Subcarrier pairing based subcarrier suppression for OFDM systems with decode-and-forward network coding

Subcarrier suppression (SS), a recently proposed technique for orthogonal frequency division multiplexing (OFDM) transmissions that suppresses subcarriers with bad channel condition, has been known as an efficient technique to improve bit error rate (BER) performance. In this paper, we consider a two way relay network (TWRN) applying SS with decode-and-forward physical layer network coding (DF-PLNC). According to the asymmetry nature of SS, some subcarriers are suppressed on one side. For these subcarriers, one way relay (OWR) is adopted, which reduces the performance of system since the channel condition of the second hop for OWR is bad. To solve this problem, we propose a modified SS scheme combined with subcarrier pairing (SP), called SP based SS (SPSS) where subcarriers that adopt OWR in opposite directions are paired. As a result, BER performance could be improved. Numerical results show that SPSS outperforms traditional SS schemes without pairing in terms of BER performance. Simulations together with analysis verify the potential benefits for combination of SP and SS.