Quasi-orthogonal space-frequency coding in non-coherent cooperative broadband networks

© 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.So far, complex valued orthogonal codes have been used differentially in cooperative broadband networks. These codes however achieve less than unitary code rate when utilized in cooperative networks with more than two relays. Therefore, the main challenge is how to construct unitary rate codes for non-coherent cooperative broadband networks with more than two relays while exploiting the achievable spatial and frequency diversity. In this paper, we extend full rate quasi-orthogonal codes to differential cooperative broadband networks where channel information is unavailable. From this, we propose a generalized differential distributed quasi-orthogonal space-frequency coding (DQSFC) protocol for cooperative broadband networks. Our proposed scheme is able to achieve full rate, and full spatial and frequency diversity in cooperative networks with any number of relays. Through pairwise error probability analysis we show that the diversity gain of our scheme can be improved by appropriate code construction and sub-carrier allocation. Based on this, we derive sufficient conditions for the proposed code structure at the source node and relay nodes to achieve full spatial and frequency diversity.Peer reviewe

Design guidelines for spatial modulation

A new class of low-complexity, yet energyefficient Multiple-Input Multiple-Output (MIMO) transmission techniques, namely the family of Spatial Modulation (SM) aided MIMOs (SM-MIMO) has emerged. These systems are capable of exploiting the spatial dimensions (i.e. the antenna indices) as an additional dimension invoked for transmitting information, apart from the traditional Amplitude and Phase Modulation (APM). SM is capable of efficiently operating in diverse MIMO configurations in the context of future communication systems. It constitutes a promising transmission candidate for large-scale MIMO design and for the indoor optical wireless communication whilst relying on a single-Radio Frequency (RF) chain. Moreover, SM may also be viewed as an entirely new hybrid modulation scheme, which is still in its infancy. This paper aims for providing a general survey of the SM design framework as well as of its intrinsic limits. In particular, we focus our attention on the associated transceiver design, on spatial constellation optimization, on link adaptation techniques, on distributed/ cooperative protocol design issues, and on their meritorious variants

Dispensing with Channel Estimation…

In this article, we investigate the feasibility of noncoherent detection schemes in wireless communication systems as a low-complexity alternative to the family of coherent schemes. The noncoherent schemes require no channel knowledge at the receiver for the detection of the received signal, while the coherent schemes require channel inherently complex estimation, which implies that pilot symbols have to be transmitted resulting in a wastage of the available bandwidth as well as the transmission power

Single-RF spatial modulation requires single-carrier transmission: frequency-domain turbo equalization for dispersive channels

In this paper, we propose a broadband single-carrier (SC) spatial-modulation (SM) based multiple-input multipleoutput (MIMO) architecture relying on a soft-decision (SoD) frequency-domain equalization (FDE) receiver. We demonstrate that conventional orthogonal frequency-division multiplexing (OFDM)-based broadband transmissions are not readily suitable for the single–radio frequency (RF) assisted SM-MIMO schemes, since this scheme does not exhibit any substantial performance advantage over single-antenna transmissions. To circumvent this limitation, a low-complexity soft-decision (SoD) FDE algorithm based on the minimum mean-square error (MMSE) criterion is invoked for our broadband SC-based SM-MIMO scheme, which is capable of operating in a strongly dispersive channel having a long channel impulse response (CIR) at a moderate decoding complexity. Furthermore, our SoD FDE attains a near-capacity performance with the aid of a three-stage concatenated SC-based SM architecture

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

Maximum likelihood detection for differential unitary space-time modulation with carrier frequency offset

Can conventional differential unitary space time modulation (DUSTM) be applied when there is an unknown carrier frequency offset (CFO)? This paper answers this question affirmatively and derives the necessary maximum likelihood (ML) detection rule. The asymptotic performance of the proposed ML rule is analyzed, leading to a code design criterion for DUSTM by using the modified diversity product. The resulting proposed decision rule is a new differential modulation scheme in both the temporal and spatial domains. Two sub-optimal multiple-symbol decision rules with improved performance are also proposed. For the efficient implementation of these, we derive a modified bound intersection detector (BID), a generalization of the previously derived optimal BID for the conventional DUSTM. The simulation results show that the proposed differential modulation scheme is more robust against CFO drifting than the existing double temporal differential modulation

A Novel Multiple-Output DUSTF Coding on High Mobility MIMO-Wireless Communication Systems

In the future, wireless access system will operate in high data rate transmission and high mobility environment, to support private and public access. For such an environment, it is necessary to develop a system that has a higher spectrum efficiency and is able to mitigate selective fading problems. A novel multiple-output differential unitary space-time frequency (DUSTF) coding scheme is proposed to overcome those problems. The implementation of this inner coding scheme is unified with MIMO system, so that the scheme has a good spectrum efficiency. The differential space-time modulation in this proposed scheme is intended to operate in a non-coherent channel transmission scheme and to guarantee the system performance. In order to combat the selective fading problems, the multi-carrier space frequency scheme is utilized in the proposed scheme. In general, simulation result shows that the MIMO wireless system with the multiple-output DUSTF coding scheme in a non-coherent channel transmission scheme provides a good system performance. The proposed scheme can outperforms other previously published inner coding scheme for high mobility and high SNR. The system also achieves a good channel capacity