Design And Implementation Of Fpga-based Wireless Channel Emulator

The requirement and quality of wireless communication system has become more and more important in our daily life .The research of wireless communication equipment is becoming more and more difficult. For the reasons, the system testing is becoming more and more important among the proportion of design. The test engineers need to simulate all kinds of characteristics of radio mobile channel in the laboratory for shorting the designing time and debugging the system. The multi-channel emulator is a necessary device to debug wireless communication system today.The paper has implementd frequency-selective radio mobile channels base on the channel of Clarke. Radio mobile channel which uses the arithmetic of improved Jakes model is implemented with Altera StratixII EP2S180. It implement uplink receiving of four transmit antennas data. Every antenna has eight recognizable multipaths and every path is made up of 64 reflectors. The multipaths and reflectors are chosen all alone. Initial angle and initial phase of reflectors can be set certain values. The angle and phase of reflectors is homogeneous randomizer. After that, the different reflectors are not correlative in the same path. The radio mobile channel is WSSUS (Wide-Sense Stationary-Uncorrelated Scattering) channel. The device simulates the channel propagation characteristics of the ground wireless fading channels. The uplink receiving data are deposited in the SDRAM. After starting the test, the data get across the radio mobile channel under the control of CPU. Then, they are demodulated by the BaseBand Processing veneer. The paper gets the BER (Bit Error Rate) and BLER (Block Error Rate) of uplink data at last. They can be used to evaluate the performance of base station.Firstly, the test request of communication device in 3GPP TS 25.141 protocol and characteristics of wireless communication system are researched. The system designing scheme of wireless channel emulator is discussed and perfected.Secondly, aiming at resource configuration in the FPGA (Field Programmable Gate Array), the difficulty and resource are researched when frequency-selective fading channel is implemented with FPGA. Then, the module is divided such as time-delay module, rayleigh-fading module, LVDS (Low-voltage Differential Signaling) module and so on. The paper has finished the modules from RTL code exploitation, simulation, board debugging and combining debug between all modules and background software. Finish the correcting from two antennas to four antennas. The frequency of four antennas is one time higher than that of two antennas. The resources which are consumed in the FPGA are reduced large.Finally, Radio mobile channel which is base on Jakes model is implemented with Altera StratixII EP2S180. After finishing the hardware design, the paper tests the E_b/N₀ (Signal Noise Ratio) in different transmitting environments and different transmitting operations. The results of single antenna and multi-antenna answer for protocol requests.