FrFT-based EO-STBC multicarrier system for transmission over doubly-dispersive channels

Abstract

This paper focuses on the enhancement of extended orthogonal space-time block coding (EO-STBC) when transmitting over a doubly-dispersive channel. The frequency selective nature of the channel favours the combination with a multicarrier approach such as orthogonal frequency division multiplexing (OFDM). However, as Doppler spread increases, OFDM loses its orthogonality, resulting in severe inter-symbol (ISI) and inter-carrier interference (ICI). This is addressed firstly by the generalisation of OFDm to fractional Fourier transform (FrFT)-based multicarrier approaches, which can provide better resilience in the presence of Doppler spread. Secondly, in higher mobility scenarios, an equalisation scheme is employed, whose lower complexity in an FrFT-based multicarrier setting can further minimised by a reduction of the equaliser. Simulation results highlighting the potential performance improvements are presented

A Low-Complexity Equalizer for Video Broadcasting in Cyber-Physical Social Systems Through Handheld Mobile Devices

“…The complexity of the DFrFT-OCDM system is almost the same as the OFDM system [2], [8], [17], and both cannot diagonalize the time-variant channel matrix. However, the DFrFT-OCDM can compress the power spreading in the channel matrix much more efficiently than OFDM.…”

MIMO-OFDM/OCDM low-complexity equalization under a doubly dispersive channel in wireless sensor networks

“…In previous studies, 3,[14][15][16] the loss of OFDM orthogonality in doubly dispersive channels was studied and multicarrier schemes based on DFrFT and DFrCT were developed that the DFrFT and the DFrCT-OCDM schemes granted better performance in the doubly dispersive channel scenario. Therefore, a novel combination of the DFrFT and DFrCT-OCDM systems with Alamouti and EO-STBC is proposed in the following sections, together with investigating the combination of conventional and low-cost equalization approaches.…”

“…It is a diversity scheme that can accomplish both full diversity gain and full rate via an additional feedback link from the receiver to the transmitter, to update the phase rotations applied in the transmitter; accordingly, both full diversity and array gain are ensured. 15,33 The CSI from the receiver is fed back to the transmitter to optimize these rotations with the assumption that they are on time and errorless for easiness. EO-STBC can be simply derived in MCM schemes such as OFDM or OCDM 15 in broadband scenarios.…”

“…It is a diversity scheme that can accomplish both full diversity gain and full rate via an additional feedback link from the receiver to the transmitter, to update the phase rotations applied in the transmitter; accordingly, both full diversity and array gain are ensured. 15,33…”

“…The CSI from the receiver is fed back to the transmitter to optimize these rotations with the assumption that they are on time and errorless for easiness. EO-STBC can be simply derived in MCM schemes such as OFDM or OCDM 15 in broadband scenarios.…”