Enhanced Multicarrier Techniques for Professional Ad-Hoc and Cell-Based Communications (EMPhAtiC) Document Number D3.3 Reduction of PAPR and non linearities effects

Livrable d'un projet Européen EMPHATICLike other multicarrier modulation techniques, FBMC suffers from high peak-to-average power ratio (PAPR), impacting its performance in the presence of a nonlinear high power amplifier (HPA) in two ways. The first impact is an in-band distortion affecting the error rate performance of the link. The second impact is an out-of-band effect appearing as power spectral density (PSD) regrowth, making the coexistence between FBMC based broad-band Professional Mobile Radio (PMR) systems with existing narrowband systems difficult to achieve. This report addresses first the theoretical analysis of in-band HPA distortions in terms of Bit Error Rate. Also, the out-of band impact of HPA nonlinearities is studied in terms of PSD regrowth prediction. Furthermore, the problem of PAPR reduction is addressed along with some HPA linearization techniques and nonlinearity compensation approaches

Numerical Simulation and Design of Low PAPR FBMC Communication System for 5G Applications

Unlike SC-FDMA (Single-Carrier Frequency Division Multiple Access), merging only DFT (Discrete Fourier Transform) addition with FBMC-OQAM (filter group multi-carrier with offset quadrature amplitude modulation) only cuts the marginal PAPR. (Peak-to-average power ratio). To take advantage of the single carrier effect of DFT extension, special conditions for the coefficients of the IQ (in-phase and quadrature phase) channels of every single subcarrier ought to be met. As a beginning point, we first originate this form, which we call the ITSM (Identical Time-Shifted Multi-Carrier) condition. Then, depending on this condition, we put forward a new FBMC for low PAPR. The foremost features of the offered way out are summarized as: First, to additionally raise the PAPR reduction, we created four candidate versions of the FBMC waveform for DFT spreading out and ITSM conditions and carefully chosen one with the least peak power. Even with various candidate generations, unlike the traditional SI (Side information) based PAPR reduction scheme, the focal computational fragments (such as DFT and IDFT) are shared and need only be executed one time. Therefore, matched to the prior DFT-expanded FBMC, the overhead in complexity is small, and the recommended pattern can realize a PAPR reduction comparable to SC-FDMA. Second, in the projected pattern each one pass on only two bits of SI from a block of FBMC-OQAM symbols. And so, the SI overhead is meaningfully lesser than a conventional SI-based scheme such as SLM (Selective Mapping) or PTS (Partial Transmission Sequence).The whole work is executed using MATLAB software. The PAPR of FBMC system has been significantly reduced after the application of proposed algorithm. PAPR was reduced by 25 % after the use of DFT spreading and ITSM conditioning

Prediction of Spectral Regrowth for FBMC-OQAM system using Cumulants

Relevance of Filter Bank Multi-Carrier (FBMC) systems along with Offset Quadrature Amplitude Modulation (OQAM) for 5G Radio Access Technology (RAT) cannot be ruled out. FBMC-OQAM modulation technique has many attractive features over OFDM that make it more appealing to be the radio waveform in 5G. However, being a multi-carrier modulation technique, it has high PAPR and prone to spectral regrowth in the presence of a non-linear high power amplifier (HPA), which is a vital component in contemporary modern communication systems. This spectral regrowth indicate that the excellent frequency localization property of the FBMC-OQAM signals no longer holds in the presence of a non-linear HPA. So, there is a dire need to predict the extant of spectral regrowth induced by the HPA non-linearities. With cumulants, it is possible to predict the power spectral density (PSD) of the HPA output. Prediction of spectral regrowth in the case of OFDM systems was already done and in this paper it is extended to FBMC based systems. HPA of Salehs model is used for simulations but prediction can be done for any measured or modeled HPA after polynomial fitting of its AM/AM and AM/PM distortion characteristics