Low envelope fluctuation OFDM waveform design under subcarrier constraints

Area of Science:

• Signal Processing
• Telecommunications Engineering
• Optimization Theory

Background:

• Orthogonal frequency-division multiplexing (OFDM) systems often suffer from high envelope fluctuations, which can degrade performance.
• Existing methods for envelope reduction in OFDM may lack efficiency or fail to meet subcarrier constraints.

Purpose of the Study:

• To propose a novel weight design mechanism for OFDM systems to reduce envelope fluctuations.
• To develop an optimization approach that satisfies subcarrier constraints and maintains a fixed energy budget.
• To enhance the constant-envelope approximation of OFDM signals.

Main Methods:

• Introduced a new time-domain metric to guide the OFDM waveform towards a constant-envelope structure.
• Formulated and solved a non-convex optimization problem for subcarrier weight design, minimizing envelope variance.
• Employed constraint relaxation and reintroduction to transform the problem into an iterative unconstrained maximization, converging to a local optimum.

Main Results:

• The proposed method effectively suppresses envelope fluctuations in OFDM signals.
• The design successfully satisfies pre-assigned subcarrier weights and upper bounds on others.
• Numerical results show superior performance compared to existing methods in terms of efficiency and constant-envelope approximation.

Conclusions:

• The developed OFDM weight design mechanism offers an efficient solution for reducing envelope fluctuations.
• The iterative optimization approach provides a practical method for achieving near-constant-envelope OFDM signals.
• This work contributes to improved performance and efficiency in OFDM-based communication systems.