Index modulation techniques for 5G wireless networks

Abstract

The increasing demand for higher data rates, better quality of service, fully mobile and connected wireless networks lead the researchers to seek new solutions beyond 4G wireless systems. It is anticipated that 5G wireless networks, which are expected to be introduced around 2020, will achieve ten times higher spectral and energy efficiency than current 4G wireless networks and will support data rates up to 10 Gbps for low mobility users. The ambitious goals set for 5G wireless networks require dramatic changes in the design of different layers for next generation communications systems. Massive multiple-input multiple-output (MIMO) systems, filter bank multicarrier (FBMC) modulation, relaying technologies, and millimeter-wave communications have been considered as some of the strong candidates for the physical layer design of 5G networks. In this article, we shed light on the potential and implementation of index modulation (IM) techniques for MIMO and multi-carrier communications systems which are expected to be two of the key technologies for 5G systems. Specifically, we focus on two promising applications of IM: spatial modulation (SM) and orthogonal frequency division multiplexing with IM (OFDM-IM), and we discuss the recent advances and future research directions in IM technologies towards spectral and energy-efficient 5G wireless networks.I. INTRODUCTION After more than 20 years of research and development, the achievable data rates of today's cellular wireless communications systems are several thousands of times faster compared to earlier 2G wireless systems. However, unprecedented levels of spectral and energy efficiency are expected from 5G wireless networks to achieve ubiquitous communications between anybody, anything, and anytime [1]. In order to reach the challenging objectives of 5G wireless networks, the researchers have envisioned novel physical layer (PHY) concepts such as massive multiple-input multiple-output (MIMO) systems and non-orthogonal multi-carrier communications schemes. However, the wireless community is still working day and night to come up with new and more effective PHY solutions towards 5G networks. There has been a growing interest on index modulation (IM) techniques over the past few years. IM, in which the indices of the building blocks of the considered communications systems are used to convey additional information bits, is a novel digital modulation scheme with high spectral and energy efficiency. Spatial modulation (SM) and orthogonal frequency division multiplexing with IM (OFDM-IM) schemes, where the corresponding index modulated building blocks respectively are the transmit antennas of a MIMO system and the subcarriers of an OFDM system, appear as two interesting as well as promising applications of the IM concept.After the pioneering works of Mesleh et al.[2] and Jeganathan et al.[3], SM techniques have attracted significant attention over the past few years. Although having strong and well-established competitors such as vertical Bell Labs layered space-ti...

TCM for OFDM-IM

“…3 shows the bit error rates (BERs) of uncoded OFDM-IM and the two TCM-OFDM-IM schemes when d g is fixed (i.e., the elements of d g are assumed to be 1). For ML decoding, in this case, the cost of each cluster g is (6). It can be shown that the diversity order of uncoded OFDM-IM is 2 and that of the rate-2/3 TCM scheme is 4 as expected.…”

“…In [5], the optimal number of active subcarriers is studied to improve the spectral efficiency as well as energy efficiency. An overview of various IM techniques is presented in [6], [7] and a performance analysis is carried out when a maximum likelihood (ML) detector is employed in [8].…”

High competence MIMO-OFDM with generalized led index modulation

“…The resulting time-domain OFDM frame: XT = [ X0 …..Xn] T , cannot be communicated through a VLC channel because of its complex-valued and bipolar (positive and negative valued) elements. Here a new LED index modulation based MIMO transmission technique has been developed to rectify this issue [6]. After parallel-to-serial (P/S), the real and imaginary parts of the complex signal xk are split as xk = xk;R + j xk;I .…”

Impact of CSI Uncertainty on MCIK-OFDM: Tight Closed-Form Symbol Error Probability Analysis

“…The MCIK-OFDM with hybrid low complexity greedy detection and multiple antenna diversity reception is proposed in [17]. The detailed survey of IM techniques can be found in [18], [19] It is noteworthy that most of existing works focus on the BER performance analysis for the ML detection [20]- [22], or for the energy detectors like the GD [23], [24], while little work on the SEP analysis for MCIK-OFDM has been done. In fact, existing expressions for the BER are not able to provide a comprehensive insight into the achievable diversity order and coding gain of system.…”