method and apparatus, and a corresponding reception method and apparatus

Transceiving method and apparatus for modulation signal transmission in filter bank multi-carrier communication system

A method and an apparatus for transmitting and receiving data in a filter bank based multicarrier communication system are provided. The method includes receiving a plurality of data blocks and performing an Inverse Fast Fourier Transform (IFFT) operation on the plurality of data blocks, multiplying the plurality of data blocks on which IFFT has been performed and time axis filter coefficients,and transmitting a result obtained by adding the plurality of multiplied data blocks as a multi carrier signal.

Chanhong Kim

Papers

A New Filter-Bank Multicarrier System With Two Prototype Filters for QAM Symbols Transmission and Reception

A new filter-bank multicarrier system for QAM signal transmission and reception

Synchronization Sequence Design for FBMC/OQAM Systems

Transceiving method and apparatus for modulation signal transmission in filter bank multi-carrier communication system

Method and apparatus for transmitting and receiving data in multicarrier communication system