Adaptive Technologies Of Hybrid Carrier Based On WFRFT Facing Coverage And Spectral Efficiency Balance

With the rapid development of mobile communication,the spectrum resources are in pressing demand.The current research focus on how to both improve the transmission efficiency and expand the coverage under the condition of limited bandwidth.Adaptive Modulation and Coding(AMC)and power control are adopted to solve the problems mentioned above in recent years.Considering the Orthogonal Frequency Division Multiplexing(OFDM)scheme with high spectral efficiency and the Single Carrier-Frequency Domain Equalization(SC-FDE)scheme with wide coverage,this thesis combines carrier schemes switching with AMC and power control to maximize system throughput.Due to the incompatibility between OFDM and SC-FDE,carrier schemes switching is difficult to put into effect.The proposal of Hybrid Carrier(HC)communication system based on Weighted-type Fractional Fourier Transform makes the integration of OFDM and SC-FDE possible,which solves the problem of smooth transition between two schemes.Thus,the HC system can achieve a dynamic balance between high speed transmission and wide coverage.This thesis simulates the Peak-to-Average Power Rate(PAPR)performance of the HC signals and elaborates the relationship between Maximum Average Transmit Power(MATP)and PAPR.It is verified that the HC signals have compromising PAPR and MATP performances between OFDM and SC-FDE.Then the relationships between coverage and spectral efficiency in flat fading and frequency-selective fading channels are analyzed based on the simulation.Different carrier schemes have the same Bit Error Rate(BER)and spectral efficiency performances in flat fading channels.Thus,the given carrier scheme can only rely on the switching of different Modulation and Coding Schemes(MCSs)to achieve both better spectral efficiency and wider coverage.On the other hand,different carrier systems have different PAPR characteristics,so the MATP and coverage are also different.This thesis proposes corresponding strategies for different kinds of UEs through the simulation results.In the more common frequency-selective fading channels,different carrier schemes have different BER performances.Compared with the flat fading channels,the frequency-selective channels can also achieve gain through carrier schemes switching.Based on the block error rate and PAPR performances of different carrier schemes in flat fading channels,this thesis proposes a strategy on uplink power control parameters calculation so that the terminal can transmit at the lowest power under the condition of ensuring reliability.Then according to the carrier schemes and MCSs switching strategy,the optimal carrier scheme and MCS in the frequency-selective fading channels are obtained to maximize the overall spectral efficiency of the system.