發(fā)布時間：2018-06-16 16:33

  本文選題：自適應(yīng)資源分配 + 服務(wù)質(zhì)量　； 參考：《蘭州交通大學(xué)》2017年碩士論文

【摘要】：無線多媒體業(yè)務(wù)的快速發(fā)展,要求LTE系統(tǒng)具有高吞吐量、低時延和滿足用戶服務(wù)質(zhì)量要求(QoS)的特性。這就使得有限的頻帶資源與不斷增長的數(shù)據(jù)業(yè)務(wù)需求之間的矛盾日益嚴(yán)重。OFDM作為LTE下行鏈路的核心技術(shù)之一,能夠顯著提高頻帶利用率和數(shù)據(jù)傳輸速率,使系統(tǒng)能更加靈活的調(diào)度資源。因此在OFDM技術(shù)的基礎(chǔ)上,如何合理高效地調(diào)度資源并兼顧用戶QoS是一個需要研究的問題。論文首先介紹了LTE系統(tǒng)架構(gòu)、QoS機(jī)制以及LTE下行關(guān)鍵技術(shù)—OFDM技術(shù)原理、系統(tǒng)實(shí)現(xiàn),分析了無線信道衰落特性,為后續(xù)建模仿真提供了理論支持。而后引入了兩個資源優(yōu)化分配準(zhǔn)則,即速率自適應(yīng)準(zhǔn)則RA和余量自適應(yīng)準(zhǔn)則MA。對這兩種準(zhǔn)則下的一些資源分配算法進(jìn)行了理論分析和性能仿真,其中包括單用戶資源分配的注水算法、貪婪算法,多用戶資源分配的MaxSNR+WPA算法、RR+EPA算法、Shen算法。在分析各個算法原理和優(yōu)缺點(diǎn)的基礎(chǔ)上,發(fā)現(xiàn)現(xiàn)有LTE下行鏈路資源分配仍有許多待解決的問題,如用戶間公平性較差、無法保證QoS、效率低等。重點(diǎn)研究了在LTE下行多用戶環(huán)境下,基于QoS的自適應(yīng)資源分配算法。針對這個研究方向,首先基于RA準(zhǔn)則將資源分配分為子載波分配與功率分配。在子載波分配過程中,首先依照RR算法為每個用戶分配一個子載波,再結(jié)合用戶目前信道狀態(tài)信息、業(yè)務(wù)類型、速率約束因子分配剩余子載波,速率約束因子可根據(jù)用戶業(yè)務(wù)類型動態(tài)調(diào)整,其決定了用戶速率的上限;在功率分配過程中,由于已經(jīng)完成了子載波的分配,此時RA優(yōu)化問題可放松為一個凸優(yōu)化問題,結(jié)合已完成的子載波分配方案剔除增益噪聲比過小的子載波并以此作為一個約束條件簡化該優(yōu)化問題,化簡至只有一個未知變量的情況下利用二分搜索迭代算法迭代出該問題的最優(yōu)解,再利用該最優(yōu)解求出系統(tǒng)中每個用戶的動態(tài)注水線,此時采用注水思想完成功率分配。最后通過MATLAB仿真工具,從基站、用戶、噪聲、路徑損耗等幾個方面進(jìn)行建模,結(jié)合城市宏小區(qū)(Uma)場景參數(shù)配置以及3GPP 36.942協(xié)議規(guī)范設(shè)置相應(yīng)仿真參數(shù),搭建靜態(tài)LTE系統(tǒng)級仿真環(huán)境。在小區(qū)吞吐量、用戶SINR、單一業(yè)務(wù)場景下的用戶容量、混合業(yè)務(wù)場景下的用戶容量這幾個方面對提出算法進(jìn)行了仿真分析。結(jié)果表明,提出算法能夠在用戶公平性與系統(tǒng)吞吐量之間進(jìn)行平衡,資源分配更加靈活,可通過設(shè)置不同比例公平因子來控制用戶傳輸速率上限,在不同業(yè)務(wù)類型下實(shí)現(xiàn)了差異化資源調(diào)度,分別從用戶間公平性、用戶通信鏈路質(zhì)量、不同業(yè)務(wù)傳輸速率保證等幾個方面滿足了用戶的服務(wù)質(zhì)量(QoS)要求,同時具有較快的收斂速度。
[Abstract]:The rapid development of wireless multimedia services requires that LTE systems have the characteristics of high throughput, low delay and QoS. As one of the core technologies of LTE downlink, OFDM can significantly improve the bandwidth efficiency and data transmission rate, which makes the contradiction between the limited frequency band resources and the increasing demand for data services increasingly serious, as one of the core technologies of LTE downlink. Make the system more flexible scheduling resources. Therefore, on the basis of OFDM technology, how to reasonably and efficiently schedule resources and take account of user QoS is a problem that needs to be studied. Firstly, this paper introduces the QoS mechanism of LTE system architecture and the principle and implementation of OFDM technology, which is the key technology of LTE downlink. The characteristics of wireless channel fading are analyzed, which provides theoretical support for subsequent modeling and simulation. Then two optimal resource allocation criteria are introduced, that is, rate adaptive criterion RA and residual adaptive criterion MA. Some resource allocation algorithms under these two criteria are theoretically analyzed and simulated, including water injection algorithm for single user resource allocation, greedy algorithm, MaxSNR WPA algorithm for multi-user resource allocation, RR EPA algorithm and Shen algorithm for multi-user resource allocation. On the basis of analyzing the principle of each algorithm and its advantages and disadvantages, it is found that there are still many problems to be solved in LTE downlink resource allocation, such as poor fairness among users, poor QoS, low efficiency and so on. The adaptive resource allocation algorithm based on QoS in LTE downlink multiuser environment is studied. In this research direction, resource allocation is divided into subcarrier allocation and power allocation based on RA criterion. In the subcarrier allocation process, one sub-carrier is assigned to each user according to RR algorithm, and then the remaining sub-carrier is allocated according to the current channel state information, service type, rate constraint factor, etc. The rate constraint factor can be dynamically adjusted according to the user service type, which determines the upper limit of the user rate. In the power allocation process, the RA optimization problem can be relaxed as a convex optimization problem because the sub-carrier allocation has been completed. Combined with the completed subcarrier allocation scheme, the subcarriers with too small gain and noise ratio are eliminated and used as a constraint to simplify the optimization problem. In the case of only one unknown variable, the optimal solution of the problem is iterated out by using the binary search iterative algorithm, and then the dynamic water injection line of each user in the system is obtained by using the optimal solution, and the power distribution is accomplished by using the water injection idea. Finally, through MATLAB simulation tools, from the base station, user, noise, path loss and other aspects of modeling, combined with the urban macro cell Uma) scene parameters configuration and 3GPP 36.942 protocol specification to set the corresponding simulation parameters. Build static LTE system level simulation environment. The proposed algorithm is simulated and analyzed in the aspects of cell throughput, user SINR, user capacity in single service scenario and user capacity in mixed service scenario. The results show that the proposed algorithm can balance user fairness and system throughput, and the allocation of resources is more flexible, and the upper limit of user transmission rate can be controlled by setting different proportional fairness factors. The differentiated resource scheduling is realized under different service types, which satisfies the QoS requirements of users from the aspects of user fairness, user communication link quality, different service transmission rate assurance and so on. At the same time, the convergence rate is faster.
【學(xué)位授予單位】：蘭州交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TN929.5

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本文編號：2027369