Successive-relaying-aided decode-and-forward coherent versus noncoherent cooperative multicarrier space–time shift keying

Abstract—Successive-relaying-aided (SR) cooperative multi-carrier (MC) space–time shift keying (STSK) is proposed for frequency-selective channels. We invoke SR to mitigate the typical 50% throughput loss of conventional half-duplex relaying schemes and MC code-division multiple access (MC-CDMA) to circumvent the dispersive effects of wireless channels and to reduce the SR-induced interference. The distributed relay terminals form two virtual antenna arrays (VAAs), and the source node (SN) successively transmits frequency-domain (FD) spread signals to one of the VAAs, in addition to directly transmitting to the destination node (DN). The constituent relay nodes (RNs) of each VAA activate cyclic-redundancy-checking-based (CRC) selective decode-and-forward (DF) relaying. The DN can jointly detect the signals received via the SN-to-DN and VAA-to-DN links using a low-complexity single-stream-based joint maximum-likelihood (ML) detector. We also propose a differentially encoded cooperative MC-CDMA STSK scheme to facilitate communications over hostile dispersive channels without requiring channel estimation (CE). Dispensing with CE is important since the relays cannot be expected to altruistically estimate the SN-to-RN links for simply supporting the source. Furthermore, we propose soft-decision-aided serially concatenated recursive systematic convolutional (RSC) and unity-rate-coded (URC) cooperative MC STSK and investigate its performance in both coherent and noncoherent scenarios

Successive-relaying-aided decode-and-forward coherent versus noncoherent cooperative multicarrier space–time shift keying

Abstract—Successive-relaying-aided (SR) cooperative multi-carrier (MC) space–time shift keying (STSK) is proposed for frequency-selective channels. We invoke SR to mitigate the typical 50% throughput loss of conventional half-duplex relaying schemes and MC code-division multiple access (MC-CDMA) to circumvent the dispersive effects of wireless channels and to reduce the SR-induced interference. The distributed relay terminals form two virtual antenna arrays (VAAs), and the source node (SN) successively transmits frequency-domain (FD) spread signals to one of the VAAs, in addition to directly transmitting to the destination node (DN). The constituent relay nodes (RNs) of each VAA activate cyclic-redundancy-checking-based (CRC) selective decode-and-forward (DF) relaying. The DN can jointly detect the signals received via the SN-to-DN and VAA-to-DN links using a low-complexity single-stream-based joint maximum-likelihood (ML) detector. We also propose a differentially encoded cooperative MC-CDMA STSK scheme to facilitate communications over hostile dispersive channels without requiring channel estimation (CE). Dispensing with CE is important since the relays cannot be expected to altruistically estimate the SN-to-RN links for simply supporting the source. Furthermore, we propose soft-decision-aided serially concatenated recursive systematic convolutional (RSC) and unity-rate-coded (URC) cooperative MC STSK and investigate its performance in both coherent and noncoherent scenarios

MC-CDMA aided multi-user space-time shift keying in wideband channels

In this paper, we propose multi-carrier code division multiple access (MC-CDMA)-aided space-time shift keying (STSK) for mitigating the performance erosion of the classic STSK scheme in dispersive channels, while supporting multiple users. The codewords generated by the STSK scheme are appropriately spread in frequency-domain (FD) and transmitted over a number of parallel frequency-?at subchannels. We propose a new receiver architecture amalgamating the single-stream maximum-likelihood (ML) detector of the STSK system and the multiuser detector (MUD) of the MC-CDMA system. The performance of the proposed scheme is evaluated for transmission over frequency-selective channels in both uncoded and channel-coded scenarios. The results of our simulations demonstrate that the proposed scheme overcomes the channel impairments imposed by wideband channels and exhibits near-capacity performance in a channel-coded scenario

OFDMA/SC-FDMA aided space-time shift keying for dispersive multi-user scenarios

Motivated by the recent concept of Space-Time Shift Keying (STSK) developed for achieving a flexible diversity versus multiplexing gain trade-off, we propose a novel Orthogonal Frequency Division Multiple Access (OFDMA)/Single Carrier Frequency Division Multiple Access (SC-FDMA) aided multi-user STSK scheme for frequency-selective channels. The proposed OFDMA/SC-FDMA STSK scheme is capable of providing an improved performance in dispersive channels, while supporting multiple users in a multiple antenna aided wireless system. Furthermore, the scheme has the inherent potential of benefitting from the low-complexity single-stream Maximum-likelihood (ML) detector. Both an uncoded and a sophisticated near-capacity coded OFDMA/SC-FDMA STSK scheme were studied and their performances were compared in multiuser wideband Multiple-Input Multiple-Output (MIMO) scenarios. Explicitly, OFDMA/SC-FDMA aided STSK exhibits an excellent performance even in the presence of channel impairments due to the frequency-selectivity of wideband channels and proves to be a beneficial choice for high capacity multi-user MIMO systems

A Reduced-Complexity Detector for OFDMA/SC-FDMA-aided Space-Time Shift Keying

We propose a novel reduced-complexity detector for the orthogonal frequency division multiple access (OFDMA)/single-carrier frequency division multiple access (SC-FDMA)-aided space-time shift keying (STSK) architecture. STSK employing OFDMA/SC-FDMA has recently been shown to be beneficial in dispersive multiuser downlink/uplink scenarios. These schemes exhibit excellent performance at a considerably reduced decoding complexity. We can employ a single-stream maximum-likelihood (ML) detector, since a single dispersion matrix (DM) is activated at any signalling interval. In this paper, we propose a new detector, which is capable of further reducing the decoding complexity. The proposed detector is particularly suitable for STSK-based transmission over frequency-selective multiple-input multiple-output (MIMO) channels employing frequency-domain equalization (FDE). The complexity of the proposed scheme is quantified and it is observed that the scheme maintains its superior multiple-antenna performance at a significantly reduced complexit

Unified MIMO-multicarrier designs: a space–time shift keying approach

A survey and tutorial is provided on the subject of multiple-input multiple-output (MIMO) multicarrier (MC) systems relying on the space-time shift keying concept. We commence with a brief review of the family of MIMO systems, which is followed by the design of space-time shift keying (STSK) systems in the context of MC modulation-based transmissions over dispersive wireless channels. Specifically, the STSK scheme is amalgamated with orthogonal frequency division multiplexing (OFDM),MC code division multiple access (MC-CDMA), orthogonal frequency division multiple access (OFDMA) and singlecarrier frequency division multiple access (SC-FDMA). We also provide a rudimentary introduction to MC differential STSK (MC DSTSK) employing both conventional differential detection (CDD) and multiple-symbol differential sphere decoding (MSDSD) for the sake of dispensing with channel estimation (CE).We conclude with the design recipes of coherent versus noncoherent MC STSK schemes, complemented by a range of future research ideas

OFDM aided space-time shift keying for dispersive downlink channels

The performance of a Space-Time Shift Keying (STSK) scheme was shown to degrade in frequency-selective fading channels. Hence, we propose Orthogonal Frequency Division Multiplexing (OFDM) combined with STSK for frequency-selective broadband channels. Furthermore, we consider both an uncoded and a near-capacity coded scenario. Our results show that a STSK system combined with OFDM is capable of overcoming the impairments of dispersive channels, hence approaching the same performance as in a flat-fading channel

Subcarrier-index modulated multicarrier space-time shift keying: achievable rate, performance, and design guidelines

Multicarrier (MC) space-time shift keying (STSK) relying on the concept of subcarrier-index modulated orthogonal frequency division multiplexing (SIM-OFDM) is proposed. In conventional MC-STSK system, the performance erosion of STSK in dispersive channels is mitigated by employing OFDM. The SIM-OFDM aided MC-STSK activates a specified limited number of subcarriers for transmitting the STSK codewords. The indices of the activated subcarriers provide additional multiplexing gain. A new receiver architecture, which uses the single-stream maximum-likelihood (ML) detector of STSK and the subcarrier activation principle of SIM-OFDM, is designed. A soft decision logarithmic likelihood ratio (LLR) based detector is also conceived. Helpful design guidelines are provided for the system. The achievable rate, complexity, and performance of the system are analytically quantified and verified with the aid of numerical simulations. The system is capable of overcoming the impairments imposed by wideband channels, is benefited from index modulation as well as from STSK. The scheme exhibits an improved error performance compared to the classic OFDM-based STSK as a result of the more reliable detection of the subcarrier index bits.</p

Co-located and distributed multicarrier space-time shift keying for wideband channels

Multicarrier (MC) transmissions are proposed for the space time shift keying (STSK) concept. Specifically, OFDM, MC CDMA and OFDMA/SC-FDMA-aided STSK are proposed for transmissions over dispersive wireless channels. Additionally, a successive relaying (SR) aided cooperative MC STSK scheme is conceived for gleaning cooperative space time diversity and for mitigating the half-duplex throughput loss of conventional relaying. Furthermore, a multiple-symbol differential sphere decoding (MSDSD) aided multicarrier STSK arrangement is proposed to dispense with channel estimation (CE).We design a novel modality of realizing STSK amalgamated with OFDM for facilitating high-rate data-transmissions through a number of low-rate parallel subchannels, thus overcoming the dispersion induced by broadband channels. A MC-CDMA aided STSK system is also proposed for mitigating the channel-induced dispersion, while providing additional frequency-domain (FD) diversity and supporting multiuser transmissions. As a further advance, we design OFDMA and SC FDMA-aided STSK systems, which are capable of communicating in dispersive multiuser scenarios, whilst maintaining a low peak-to-average power ratio (PAPR) in the SC-FDMA-aided STSK uplink. Additionally, complexity reduction techniques are proposed for OFDMA/SC-FDMA-aided STSK.We also conceive the concept of SR aided cooperative multicarrier STSK for frequency-selective channels for mitigating the typical 50% throughput loss of conventional half-duplex relaying in the context of MC-CDMA and for reducing the SR-induced interferences. We additionally propose a differentially encoded cooperative MC-CDMA STSK scheme for facilitating communications over hostile dispersive channels without requiring CE.Finally, the noncoherent multicarrier STSK arrangement is further developed by using MSDSD. The conventional differential detection suffers from a typical 3-dB performance loss, which is further aggravated in the presence of high Doppler frequencies. Hence, for the sake of mitigating this performance loss in the face of high Doppler scenarios, while maintaining a modest decoding complexity, both a hard-decision-based as well as an iterative soft-decision multiple-symbol differential sphere decoding aided multicarrier STSK arrangement is developed