發(fā)布時間：2018-07-14 12:25

【摘要】：隨著無線局域網(wǎng)(WLAN)技術(shù)的迅猛發(fā)展,對無線局域網(wǎng)標(biāo)準(zhǔn)的制定和研究也從未停止腳步。IEEE 802.11系列標(biāo)準(zhǔn)歷經(jīng)802.11a/b/g/n/ac,數(shù)據(jù)傳輸速率實現(xiàn)一次又一次的突破,無線局域網(wǎng)的整體性能也進(jìn)一步提升。但是,隨著用戶數(shù)量越來越多且低頻段(2.4/5GHz)頻譜資源趨于緊張,勢必要開發(fā)新的頻段來滿足用戶不斷增長的需求,因此,毫米波段得到廣泛關(guān)注。IEEE 802.11ad標(biāo)準(zhǔn)作為60GHz的無線局域網(wǎng)標(biāo)準(zhǔn),具有相當(dāng)廣闊的市場發(fā)展前景。而增強的802.11ad標(biāo)準(zhǔn)引入了 MIMO及信道匯聚技術(shù),將傳輸場景擴展為長距離大時延傳輸,盡可能地滿足用戶體驗。本文以IEEE 802.1 1ad標(biāo)準(zhǔn)為基礎(chǔ),以增強1 1ad為向?qū)?研究適合于60GHz無線局域網(wǎng)通信系統(tǒng)要求的同步及信道估計技術(shù)。首先,對IEEE 802.11ad標(biāo)準(zhǔn)的3種物理層幀結(jié)構(gòu)及適用場景進(jìn)行介紹,簡單描述單載波系統(tǒng)及多載波OFDM系統(tǒng)的基本原理,并對兩種系統(tǒng)進(jìn)行簡單的分析比較。然后,基于物理幀前導(dǎo)的短訓(xùn)練(STF)字段,介紹了 SchmidlCox,Minn及基于格雷序列的時間同步算法。在時間同步的基礎(chǔ)上,進(jìn)行頻偏估計和補償,將LW,Kay,LR,Fitz頻偏估計算法在11ad信道模型中進(jìn)行仿真驗證。接下來針對增強11ad標(biāo)準(zhǔn),在大時延、MIMO、信道匯聚場景下,提出一種基于格雷互補序列的E-STF設(shè)計方案,并對序列的時間同步及頻偏估計性能進(jìn)行仿真分析。接著,針對前導(dǎo)信道估計(CE)字段,重點分析頻域LS信道估計及基于格雷序列的時域相關(guān)信道估計算法,仿真表明時域相關(guān)算法不僅估計性能優(yōu)異而且實現(xiàn)復(fù)雜度低。根據(jù)信道估計得到的結(jié)果,對數(shù)據(jù)進(jìn)行頻域均衡,主要討論線性均衡ZF和MMSE均衡算法,搭建鏈路級仿真平臺進(jìn)行驗證,因為MMSE算法分析噪聲和干擾的影響,均衡性能要略優(yōu)于迫零算法。最后針對大時延、MIMO、信道匯聚場景,提出一種新的基于格雷互補序列的同步及信道估計訓(xùn)練序列設(shè)計方案,該方案將MIMO信道估計轉(zhuǎn)化為多條SISO信道估計,實現(xiàn)簡單,而且估計性能較好。同時,可以根據(jù)系統(tǒng)的要求,選擇不同的零旁瓣長度及序列長度,增加了系統(tǒng)的靈活性和可操作性。論文的相關(guān)分析對于毫米波通信系統(tǒng)條件下的低復(fù)雜度的同步和信道估計技術(shù)設(shè)計具有一定參考價值。
[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.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TN925.93

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本文編號：2121639