Research About The Performance Of Wireless Transmission System Based On Filtered-OFDM

Filtered-OFDM technology is an important improvement on the traditional OFDM.While maintaining the advantages of the conventional OFDM,sub-band interference also can be reduced by adding sub-band filters.And more flexible parameter configuration can be performed in each sub-band which makes F-OFDM can adapt to more complex application scenarios.F-OFDM has become an important 5G candidate waveform now.In this paper,the sub-band filter is designed based on Hanning window in F-OFDM system,and the performance of F-OFDM system is simulated based on two sub-bands.In our simulation,the two sub-bands included in the F-OFDM system are set different parameters such as modulation scheme,cyclic prefix length and IFFT points.The simulation proves that the out-of-band leakage of the F-OFDM system is effectively suppressed by the sub-band filter.However,the F-OFDM signal has the same problem of high PAPR.The F-OFDM signal requires high performance for the system power amplifier and it is prone to signal distortion when transmitting.Unfortunately owing to high PAPR.There is no PAPR suppression algorithm for F-OFDM systems currently.In this paper,PAPR suppression algorithm of clipping with sub-band filter and companding transform with sub-band filter in F-OFDM system are proposed.The simulation results show that both the clipping with sub-band filter algorithm and the companding transform with sub-band filter algorithm can effectively suppress the PAPR of F-OFDM signal,and the sub-band filter can effectively suppress the out-of-band leakage and signal distortion caused by clipping or companding.Besides,the F-OFDM system also maintains a good bit error rate performance.Based on the deep research on F-OFDM technology,it is found that F-OFDM has flexible sub-band configuration parameters as a great advantage.Based on this,this paper proposes to use F-OFDM as the modulation technique with continuous or non-contiguous sub-band channels bonding technology to reuse the idle WiFi bands,identified by spectrum sensing technology flexibility,in the scenario of LTE-U and Wifi coexistence.The simulation proves that the non-continuous or continuous sub-band channel bonding in F-OFDM system can meet the requirement of spectrum protection in 802.11a standard and the unlicensed idle band identified by cognitive radio technology can be reused,the utilization of the spectrum can be greatly improved.