Precoding with adaptive subcarrier grouping in MIMO-OFDM systems

With the increase of physical antenna and subcarrier numbers in MIMO-OFDM systems, the signal precoding complexity overburden and channel side information feedback amount would become enormous and intolerable. To solve this problem, previous works mainly focused on fixed subcarrier grouping size and MIMO precoded signals in the same group. It could reduce the system overburden, but such a process would lead to system capacity loss due to the channel mismatch in the precoding procedure. In this paper, we consider a MIMO-OFDM system over the frequency self-correlation of i.i.d. Rayleigh channels and investigate the relationship between group size and capacity loss. By exploiting our developed theoretical results, we also propose an adaptive subcarrier grouping algorithm, which not only enables to have a good control of system service quality but also to reduce system overburden significantly. Numerical results are shown to validate our theoretical results, which also provide valuable insights on the system design of MIMO-OFDM systems.