Correcting CNA phase mismatch phenomena in frequency blind equalization for OFDM systems

• This paper proposes an adaptation of the CAN blind equalizer to OFDM.
• A correction of the CNA phase mismatch is proposed.
• A sub-optimal initialization of the blind equalizer is derived.

This paper presents an adaptation of the constant norm algorithm (CNA) class for frequency blind equalization in orthogonal frequency division multiplexing (OFDM) modulation. Originally designed in single-carrier systems, the convergence analysis of CNA is investigated in OFDM. It results that a phase adaptation of the equalizer coefficient has to be undertaken to ensure a convergence toward the expected value, leading to the proposed phase adaptation procedure (PAP). Furthermore, a sub-optimal initialization strategy is proposed, which allows to improve the convergence speed of the algorithm. Simulations show that the proposed CNA with PAP outperforms the constant modulus algorithm (CMA) for both the convergence speed and the steady-state performance. Furthermore, a gain in number of iterations of up to 50% is achieved when the proposed sub-optimal initialization is used compared with a fixed initialization value.