基于联合参考的多天线信号合成关键技术研究

发布时间：2018-08-17 13:16

【摘要】：随着无线通信的发展,对低信噪比信号的接收得到越来越多的重视。在微弱信号环境下,利用单个天线难以进行有效接收,一种有效的解决方法是采用多天线信号合成技术提高信噪比。在传统的以固定单路信号为参考的合成方案中,参考信号如果信噪比更低或者经历了更恶劣的衰落信道,将严重影响参数估计精度,从而降低合成性能。因此,从构造更优参考信号的角度提高信号合成性能具有重要研究意义。本论文围绕多天线信号合成中构造更优参考信号的目标,针对高斯信道下多天线信号时延对准问题和频率选择性衰落信道下多天线信号合成问题展开研究。论文主要工作及创新点如下:1.针对高斯信道下多天线信号时延对准中参考信号构造问题,首先借助匹配滤波器界,理论推导了时延对准误差对合成性能影响的显式表达式,结果表明在保证合成信噪比增益的前提下,天线数目越多对时延对准性能要求越高;然后,在分析合成参考算法收敛性的基础上,通过构造联合参考,将合成输出信号作为参考信号,提出了一种基于部分补偿的多天线信号时延对准算法(部分补偿算法),并证明了算法的恒收敛特性。理论分析和仿真实验表明,该算法能够克服合成参考算法中时延交替震荡现象,具有更强的鲁棒性。2.在非均匀天线组阵条件下,针对部分补偿算法中补偿系数最优化问题,以算法收敛速度最快为目标函数建立数学模型。通过对模型进行求解,推导得到最优补偿系数和时延中心的显式表达式。理论推导表明,最优补偿系数由各路信号信噪比决定,信噪比越大,最优补偿系数越小;而时延中心为初始信号时延的加权平均,加权值即为信号信噪比。仿真结果显示,与合成参考算法相比,部分补偿算法具有更快的算法收敛速度和更高的时延对准性能。3.针对频率选择性衰落信道下多天线信号合成中参考信号构造问题,首先从均衡器输出均方误差的角度证明了空间分集均衡器(SDE)与基于频域分量最大比合并算法(FMRC)的接收结构,这两者性能上的等价性,从而在理论上证明了FMRC算法的有效性;然后,对FMRC算法中固定参考信道的相频响应特性对合成信号盲均衡性能的影响进行分析。从避免固定参考带来合成信号盲均衡性能下降的角度,构造平均相位参考,同时利用两路信号合成不存在信道间相位模糊的优点,提出了一种基于两两逐路合成的平均相位参考算法。该算法计算量仅与天线数目成正比,复杂度较低,并且通过仿真实验验证了该算法的有效性。4.设计并实现了8天线信号合成系统,达到预期设计指标要求。首先根据系统指标要求,设计了8天线信号合成系统总体设计方案;然后,针对实际应用环境给出了软、硬件实现方案,并完成了部分补偿算法等参数估计算法的DSP程序设计和实现、PC端合成器控制软件设计与实现、FPGA与DSP高速接口设计与实现等主要工作;最后,通过合成性能测试与实际业务测试对系统进行了检验,达到预期指标要求。
[Abstract]:With the development of wireless communication, more and more attention has been paid to the reception of low signal-to-noise ratio (SNR) signals. In weak signal environment, it is difficult to receive effectively with a single antenna. An effective solution is to improve SNR by using multi-antenna signal synthesis technology. If the signal has a lower signal-to-noise ratio or undergoes a worse fading channel, the parameter estimation accuracy will be seriously affected and the synthesis performance will be reduced. Therefore, it is of great significance to improve the signal synthesis performance from the perspective of constructing a better reference signal. The main work and innovations of this paper are as follows: 1. Aiming at the problem of reference signal construction in time delay alignment of multi-antenna signals in Gaussian channel, the time delay alignment is theoretically deduced by means of matched filter bound. Explicit expression of the effect of errors on synthesis performance shows that the more antenna number, the higher delay alignment performance is required under the premise of guaranteeing the gain of synthetic signal-to-noise ratio (SNR); then, based on the analysis of convergence of synthetic reference algorithm, a joint reference is constructed to take the synthetic output signal as the reference signal, and a part-based approach is proposed. Theoretical analysis and simulation results show that the proposed algorithm can overcome the time-delay oscillation phenomenon in the synthetic reference algorithm and has stronger robustness. 2. Compensation for the partial compensation algorithm under the condition of non-uniform antenna array. The mathematical model is established with the fastest convergence speed as the objective function. The explicit expressions of the optimal compensation coefficient and the delay center are derived by solving the model. The simulation results show that compared with the synthetic reference algorithm, the partial compensation algorithm has faster convergence speed and higher delay alignment performance. 3. To solve the problem of reference signal construction in multi-antenna signal synthesis under frequency selective fading channels, the first step is equalization. From the point of view of the output mean square error, the performance equivalence between the spatial diversity equalizer (SDE) and the frequency domain component maximum ratio combining (FMRC) algorithm is proved, which proves the effectiveness of the FMRC algorithm theoretically. Then, the blind equalization of the synthetic signal to the phase frequency response characteristics of the fixed reference channel in the FMRC algorithm is given. An average phase reference algorithm based on two-to-two path synthesis is proposed to avoid the degradation of blind equalization performance of synthesized signals due to the fixed reference band. 4. A 8-antenna signal synthesis system is designed and implemented to meet the expected design requirements. Firstly, according to the system requirements, the overall design scheme of the 8-antenna signal synthesis system is designed. Then, the software and hardware implementation schemes are given for the practical application environment. The DSP program design and implementation of the partial compensation algorithm and other parameter estimation algorithm, the PC synthesizer control software design and implementation, the design and implementation of the high-speed interface between FPGA and DSP are completed. Finally, the system is tested by the synthetic performance test and the actual business test, and the expected target is achieved.
【学位授予单位】：解放军信息工程大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN820

【参考文献】