Algebraic Multiuser Space-Frequency Block Codes

In this paper, we consider a wireless multiuser multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) uplink scenario, where the information sequences of all users are encoded by individual space-frequency block codes (SFBC). At the receiver, joint maximum likelihood detection is applied using the sphere decoding algorithm. Using a truncated union-bound approximation, we propose the design criteria of multiuser SFBCs for frequency selective fading MIMO multiple access channels (MAC). Next, we show how, by combining the structure of algebraic perfect space-time block codes, a family of multiuser SFBCs can be constructed to fulfill the design criteria. Finally, we show that the proposed SFBC outperforms previously known codes.