摘要
Orthogonal Frequency Division Multiplexing(OFDM)is very suitable for high data rate transmission in wide band wireless channel for the excellent capability to mitigate the frequency selective fading and Inter-Symbol Interference(ISI).In WiMAX system,Orthogonal Frequency Division Multiple Access(OFDMA)is adopted as the basic multiple access scheme,and different pilot patterns has been defined for both uplink and downlink channels.Pilot pattern should be changed,especially when Multiple Input Multiple Output(MIMO)technique is combined with OFDMA,in order to support multiple antennas.There are five pilot patterns in the WiMAX-MIMO-OFDMA system,namely:Downlink-Partially Used Sub-Channel(DL-PUSC),Downlink-Fully Used Sub-Channel(DL-FUSC),Downlink-Optional Fully Used Sub-Channel(DL-OFUSC),Uplink-Partially Used Sub-Channel(UL-PUSC)and Uplink-Optional Partially Used Sub-Channel(UL-OPUSC).Moreover,by analyzing the simulation results of time domain Least Square(LS),frequency domain LS,and Fast Fourier Transform(FFT)-based channel estimation algorithms,the best pilot pattern can be found.Based on the simulation comparison of several channel estimation methods in the WiMAX-MIMO-OFDMA system presented in this article,the best channel estimation for each pilot pattern is concluded.
Orthogonal Frequency Division Multiplexing(OFDM)is very suitable for high data rate transmission in wide band wireless channel for the excellent capability to mitigate the frequency selective fading and Inter-Symbol Interference(ISI).In WiMAX system,Orthogonal Frequency Division Multiple Access(OFDMA)is adopted as the basic multiple access scheme,and different pilot patterns has been defined for both uplink and downlink channels.Pilot pattern should be changed,especially when Multiple Input Multiple Output(MIMO)technique is combined with OFDMA,in order to support multiple antennas.There are five pilot patterns in the WiMAX-MIMO-OFDMA system,namely:Downlink-Partially Used Sub-Channel(DL-PUSC),Downlink-Fully Used Sub-Channel(DL-FUSC),Downlink-Optional Fully Used Sub-Channel(DL-OFUSC),Uplink-Partially Used Sub-Channel(UL-PUSC)and Uplink-Optional Partially Used Sub-Channel(UL-OPUSC).Moreover,by analyzing the simulation results of time domain Least Square(LS),frequency domain LS,and Fast Fourier Transform(FFT)-based channel estimation algorithms,the best pilot pattern can be found.Based on the simulation comparison of several channel estimation methods in the WiMAX-MIMO-OFDMA system presented in this article,the best channel estimation for each pilot pattern is concluded.
