| In order to meet the increasing demand of users for wireless communication,Terahertz(THz)technology makes it possible to achieve high data transmission rate and high bandwidth.Terahertz wave refers to electromagnetic wave in the frequency domain ranging from 0.1 THz to 10 THz(wavelength ranging from 30 μm to 3 mm),which is located between microwaves and infrared light in the electromagnetic spectrum.The special position of terahertz wave in the spectrum determines that it can meet the demand of wireless back network for ultra-high data transmission rate and ultra-high throughput.According to the research results in recent years,THz links operating in the 300 GHz band with data rates of more than 100 Gbit/s are feasible.As a result,the high bandwidth and high-speed performance of terahertz is expected to support the transition of future high-capacity backhaul networks from underground wired fiber connections to wireless connections.However,photonic terahertz waves still have their limitations,such as: 1)Terahertz communication has high requirements on receivers,so it is necessary to jointly design a complete photonic wireless link and use advanced digital signal processing methods to reduce bit error rate and improve the communication performance of wireless links.2)Terahertz waves in outdoor long-distance transmission will be affected by the absorption effect of gas molecules and the scattering effect of suspended particles in the atmospheric channel,resulting in serious energy loss.To solve the first problem,the digital signal processing algorithm is applied to the transmitter and receiver of the photonic terahertz wireless backhaul link to compensate the amplitude and phase distortion of the terahertz wave in the transmission channel,improve the wireless transmission performance of the communication system,expand the transmission distance of the wireless link,and carry out a digital simulation.To solve the second problem,the paper establishes the atmospheric channel model by studying the generation mechanism and calculation method of absorption effect and scattering effect,so as to analyze the influence of terahertz in free path transmission.In combination with ITU-R atmospheric attenuation propagation model,VVW model and FL model,this paper simulates terahertz absorption and scattering effects under rain,fog and haze,and terahertz wave phase shift caused by atmospheric molecules in long-distance transmission links by numerical simulation.Finally,the experimental verification of the photonic terahertz wave backhaul system is carried out,and the transmission performance and reliability of the outdoor long distance D band terahertz wave are studied and analyzed.The bit error rate performance of photonic terahertz backhaul communication with carrier frequency of120 GHz～150 GHz is tested experimentally.By using UTC-PD as optical hybrid terahertz transmitter,combined with high spectral efficiency modulation format and advanced digital signal processing technology,this paper realizes wireless transmission of 15 Gbaud baud rate 16-QAM signal over 80 m wireless communication distance,successfully expanding the capacity of photonic terahertz wireless communication system.The bit rate and distance product reached 4800Gbit/s·m.The results of this paper are expected to provide a systematic modulation and demodulation technical idea for terahertz back transmission system,which is expected to be used in outdoor long-distance high-speed terahertz wireless backhaul communication. |
PDF Full Text Request