提出一种应用于强度调制直接检测光正交频分复用（IMDD-OFDM）传输系统的低开支、高准确度的信道估计算法.该算法充分考虑系统噪声特性，利用梳状导频插入结构，结合符号间平均与子载波间频域线性插值的思想，在低开支导频条件下实现较高的估计准确度.仿真和理论推导结果表明:与传统平均算法和直接线性插值算法相比，基于梳状导频先平均后线性插值的算法估计出来的信道特性更能接近实际信道的.实验结果表明：在误码率为3.8×10－3处，本文所提出的算法仅使用0.78%导频开支即可与使用20%导频开支的平均算法获得相同的接收灵敏度；同时，与传统估计算法相比，该算法与导频开支无关，能较好抗系统中的高斯噪声，获得与真实信道较为接近的估计性能.

A low overhead and high accurate channel estimation algorithm was proposed and experimently verified in Intensity Modulation Direct Detection Orthogonal Frequency Division Multiplexing (IMDD-OFDM) optical transmission system. By fully considering system noise feature, this algorithm utilized the comb-type pilot insertion scheme, and combined the teachniques of symbol averaging and linear interpolation method within subcarriers, which could achieve a high estimation accuracy and a low overhead. The results are shown in simulaiton and theoretical derivation that, compared with the common channel estimations, the algorithm we proposed can achieve a better performance which is more close to the characteristic of real system channel. The experiment results demonstrate that, at a Bit Error Ratio (BER) of 3.8×10－3, this algorthim only with 0.78% pilot overhead can achieve the same performance to compare with that of the 20.31 % pilot overhead of normal frequency domain avageral algorithm. In additon, compared with other normal algorthims, our algorithm is irrelevant to the pilot overhead, can effectively reduce the mean squared error of channel estimation and achieve a high tolerance for the Gaussion noise of system, thus achieving relatively close performance to the real channel feature.