本文關(guān)鍵詞： 大規(guī)模天線 天線校準(zhǔn) 混合波束賦形 60GHz 網(wǎng)絡(luò) MIMO　出處：《北京郵電大學(xué)》2014年博士論文　論文類型：學(xué)位論文

【摘要】：在過去的20多年里,多輸入多輸出(Multiple-Input and Multiple-Output, MIMO)技術(shù)得到了廣泛的發(fā)展和成功的應(yīng)用。在傳統(tǒng)MIMO系統(tǒng)中,收發(fā)端使用的天線數(shù)量一般小于8根,屬于小規(guī)模多天線系統(tǒng)。理論研究已指出,增加天線數(shù)可以增加MIMO系統(tǒng)空間自由度從而提高系統(tǒng)速率和可靠性。此外,隨著天線數(shù)量的增加,系統(tǒng)還可以獲得更高效的能量利用率以及高的魯棒性和安全性。為了滿足未來對(duì)更高速無線傳輸?shù)男枨?使用較大規(guī)模天線被認(rèn)為是未來寬帶無線通信系統(tǒng)的一個(gè)重要特征之一。由于時(shí)分雙工(Time Division Duplexing,TDD)具有無線信道互易性的天然優(yōu)勢(shì),較大規(guī)模天線系統(tǒng)更適合于在TDD模式下工作。 論文基于TDD模式的多用戶場景,結(jié)合實(shí)際部署時(shí)所遇到的部分問題挑戰(zhàn),研究兩類典型且特殊的較大規(guī)模天線陣列的發(fā)送端預(yù)處理關(guān)鍵問題和解決方案。第一類是射頻／模擬前端數(shù)少于天線數(shù)的集中式較大規(guī)模天線陣列。使用此類天線的典型系統(tǒng)為毫米波無線通信系統(tǒng)。在天線數(shù)與射頻／模擬前端數(shù)相等的傳統(tǒng)多天線系統(tǒng)中,陣列波束賦形能夠全部在數(shù)字基帶上實(shí)現(xiàn)。而當(dāng)射頻／模擬前端數(shù)少于天線數(shù)時(shí),為了能夠充分利用天線陣列的增益,需要將一部分波束賦形轉(zhuǎn)移到模擬域上進(jìn)行,將另一部分留在數(shù)字域上進(jìn)行,從而形成兩級(jí)波束賦形的結(jié)構(gòu)。另外,受到實(shí)現(xiàn)復(fù)雜度的限制,模擬域波束賦形的靈活性不如數(shù)字域波束賦形。傳統(tǒng)的純數(shù)字基帶的預(yù)處理技術(shù)不能直接應(yīng)用到這類天線系統(tǒng)中。針對(duì)此類天線結(jié)構(gòu),論文著眼研究在低成本毫米波系統(tǒng)中的多用戶方案以及多用戶模擬／數(shù)字混合波束賦形的優(yōu)化問題。第二類陣列為分布式協(xié)作虛擬陣列,其中天線數(shù)與射頻/模擬前端數(shù)相等。相應(yīng)的一個(gè)典型系統(tǒng)為網(wǎng)絡(luò)MIMO系統(tǒng)。天線射頻／模擬前端的收、發(fā)模塊系數(shù)失配(簡稱收、發(fā)模塊系數(shù)失配)是實(shí)際TDD系統(tǒng)中普遍存的一個(gè)非理想因素。它導(dǎo)致多天線系統(tǒng)中陣列天線間失配并影響上、下行基帶信道矩陣的互易性,從而能夠?qū)赥DD的多用戶MIMO系統(tǒng)帶來嚴(yán)重影響。對(duì)于此類陣列,本文深入分析天線間失配的影響特性并著重研究網(wǎng)絡(luò)MIMO中分布式天線校準(zhǔn)技術(shù)。論文的主要?jiǎng)?chuàng)新點(diǎn)包括： 第一,針對(duì)使用低成本相控陣列的60GHz無線系統(tǒng),論文研究該系統(tǒng)中低復(fù)雜度多用戶實(shí)現(xiàn)方案。所提方案分為調(diào)度、波束賦形訓(xùn)練和數(shù)字域干擾抑制三個(gè)階段,解決的關(guān)鍵問題為用戶的配對(duì)以及模擬/數(shù)字波束賦形的確定。方案可與現(xiàn)有60GHz無線系統(tǒng)中常用的單用戶波束賦形訓(xùn)練過程相結(jié)合,調(diào)度相互間干擾不強(qiáng)的多個(gè)用戶。發(fā)端使用模擬波束賦形提高鏈路質(zhì)量,使用數(shù)字預(yù)編碼消除調(diào)度用戶間干擾。在數(shù)字域干擾抑制階段,可利用TDD信道互易性以較低的開銷獲得發(fā)端與收端用戶間的等效信道。該方案的低復(fù)雜性主要在于它無需對(duì)收、發(fā)端間大規(guī)模信道矩陣做顯性檢測,同時(shí)也不要求知道用戶地理位置信息。論文基于IEEE802.11ad的信道模型對(duì)所提方案在視距(Line-of-Sight, LoS)和非視距(Non-Line-of-Sight, NLoS)場景下進(jìn)行了評(píng)估,仿真結(jié)果顯示,所提調(diào)度方案可以有效的避免用戶間強(qiáng)干擾并得到較好的平均信干噪比(Signal-to-Noise-Ratio, SINR)。此外,當(dāng)多普勒效應(yīng)不明顯時(shí),在數(shù)字域進(jìn)一步做干擾抑制后,低SINR區(qū)域能夠獲得較明顯的性能改善。而當(dāng)存在信道信息過時(shí)的情況時(shí),模擬波束賦形的性能幾乎不受多普勒效應(yīng)影響,但數(shù)字基帶上進(jìn)行的多用戶干擾抑制的性能易受到明顯影響。論文所提出的多用戶方案適用于環(huán)境變化不劇烈的場景。 第二,針對(duì)多用戶模擬／數(shù)字混合波束賦形,論文研究兩個(gè)相互聯(lián)系的優(yōu)化問題：(1)當(dāng)存在每個(gè)子載波用戶SINR約束時(shí),最小化平均每個(gè)子載波的發(fā)射功率；(2)當(dāng)存在平均每個(gè)子載波的發(fā)射功率約束時(shí),最大化最小SINR。所研究內(nèi)容是對(duì)傳統(tǒng)針對(duì)純數(shù)字波束賦形優(yōu)化研究的擴(kuò)展,同時(shí)也是對(duì)已有單用戶模擬／數(shù)字混合波束賦形向多用戶的擴(kuò)展。論文分別對(duì)上述兩個(gè)混合波束賦形的優(yōu)化問題進(jìn)行可行性分析、研究相關(guān)問題最優(yōu)解處的相關(guān)性質(zhì)并且結(jié)合半正定規(guī)劃(semi-definite program,SDP)松弛法給出兩個(gè)優(yōu)化問題的次優(yōu)求解算法。最后,通過仿真評(píng)估所提算法的收斂性能和收斂值。該部分所研究問題不僅適用于毫米波無線系統(tǒng),也適用于工作在低頻段但對(duì)功耗和成本敏感的較大規(guī)模天線系統(tǒng)。基于仿真結(jié)果可以得到以下結(jié)論。當(dāng)不同子載波的信道間相關(guān)性較高,模擬/數(shù)字混合波束賦形在最優(yōu)性能方面可以逼近相同天線下的純數(shù)字波束賦形。反之,當(dāng)子載波信道間相關(guān)性低時(shí),由于使用頻域平坦的模擬波束賦形權(quán)重,混合波束賦形性能與相同天線下純數(shù)字波束賦形性能差距較明顯。此外,在60GHz LoS信道模型下,優(yōu)化后的每個(gè)射頻/模擬前端的模擬波束賦形的方向與用戶間的空間分離度有關(guān)。當(dāng)用戶空間分離度較高時(shí),將不同射頻/模擬前端的模擬波束賦形的主瓣分別指向不同的用戶,即在模擬域上進(jìn)行部分多用戶間干擾抑制能夠獲得較低的發(fā)射功率或較高的Max-min STNR。而當(dāng)用戶空間分離度較低時(shí),今每個(gè)射頻/模擬前端的模擬波束賦形方向同時(shí)指向所有用戶,而讓數(shù)字域波束賦形完成多用戶間干擾抑制,往往能夠獲得更低的發(fā)射功率或更高的Max-min SINR。 第三,針對(duì)TDD大線間失配的問題以及網(wǎng)絡(luò)MIMO甲大線校準(zhǔn)技術(shù),論文分析了天線間失配的影響特性并提出了兩根相鄰分布式天線間校準(zhǔn)改進(jìn)算法以及適用任意規(guī)模分布式天線校準(zhǔn)系數(shù)計(jì)算的方案,具體如下�，F(xiàn)有的研究已指出基帶信道不互易會(huì)引入MIMO多用戶間干擾。然而針對(duì)天線間失配造成的多用戶間干擾的統(tǒng)計(jì)特性以及預(yù)編碼的擾動(dòng)分析的研究還較少。當(dāng)基站側(cè)天線間失配時(shí),論文分析了僅有幅度失配所產(chǎn)生多用戶間干擾功率和僅有相位失配時(shí)所產(chǎn)生多用戶間干擾功率之間的關(guān)系。該關(guān)系可用于比較由幅度失配和相位失配引起的多用戶間干擾的大小。而當(dāng)用戶天線間失配時(shí),本文分析了基于奇異值分解(Singular Value Decomposition, SVD)分解和Moore-Penrose偽逆的預(yù)編碼的部分?jǐn)_動(dòng)特性。對(duì)天線間失配影響的分析結(jié)果不僅能讓我們更深入的認(rèn)識(shí)天線間失配對(duì)MIMO(包括網(wǎng)絡(luò)MIMO)系統(tǒng)的影響,而且也有助于實(shí)際天線校準(zhǔn)方案的設(shè)計(jì)。天線校準(zhǔn)的目的在于減小或消除天線間失配的影響。傳統(tǒng)集中式陣列天線的天線校準(zhǔn)方法通常需要借助硬件支持,不適合擴(kuò)展用于校準(zhǔn)分布式的天線。相比較而言,空口校準(zhǔn)技術(shù)更適合于分布式天線的場景。對(duì)于基于空口的兩根分布式基站天線間的校準(zhǔn),本文提出一種對(duì)現(xiàn)有方法的改進(jìn)方法。該改進(jìn)方法是對(duì)現(xiàn)有方法的一個(gè)擴(kuò)展,它可以獲得比現(xiàn)有方法更小的校準(zhǔn)誤差。此外,本文進(jìn)一步研究適用于任意規(guī)模的分布式天線系統(tǒng)的校準(zhǔn)系數(shù)計(jì)算方案。該方案結(jié)合分集的思想,通過合并由多個(gè)參考源計(jì)算的臨時(shí)校準(zhǔn)系數(shù)得到每根分布式天線的最終校準(zhǔn)系數(shù)。論文還給出了兩種確定每根分布式天線最終校準(zhǔn)系數(shù)的算法。仿真結(jié)果驗(yàn)證了文章所得相關(guān)性質(zhì)并比較了不同參數(shù)下不同校準(zhǔn)方法的性能。
[Abstract]:In the past 20 years, multiple input multiple output (Multiple-Input and Multiple-Output MIMO) technology has been widely developed and successfully applied in traditional MIMO system, which uses the number of receiving antenna is generally less than 8, is a small multi antenna system. The theoretical research has pointed out that the increase of antenna number can be increased MIMO degrees of freedom so as to improve the system speed and reliability. In addition, with the increase of the number of antennas, the system can also get more efficient use of energy efficiency and robustness and high safety. In order to meet the future demand for more high-speed wireless transmission, the use of large scale antenna is considered an important feature of the future broadband the wireless communication system. Due to the time division duplex (Time Division, Duplexing, TDD) with wireless channel reciprocity natural advantages, more suitable for large scale antenna system in TDD mode Work.
The multi user scenarios based on TDD model, combined with the actual problems encountered some challenges when deployed, on large scale antenna array of two typical and special sending pretreatment key problems and solutions. The first is the centralized large-scale antenna array RF / analog front-end number less than the number of antennas. The typical use of such system antenna for millimeter wave wireless communication system. The number of antennas and RF / analog front-end is equal to the number of the traditional multi antenna system, array beamforming can achieve full digital baseband and RF / analog front-end. When the number is less than the number of antennas, in order to make full use of the antenna array gain, need to be a part of the beam shaped transfer to simulation domain, will be another part in the digital domain, thus forming a structure of two level beamforming. In addition, by the complexity of the limit mode To be less flexible than digital domain beamforming domain beamforming. Not pretreatment technology of pure digital baseband traditional direct application to the antenna system. The antenna structure based on the low cost millimeter wave system in multi-user scheme and the optimization problem of multi user analog / digital hybrid beamforming second kinds of array shape. For the distributed collaborative virtual array, the number of antennas and RF / analog front-end is equal to the number. A typical system corresponding to MIMO network system. The receiving antenna RF / analog front-end module, the mismatch in coefficient (the receiving module, the mismatch in coefficient) is a non ideal factors generally practical TDD system. It leads to antenna array mismatch between and influence on multiple antenna system, the reciprocity of downlink channel matrix, which can be of multi user MIMO system based on TDD to have a serious impact. In this kind of array, this paper analyzes the influence characteristics of antenna mismatch deeply, and focuses on the research of distributed antenna calibration technology in network MIMO.
First, 60GHz wireless systems for use in low cost phased array, the study of low complexity multiuser system implementation scheme. The proposed scheme consists of scheduling, beamforming training and digital domain interference suppression in three stages, the key to solve the problem of user pairing and analog / digital beamforming is determined. The scheme can be combined with a single user beamforming training process commonly used in existing 60GHz wireless system, the mutual interference between multiple users scheduling is not strong. The originator of analog beamforming to improve the link quality, the use of digital pre encoding to eliminate the interference between users. The scheduling phase interference suppression in the digital domain, can use the TDD channel reciprocity with low overhead for start and end users receive the equivalent channel. The low complexity of the scheme lies in that it does not need to receive, which major channel matrix do explicit detection, also don't ask Know the location of the user information. The paper based on the IEEE802.11ad channel model of the proposed scheme on the horizon (Line-of-Sight, LoS) and non line of sight (Non-Line-of-Sight, NLoS) scenarios were evaluated, the simulation results show that the proposed scheduling scheme can effectively avoid interference among users and get better average signal to interference and noise ratio (Signal-to-Noise-Ratio, SINR). In addition, when the Doppler effect is not obvious, further interference suppression in the digital domain, low SINR performance can be improved obviously. When the channel information is out of date when the performance of analog beamforming is almost not affected by the Doppler effect, but the performance of multi user interference suppression the digital baseband easily affected. Many users proposed by this paper is suitable for the environment does not change violent scenes.
Second, for multiuser analog / digital hybrid beamforming, on two interrelated optimization papers: (1) when each subcarrier user SINR constraints, to minimize the average transmit power of each sub carrier; (2) when the transmit power constraints are the average of each sub carrier, the maximum minimum SINR. the research contents of the traditional for the pure digital beamforming optimization of the expansion, but also on the existing single user analog / digital hybrid beamforming is extended to multiple users. This paper analyzes the feasibility of the optimization problem of two hybrid beamforming and related properties of the optimal solution of issues related to research and combination semidefinite programming (semi-definite program SDP) relaxation method gives two suboptimal algorithms for solving optimization problems. Finally, through the simulation and evaluation of the convergence of the algorithm and the convergence value of the part. The study is not only suitable for millimeter wave wireless system, is also suitable for working at low frequency but for larger antenna system power consumption and cost sensitive. The simulation results can be obtained. The following conclusions based on different sub carrier channel when the high correlation between the analog / digital hybrid beamforming in optimal performance can approximate pure digital beam the same shaped antenna. On the contrary, when the subcarrier channel correlation is low, because the analog beamforming weights using frequency-domain flat shape, properties of pure digital beamforming hybrid beamforming performance with the same antenna gap is obvious. In addition, in the 60GHz LoS channel model, simulation of beamforming each RF / after optimization of the analog front end of the direction and the spatial separation between users. When the user space separation degree is high, the main lobe beam simulation of different RF / analog front-end shaped respectively Pointing to different users, namely in the analog domain on the part of multiuser interference suppression can obtain lower transmit power or higher Max-min STNR. when the user space separation degree is low, the analog beamforming direction of each RF / analog front-end simultaneously to all users, and make digital beamforming complete domain multiuser interference suppression, often able to obtain lower transmit power or higher Max-min SINR.
Third, according to the TDD line between the mismatch problem and a large network MIMO line calibration technology, this paper analyses the influence of the characteristics of mismatch between the antenna and presents two adjacent distributed antenna calculation algorithms and the application of arbitrary scale distributed antenna calibration coefficient calibration improvement scheme, as follows. The existing research has pointed out that the baseband channel reciprocity will introduce MIMO interference between users. However, according to the statistical characteristics of multiuser antenna mismatch caused by interference between the study and the perturbation analysis of precoding is less. When the base station antenna mismatch, the paper analyzes only the amplitude mismatch generated power and phase only inter user interference generated the relationship between the multi user interference power mismatch between. This relationship can be used for multiple users by comparing the amplitude mismatch and phase mismatch between the size of interference. When the user antenna mismatch This paper analyzes, based on the singular value decomposition (Singular Value, Decomposition, SVD) decomposition and Moore-Penrose pseudo inverse precoding part. Analysis of disturbance characteristics between the antenna mismatch results not only can let us know more deeply between the antenna mismatch MIMO (including network MIMO) system, but also help design in the actual antenna calibration scheme. Antenna calibration aims to reduce or eliminate the effects of antenna mismatch between the antenna calibration method. The traditional centralized array antenna often need to use the hardware support, not suitable for extension for distributed antenna calibration. By comparison, empty calibration technique is more suitable for distributed antenna calibration for scene. Two distributed base station antenna based on the interface, this paper presents an improved method to the existing method. The improved method is an extension of the existing methods, it can Better than existing methods of calibration error smaller. In addition, the calculation of calibration coefficients distributed antenna system are further studied in this paper is suitable for any size of the scheme. This scheme combines diversity, the final calibration coefficients obtained from each distributed antenna through temporary calibration coefficients combined calculation by multiple reference sources. This paper also presents two kinds of to determine each distributed antenna final calibration coefficient algorithm. Simulation results show the properties and performance of different calibration methods were compared under different parameters.

【學(xué)位授予單位】：北京郵電大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TN919.3

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本文編號(hào)：1453365