About this Research Topic
Mobile communications with high terminal mobilities have become an everyday commodity. In the last decades, they have evolved from being an expensive technology for selected individuals to be used by most populations as a necessity. This thirstiness to communicate makes essential to develop a mobile technology better suited to meet the upcoming needs with respect to service variety and applications and services heterogeneity, namely massive machine type communications (mMTC); Tactile Internet, IoT and unmanned aerial vehicle (UAV) communications, to name a few.
The continuous upsurge of traffic and service demands and applications supporting more intelligent techniques like Artificial Intelligence (AI), has motivated industry and academia researchers to work on the conceptualization of the next mobile communications standard. The sixth-generation wireless communications, 6G, is expected to expand the coverage, reduce the latency and provide higher data speeds exceeding 100 Gbps. It will also guarantee an efficiently use of the available frequency spectrum which is from the upper part of the millimeter wave (mmWave) band to the “terahertz wave”, as recommended by the U.S. Federal Communications Commission. Other targets are to: increase data rates, improve coverage, control power consumption, reduce complexity, densify connections, i.e. massive IoT connectivity, M2M communication and end-to-end transmission time. However, various existing technologies should be further developed for 6G such as Massive MIMO, mmWave, ultra-dense networks, etc. Some of them generally face a high interference level that exists in the received signal and that also minimizes the energy spreading. This in turn dramatically disturbs and degrades the signal quality, which necessitates reworking the physical layer and therefore designing new waveforms for wireless communication.
In 4G and 5G, Orthogonal Frequency Division Multiplexing (OFDM) transmission has been adopted and is used as a broadband transport modulation in the physical layer of many high data rate wireless communication systems. However, OFDM has some limitations such as the sporadic access generated by the mMTC devices in the IoT, which imposes a vital need to uncoordinated user transmissions. As such, 5G and beyond waveforms designs were constrained to relax the strict synchronization and orthogonality conditions of OFDM. Then, one of main focus of researchers is to propose non-orthogonal wireless multicarrier schemes, with well-localized waveforms in time and frequency. These waveforms should be robust to relaxed time/frequency synchronization requirements that are expected in several future applications. To this end many multicarrier modulation waveforms have been proposed in the literature among them we can cite, Generalized Frequency Division Multiplexing (GFDM), Filter Bank Multicarrier Modulation (FBMC) and Universal Filtered Multi-Carrier (UFMC). These waveforms and many others were proposed as alternative access techniques for 5G and each one of them has its advantages and limitations that represent a main concern of several researches.
This research topic, “Waveform Design for Beyond 5G networks”, aims to offer a platform for researchers to present new concepts and new research work and results on designing optimized and flexible Tx/Rx waveforms to support 6G requirements. Topics of interest include, but are not limited to the followings:
• Multi-pulse OFDM
• Signal waveform design for wireless, optical and wireless-optical applications.
• Waveform design for Massive MIMO and multi-user MIMO systems • Waveform design for IoT Connectivity
• Advanced modulation schemes in combination with waveform design
• Application of AI techniques to waveform design
• Waveform design for enhanced and simplified channel estimation, equalization and compensation • Waveform
design for efficient and simplified interference cancellation
• Waveform design for satellite communications with reduced PAPR
• Power efficient precoding
• Waveform design for Non orthogonal multiple access (NOMA)
• Waveform design for UAV communications
• Waveform design for faster-than-Nyquist (FTN) signaling
• Waveform design for increased resilience to synchronization imperfections
• Waveform design for increased resilience to multiple access interference
• AI based transceivers for joint DPD and PAPR reduction
• RF impairment mitigation techniques for post-OFDM waveforms
• SDR implementation of post-OFDM based transceivers
Keywords: 6G, Waveforms, Massive MIMO, UAV, IoT, Multi-pulse, OMA, NOMA, DPD, PAPR
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