异构蜂窝网络能量效率问题研究
发布时间：2018-08-08 20:27
【摘要】：移动通信业务流量近二十年来始终保持高速增长,稀缺的频谱资源严重制约无线通信的发展。为满足用户需求,提升传统蜂窝网络容量的主要方法是增加小区数量,提高单位面积上的频谱利用率。小区数量的增加必然会带来基站数目的大量增加,这样不但增加了通信网络的成本,同时也带来了大量的能量消耗。在以LTE-Advanced(Long Term Evolution-Advanced,LTE-A)为代表的4G网络标准中,异构蜂窝网络作为一项既能够满足业务需求的增长,同时符合绿色环保要求的技术手段而得到广泛关注。在异构蜂窝网络中,低功率基站和用户之间距离相对较近,能够有效提高区域频谱的复用率、增大了蜂窝系统的容量并改善通信黑洞地区用户的服务质量,同样由于两者之间的距离较短,所需的发射功率也得到极大地降低,所以异构网络技术在节能减排方面也有着巨大的潜力。综上所述,包含有不同发射功率基站的蜂窝无线网络既能够满足日益增长的用户需求,同时也能极大地降低能耗,这也是本毕业论文的研究内容。本文的主要贡献如下：1.建立系统模型来描述异构蜂窝无线网络。在我们建立的模型中,考虑了不同类型基站的特性,比如其发射功率,覆盖范围以及回程链路,同时也考虑了异构网络中小区间相互干扰这一重要技术问题,因此我们的模型能够用来模拟实际系统中的异构蜂窝网络。2.提出一个中继认知网络中的最优功率分配问题,目标是最大化系统的能量效率,同时考虑功率限制,流量需求以及对主用户造成的干扰。由于规约出的优化问题是非凸的,我们首先通过下镜图法将其变为一个凸问题,通过障碍法对其进行求解。在障碍法求解过程中,通过研究问题的特殊结构提出一个快速计算牛顿步长的的算法,极大地降低了算法复杂度。3.提出一个异构蜂窝网络能量最小化的资源分配问题,同时考虑系统用户的服务要求。用户的子信道分配和功率优化通过一个两步式算法来实现。我们首先提出了一个低复杂度,低信息交互的子信道分配策略；随后通过研究用户速率的凹下界将规约的问题转变为凸问题,最后提出一个高效的迭代算法来求解近似后的问题。数值仿真结果表明,我们提出的算法能够有效的降低系统的能量消耗,同时收敛很快且稳定,适合在实际场景中应用。总之,对于异构网络的资源分配问题,本论文给出了快速且有效的算法,相比于前人最大化系统容量方面的工作,本文为未来系统在绿色通信方面的应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.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：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.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN929.5
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