【摘要】：人們對無線通信的高速率需求日益增強,利用有限的時頻資源實現(xiàn)更高的數(shù)據(jù)傳輸速率顯得愈加重要。MIMO技術(shù)能夠顯著提升通信系統(tǒng)容量,緩解頻率資源日益緊張的現(xiàn)狀,已經(jīng)被多個無線通信標準所采用。然而,在LTE上行鏈路中,終端設(shè)備在功耗、成本等方面受到限制,通常只能配置一根發(fā)射天線,不能通過MIMO技術(shù)的空分復(fù)用提高數(shù)據(jù)傳輸速率。為解決這一問題,虛擬MIMO技術(shù)將多個用戶虛擬配對,組成虛擬MIMO系統(tǒng),占用相同的時頻資源傳輸數(shù)據(jù),能夠在不提升終端硬件規(guī)格的前提下,有效改善頻譜利用率和系統(tǒng)容量。在虛擬MIMO系統(tǒng)中,用戶配對算法直接影響著系統(tǒng)性能。本文針對LTE上行虛擬MIMO系統(tǒng)中的用戶配對算法,進行了如下的研究工作:第一,搭建LTE上行系統(tǒng)級仿真平臺。結(jié)合LTE上行系統(tǒng)模型和3GPP相關(guān)協(xié)議,按照系統(tǒng)級仿真流程,對LTE上行系統(tǒng)進行仿真建模,為LTE上行虛擬MIMO系統(tǒng)中的用戶配對算法的性能驗證提供了仿真平臺。第二,研究LTE上行虛擬MIMO系統(tǒng)中的對稱資源用戶配對算法。首先,提出的貪婪多用戶配對算法以簡化的容量因子作為度量值,每次選出一個最優(yōu)用戶,并在確保能給系統(tǒng)帶來額外容量的情況下選其為配對用戶。然后,在貪婪算法的基礎(chǔ)上,用多個二階行列式的乘積代替高階行列式,得到了復(fù)雜度更低的簡化算法。最后,在簡化算法的基礎(chǔ)上結(jié)合比例公平準則,兼顧系統(tǒng)容量和用戶公平性。仿真表明,在LTE上行虛擬MIMO系統(tǒng)中,每個小區(qū)40個用戶,配對深度為4時,與雙重比例公平配對算法相比,簡化的貪婪比例公平多用戶配對算法獲得的5%邊緣用戶吞吐量和小區(qū)平均吞吐量分別提升116.67%和13.41%。第三,研究LTE上行虛擬MIMO系統(tǒng)中的非對稱資源用戶配對算法。提出的部分非對稱資源配對算法首先對頻率資源進行分塊,然后從每段的第一個RB開始選擇配對用戶,接著進行RB擴展,直至分配完全部RB。提出的完全非對稱資源配對算法完全不考慮已調(diào)度用戶的RB占用情況,根據(jù)比例公平準則選擇配對用戶。仿真表明:在兩用戶配對的LTE上行虛擬MIMO系統(tǒng)中,每個小區(qū)40個用戶時,與雙重比例公平配對算法相比,兩種算法獲得的5%邊緣用戶吞吐量分別提升236.73%和256.79%,獲得的小區(qū)平均吞吐量分別提升40.70%和47.38%。本文針對MIMO技術(shù)在上行系統(tǒng)中受到限制的問題,對LTE上行虛擬MIMO系統(tǒng)中的用戶配對算法進行了研究,提出了對稱資源下的貪婪、簡化的貪婪和簡化的貪婪比例公平算法,以及非對稱資源下的部分非對稱和完全非對稱算法。提出的算法可以用于LTE、LTE-Advanced及其它采用虛擬MIMO技術(shù)的通信系統(tǒng),能夠提升頻譜利用率和系統(tǒng)容量,改善通信質(zhì)量。
[Abstract]:With the increasing demand for high-speed wireless communication, it is more and more important to use limited time-frequency resources to achieve higher data transmission rate. MIMO technology can significantly improve the capacity of communication system and alleviate the increasing shortage of frequency resources. Has been adopted by multiple wireless communication standards. However, in the LTE uplink, the terminal devices are limited in power consumption and cost, usually only one transmit antenna can be configured, and the data transmission rate can not be improved by the space division multiplexing of MIMO technology. In order to solve this problem, virtual MIMO technology pairs multiple users into a virtual MIMO system, which takes up the same time-frequency resources to transmit data, and can improve spectrum efficiency and system capacity effectively without raising the hardware specification of the terminal. In the virtual MIMO system, the performance of the system is directly affected by the user pairing algorithm. In this paper, the user pairing algorithm in LTE uplink virtual MIMO system is studied as follows: firstly, the simulation platform of LTE uplink system level is built. Combined with the LTE uplink system model and 3GPP related protocols, according to the system level simulation flow, the LTE uplink system is simulated and modeled, which provides a simulation platform for the performance verification of user pairing algorithm in LTE uplink virtual MIMO system. Secondly, the symmetric resource user pairing algorithm in LTE uplink virtual MIMO system is studied. Firstly, the proposed greedy multi-user pairing algorithm takes the simplified capacity factor as the metric to select one optimal user at a time, and chooses it as the paired user under the condition that it can bring extra capacity to the system. Then, on the basis of greedy algorithm, a simplified algorithm with lower complexity is obtained by using the product of multiple second-order determinant instead of higher-order determinant. Finally, based on the simplified algorithm, the proportional fairness criterion is combined to take into account the system capacity and user fairness. Simulation results show that in the LTE uplink virtual MIMO system, 40 users per cell with a pairing depth of 4 are compared with the dual proportional fair pairing algorithm. The 5% edge user throughput and the cell average throughput obtained by the simplified greedy proportional fair multi-user pairing algorithm increased by 116.67% and 13.41%, respectively. Thirdly, the user pairing algorithm of asymmetric resources in LTE uplink virtual MIMO system is studied. The proposed partial asymmetric resource pairing algorithm first blocks the frequency resource, then selects the pairing user from the first RB of each segment, then extends the RB until all the RB. is allocated. The proposed completely asymmetric resource pairing algorithm does not consider the RB occupation of scheduled users at all, and selects pairing users according to the proportional fairness criterion. The simulation results show that compared with the dual proportional fair pairing algorithm, the throughput of 5% edge users in the two-user paired LTE uplink virtual MIMO system increases by 236.73% and 256.79%, respectively, when 40 users are in each cell. The average cell throughput was increased by 40.70% and 47.38% respectively. Aiming at the limitation of MIMO technology in uplink system, this paper studies the user pairing algorithm in LTE uplink virtual MIMO system, and puts forward the greedy, simplified greedy and simplified greedy proportional fair algorithm under symmetric resources. And partially asymmetric and completely asymmetric algorithms under asymmetric resources. The proposed algorithm can be used in LTE,LTE-Advanced and other communication systems using virtual MIMO technology, which can improve spectrum efficiency and system capacity, and improve communication quality.
【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN929.5
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本文編號：2471518