MIMO-OFDM系统的SAGE-ISD联合估计检测算法

SAGE-ISD joint estimation and detection algorithm in MIMO-OFDM systems

针对采用最小均方误差估计MIMO-OFDM系统信道时计算复杂度高,以及采用期望最大化算法存在收敛速度慢等缺陷,提出一种新的联合估计检测算法,将线性最小均方误差信道估计、广义空间迭代期望最大化算法和改进球形译码检测算法相结合进行联合估计检测,采用线性最小均方误差信道估计对信道进行信道初估计,并利用联合迭代技术结合广义空间迭代期望最大化算法及改进球形译码检测算法进行信道估计校正和信号检测,从而提高系统的可靠性。理论研究和仿真结果表明:在相同误比特率下,算法性能优于传统的检测算法,其与理想信道估计下的最大似然检测算法仅平均相差0.5 dB。该算法在较少的迭代次数下,可获得较理想的信道估计和检测结果,并以较低系统复杂度的代价,逼近理想信道估计下的最大似然检测算法。

A new joint estimation and detection algorithm was put forward, aiming at the disadvantages of high computational complexity of channel estimation for MIMO-OFDM system when using minimum mean square error and slow convergence speed when using expectation maximization algorithm. The algorithm combines LMMSE channel estimation, SAGE algorithm and improved sphere decoding algorithm to obtain joint estimation and detection. It employs linear minimum mean square error channel estimation to achieve rough estimation, and then uses joint iteration technology to get channel estimation adjustment and signal detection combining SAGE algorithm, which improves sphere decoding algorithm, and thereby enhances the reliability of the system. Theoretical analysis and simulation results show that, with the same bit error rate, the performance of our algorithm is superior to that of traditional detection algorithm. The mean difference with ideal channel estimation under the maximum likelihood algorithm is only 0.5 dB. The algorithm can obtain rather perfect result of channel estimation and detection with fewer iterative times. Meanwhile, it approaches the ideal channel estimation under the maximum likelihood algorithm with lower complexity.