Reduced Complexity MIMO Concatenated Code in Fading Channels

In conventional concatenations of Convolutional Codes (CC) and Space-Time Block Codes (STBC), the CC and STBC are utilized to provide coding gain and spatial diversity, respectively. We propose a concatenated code that achieves the full system diversity by appropriately selecting the outer CC with an inner reduced-rank STBC. The advantage of the lower rank STBC is that the number of RF chains can be reduced. For any number of RF chains, R, we show that a desirable diversity order Y can be easily achieved i.e., 1 ≤ R ≤ Y. Using trellis diagram, we formalize the method to determine the maximum diversity.