An effective iterative clipping for coded CI/OFDM systems over the nonlinearity of SSPA

This paper proposes an effective iterative clipping (IC) on a coded carrier interferometry OFDM (CI/OFDM) system for improving the system performances over the nonlinearity of a solid state power amplifier (SSPA). An additional filtering is not required to remove the out-of-band (OOB) spectrum radiation as required in the conventional clipping method. The IC is designed with a minimized computational complexity though the iteration is performed. The results confirm that the CI/OFDM with the proposed IC presents many advantages in terms of BER performance and OOB spectrum radiation. Based on the optimization on BER and OOB spectrum, it is found that 2 and 3 iterations is an effective number for the IC in OFDM and CI/OFDM systems, respectively. The total degradation (TD) improvement by the effective IC in CI/OFDM is about 0.32 dB for QPSK and 2.1 dB for 64 QAM symbol on an SSPA with an output-back-off (OBO) 4dB and 8 dB, respectively.