A 2-D Interpolation-Based QRD Processor With Partial Layer Mapping for MIMO-OFDM Systems

The rapid growth of wideband communication devices, such as smart phones and tablets, has dramatically increased the throughput requirements of communication systems. Multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) has been widely recognized as the potential technology to achieve this requirement. The main implementation bottleneck lies in the high-complexity MIMO detections for thousands of subcarrier symbols in the MIMO-OFDM receiver. The QR decomposition processor is an essential preprocessing module for many MIMO decoders because the QR decomposition helps improve the decoding efficiency significantly by providing the tree-search structure for the MIMO detection algorithms. This paper presents a low-complexity 2-D interpolation-based QR decomposition (2-D-IQRD) with a partial layer mapping scheme to reduce computational complexity. The proposed 2-D-IQRD processor also adopts a scaling technique to reduce the signal dynamic-range problem in the traditional IQRD algorithm. These proposed methods successfully address the limitation of the interpolation-based QRD processor caused by successive multiplications in layer mapping and inverse layer mapping. Therefore, the 2-D interpolation can greatly reduce complexity and improve the BER performance of fast-fading MIMO-OFDM systems. This paper designs and implements the proposed architecture using a 90-nm CMOS technology. The implementation results show that the proposed architecture achieves 45.6 MQRD/s.