基于随机旋转的准正交空时分组码研究

为了提高准正交空时分组码的性能，该文提出基于随机旋转的准正交空时分组码(Random-rotation QO-STBC)的发射分集方法。这种方法对每个输入信息符号序列进行随机旋转，使准正交空时分组码的符号间干扰(ISI)随机化。仿真结果表明，在41 MIMO QPSK调制系统中，采用最大似然检测方法，当误码率为10-5时，新的发射方案比传统的两种准正交空时分组码误码性能有约4dB的增益；当误码率低于10-4时，RR-J码相比于ST-LCP码，仍表现出0.51dB增益；当SNR高于16dB时，RR-J与CFR具有几乎相同的误码性能。文章讨论了实际系统中随机旋转矩阵数受限情况下性能的损失，仿真结果显示当可用随机旋转矩阵数大于16时，对系统性能的影响可以忽略。

Study on Random-Rotation Quasi-orthogonal Space-Time Block Code

In order to improve the performance of Quasi-Orthogonal SpaceTime Block Code(QO-STBC), a Random-Rotation QO-STBC(RR-QO-STBC) is proposed. This transmission diversity scheme randomly rotates every information symbol vector, thus the inter-symbol interference between multi-antennas of QO-STBC is randomized and alleviated. Simulation results suggest, in 41 MIMO QPSK modulation system, under the ML detection rule，the proposed scheme outperforms the conventional QO-STBC about 4dB when the BER is 10-5, and also better than ST-LCP 0.51dB when the BER is below 10-4; The new scheme owns similar performance with the CFR scheme when SNR is above 16dB. The performance loss due to the limitation of number of random-rotation matrixes in the practical scenario is investigated. When the number of matrixes is greater than 16, the performance loss is negligible.