Achieving Enhanced Spectral Efficiency for Constant Envelope Transmission in CP-OFDMA Framework

Area of Science:

• Wireless communication systems
• Signal processing for telecommunications
• Next-generation mobile networks

Background:

• Orthogonal frequency-division multiplexing (OFDM) is standard for 6G due to its efficiency, but suffers from high peak-to-average power ratio (PAPR).
• High PAPR degrades power amplifier efficiency and causes nonlinear distortion, critical issues for power- and cost-constrained 6G networks.

Purpose of the Study:

• To propose a novel constant-envelope cyclic-prefix OFDM (CE-CP-OFDM) transceiver architecture.
• To maintain high spectral efficiency while significantly reducing PAPR in 6G systems.
• To address challenges posed by nonlinear distortion and power efficiency.

Main Methods:

• Developed a spectrally efficient subcarrier mapping scheme with partial frequency overlap.
• Introduced an optimal multiuser CE pilot design using frequency-domain phase shifts and generalized DFT-based sequences.
• Proposed a joint delay-frequency-domain channel estimation and an iterative frequency-domain LMMSE equalizer.

Main Results:

• The proposed CE-CP-OFDM transceiver maintains high spectral efficiency.
• Achieved significantly lower PAPR compared to conventional OFDM waveforms.
• Demonstrated superior bit-error-rate performance in frequency-selective fading channels.

Conclusions:

• CE-CP-OFDM is a viable waveform for 6G networks, balancing spectral efficiency and power efficiency.
• The proposed transceiver design effectively mitigates nonlinear distortion and interference.
• The approach offers a promising solution for future power- and cost-constrained wireless systems.