2 research outputs found
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
Index modulation-aided IQ imbalance compensator for OTFS communications systems
Design of simple transceiver architectures is inevitable in order to provide low computational complexity, low power consumption and affordable cost in beyond 5G (B5G) wireless systems, but it results in hardware impairments that significantly degrade the performance reliability of transmission. In this paper, among these hardware impairments, we discuss in-phase and quadrature (IQ) imbalance in orthogonal time frequency space (OTFS), which is a recent waveform considered as a potential candidate for B5G systems to relax the vulnerability against time-variant wireless channels. To mitigate the effect of IQ imbalance for OTFS, we propose an energy and spectral efficient IQ imbalance compensation scheme with the aid of index modulation (IM), which provides an attractive flexibility in the system design. In contrast to conventional solutions used in classical wireless technologies, such as iterative and pilot-based techniques, the proposed scheme avoids additional energy consumption and significant spectral efficient loss during the estimation and compensation of the IQ imbalance effect. The obtained bit error rate (BER) results validate the accuracy of the proposed compensator for different OTFS system configurations considering perfect/imperfect channel state information in practical scenarios