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

Cooperative Symbol-Based Signaling for Networks with Multiple Relays

Wireless channels suffer from severe inherent impairments and hence reliable and high data rate wireless transmission is particularly challenging to achieve. Fortunately, using multiple antennae improves performance in wireless transmission by providing space diversity, spatial multiplexing, and power gains. However, in wireless ad-hoc networks multiple antennae may not be acceptable due to limitations in size, cost, and hardware complexity. As a result, cooperative relaying strategies have attracted considerable attention because of their abilities to take advantage of multi-antenna by using multiple single-antenna relays. This study is to explore cooperative signaling for different relay networks, such as multi-hop relay networks formed by multiple single-antenna relays and multi-stage relay networks formed by multiple relaying stages with each stage holding several single-antenna relays. The main contribution of this study is the development of a new relaying scheme for networks using symbol-level modulation, such as binary phase shift keying (BPSK) and quadrature phase shift keying (QPSK). We also analyze effects of this newly developed scheme when it is used with space-time coding in a multi-stage relay network. Simulation results demonstrate that the new scheme outperforms previously proposed schemes: amplify-and-forward (AF) scheme and decode-and-forward (DF) scheme

Energy Efficient Transmission over Space Shift Keying Modulated MIMO Channels

Energy-efficient communication using a class of spatial modulation (SM) that encodes the source information entirely in the antenna indices is considered in this paper. The energy-efficient modulation design is formulated as a convex optimization problem, where minimum achievable average symbol power consumption is derived with rate, performance, and hardware constraints. The theoretical result bounds any modulation scheme of this class, and encompasses the existing space shift keying (SSK), generalized SSK (GSSK), and Hamming code-aided SSK (HSSK) schemes as special cases. The theoretical optimum is achieved by the proposed practical energy-efficient HSSK (EE-HSSK) scheme that incorporates a novel use of the Hamming code and Huffman code techniques in the alphabet and bit-mapping designs. Experimental studies demonstrate that EE-HSSK significantly outperforms existing schemes in achieving near-optimal energy efficiency. An analytical exposition of key properties of the existing GSSK (including SSK) modulation that motivates a fundamental consideration for the proposed energy-efficient modulation design is also provided

Optical Asymmetric Modulation for VLC Systems

The explosive growth of connected devices and the increasing number of broadband users have led to an unprecedented growth in traffic demand. To this effect, the next generation wireless systems are envisioned to meet this growth and offer a potential data rate of 10 Gbps or more. In this context, an attractive solution to the current spectrum crunch issue is to exploit the visible light spectrum for the realization of high-speed commutation systems. However, this requires solutions to certain challenges relating to visible light communications (VLC), such as the stringent requirements of VLC-based intensity modulation and direct detection (IM/DD), which require signals to be real and unipolar. The present work proposes a novel power-domain multiplexing based optical asymmetric modulation (OAM) scheme for indoor VLC systems, which is particularly adapted to transmit high-order modulation signals using linear real and unipolar constellations that fit into the restrictions of IM/DD systems. It is shown that the proposed scheme provides improved system performance that outperforms alternative modulation schemes, at no extra complexity

Double spatial media based modulation.

Masters Degree. University of KwaZulu-Natal, Durban.Multiple-input multiple-out (MIMO) systems have become an increasingly popular technology in wireless communications due to their high data rates and increased reliability. However, several drawbacks degrade the performance of MIMO systems. Inter-channel interference, inter- antenna synchronization, low energy e ciency, and relatively high-complexity receive algorithms are several of the challenges that MIMO systems face. As such, spatial modulation (SM) was introduced as a scheme that is capable of exploiting the advantages of MIMO systems, while simultaneously mitigating its drawbacks. SM provided an excellent method of exploiting spatial diversity, which eventually replaced MIMO systems. However, as the use of SM became more prominent, its drawbacks became more apparent. The spectral e ciency of SM is limited by the logarithmic relationship between spectral efficiency and the number of transmit antennas. Several SM-based transmission schemes, such as quadrature spatial modulation and double spatial modulation (DSM), were introduced with the prospect of improving the spectral efficiency of SM. These schemes have a single radio frequency (RF) chain; therefore, relatively low-complexity receive algorithms are employed. Conventional transmission techniques are referred to as source-based modulation (SBM). Media-based modulation (MBM) is a new attractive transmission scheme that has been recently receiving increased research attention. MBM employs the use of RF mirrors to vastly improve the error performance and/or spectral efficiency of modulation schemes. It has been demonstrated that MBM, coupled with SBM techniques, vastly improves the error performance and can potentially increase the spectral efficiency of these systems. In this dissertation, DSM is extended to employ MBM, such as to improve error performance. The proposed transmission scheme is called double spatial media-based modulation (DSMBM). The theoretical average bit error probability (ABEP) of DSMBM over an independent and identically distributed Rayleigh frequency- at fading channel in the presence of additive white Gaussian noise is formulated. The theoretical ABEP of DSMBM is validated by Monte Carlo simulations, where the error performance matches the theoretical ABEP at high signal-to-noise ratios (SNRs). Lastly, coded channels are investigated. Typically soft-output detection coupled with soft-input channel decoding yields a signicant SNR gain. Motivated by this, this dissertation further proposes a soft-output maximum-likelihood detector for the DSM and DSMBM schemes.List of acronyms on pages xv-xvi

On Low-Resolution ADCs in Practical 5G Millimeter-Wave Massive MIMO Systems

Nowadays, millimeter-wave (mmWave) massive multiple-input multiple-output (MIMO) systems is a favorable candidate for the fifth generation (5G) cellular systems. However, a key challenge is the high power consumption imposed by its numerous radio frequency (RF) chains, which may be mitigated by opting for low-resolution analog-to-digital converters (ADCs), whilst tolerating a moderate performance loss. In this article, we discuss several important issues based on the most recent research on mmWave massive MIMO systems relying on low-resolution ADCs. We discuss the key transceiver design challenges including channel estimation, signal detector, channel information feedback and transmit precoding. Furthermore, we introduce a mixed-ADC architecture as an alternative technique of improving the overall system performance. Finally, the associated challenges and potential implementations of the practical 5G mmWave massive MIMO system {with ADC quantizers} are discussed.Comment: to appear in IEEE Communications Magazin