Low-latency Carrier Aggregation Technique For 5G Mobile Fronthaul

The rapid growth of mobile data traffic,device connections,new services and new applications including virtual reality,Internet of vehicles,tele-medical and smart city have promoted the commercialization of the fifth generation of mobile communications(5G).Normally,the mobile fronthaul network of 5G wireless access network architecture is defined as the fiber connection from the distributed unit(DU)to the active antenna unit(AAU).Code division multiplexing(CDM)-based carrier aggregation(CA)scheme has the potential of low computational complexity.However,as the number of aggregated carriers increases,the peak average power ratio(PAPR)of aggregated signals worsens.After the electrical-to-optical conversion,the clipping noise occurs,leading to the degradation of fiber optical transmission performance.In this thesis,we carry out both numerical investigation and experimental verifications in order to suppress the latency of CA signal processing while reduce the PAPR of CA signal for the code reservation technique technology arising in the mobile fronthaul system.The main research results of my thesis are summed up as follows,(1)Under the condition of aggregating 16 New Radio(NR)signals,we systematically compares the algorithm complexity,spectral efficiency and fronthaul transmission performance between the FDM-based and CDM-based CA schemes.(2)We theoretically identify that traditional code reservation technique for the PAPR suppression of the CA signal has huge latency of signal processing,due to the occurrence of large number of iterations.Our numerical simulation results indicate that in comparison with traditional code reservation scheme,our proposed lowlatency code reservation scheme can save 36% iterations,under the condition of the same PAPR mitigation value.(3)When the 16 × 100 MHz 64 QAM 5G NR signals are aggregated in the code domain with the proposed low-latency code reservation scheme,the receiver sensitivity can be increased by 1.2d B after 10 km standard single mode fiber(SSMF)transmission.Our proposed low-latency code reservation scheme can not only reduce the signal processing delay,but also ensures the excellent fronthaul transmission performance.