V-BLAST OFDM系统的信道估计方法

下一代宽带无线通信系统的核心技术MIMO-OFDM(Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing)能显著提高系统的容量,但要获得该技术所带来的性能优势,快速、准确的信道估计是关键。为降低V-BLAST OFDM(Vertical-Bell Laboratory Layered Space-Time Orthogonal Frequency Division Multi-plexing)系统中信道估计的运算复杂度和提高估计精度,提出了一种基于CAZAC(Constant Amplitude ZeroAuto Correlation)序列的信道估计方法。该方法避免了矩阵求逆运算,利用该序列良好的自相关性,通过相关运算可消除多发送天线信号间及多径信号间的相互干扰,并且明显抑制了噪声对估计性能的影响,使信道估计的性能得以显著提高。理论分析和计算机仿真结果表明,该方法无需多径时延估计,较已知功率时延谱与未知功率时延谱的传统信道估计算法,可分别获得约1 dB和2 dB的性能增益。

Channel Estimation Method for V-BLAST OFDM Systems

MIMO-OFDM(Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing) is the key technique for next generation broadband wireless communication.V-BLAST OFDM(Vertical-Bell Laboratory Layered Space-Time Orthogonal Frequency Division Multiplexing) is a kind of MIMO-OFDM system based on spatial multiplexing and it can improve system capacity obviously.To obtain good system performance,fast and accurate channel estimation is very important.Good channel estimation is the precondition of correlated detection,demodulation,equalization,space times decode and channel decode.A new channel estimation method used in V-BLAST OFDM systems is proposed.The channel estimation method which is based on CAZAC(Constant Amplitude Zero Auto Correlation) sequence do not need the matrix inverse computation and can eliminate interference between different transmit antennas signal and multipath signal.And the method can decrease the influence of noise in channel estimation by correlation computation.Theoretical analysis and computer simulations show that 1 dB and 2 dB system performance gain can be obtained using the proposed method than the traditional method that power delay profile is known and unknown.