Research On Wireless Channel Emulation Method And Equipment Development

The difference of channel characteristics is one of the core differences between wireless communication and wired communication.Wireless channel provides a direct carrier and medium for the transmission of electromagnetic wave,and its characteristics directly affect the performance of the whole wireless communication system.Therefore,learning,understanding and utilizing the wireless channel is the basis of designing and developing a new generation of wireless communication system.Since the actual wireless channel is very sensitive,uncontrollable and non-repeatable,it is not an effective method to directly test and verify the developed wireless communication base station,terminal and corresponding wireless communication algorithm in the real environment.Therefore,a wireless channel emulator needs to be developed to meet the comprehensive evaluation of system performance.It simulates various common wireless channel environments in the laboratory environment,and can be applied to the development and verification of base stations and terminals.This paper mainly carries out the following research work:1.A method of heterogeneous computing to accelerate the generation of wireless channel coefficients.With the large-scale application of Massive MIMO technology in 5G communication,and the increasing refinement and standardization of wireless channel models,the scale of wireless channel coefficients shows an explosive growth trend,and the original generation method of channel coefficients based on CPU exposes the shortcoming of too long time.This paper adopts the heterogeneous computing method with "CPU+GPU" as the core and uses CUDA as acceleration architecture.The channel coefficients are processed by module,which saves one or two orders of magnitude of time compared with the previous calculation method.2.Frequency-domain wireless channel emulation method.In this paper,a wireless channel emulation method based on frequency-domain is studied.The main idea is that equal the convolution in time-domain to the multiplication in frequency-domain to reduce the hardware resource in channel emulation.In this paper,the feasibility of frequency-domain method is verified by software and hardware,and the results are analyzed.What’s more,the accuracy of fixed-point on the results is compared and analyzed in the implementation.The results show that compared with the time-domain method,the frequency-domain method greatly reduces the hardware resource consumption for the OFDM systems which are commonly used in the 1024-point or 4096-point orthogonal subcarriers.At the same time,the emulation of fixed-point number is accurate to four decimal points,which ensures the accuracy of channel emulation.3.Design,verification and test of baseband hardware platform for MIMO channel emulation.Aiming at the requirement of channel emulation method verification,this paper develops a verification platform supporting 2×2 MIMO channel emulation based on CPU+FPGA So C as the core.The hardware platform supports the channel emulation of 2×2 in the frequency range of 75MHz-6GHz and 200 MHz bandwidth.Meanwhile,based on the hardware platform mentioned above,the hardware resource consumption between frequency-domain method and time-domain method is conducted.Compared with commercial channel emulators,the performance of heterogeneous computing acceleration method is verified.Finally,this paper summarizes the research work above,affirms the obtained results,points out the shortcomings of this research,and puts forward the direction of improvement.