Research On MIMO Detection Algorithm And Its Application In Downlink LTE System

In order to further satisfy people to the higher requirement of the wireless communication transmission performance and the rate, the Long Term Evolution (LTE) of mobile communication technology was started at the end of2004. LTE system adopts Multiple-Input Multiple-Output (MIMO) as one of the core technology, on the network side with multiple antennas transmitting, each receiving antenna to receive the data which is the superposition of the data transmitting in wireless channel on the User Equipment (UE)side, so on the receiving side needs favorable signal detection algorithm to detected the transmitting signal as accurate as possible. Signal detection technology will directly affect the computational complexity and the detection performance of the system.Signal detection technology will directly affect the computational complexity and the detection performance of the system. This paper focuses on researching the signal detection algorithm for downlink LTE system. On the basis of mainly introducesing the key technologies and the traditional signal detection algorithms of the LTE system, we analyzed the lattice reduction aided algorithms for signal detection in detail, presented an improvement scheme. In addition through the simulation verify the feasibility and superiority of the algorithm. The main work is as follows:Firstly, we introduce the technology and the channel model of the spatial reuse MIMO system. Analyzing the basic principle and the processing flow of the traditional signal detection algorithms and the lattice reduction aided algorithms in detail. By means of contrasting the bit error rate(BER) performance and computational complexity of the different algorithms, start from the shortage of the existing algorithms, put forward the improvement lattice reduction aided signal detection algorithm which based on the Lenstra, Lenstra, Lovasz(LLL) algorithm. The improvement scheme was putted forward on the basis of a decision feed backing lattice reduction aided detection algorithm, in addition, taking a full consideration to the order of the sentence correction effect on the performance of signal detection.Secondly, due to the theory of the lattice reduction aided signal detection algorithm which is introduced in chapter three, chapter four focuses on studying a kind of efficient algorithm named element-based lattice reduction(ELR).We summarize the process, state the orthogonality deficiency(od) and the error performance of the ELR algorithm. In addition, on the basis of zero forcing(ZF) criterion, we infer the upper and lower bounds of the element-based lattice reduction aided detection algorithm in the MIMO system.Finally, we simulate all kinds of the signal detection algorithms. We design the link level simulation platform in the downlink LTE system, including five modules such as source and sink, modulation and demodulation, encoding and coding, channel model and signal detection. We build the simulation platform with MATLAB software. In allusion to the traditional signal detection algorithms, we compare the bit error rate (BER) through simulation results, with different algorithms, various numbers of transmitting antennas and receiving antennas and different modulations environment. Where after, this thesis simulates the perfonnance and analyzes the complexity of the improvement scheme with LLL lattice reduction aided detection algorithm. Simulation results and academic analysis verify the correctness of the conclusions about the improvement detection. In the end, we simulate the ELR lattice reduction aided detection algorithm and compare with LLL algorithm. This study has certain reference value and great relevance to future development in MIMO signal detection of downlink LTE system.