星地一体化网络的无线资源管理方法研究

发布时间：2018-05-07 19:59

本文选题：星地一体化网络 + 无线资源管理　；参考：《哈尔滨工业大学》2014年博士论文

【摘要】：随着移动智能终端的普及及其应用多元化的发展，移动数据流量呈爆炸性增长，移动卫星网络（MSS, Mobile Satellite System）作为下一代网络的重要组成部分，也面临着为用户提供高带宽连接的挑战。卫星通信依赖于视距（LOS, Line of Sight）连接，在有遮挡的环境下信号强度将大幅衰减，因此，利用地面网络的覆盖特性对卫星覆盖进行补充，将二者融合，构建星地一体化网络，实现高速移动宽带网络的全天候以及全地域无缝覆盖，得到了广泛的关注与研究。星地一体化网络从本质上来说是异构的无线网络，从拓扑结构来看，包括天基网络与地基网络两部分：天基网络为位于不同轨道的移动卫星或星座，地基网络为基于地面无线标准部署的蜂窝网络，二者由移动卫星网络统一管理，构成一体化的网络。星地一体化网络的特点是，，移动卫星网络通过在地面部署基于MSS频段的地面蜂窝网络，改善传统卫星信号遭阻挡区域的覆盖，能够带来系统用户数的提升以及网络资源的更充分利用。此目标的实现依赖于在一体化网络架构下对系统频率、功率、带宽、接入权限等资源进行高效分配与管理，克服两种网络在传输机制、接入技术、组织方式等方面的差异，为用户提供无缝透明的服务质量。因此，本文给出面向未来移动通信需求的星地一体化网络架构，对无线资源管理方法进行深入研究，得到了一些具有积极意义和参考价值的方法和结论。主要的研究工作与成果可概括为以下几个方面：首先，给出星地一体化网络架构及无线资源管理的理论基础。从技术及应用层面出发，部署集中式架构的地基蜂窝网络，并与天基移动卫星网络进行一体化设计，实现高带宽与全球无缝的覆盖。基于此框架，深入分析了星地一体化网络分层小区间的干扰对系统频谱效率（Spectral efficiency）以及能量效率（Energy efficiency）的影响，为后续星地一体化网络能量高效的分层干扰管理奠定理论基础；给出一个通用的公平QoS映射方法，利用多媒体业务的自适应带宽调整特性ABA（Adaptive Bandwidth Adaptation），在移动卫星网络与地面网络之间非对称地调整业务的服务等级，为后续的呼叫接入控制提供接入用户数增益；给出了支持卫星接口的媒质无关切换（MIH，Media Independent Handover）机制，为后续的垂直切换提供底层消息传输支持。其次，由于星地一体化网络利用卫星波束小区、宏蜂窝小区、微蜂窝小区来灵活地实现对热点区域、非热点区域以及零星业务区域的无缝覆盖，导致分层小区间存在干扰。目前对这种分层干扰的管理一般通过在卫星波束小区与地面小区间复用频率以实现干扰避免，在地面小区间进行干扰协调。本文提出了能量高效的干扰协调策略IC-LC，针对由于卫星摄动或运动对地面小区产生干扰的情况，利用矩阵带状化MR（Matrix Relaxation）算法和流功率分配SPA（Stream Power Allocation）算法进行波束赋形与发射功率分配，以较低的运算复杂度对地面小区间的干扰进行协调，有效抑制小区间的干扰。通过建立模块化的能耗模型，验证了IC-LC的低运算复杂度可降低处理中心的处理能耗，实现对系统能量效率的优化。再次，呼叫接入控制CAC（Connection Admission Control）负责调度星地一体化网络中用户的呼叫请求，并为其分配资源进行准入控制。由于星地一体化网络中存在不同覆盖区的新呼叫以及切换呼叫（包括水平切换与垂直切换），需要根据呼叫的特性以及网络状况确定调度与准入控制准则。本文将接入调度转换为带优先级的多服务队列调度MSQS（Multi-Server Queue Scheduling）问题，基于系统状态的遍历性以及平稳状态的存在性，提出了N-非强占优先排队准则N-NPPQ（N-Non Preemptive Priority Queue），利用N-队列动态调度新呼叫与切换呼叫；并进一步针对垂直切换与水平切换呼叫提出基于资源预留的准入控制准则，利用卫星波束小区稳定状态的准可逆性，将波束小区进行虚拟窗划分并计算切换概率来建立动态的预留池，有效平衡了垂直切换与水平切换呼叫之间的接入矛盾。接入调度以及准入控制共同完成呼叫接入控制，有效降低了由于系统资源调配不均所导致的呼叫阻塞率，优化了预留资源的利用率。最后，垂直切换使星地一体化网络中的用户能够在移动卫星网络与地面网络间无缝漫游，并能够根据用户需求以及网络状态使用户始终连接到最佳的网络。垂直切换包括网络发现、切换触发与切换判决、切换执行等步骤，其中切换触发与切换判决用于确定是否触发垂直切换并确定切换目标网络，是实现无缝垂直切换的重要前提及保障。鉴于不必要的切换触发将产生不必要的信令开销及资源浪费，同时导致失败切换与不必要切换，本文提出基于多阈值的切换触发算法，通过预测用户在地面蜂窝小区中的滞留时间及信道占用时间，计算得到多个切换阈值来触发用户由移动卫星网络到地面网络的垂直切换，降低了已有基于接收信号强度（RSS, Received Signal Strength）以及速率感知的切换触发策略存在的失败切换与不必要切换数。鉴于星地一体化网络中移动卫星网络时延较长，垂直切换判决需要尽快完成，提出了基于信用评价的切换判决算法，利用用户对网络的评价作为垂直切换判决的参考，避免传统的多属性切换判决算法在星地一体化网络中所需的参数收集、计算以及长判决时延。
[Abstract]:With the popularity of mobile intelligent terminals and the development of diversified applications, mobile data traffic has exploded. As an important part of the next generation network, MSS (Mobile Satellite System) is also facing the challenge of providing high bandwidth connections for users. Satellite communications depend on the view distance (LOS, Line of Sight) connections, In the environment of occlusion, the signal intensity will be greatly attenuated. Therefore, the coverage of the ground network is used to supplement the satellite coverage. The integration of the two, the integrated network of star and earth, the all-weather and seamless coverage of the high speed mobile broadband network is achieved, and extensive attention and research have been obtained.
The star ground integration network is essentially a heterogeneous wireless network. From the topology structure, it includes two parts: space-based network and foundation network: the space-based network is a mobile satellite or constellation located in different orbit. The foundation network is a cellular network based on the ground wireless standard, and the two is managed by a mobile satellite network. The characteristic of the integrated network is that the mobile satellite network deploys the ground cellular network based on the MSS frequency band on the ground to improve the coverage of the traditional satellite signals, which can bring about the increase of the number of users and the more full use of the network resources. The realization of this goal depends on the integrated network architecture. Under the system frequency, power, bandwidth, access rights and other resources to efficient allocation and management, to overcome the two networks in the transmission mechanism, access technology, organization and other aspects of the difference, to provide users with seamless transparent quality of service.
Therefore, this paper gives an integrated satellite to ground network architecture for future mobile communication requirements, and studies the wireless resource management methods in depth, and obtains some positive and reference methods and conclusions. The main research work and results can be summarized as follows:
First, we give a theoretical basis for the integrated network architecture and wireless resource management. From the technical and application level, the foundation cellular network is deployed and integrated with the space-based mobile satellite network to achieve the seamless coverage of high bandwidth and global. Based on this framework, the integrated network of star and earth network is analyzed. The impact of inter cell interference on Spectral efficiency and energy efficiency (Energy efficiency) lays a theoretical foundation for the hierarchical interference management of the subsequent integrated network energy efficient network. A universal fair QoS mapping method is given, and the adaptive bandwidth adjustment characteristic ABA (Adaptiv) is used in multimedia services (Adaptiv). E Bandwidth Adaptation), the service level of the service is adjusted asymmetrically between the mobile satellite network and the ground network, and the access user number gain is provided for the subsequent call access control, and the medium independent switching (MIH, Media Independent Handover) mechanism supporting the satellite interface is given to provide the underlying message transmission for the subsequent vertical handover. Lose support.
Secondly, satellite and ground integration network uses satellite beam cell, macro cellular cell and microcellular cell to achieve seamless coverage of hot area, non hot area and sporadic business area, which leads to interference between layered communities. The management of this layered interference is generally passed in satellite beam cell and ground cell. In this paper, an energy efficient interference coordination strategy, IC-LC, is proposed in this paper. In this paper, the matrix banded MR (Matrix Relaxation) algorithm and the flow power allocation SPA (Stream Power Allocation) algorithm are used to interfere with the ground cell due to satellite perturbations or motion. The beamforming and transmitting power allocation are carried out to coordinate the interference between the ground cells with a lower computational complexity, and the interference between the cells is effectively suppressed. By establishing a modular energy consumption model, the low computing complexity of IC-LC can be proved to reduce the energy consumption of the processing center and achieve the optimization of the energy efficiency of the system.
Again, the call access control CAC (Connection Admission Control) is responsible for scheduling the call requests of users in the integrated network and assigning resources for access control. Due to the existence of new calls and switching calls (including horizontal and vertical handover) in the star ground integration network, the call needs to be based on the call. This paper transforms the access scheduling into a multi service queue scheduling MSQS (Multi-Server Queue Scheduling) problem with priority. Based on the ergodicity of the system state and the existence of the stationary state, the N- non strong dominant first queuing criterion N-NPPQ (N-Non Preemptive Priority Queu) is proposed in this paper. E), using the N- queue to dynamically schedule new calls and switching calls, and further put forward the access control criteria based on resource reservation for vertical and horizontal switching calls. Using the quasi reversibility of the stable state of the satellite beam cell, the virtual window is divided and the switching probability is calculated to establish a dynamic reservation pool. The access scheduling and admittance control jointly complete call access control, which effectively reduces the call blocking rate caused by unequal resource allocation and optimizes the utilization of reserved resources.
Finally, vertical handover enables users in the integrated network to roam seamlessly between the mobile satellite network and the ground network, and can always connect users to the best network according to user needs and network status. Vertical handover includes network discovery, switching triggering and switching decisions, switching execution and other steps, in which switching triggers are triggered. The handoff decision is used to determine whether to trigger vertical handover and to determine the switching target network. It is an important prerequisite and guarantee for seamless vertical handoff. In view of the unnecessary switching triggers will produce unnecessary signaling overhead and resource waste, and cause failure switching and unnecessary switching, this paper proposes a switching trigger based on multiple thresholds. By predicting the retention time of the user in the cellular cell and the time of the channel occupancy, multiple switching thresholds are calculated to trigger the user's vertical handover from the mobile satellite network to the ground network, and the existing switching trigger strategy based on the received signal intensity (RSS, Received Signal Strength) and rate perception is reduced. In view of the long delay of the mobile satellite network in the stellar integrated network, the verdict of vertical switching needs to be completed as soon as possible. A handoff decision algorithm based on credit evaluation is proposed, and the user's evaluation of the network is used as a reference for the vertical handoff decision, so the traditional multi attribute handoff algorithm is avoided in the star ground. Parameter collection, computation and long decision delay in the physical network.

【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN929.5

【参考文献】