毫米波无线局域网同步及信道估计技术研究
发布时间：2018-07-14 12:25
【摘要】：随着无线局域网(WLAN)技术的迅猛发展,对无线局域网标准的制定和研究也从未停止脚步。IEEE 802.11系列标准历经802.11a/b/g/n/ac,数据传输速率实现一次又一次的突破,无线局域网的整体性能也进一步提升。但是,随着用户数量越来越多且低频段(2.4/5GHz)频谱资源趋于紧张,势必要开发新的频段来满足用户不断增长的需求,因此,毫米波段得到广泛关注。IEEE 802.11ad标准作为60GHz的无线局域网标准,具有相当广阔的市场发展前景。而增强的802.11ad标准引入了 MIMO及信道汇聚技术,将传输场景扩展为长距离大时延传输,尽可能地满足用户体验。本文以IEEE 802.1 1ad标准为基础,以增强1 1ad为向导,研究适合于60GHz无线局域网通信系统要求的同步及信道估计技术。首先,对IEEE 802.11ad标准的3种物理层帧结构及适用场景进行介绍,简单描述单载波系统及多载波OFDM系统的基本原理,并对两种系统进行简单的分析比较。然后,基于物理帧前导的短训练(STF)字段,介绍了 SchmidlCox,Minn及基于格雷序列的时间同步算法。在时间同步的基础上,进行频偏估计和补偿,将LW,Kay,LR,Fitz频偏估计算法在11ad信道模型中进行仿真验证。接下来针对增强11ad标准,在大时延、MIMO、信道汇聚场景下,提出一种基于格雷互补序列的E-STF设计方案,并对序列的时间同步及频偏估计性能进行仿真分析。接着,针对前导信道估计(CE)字段,重点分析频域LS信道估计及基于格雷序列的时域相关信道估计算法,仿真表明时域相关算法不仅估计性能优异而且实现复杂度低。根据信道估计得到的结果,对数据进行频域均衡,主要讨论线性均衡ZF和MMSE均衡算法,搭建链路级仿真平台进行验证,因为MMSE算法分析噪声和干扰的影响,均衡性能要略优于迫零算法。最后针对大时延、MIMO、信道汇聚场景,提出一种新的基于格雷互补序列的同步及信道估计训练序列设计方案,该方案将MIMO信道估计转化为多条SISO信道估计,实现简单,而且估计性能较好。同时,可以根据系统的要求,选择不同的零旁瓣长度及序列长度,增加了系统的灵活性和可操作性。论文的相关分析对于毫米波通信系统条件下的低复杂度的同步和信道估计技术设计具有一定参考价值。
[Abstract]:With the rapid development of wireless local area network (WLAN) technology, the establishment and research of WLAN standards have never stopped. The IEEE 802.11 series standards have experienced 802.11a / b / g / nr.ac. data transmission rate has been broken through again and again. The overall performance of WLAN is also further improved. However, with the increasing number of users and the shortage of spectrum resources in the low frequency band (2.4 / 5GHz), new frequency bands are bound to be developed to meet the growing needs of users. The millimeter band 802.11ad standard, as a 60GHz WLAN standard, has a wide market prospect. The enhanced 802.11ad standard introduces 802.11ad and channel convergence technology to extend the transmission scene to long distance and long delay transmission to satisfy the user experience as much as possible. Based on 802.1 1ad standard and enhanced 1 1ad as guide, this paper studies synchronization and channel estimation techniques suitable for 60GHz WLAN communication system. Firstly, three kinds of physical layer frame structures and applicable scenarios of 802.11ad standard are introduced, and the basic principles of single carrier system and multi-carrier OFDM system are briefly described, and the two systems are analyzed and compared. Then, based on the short training (STF) field of physical frame leading, Schmidl CoxCon Minn and the time synchronization algorithm based on Gray sequence are introduced. On the basis of time synchronization, the frequency offset estimation and compensation are carried out, and the LRX Fitz frequency offset estimation algorithm is simulated in the 11ad channel model. Then, aiming at the enhanced 11ad standard, an E-STF design scheme based on Gray complementary sequence is proposed in this paper, and the performance of time synchronization and frequency offset estimation is analyzed by simulation. Then, for the CE field, the frequency domain LS channel estimation and the time-domain correlation channel estimation algorithm based on Gray sequence are analyzed. The simulation results show that the time-domain correlation algorithm not only has excellent estimation performance but also has low implementation complexity. According to the results of channel estimation, the data are equalized in frequency domain. The linear equalization algorithms ZF and MMSE equalization algorithms are mainly discussed, and the link level simulation platform is built to verify them, because the MMSE algorithm analyzes the influence of noise and interference. The equalization performance is slightly better than the zero-forcing algorithm. Finally, a new design scheme of synchronization and channel estimation training sequence based on Gray complementary sequence is proposed for the MIMO-channel convergence scenario with large delay. The scheme converts MIMO channel estimation into multiple SISO channel estimation, and the implementation is simple. And the estimated performance is good. At the same time, different length of zero sidelobe and sequence length can be selected according to the requirements of the system, which increases the flexibility and maneuverability of the system. The correlation analysis in this paper is useful for the design of low complexity synchronization and channel estimation techniques in millimeter wave communication systems.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN925.93
本文编号：2121639
[Abstract]:With the rapid development of wireless local area network (WLAN) technology, the establishment and research of WLAN standards have never stopped. The IEEE 802.11 series standards have experienced 802.11a / b / g / nr.ac. data transmission rate has been broken through again and again. The overall performance of WLAN is also further improved. However, with the increasing number of users and the shortage of spectrum resources in the low frequency band (2.4 / 5GHz), new frequency bands are bound to be developed to meet the growing needs of users. The millimeter band 802.11ad standard, as a 60GHz WLAN standard, has a wide market prospect. The enhanced 802.11ad standard introduces 802.11ad and channel convergence technology to extend the transmission scene to long distance and long delay transmission to satisfy the user experience as much as possible. Based on 802.1 1ad standard and enhanced 1 1ad as guide, this paper studies synchronization and channel estimation techniques suitable for 60GHz WLAN communication system. Firstly, three kinds of physical layer frame structures and applicable scenarios of 802.11ad standard are introduced, and the basic principles of single carrier system and multi-carrier OFDM system are briefly described, and the two systems are analyzed and compared. Then, based on the short training (STF) field of physical frame leading, Schmidl CoxCon Minn and the time synchronization algorithm based on Gray sequence are introduced. On the basis of time synchronization, the frequency offset estimation and compensation are carried out, and the LRX Fitz frequency offset estimation algorithm is simulated in the 11ad channel model. Then, aiming at the enhanced 11ad standard, an E-STF design scheme based on Gray complementary sequence is proposed in this paper, and the performance of time synchronization and frequency offset estimation is analyzed by simulation. Then, for the CE field, the frequency domain LS channel estimation and the time-domain correlation channel estimation algorithm based on Gray sequence are analyzed. The simulation results show that the time-domain correlation algorithm not only has excellent estimation performance but also has low implementation complexity. According to the results of channel estimation, the data are equalized in frequency domain. The linear equalization algorithms ZF and MMSE equalization algorithms are mainly discussed, and the link level simulation platform is built to verify them, because the MMSE algorithm analyzes the influence of noise and interference. The equalization performance is slightly better than the zero-forcing algorithm. Finally, a new design scheme of synchronization and channel estimation training sequence based on Gray complementary sequence is proposed for the MIMO-channel convergence scenario with large delay. The scheme converts MIMO channel estimation into multiple SISO channel estimation, and the implementation is simple. And the estimated performance is good. At the same time, different length of zero sidelobe and sequence length can be selected according to the requirements of the system, which increases the flexibility and maneuverability of the system. The correlation analysis in this paper is useful for the design of low complexity synchronization and channel estimation techniques in millimeter wave communication systems.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN925.93
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