High-throughput QR decomposition for MIMO detection in OFDM systems

In this paper, we aim to design and implement a high-throughput QR decomposition architecture for 4 × 4 MIMO signal detection problems. A real-value decomposed MIMO system model is handled and thus the channel matrix to be processed is extended to the size 8×8. Instead of direct factorization, we propose a QR decomposition scheme by cascading one complex-value and one real-value Givens rotation blocks, which can save 44% hardware complexity. The systolic array is adopted for hardware implementation to facilitate pipeline design. Then, the requirement of skewed inputs to the conventional complex-value QR-decomposition systolic array is improved and 37% of delay elements are removed. The real-value Givens rotation stage is implemented by a stacked triangular systolic array to match with the throughput of the complex-value one. We have implemented the proposed design in 0.18 μm CMOS technology with 152K gates. From post-layout simulations, the maximum operating frequency can achieve 90.09MHz. The proposed scheme not only reduces the hardware complexity, but also supports high throughput for MIMO-OFDM signal detection up to 2.16 Gbps under stationary channels.