Word length study and architecture design of a K-best based MIMO-OFDM detector algorithm

The combination of multiple-input multiple-output (MIMO) and orthogonal frequency-division multiplexing (OFDM) has been adopted for high-data-rate transmission. A word length study and a top level architecture of a K-best based list sphere detector (LSD) algorithm for a MIMO-OFDM system are introduced in this paper. The word lengths were determined with computer simulations for 2 times 2 and 4 times 4 antenna systems with quadrature phase shift keying (QPSK), 16-quadrature amplitude modulation (QAM) and 64-QAM. The resulting word lengths can be used in the hardware implementation of the K-best LSD and they will lead to optimal floating point performance. The architecture was designed for a 2 times 2 antenna system with operating modes for QPSK and 16-QAM. Also a top level structure of a 4 times 4 MIMO detector is presented. The architecture allows the use of a variable list size.