基于非均匀分布的MIMO OFDM系统最优导频序列设计

Optimal Pilot Sequence Design Based on Nonuniform Placement for MIMO OFDM Systems

在OFDM系统中,为了避免发送端低通滤波器的影响,一些处在所分配带宽边缘的子载波是不用来进行数据传输的,这些子载波通常被称为虚拟子载波。由于虚拟子载波的存在,某些情况下传统最优的均匀分布导频序列是不可用的,该文基于使多输入多输出(MIMO)OFDM系统中最小二乘信道估计的均方误差达到最小的准则,推导了非均匀分布最优导频序列。可以证明,此时的最优导频序列必须通过求解一约束不等式组来得到。仿真结果显示了所提方法的有效性。

In Orthogonal Frequency Division Multiplexing （OFDM） systems, to avoid influence of the low-pass filter on the transmitter side, some subcarriers on both edges of the allocated bandwidth are not used for transmission. These subcarriers are usually called virtual subcarriers which cause approach of conventional uniformly placed pilot tones inapplicable in some situations. Therefore, in this letter, based on nonuniform pilot tone placement, the optimal pilot sequences are derived, which can achieve the minimum metal square error of the least squares estimate for Multiple-Input Multiple-Output （MIMO） OFDM systems. Simulation results demonstrate the effectiveness of the nronosed annroach.