LTE-A链路级仿真及关键技术研究

发布时间：2018-01-15 09:50

本文关键词：LTE-A链路级仿真及关键技术研究　出处：《东南大学》2016年硕士论文　论文类型：学位论文

更多相关文章： LTE/LTE-A DFT-S-OFDM 波束赋形

【摘要】：从2G到3G,到3.9G,即：LTE,到现在的4G,即LTE-A,无线通信技术一直在理论到应用的路上不断发展与成熟,这个过程中,通过仿真对通信技术从理论上进行正确性证明以及发展是不可或缺的部分。本文对LTE-A系统在链路层进行仿真,并对其关键技术进行了研究与改进。本文首先对LTE/LTE-A的发展进程进行了简单介绍,针对链路仿真特性,研究了LTE/LTE-A关键技术,即MIMO技术、OFD M技术、物理层上行链路、物理层下行链路设计原理。针对仿真中采用开环方案,文中重点研究了通信系统中的常用信道模型,对比不同信道特性,给出了链路仿真中使用的信道模型方案。本文给出了一种基于STR算法的抑制DFT-S-OFDM信号峰均功率比的改进算法。物理层上行链路中使用的SC-FDMA技术使得单载波具有与多载波类似的正交性,能满足多用户的需求,并且使得上下行传输可以共用很多参数。DFT-S-OFDM技术是SC-FDMA信号的频域生成方式,通过简单的DFT变换生成SC-FDMA信号,降低了系统的实现复杂性,但是DFT-S-OFDM技术使得信号峰均功率比显著增加,从而降低了终端的功放效率,针对此问题,文中给出了可以有效的抑制DFT-S-OFDM信号峰均功率比的STR改进算法,通过软件仿真验证了该改进算法的性能,并将此改进算法应用于物理层上行链路传输的仿真平台,该平台使用MATLAB仿真软件搭建,其信号处理流程遵循3GPP协议规定。文中基于上述平台,在不同的信道场景下(包括AWGN、EPA信道)对优化后的DFT-S-OFDM技术对调制编码方式(Modulation and Coding Scheme, MCS)的性能表现进行研究。本文研究了最能体现TD-LTE系统特性的帧结构,给出了一种TD-LTE系统下行传输的链路级仿真方案。FDD-LTE系统和TD-LTE系统的上行链路处理流程是一样的,均是基于SC-FDN MA技术,而下行则是不同的,FDD-LTE系统的下行链路根据码本对发射信号进行预编码,而TD-LTE的下行使用的预编码方案是波束赋形。文中给出的仿真方案模拟TD-LTE系统,对上行、下行数据使用半双工方式传输,使用仿真软件MATLAB搭建了该物理层链路传输的仿真平台,研究了TD-LTE系统中的波束赋形技术在AWGN和EPA信道场景下对调制编码方式(MCS)的性能表现。本文改进了基于RBIR算法的物理层抽象技术(L2S方法),减小了L2S方法对BLER的预测误差。经典的RBIR算法的做法是计算出平均的RBIR后反查询SINR-RBIR映射表,得到有效信噪比,再查询AWGN信道的SINR-BLER参考曲线来预测系统级的BLER,改进方案将上述的两步合为一步,以减少由查询步骤产生的插值误差,大量的仿真验证了上述改进算法相比原算法的性能提高。最后,链路仿真结果使用上述改进的L2S方法进行分析,从而验证了L2S算法的有效性与正确性,即,运用L2S接口技术,仅进行链路级仿真就可以预测系统级的BLER性能。
[Abstract]:From 2G to 3G, to 3.9G, that is to say, to the current 4G, that is LTE-A, wireless communication technology has been developing and maturing in the process of theory and application. It is an indispensable part to prove the correctness and development of communication technology in theory by simulation. This paper simulates the LTE-A system in link layer. And the key technology is studied and improved. Firstly, the development process of LTE/LTE-A is briefly introduced, and the key technology of LTE/LTE-A is studied according to the characteristics of link simulation. That is, MIMO technology, physical layer uplink, physical layer downlink design principle. In view of the simulation of open-loop scheme, this paper focuses on the common channel model in communication system. Compare different channel characteristics. The channel model scheme used in link simulation is given. An improved algorithm for suppressing PAPR of DFT-S-OFDM signal based on STR algorithm is presented. S used in uplink in physical layer. C-FDMA technology makes single carrier have the same orthogonality as multi-carrier. It can meet the needs of multiple users, and make the uplink and downlink transmission can share many parameters. DFT-S-OFDM technology is the frequency domain generation of SC-FDMA signal. The complexity of the system is reduced by the simple DFT transform to generate the SC-FDMA signal, but the PAPR of the signal is significantly increased by the DFT-S-OFDM technology. In order to reduce the power amplifier efficiency of the terminal, this paper presents an improved STR algorithm which can effectively suppress the PAPR of DFT-S-OFDM signal. The performance of the improved algorithm is verified by software simulation, and the improved algorithm is applied to the simulation platform of physical layer uplink transmission. The platform is built with MATLAB simulation software. The signal processing flow follows the 3GPP protocol. Based on the above platform, this paper is based on different channel scenarios (including AWGN). EPA channel) Modulation and Coding Scheme with optimized DFT-S-OFDM technique. The performance of MCSs is studied. The frame structure which can best reflect the characteristics of TD-LTE system is studied in this paper. This paper presents a link-level simulation scheme for downlink transmission of TD-LTE system. The uplink processing flow of FDD-LTE system and TD-LTE system is the same. All of them are based on SC-FDN MA technology, but downlink is the downlink of different FDD-LTE systems, which precode the transmitted signal according to the codebook. The pre-coding scheme used in the downlink of TD-LTE is beamforming. The simulation scheme presented in this paper simulates the TD-LTE system. The uplink and downlink data are transmitted in half duplex mode. The simulation platform of the physical layer link transmission is built by using the simulation software MATLAB. The beamforming technique in TD-LTE system is studied in AWGN and EPA channel scenarios. In this paper, the physical layer abstraction technique based on RBIR algorithm is improved. The prediction error of L2S method to BLER is reduced. The classical RBIR algorithm is to calculate the average RBIR backward query SINR-RBIR map table and obtain the effective signal-to-noise ratio (SNR). Then the SINR-BLER reference curve of the AWGN channel is queried to predict the system level BLER.The improved scheme combines the above two steps into one step to reduce the interpolation error generated by the query step. A large number of simulations verify the performance of the improved algorithm compared with the original algorithm. Finally, the link simulation results are analyzed using the improved L2S method, which verifies the validity and correctness of the L2S algorithm. That is, using L2S interface technology, only link level simulation can predict system level BLER performance.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN929.5

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