Adaptive frequency diversity in MIMO-OFDM systems based on spatial multiplexing

This work presents a technique to adapt the frequency diversity order in a multicarrier multiantenna system. In particular, this study focuses on the combination of group-orthogonal code-division multiplex OFDM (GO-CDM OFDM), a multicarrier technique that has been shown to outperform conventional OFDM, with spatial multiplexing. Assuming a maximum likelihood detector (ML) is used at the receiver, the proposed method is shown to be effective in estimating the instantaneous channel rank, allowing the system to be dynamically configured to achieve the maximum diversity order while keeping computational complexity as low as possible. This technique can be a useful enhancement for those systems that are required to operate in a wide variety of scenarios subject to a tight computationl/power budget (e.g. mobile terminals), thus precluding them from using a worst-case designed solution.