Performance of GFDM Systems Using Quadratic Programming Pulse Shaping Filter Design

Abstract

Generalized Frequency Division Multiplexing (GFDM) has been considered as an attractive candidate to replace Orthogonal Frequency Division Multiplexing (OFDM) for the fifth generation (5G) mobile networks. GFDM system has better spectral characteristics compared to the OFDM system due to the use of properly selected pulse shaping filters. Non-causal ideal filters, such as the raised cosine (RC), are commonly used in the GFDM systems. In practical implementation, non-causal filters need to be truncated and shifted, which will increase the out-of-band (OOB) radiation of the signal and will introduce delay to the system. High OOB radiation will cause interferences between the adjacent channels, thus it should be minimized. This paper proposes to minimize the OOB radiation of the GFDM system using the designed pulse shaping filters. The pulse shaping filters are designed using the computationally efficient quadratic programming (QP) approach. Numerical results illustrate that OOB radiation level of the GFDM system is lower when the QP filters are used compared to the conventional RC filter. Further investigation shows that the use of the QP filters are efficient in increasing the high power amplifier (HPA) efficiency, improving the spectral efficiency, and reducing the BER at the receiver.

Keywords

• 5G
• filter design
• GFDM
• HPA
• nonlinearity
• OOB radiation