Design a high throughput MIMO-OFDM transceiver and the linear MMSE MIMO detector on a resource limited hardware platform for mobile device is very challenging. In this paper, we study the linear MMSE detector problem and propose a realistic algorithm implementation for a linear MMSE MIMO detector on real hardware. We observed the scaling invariant property of QR decomposition and proposed a dynamic scaling algorithm for QR decomposition. Our algorithm maintains the data in the same range during the factorization process. Our algorithm is very amicable for a fixed point implementation on a hardware platform without floating point units (i.e. low-end FPGA). We have successfully implemented and synthesized the algorithm on Xilinx Vertex-4 FPGAs and shows good numerical stability. Our desgin is very general and applicable to other future MMSE-based MIMO detector algorithm (i.e. 8 × 8 MIMO).