In this letter, an adaptive detection scheme for a multiple-input multiple-output (MIMO) system is proposed. In order to reduce the complexity of the decoding steps, the initial symbol is obtained by a MMSE equalizer and then the symbol ordering is performed by the channel state. After the received symbols are divided according to the channel state, some of the symbols are detected by using the MMSE detector with low complexity. With cancelation processing, the remainder symbols are detected for the K-best detector. The proposed adaptive detection scheme combines the MMSE and K-best detector based on the channel state. Therefore, the proposed adaptive detector achieves a good performance.

In this letter, a novel adaptive detector that combines DFE and QRD-M is proposed for MIMO-OFDM system. QR decomposition (QRD) is commonly used in many MIMO detection algorithms. In particular, sorted QR decomposition (SQRD) is an advanced algorithm that improves MIMO detection performance. The proposed detector uses SQRD to achieve better performance. To reduce the computational complexity, the received layers of each subcarrier are ordered by using the post SNR and are detected by DFE and QRD-M detector based on the order. Therefore, the proposed detector structure is varied according to the channel state. In other words, the proposed detector achieves a good tradeoff between complexity and performance. A simulation confirms the substantial performance improvements of the proposed adaptive detector with only slightly greater complexity than the conventional detector.