Lixia Xiao

Single-Carrier SM-MIMO: A Promising Design for Broadband Large-Scale Antenna Systems

The main limitations of employing large-scale antenna (LSA) architectures for broadband frequency-selective channels include, but are not limited to their complexity, power consumption, and the high cost of multiple radio frequency (RF) chains. Promising solutions can be found in the recently proposed family of single-carrier (SC) spatial modulation (SM) transmission techniques. Since the SM schemes transmit antenna (TA) activation process is carried out in the context of a SC-SM architecture, the benefits of a low-complexity and low-cost single-RF transmitter are maintained, while a high MIMO multiplexing gain can be attained. Moreover, owing to its inherent SC structure, the transmit signals of SC-SM have attractive peak power characteristics and a high robustness to RF hardware impairments, such as the RF carrier frequency offset (CFO) and phase noise. In this paper, we present a comprehensive overview of the latest research achievements of SC-SM, which has recently attracted considerable attention. We outline the associated transceiver design, the benefits and potential tradeoffs, the LSA aided multiuser (MU) transmission developments, the relevant open research issues as well as the potential solutions of this appealing transmission technique.

Efficient Compressive Sensing Detectors for Generalized Spatial Modulation Systems

Generalized spatial modulation (GSM) is a novel multiple-input–multiple-output (MIMO) technique, which relies on a sparse use of radio-frequency (RF) front ends at the transmitter. In this paper, low-complexity and compressive-sensing (CS)-based detectors for GSM systems are proposed. First, an extension of the normalized CS detector (E-NCS) based on the orthogonal matching pursuit (OMP) algorithm is proposed, which is shown to be suitable for large-scale GSM implementations, due to its low complexity. Furthermore, to mitigate the error floor effect of the E-NCS detector, two efficient CS (ECS) detectors based on the OMP algorithm are designed with the aid of a preset threshold. Specifically, different searching algorithms are designed, whose objective is to balance computational complexity and system performance. An upper bound for the average bit error probability (ABEP) of the first ECS detector is derived and used to optimize the preset threshold. Simulation results show that the proposed ECS detectors are capable of achieving a considerable reduction in computational complexity, compared with other near-optimal algorithms, with a negligible performance loss.

A Low-Complexity Detection Scheme for Generalized Spatial Modulation Aided Single Carrier Systems

Generalized spatial modulation (GSM), which combines spatial modulation (SM) and vertical Bell Laboratories layered space-time (V-BLAST), is a novel attractive multi-input multi-output (MIMO) technique. In this letter, a low-complexity near-optimal detection scheme is presented for GSM aided single carrier (SC) transmission over dispersive channels. Compared to the conventional partial interference cancellation receiver with successive interference cancellation (PIC-R-SIC), the proposed scheme offers a near maximum likelihood (ML) detection performance while avoiding complicated matrix operations, which allows it to exhibit a lower computational complexity. Simulation results show that the proposed scheme provides a considerable performance improvement compared to PIC-R-SIC, especially in rank-deficient channels scenarios.

A Low-Complexity Detection Scheme for Differential Spatial Modulation

Differential spatial modulation (DSM), which does not require the channel state information at the receiver, is an attractive alternative to its coherent counterpart. The optimal maximum-likelihood (ML) detector of the DSM system employs the classic block-by-block method for jointly detecting the activated antenna matrix (AM) and the modulation symbols, resulting in high computational complexity. In this letter, a low-complexity near-ML detector, which operates on a symbol-by-symbol basis, is proposed for the DSM scheme. Specifically, in each block, the index of the activated transmit antenna and modulation symbol in each time slot are first obtained, and then, these antenna indices are utilized to simply determine the index of the activated AM. Simulation results show that the proposed algorithm is capable of offering almost the same performance as that of the ML detector with more than 90% reduction in complexity.

An Improved Soft-Input Soft-Output Detector for Generalized Spatial Modulation

Generalized spatial modulation (GSM) is a recently proposed appealing multi-input multi-output (MIMO) transmission technique, which is capable of striking a tradeoff between the achievable transmission rate and the cost of radio frequency (RF) chains. In this letter, a novel low-complexity near-optimal soft decision (SoD)-aided detector is proposed for GSM, which considerably reduces the search space by employing a block minimum mean-squared error (B-MMSE) algorithm. Our simulation results show that the proposed detector is capable of achieving a better tradeoff between bit-error-rate (BER) performance and computational complexity compared with the existing matched filter (MF)-based SoD algorithms.

Low-Complexity Signal Detection for Large-Scale Quadrature Spatial Modulation Systems

In this letter, a novel low-complexity detector based on the concept of compressive sensing (CS) is proposed for a novel multiple-input multiple-output system, namely, quadrature spatial modulation (QSM). In particular, the CS algorithm is performed in the real-valued system model, and the activated antenna indices, which are used to transmit the real and imaginary parts of QSM symbols, can be estimated separately. In order to further improve the performance of QSM, a novel search strategy is proposed. Simulation results show that the proposed detector is capable of achieving a considerable reduction in complexity compared with the maximum likelihood counterpart with negligible performance loss.

Performance evaluation in PAPR and ICI for ISIM-OFDM systems

Interleaved subcarrier-index modulation for orthogonal frequency division multiplexing (ISIM-OFDM) is a recently developed technique, where the indices of OFDM subcarriers are utilized to convey information bits and subcarrier-level interleaving scheme is considered. For the conventional OFDM system, the main drawbacks lie in the high peak-to-average power ratio (PAPR) at transmitter and its sensitiveness to inter-carrier interference (ICI) in a highly mobile environment. In this paper, the performance evaluation in PAPR and ICI for ISIM-OFDM system is presented. Simulation results show that ISIM-OFDM system can efficiently reduce the PAPR and is more robust to ICI compared with traditional OFDM system.

Spatial modulaiton for 5G MIMO communications

Spatial modulation (SM) is a class of novel multi-input multi-output (MIMO) techniques for wireless communications. In SM-MIMO, only part of the transmit antennas are active for transmission, which avoids the interference among multiple antennas and simplifies the structure of MIMO transceiver. In this paper, we summarize the recent researches related to SM-MIMO, to demonstrate the flexibility and effectiveness of the new technique. Furthermore, we show some potential applications of SM-MIMO in future 5G wireless communications.

Low-complexity tree search-based detection algorithms for generalized spatial modulation aided single carrier systems

In this paper, we design the low-complexity tree search-based detectors for generalized spatial modulation (GSM) aided single carrier (SC) systems over dispersive channels. Specifically, we commence with a brief review of the existing detection algorithms and then extend the sphere decoding-aided (SD) tree search algorithms designed for flat fading channels to GSM-aided SC systems. Moreover, a pair of reduced-complexity tree search algorithms are proposed by employing a hybrid concept of SD and M-algorithm to balance a tradeoff between the performance and complexity. Our proposed detectors are capable of recovering the transmit signal for both the overdetermine and underdetermine antenna configurations. Simulation results show that: 1) the extended SD-aided tree search algorithms are capable of providing the same performance as the maximum likelihood (ML) algorithm with reduced complexity; 2) the proposed novel algorithms exhibit lower complexity with negligible performance loss, compared with other tree search algorithms.

Low-complexity non-coherent detection for spatial modulation OFDM systems

This letter describes a differential modulation scheme for spatial modulation orthogonal frequency division multiplexing (SM OFDM), aiming at developing low-complexity non-coherent detection without channel state information (CSI) at the receiver. By employing differential phase-shift keying (DPSK) between nonzero subcarrier at each transmit antenna, the proposed method can work with any number of transmit and receive antennas to realize high bandwidth efficiency. Additionally, the reference symbols at each transmit antenna are initialized at particular subcarriers, which are utilized to estimate the antenna indices at the receiver. Simulation results show that the proposed scheme gives rise to reasonable performance penalty in comparison to coherent SM OFDM.