In this article, we study the coding advantage of space-time-frequency block codes (STFBCs). Since in MIMO-OFDM coding there is the potential of exploiting space, time and frequency diversities and as the frequency tones of OFDM modulation are relatively substantial, the intricate structure of STFBCs makes it almost impossible to optimize the parameters of the code as the number of symbols increases in each block. Consequently, we investigate how to optimize the code parameters independently to reduce the computational complexity. Furthermore, code permutation is an important part of the STFBCs. However, due to elaborate structure of the STFBCs, it is very hard to calculate the optimum permutation. Therefore, we put forth a technique to decompose the coding advantage of the STFBCs. Using this technique, the permutation parameter can be easily introduced and optimized for STF-BCs. We then design a novel STFBC based on any given STBC and apply the proposed scheme on the proposed STFBC to illustrate the application of this technique by designing the optimum permutation for the code. Simulation results confirm that the proposed STFBC outperforms the best existing STFBCs in the literature.

中文翻译：

---

空时频分组码的编码优势优化

在本文中，我们研究了空时频分组码 (STFBC) 的编码优势。由于在 MIMO-OFDM 编码中存在利用空间、时间和频率分集的潜力，并且由于 OFDM 调制的频率音调相对较大，因此 STFBC 的复杂结构使得优化代码参数几乎是不可能的，因为符号在每个块中增加。因此，我们研究了如何独立优化代码参数以降低计算复杂度。此外，代码置换是 STFBC 的重要组成部分。然而，由于 STFBC 的复杂结构，很难计算最佳排列。因此，我们提出了一种分解 STFBC 编码优势的技术。使用这种技术，可以很容易地为 STF-BC 引入和优化置换参数。然后，我们基于任何给定的 STBC 设计了一种新颖的 STFBC，并将所提出的方案应用于所提出的 STFBC，以通过设计代码的最佳排列来说明该技术的应用。仿真结果证实，所提出的 STFBC 优于文献中现有的最佳 STFBC。