V—BLAST OFDM系统的信道估计方法

Channel Estimation Method for V-BLAST OFDM Systems

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—BLASTOFDM（Vertical—Bell Laboratory Layered Space—Time Orthogonal Frequency Division Multiplexing）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 Zero Auto 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，通过相关运算明显的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．该方法较传统信道估计算法而言，能显著提高系统性能。

MIMO-OFDM （Multiple-Input Muhiple-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 muhipath 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.