On permutation of space-time-frequency block codings

Multi-input multi-output-orthogonal frequency-division multiplexing is the foundation of next generation of wireless communication systems and space-time-frequency block coding (STFBC) is considered one of the best schemes for implementing these systems. STFBCs have very complex structures and many parameters affect their performance. Studies have shown that permutation parameter plays a very important and sensitive role in the construction of STFBCs so much so that a small variation of this parameter could cause a significant change in the value of the coding advantage (CA) which alters the code's performance. In this study, first the authors explore how the permutation parameter affects STFBCs and demonstrate that existing permutation methods do not guarantee to attain the maximum possible CA. Next, they introduce a new structure for STFBCs permutation, which is the basis for the design of a modified model of one recently published STFBC. Comparison of the simulation results from the original and modified codes confirms the latter improves the performance by up to 3 dB. This is an achievement that is also verified by theoretical analysis.