With the increase of physical antenna and subcarrier numbers in MIMO-OFDMsystems, channel side information feedback amount and signal precodingcomplexity overburden will consume much more system resource, even becomeintolerable. To solve this problem, previous works mainly focused on fixedsubcarrier grouping size and precoded MIMO signals in the same group withunitary channel state information (CSI). It could reduce the system overburden,but such a process would lead to system capacity loss due to the channelmismatch in precoding procedure. In this paper, we consider a MIMOOFDM systemover double-selective i.i.d. Rayleigh channels and investigate the quantitativerelation between group size and capacity loss theoretically. By exploiting ourdeveloped theoretical results, we also propose an adaptive subcarrier groupingalgorithm, which not only enables to have a good control of system servicequality but also to reduce system overburden significantly. Numerical resultsare shown to provide valuable insights on the system design of MIMO-OFDMsystems and indicate that the proposed subcarrier grouping scheme is extremelyefficient in some common scenarios.
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