Low-Complexity Expectation Propagation Detection for Uplink MIMO-SCMA Systems

We consider uplink sparse code multiple access (SCMA) systems associated with multiple input multiple output (MIMO), where the transmitters and the receiver are equipped with multiple antennas, for enhanced reliability (diversity gain) or improved data rate (multiplexing gain). For each diversity or multiplexing based MIMO scheme combined with SCMA, we develop low-complexity iterative detection algorithms based on the message passing algorithm (MPA) and the expectation propagation algorithm (EPA). We show that the MIMO-SCMA under EPA enjoys the salient advantage of linear complexity (in comparison to the MPA counterpart with exponential complexity) as well as enhanced error rate performances due to the MIMO transmission. We also show that the performance of EPA depends on the codebook size and the number of antennas

Multidimensional Index Modulation for 5G and Beyond Wireless Networks

This study examines the flexible utilization of existing IM techniques in a comprehensive manner to satisfy the challenging and diverse requirements of 5G and beyond services. After spatial modulation (SM), which transmits information bits through antenna indices, application of IM to orthogonal frequency division multiplexing (OFDM) subcarriers has opened the door for the extension of IM into different dimensions, such as radio frequency (RF) mirrors, time slots, codes, and dispersion matrices. Recent studies have introduced the concept of multidimensional IM by various combinations of one-dimensional IM techniques to provide higher spectral efficiency (SE) and better bit error rate (BER) performance at the expense of higher transmitter (Tx) and receiver (Rx) complexity. Despite the ongoing research on the design of new IM techniques and their implementation challenges, proper use of the available IM techniques to address different requirements of 5G and beyond networks is an open research area in the literature. For this reason, we first provide the dimensional-based categorization of available IM domains and review the existing IM types regarding this categorization. Then, we develop a framework that investigates the efficient utilization of these techniques and establishes a link between the IM schemes and 5G services, namely enhanced mobile broadband (eMBB), massive machine-type communications (mMTC), and ultra-reliable low-latency communication (URLLC). Additionally, this work defines key performance indicators (KPIs) to quantify the advantages and disadvantages of IM techniques in time, frequency, space, and code dimensions. Finally, future recommendations are given regarding the design of flexible IM-based communication systems for 5G and beyond wireless networks.Comment: This work has been submitted to Proceedings of the IEEE for possible publicatio

Hierarchical multi-functional layered spatial modulation

In pursuit of optimal Index Modulation (IM)-aided Multiple-Input Multiple-Output (MIMO) systems, where information is implicitly conveyed by relying on the on/off mechanism of the system’s components in addition to the classical amplitude, phase or frequency components, we present in a tutorial style our novel Multi-Functional (MF) architecture of Layered Multi-Set (LMS) modulation. This generalized framework subsumes various MIMO techniques exhibiting different multiplexing and diversity functionalities. Our LMS design relies on three constituents, namely the space-time (ST) unit, the layered unit as well as the spatial switching unit. More specifically, the ST unit relies on the Generalized Space-Time Shift Keying (GSTSK) scheme, where P – rather than one – out of Q ST dispersion matrices are selected for dispersing an equivalent number of PSK/QAM symbols across the antennas and time-slots. In the layered unit, multiple GSTSK codewords are stacked within the layers of codewords spread over time and space. The spatial switching unit activates Ntc out of Nt transmit antennas. Owing to its hierarchical MF architecture, our LMS system strikes a flexible design trade-off between the achievable throughput as well as the attainable diversity gain and it can potentially subsume various conventional MIMO schemes, such as Bell Lab’s Layered Space-Time (BLAST), Space-Time Block Codes (STBCs), Layered Steered Space-Time Codes (LSSTCs), Spatial Modulation (SM), Space-Shift Keying (SSK), Linear Dispersion Codes (LDCs), Generalized SM (GSM), STSK, GSTSK, Quadrature SM (QSM) as well as Multi-Set STSK (MS-STSK). Additionally, we derive the LMS system’s Discrete-input Continuous-output Memoryless Channel (DCMC) capacity, which encompasses the capacity limit of all the LMS subsidiaries. We also propose a two-stage serially concatenated soft-decision (SD) based LMS detector by relying on an inner and an outer decoder that iteratively exchange their extrinsic information in order to achieve a near-capacity performance. Last but not least, we utilize the EXtrinsic Information Transfer (EXIT) charts for analyzing the convergence behavior of our SD-aided coded LMS scheme

Dataset:"Hierarchical Multi-Functional Layered Spatial Modulation"

Dataset of the following manuscript: Hemadeh, Ibrahim; El-Hajjar, Mohammed; Hanzo, Lajos (2018), &#39;Hierarchical Multi-Functional Layered Spatial Modulation&#39;, published in IEEE Access</span