A New Sorted QR Decomposition And Its Algorithm

BLAST is a space-time code system that was presented by Foschini based on Multi-Input Multi-Output (MIMO) antenna scheme. With the growing linearly number of antennas, MIMO technology can theoretically approach the channel capacity, it requires transmit and receive antennas of MIMO system with a good combination of signals and detection capabilities. Vertical Bell Layered Space-Time Code (V-BLAST) is a typical representative of the space-time multiplexing, it is much lower complexity compared to the existing structure of T-BLAST and D-BLAST in a smooth channel conditions, and it has high transmission capacity and spectrum utilization without increasing the bandwidth and transmission power.Reducing computational complexity and improving system performance are significant for the application of MIMO systems. MIMO signal detection algorithms are divided into two types of linear and non-linear. Computational complexity of linear detection algorithm is superior to nonlinear detection algorithm complexity, but it reduces the performance of the system. QR decomposition signal detection algorithm is linear detection algorithm, which uses a combination of the received signal interference cancellation technology, and effectively avoids the numerous pseudo-inverse matrix calculation, thereby it reduces the computational complexity; sorted QR decomposition signal detection algorithm not only reduces computational complexity but also improves system performance. This paper introduces the V-BLAST system with MIMO model, then introduces several traditional MIMO signal detection algorithms including two sorting QR decomposition detection algorithms: the classic Gram-Schmidt improved algorithms and MMSE-PSA algorithms, their detection principle and numerical examples are given to verify the effectiveness of the algorithm.By analyzing the sorted QR decomposition existing detection algorithm, based on the principle of successive interference elimination, they can ensure the detected output signal as large as possible, but the signal generated order is inconsistent with the signal of output detection order. In this paper, we present a new efficient algorithm to detect the transmitted signals for V-BLAST in MIMO system. This algorithm utilizes a new sorted QR decomposition of the channel matrix, where the diagonal elements of R are obtained from bottom to top and each achieves its maximum value among all possibilities. It has a solid theoretical basis, meets the signal detection order, and each symbol value in the receiver site is as large as possible. Thus, the new algorithm clearly improves the signal detection performance compared with existing methods. Simulation results demonstrate that the proposed algorithm provides a better BER performance.