廣義分頻多工系統之濾波器設計考慮功率放大器非線性特性

Abstract

廣義分頻多工為一具有靈活度的多載波波形傳輸機制，藉由設計適當的原型濾波器可以使其具有低頻帶外輻射之特性。然而，在考慮功率放大器之非線性特性時，便會產生頻譜再生現象其會破壞低頻帶外輻射之特性，並且很有可能使得傳輸訊號違反了頻譜遮罩的規範。本研究中藉由使用-預測頻譜再生-的機制，為廣義分頻多工提出了一套設計原型濾波器的方法，使得在頻帶外輻射的表現可以滿足任何給定的頻譜遮罩規範同時也可以最大化頻譜資源使用率。模擬結果指出根據本研究所提出的機制，會產生幾項優點包括有效降低頻譜再生現象以及對於功率放大器非線性失真效應可以更有效抵抗。

Generalized frequency division multiplexing (GFDM) is a flexible multicarrier waveform that features low out-of-band emission (OOBE) with a prototype transmit filter serving as design freedom. However, in the presence of power amplifier (PA) nonlinearity, the effect of spectral regrowth may deteriorate the expected low OOBE property, and possibly make the transmission violating the requirement of a spectrum emission mask (SEM). In this study, a prototype transmit filter design method along with an idea of spectral regrowth prediction (SRP) is proposed for GFDM. The resulting OOBE can meet any given SEM with maximal spectral resource utilization in the GFDM system. Simulation results reveal the advantages of adopting the proposed scheme in spectral regrowth mitigation and resistance to PA nonlinear distortion.