On the performance of hybrid carrier system with spectrum precoding based on WFRFT

Abstract

High out-of-band (OOB) power emission has become the main shortcoming of multicarrier scheme in regard to the requirements and challenges of 5G. In this paper, two effective OOB power reduction methods, previously applied to traditional orthogonal frequency division multiplexing (OFDM) system, are proposed in hybrid carrier (HC) scheme based on weighted-type fractional Fourier transform (WFRFT). Simulation results demonstrate that, due to the flexible selection of WFRFT order in the HC system, combined bit error rate (BER) and peak-to-average power ratio (PAPR) performance advantages are gained without sidelobe impact and significant complexity increase in comparison with the OFDM scheme with spectrum precoding. In projection precoding, a smaller error vector magnitude of precoder G χ is obtained in the proposed hybrid carrier scheme. In SVD precoding with an orthogonal decoding at the receiver, better BER performance could also be acquired at WFRFT order over the fading channels. The proposed two WFRFT-based structures are complementary, and their potential scenarios are given. In addition, applying the feature of projection precoding to channel estimation, a novel pilot structure based on WFRFT is posed to reduce the introduced error of spectrum precoding and finally helps to improve the BER performance.

Performance of uplink WFRFT‐based hybrid carrier systems with non‐orthogonal multiple access

“…where P r1 is the same received average power of desired near-user signals as 7, and P r2 is the IUI average power to the near-user, which is the same as the received average power of far-user signals shown as (8). As the far-user has the same transmitting power in different WFRFT orders at the transmitter, the average IUI power from the far-user stays the same, i.e.…”

“…It is proved that the WFRFT-based user cooperation scheme can achieve significant performance advantage regarding the ergodic secrecy capacity, compared with conventional PHY-layer security oriented user cooperation schemes. In [8], it is verified that the WFRFT-based HC system can obtain better bit error ratio (BER) performance than the orthogonal frequency division multiplexing (OFDM) system, considering the spectrum precoder to reduce the out-of-band emission (OOBE). WFRFT precoded generalised frequency division multiplexing (GFDM) can also achieve better BER performance than the non-precoded GFDM over fading channels [9].…”

Biorthogonal Fourier transform for multichirp-rate signal detection over dispersive wireless channel

“…Furthermore, the affine fourier transform as a generalized FRFT is introduced to multicarrier system in [20,21]. In [22], the out-of-band power reduction methods are proposed to the weighted-type FRFT-based multicarrier system. The detectors mentioned above show better anti-ICI performance, that is proved to be feasible in ground-to-air channels.…”