異構(gòu)蜂窩網(wǎng)絡能量效率問題研究
發(fā)布時間：2018-08-08 20:27
【摘要】：移動通信業(yè)務流量近二十年來始終保持高速增長,稀缺的頻譜資源嚴重制約無線通信的發(fā)展。為滿足用戶需求,提升傳統(tǒng)蜂窩網(wǎng)絡容量的主要方法是增加小區(qū)數(shù)量,提高單位面積上的頻譜利用率。小區(qū)數(shù)量的增加必然會帶來基站數(shù)目的大量增加,這樣不但增加了通信網(wǎng)絡的成本,同時也帶來了大量的能量消耗。在以LTE-Advanced(Long Term Evolution-Advanced,LTE-A)為代表的4G網(wǎng)絡標準中,異構(gòu)蜂窩網(wǎng)絡作為一項既能夠滿足業(yè)務需求的增長,同時符合綠色環(huán)保要求的技術(shù)手段而得到廣泛關(guān)注。在異構(gòu)蜂窩網(wǎng)絡中,低功率基站和用戶之間距離相對較近,能夠有效提高區(qū)域頻譜的復用率、增大了蜂窩系統(tǒng)的容量并改善通信黑洞地區(qū)用戶的服務質(zhì)量,同樣由于兩者之間的距離較短,所需的發(fā)射功率也得到極大地降低,所以異構(gòu)網(wǎng)絡技術(shù)在節(jié)能減排方面也有著巨大的潛力。綜上所述,包含有不同發(fā)射功率基站的蜂窩無線網(wǎng)絡既能夠滿足日益增長的用戶需求,同時也能極大地降低能耗,這也是本畢業(yè)論文的研究內(nèi)容。本文的主要貢獻如下：1.建立系統(tǒng)模型來描述異構(gòu)蜂窩無線網(wǎng)絡。在我們建立的模型中,考慮了不同類型基站的特性,比如其發(fā)射功率,覆蓋范圍以及回程鏈路,同時也考慮了異構(gòu)網(wǎng)絡中小區(qū)間相互干擾這一重要技術(shù)問題,因此我們的模型能夠用來模擬實際系統(tǒng)中的異構(gòu)蜂窩網(wǎng)絡。2.提出一個中繼認知網(wǎng)絡中的最優(yōu)功率分配問題,目標是最大化系統(tǒng)的能量效率,同時考慮功率限制,流量需求以及對主用戶造成的干擾。由于規(guī)約出的優(yōu)化問題是非凸的,我們首先通過下鏡圖法將其變?yōu)橐粋�凸問題,通過障礙法對其進行求解。在障礙法求解過程中,通過研究問題的特殊結(jié)構(gòu)提出一個快速計算牛頓步長的的算法,極大地降低了算法復雜度。3.提出一個異構(gòu)蜂窩網(wǎng)絡能量最小化的資源分配問題,同時考慮系統(tǒng)用戶的服務要求。用戶的子信道分配和功率優(yōu)化通過一個兩步式算法來實現(xiàn)。我們首先提出了一個低復雜度,低信息交互的子信道分配策略；隨后通過研究用戶速率的凹下界將規(guī)約的問題轉(zhuǎn)變?yōu)橥箚栴},最后提出一個高效的迭代算法來求解近似后的問題。數(shù)值仿真結(jié)果表明,我們提出的算法能夠有效的降低系統(tǒng)的能量消耗,同時收斂很快且穩(wěn)定,適合在實際場景中應用。總之,對于異構(gòu)網(wǎng)絡的資源分配問題,本論文給出了快速且有效的算法,相比于前人最大化系統(tǒng)容量方面的工作,本文為未來系統(tǒng)在綠色通信方面的應用提供了可行的思路。
[Abstract]:The traffic of mobile communication has been increasing rapidly in the past twenty years, and the scarce spectrum resources seriously restrict the development of wireless communication. In order to meet the needs of users, the main method to improve the capacity of traditional cellular networks is to increase the number of cells and the spectral efficiency per unit area. The increase of cell number will inevitably lead to a large increase in the number of base stations, which not only increases the cost of communication networks, but also brings a lot of energy consumption. In the 4G network standard represented by LTE-Advanced (Long Term Evolution-Advanced LTE-A, heterogeneous cellular networks have been paid more and more attention as a technical means which can meet the needs of business and meet the requirements of green environment. In heterogeneous cellular networks, the distance between low power base stations and users is relatively close, which can effectively improve the reuse rate of regional spectrum, increase the capacity of cellular systems and improve the quality of service of users in communication black hole areas. Also due to the short distance between the two, the required emission power has been greatly reduced, so heterogeneous network technology has great potential in energy saving and emission reduction. To sum up the cellular wireless network with different transmission power base stations can not only meet the increasing demand of users but also greatly reduce the energy consumption which is also the research content of this thesis. The main contributions of this paper are as follows: 1. A system model is established to describe heterogeneous cellular wireless networks. In our model, we consider the characteristics of different types of base stations, such as transmission power, coverage and backhaul links, as well as the important technical problem of inter-cell interference in heterogeneous networks. Therefore, our model can be used to simulate heterogeneous cellular networks in real systems. An optimal power allocation problem in relaying cognitive networks is proposed. The goal is to maximize the energy efficiency of the system, taking into account power constraints, traffic requirements and interference to primary users. Because the optimization problem is non-convex, we first turn it into a convex problem by using the method of the lower mirror graph, and solve it by the obstacle method. In the process of solving the obstacle method, by studying the special structure of the problem, a fast algorithm for calculating Newton's step size is proposed, which greatly reduces the complexity of the algorithm. This paper proposes a resource allocation problem for heterogeneous cellular networks with energy minimization, taking into account the service requirements of system users. Subchannel allocation and power optimization are realized by a two-step algorithm. We first propose a subchannel allocation strategy with low complexity and low information interaction, and then, by studying the concave lower bound of the user rate, we transform the protocol problem into a convex one. Finally, an efficient iterative algorithm is proposed to solve the approximate problem. The numerical simulation results show that the proposed algorithm can effectively reduce the energy consumption of the system and converge quickly and stably. It is suitable for practical applications. In a word, this paper presents a fast and effective algorithm for resource allocation in heterogeneous networks. Compared with the previous efforts to maximize the system capacity, this paper provides a feasible way of thinking for the future application of the system in the field of green communication.
【學位授予單位】：南京大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TN929.5
[Abstract]:The traffic of mobile communication has been increasing rapidly in the past twenty years, and the scarce spectrum resources seriously restrict the development of wireless communication. In order to meet the needs of users, the main method to improve the capacity of traditional cellular networks is to increase the number of cells and the spectral efficiency per unit area. The increase of cell number will inevitably lead to a large increase in the number of base stations, which not only increases the cost of communication networks, but also brings a lot of energy consumption. In the 4G network standard represented by LTE-Advanced (Long Term Evolution-Advanced LTE-A, heterogeneous cellular networks have been paid more and more attention as a technical means which can meet the needs of business and meet the requirements of green environment. In heterogeneous cellular networks, the distance between low power base stations and users is relatively close, which can effectively improve the reuse rate of regional spectrum, increase the capacity of cellular systems and improve the quality of service of users in communication black hole areas. Also due to the short distance between the two, the required emission power has been greatly reduced, so heterogeneous network technology has great potential in energy saving and emission reduction. To sum up the cellular wireless network with different transmission power base stations can not only meet the increasing demand of users but also greatly reduce the energy consumption which is also the research content of this thesis. The main contributions of this paper are as follows: 1. A system model is established to describe heterogeneous cellular wireless networks. In our model, we consider the characteristics of different types of base stations, such as transmission power, coverage and backhaul links, as well as the important technical problem of inter-cell interference in heterogeneous networks. Therefore, our model can be used to simulate heterogeneous cellular networks in real systems. An optimal power allocation problem in relaying cognitive networks is proposed. The goal is to maximize the energy efficiency of the system, taking into account power constraints, traffic requirements and interference to primary users. Because the optimization problem is non-convex, we first turn it into a convex problem by using the method of the lower mirror graph, and solve it by the obstacle method. In the process of solving the obstacle method, by studying the special structure of the problem, a fast algorithm for calculating Newton's step size is proposed, which greatly reduces the complexity of the algorithm. This paper proposes a resource allocation problem for heterogeneous cellular networks with energy minimization, taking into account the service requirements of system users. Subchannel allocation and power optimization are realized by a two-step algorithm. We first propose a subchannel allocation strategy with low complexity and low information interaction, and then, by studying the concave lower bound of the user rate, we transform the protocol problem into a convex one. Finally, an efficient iterative algorithm is proposed to solve the approximate problem. The numerical simulation results show that the proposed algorithm can effectively reduce the energy consumption of the system and converge quickly and stably. It is suitable for practical applications. In a word, this paper presents a fast and effective algorithm for resource allocation in heterogeneous networks. Compared with the previous efforts to maximize the system capacity, this paper provides a feasible way of thinking for the future application of the system in the field of green communication.
【學位授予單位】：南京大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TN929.5
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