大规模MIMO BDMA传输系统通道校正方法研究

发布时间：2018-03-07 01:03

本文选题：大规模MIMO　切入点：BDMA传输　出处：《东南大学》2017年硕士论文　论文类型：学位论文

【摘要】：大规模多输入多输出(MIMO,Multiple-Input Multiple-Output)技术可以显著提升系统的频谱效率和功率效率,是下一代移动通信系统的关键技术之一。大规模MIMO波束分多址(BDMA,Beam Division Multiple Access)传输方法根据波束域信道的稀疏性,通过用户调度为不同用户分配不同的波束集合进行传输,从而将多用户MIMO链路分解为多个单用户MIMO链路,降低了传输的复杂度。然而,对于实际通信系统,完整的通信信道不仅包括空中的无线信道,也包括发射端和接收端的射频电路。射频电路引起的射频增益失配会导致各通道间存在幅度和相位的不一致性,从而降低了 BDMA传输的性能。针对这个问题,本论文对大规模MIMO BDMA传输系统中通道校正方法进行了研究。全文的主要工作如下:首先,研究了收发端通道不一致性对波束域信道能量分布以及系统遍历可达和速率上界的影响。分析表明,对于用户侧,幅相不一致性不会导致波束域信道能量发生扩散,相位不一致性不改变和速率上界且幅度不一致性对和速率上界的影响很小。对于基站侧,幅相不一致性会导致波束域信道能量的扩散以及和速率上界的降低。在通常的幅相误差范围下,基站侧相位不一致性是造成BDMA传输性能下降的主要原因。接着,提出了基于最小化波束域信道稀疏度准则的基站侧接收通道相位不一致性校正方法。根据BDMA传输的特点,通道校正中不需要得到精确的射频增益,校正准则可以变化为最小化波束域信道的稀疏度。在此基础上,推导了信道稀疏度与对应向量l1范数的关系,通过信道估计得到的上行信道信息,将最小化信道稀疏度的问题转化为了一个最小化信道向量l1范数的问题,并给出了该问题的求解方法。仿真结果表明,提出的相位校正方法可以减小上行波束域信道的能量扩散,提升BDMA上行传输的和速率性能。然后,提出了基于互易性校正的基站侧发射通道相位不一致性校正方法,基站侧发射通道的相位校正矩阵通过互易性校正矩阵与基站侧接收通道相位校正矩阵的乘积得到。利用大规模天线阵列中阵元之间的互耦特性,提出了一种分组校正算法得到互易性校正矩阵。先根据天线阵列形式和互耦强度将阵元分组,分别计算每组的互易性校正参数,再连接各组的校正参数得到最终的互易性校正矩阵。仿真结果表明,通过选择合适的分组大小,提出的互易性校正方法能达到较高的校正精度。基站侧发射通道经过校正后,BDMA下行传输的和速率性能得到了显著的提升。最后,提出了基于信道估计的硬件校正方法。在基站侧配置校正电路,控制信号使校正系统工作于三种不同的模式。校正系统工作于接收通道校正模式时,需要先进行相位补偿,再使用接收到的信号计算接收通道校正矩阵。校正系统工作于发射通道校正模式时,各阵元发送的信号经过定向耦合器后传输到接收通道,根据接收到的信号计算发射通道的校正矩阵。完成通道校正后,校正系统再工作于正常收发模式。仿真结果表明,硬件校正方法具有很高的校正精度。
[Abstract]:Large scale multi input multi output (MIMO Multiple-Input Multiple-Output) technology can significantly improve the spectrum efficiency and power efficiency of the system, is one of the key technologies of the next generation mobile communication system. Large scale MIMO beam division multiple access (BDMA Beam, Division Multiple Access) transmission method according to the sparsity of channel beam domain, different beam transmission set allocation for different users through the user scheduling, and multi user MIMO link into multiple single user MIMO link, reduces the complexity of transmission. However, in the actual communication system, the communication channel end includes not only the wireless channel in the air, including RF transmitter and receiver RF RF gain. The circuit caused by mismatch will lead to the inconsistency between the amplitude and phase of each channel, thereby reducing the transmission performance of BDMA. Aiming at this problem, this paper Calibration method for large scale MIMO channel in BDMA transmission system is studied. The main contents are as follows: firstly, the transmitter and receiver channel mismatch effects on the beam domain energy distribution system and channel ergodic achievable sum rate upper bound. Analysis shows that for the user side, amplitude and phase consistency does not result in beam domain channel energy diffusion, phase inconsistency does not change and the rate of upper bound and the increase is not consistent influence on the rate and upper bound is very small. The base station side, amplitude phase inconsistency will lead to lower diffusion beam domain channel energy and rate limit. In general the amplitude and phase error range, the base station side phase inconsistency is the main reason causing the decline of BDMA transmission performance. Then, the base station side to minimize beam domain channel sparsity criterion based on the received channel phase consistency correction method according to the BDMA. The transmission characteristics of the channel does not need RF gain accurate correction, correction criteria can change to minimize beam domain channel sparsity. On this basis, to deduce the channel sparsity and the corresponding vector L1 norm, by estimating the uplink channel information of the channel, will minimize the channel sparsity problem is transformed to a minimum channel vector L1 norm problem, and gives the method to solve the problem. The simulation results show that the proposed method can reduce the phase correction of energy diffusion wave beam domain channel, enhance the BDMA uplink transmission rate and performance. Then, the base station side reciprocity correction based on transmit channels imbalance. Phase correction method, base station transmitting channel correction matrix through reciprocity correction matrix product and the base station side receiving channel phase correction matrix is obtained. By using large scale In the antenna array mutual coupling between elements characteristics, proposes a packet correction algorithm get the reciprocity correction matrix. According to the model of antenna array mutual coupling strength and the element groups, each group reciprocity correction parameters were calculated, and then the correction parameters of connection groups reciprocity final correction matrix. The simulation results show that the by grouping, choose the right size, put forward the reciprocity correction method can achieve high calibration accuracy. The base station transmit channel after calibration, BDMA downlink transmission rate and performance has been significantly improved. Finally, the correction of channel estimation method based on the hardware circuit. The correction in base station configuration, control signal the correction system works in three different modes. The correction system is in the receiving channel calibration mode, need to first phase compensation, and then use the received signal to calculate receiving channel The correction matrix. Correction system working in the transmitting channel correction mode, the signal transmitted by each element of the directional coupler and then transmitted to the receiving channel, transmission channel correction matrix is calculated according to the received signal. Complete channel calibration, calibration system working in normal mode transceiver. The simulation results show that the hardware correction method with correction accuracy very high.

【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN919.3

【相似文献】