The field of wireless communication systems is moving towards the development of more efficient and spectrally efficient methods for data transmission. Recent research has focused on improving the performance of existing systems, such as OFDM-based grant-free access, and exploring new waveform designs, like non-orthogonal affine frequency division multiplexing. Additionally, there is a growing interest in modulation techniques that can achieve high energy efficiency, such as index and code index modulations for spread continuous phase modulation signals. These advancements have the potential to enable reliable high-mobility communications, support massive connectivity, and reduce power consumption. Noteworthy papers include:

• A paper proposing AMP-based joint activity detection and channel estimation for massive grant-free access in OFDM-based wideband systems, which achieves superior performance and lower computational complexity.
• A paper introducing a random modulation technique that guarantees asymptotic replica optimality over arbitrary norm-bounded and spectrally convergent channel matrices, achieving BER and block-error rate performance gains.
• A paper proposing a novel non-orthogonal affine frequency division multiplexing waveform for reliable high-mobility communications with enhanced spectral efficiency.
• A paper proposing two novel modulation schemes that integrate continuous phase modulation with spread spectrum techniques, achieving higher spectral and energy efficiency and strong resilience to nonlinear distortions.