异构蜂窝网络的用户卸载策略研究

发布时间：2018-02-27 01:30

本文关键词： 异构蜂窝用户卸载干扰协调资源分配卸载成本卸载收益　出处：《中国科学技术大学》2017年硕士论文　论文类型：学位论文

【摘要】：传统蜂窝网络有限的传输能力无法满足迅猛增长的移动数据业务需求,蜂窝网络运营商面对数据流量的爆炸式增长承受了巨大的压力。异构网络作为一种经济高效提升网络容量的方式得到了广泛的部署。然而,由于宏基站与微基站之间巨大的功率差异,基于传统同构蜂窝网络的小区选择策略会使得异构网络中的负载分布不均,导致宏小区拥塞的同时微小区的资源未得到充分利用,这大大限制了异构网络的性能提升。将部分用户从比较拥塞的宏小区卸载到资源富余的微小区,是低成本地提升异构网络性能的一个有效手段。用户卸载策略需要根据网络中的用户分布、负载情况、基站运营模式等实际的状态做出合适的用户卸载决策,同时需要考虑影响网络性能的多方因素如干扰协调、资源分配、商业成本与收益等。因此,本文关注的重点是联合考虑影响网络性能的多方因素研究在不同场景需求下的用户卸载策略。针对宏微基站属于相同运营商场景下的负载不均衡问题,研究了用户卸载与干扰协调策略。首先,综合考虑用户归属关系、几乎空白子帧比例因子和资源分配比例等参数构建了一个联合效用优化问题;然后,采用Gauss-Seidel的块参数分解方法将联合问题分解为三个子问题,每次优化单一参数块而将其他参数块固定,逐步迭代求解最优参数:最后,基于中间推导结果提出了具有较低复杂度的启发式算法来解决用户归属问题。仿真结果表明所提出的方案与小区覆盖扩展方案相比,能大大提升用户的边缘吞吐量和公平性。针对宏微基站属于不同运营商场景下的负载不均衡问题,研究了用户卸载与成本协调策略,重点关注蜂窝服务提供商希望租借成本较小和卸载流量较大的两个矛盾的需求。首先,构建了以卸载成本和卸载收益之差最小为目标的反向拍卖问题来在二者之间做一个权衡;然后,提出了满足市场激励相容性和个体合理性的基于反向拍卖的最优卸载机制和考虑了资源利用效率的具有较低复杂度的贪婪卸载机制。仿真结果表明,最优卸载机制能很好的权衡成本与卸载量两方面的需求,而贪婪卸载机制能在降低复杂度的同时保证成本与卸载量的折衷。
[Abstract]:The limited transmission capacity of traditional cellular network can not meet the rapidly increasing demand for mobile data services. Facing the explosive growth of data traffic, cellular network operators are under tremendous pressure. Heterogeneous networks are widely deployed as an economical and efficient way to increase network capacity. However, Because of the huge power difference between the macro base station and the microbase station, the cell selection strategy based on the traditional isomorphic cellular network will make the load distribution uneven in the heterogeneous network, resulting in the congestion of the macro cell and the underutilization of the resources of the micro cell. This greatly limits the performance of heterogeneous networks. Some users are unloaded from congested macro cells to resource-rich microcells. It is an effective method to improve the performance of heterogeneous network at low cost. The user unload strategy needs to make appropriate user uninstall decision according to the actual conditions such as user distribution, load, operation mode of base station and so on. At the same time, we need to consider various factors that affect network performance, such as interference coordination, resource allocation, business costs and benefits, etc. The focus of this paper is to study the user unload strategy under different scenarios by considering the multiple factors that affect the network performance, aiming at the load imbalance problem of the macro and micro base station under the same operator scenario. In this paper, the coordination strategy of user unload and interference is studied. Firstly, a joint utility optimization problem is constructed by considering the user ownership relationship, almost blank subframe scale factor and resource allocation ratio. Gauss-Seidel 's block parameter decomposition method is used to decompose the joint problem into three sub-problems. Each time the single parameter block is optimized and the other parameter blocks are fixed, the optimal parameters are solved iteratively step by step: finally, A heuristic algorithm with low complexity is proposed to solve the user assignment problem based on the intermediate derivation results. The simulation results show that the proposed scheme is compared with the cell coverage expansion scheme. It can greatly improve the edge throughput and fairness of users. Aiming at the load imbalance problem of macro and micro base stations belonging to different operator scenarios, the strategy of user unload and cost coordination is studied. The paper focuses on the two contradictory requirements of cellular service providers: the low rental cost and the larger unload flow. Firstly, the reverse auction problem, which aims at minimizing the difference between the unload cost and the unload income, is constructed to make a trade-off between the two. Then, the optimal unloading mechanism based on reverse auction and the greedy unloading mechanism with low complexity considering the efficiency of resource utilization are proposed to satisfy the market incentive compatibility and individual rationality. The simulation results show that, The optimal unload mechanism can balance the requirements of cost and unload, while the greedy unload mechanism can reduce the complexity and guarantee the tradeoff between the cost and the amount of unload.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.5

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