异构无线网络中频谱资源动态分配

发布时间：2018-05-04 19:18

本文选题：异构无线网络 + 异构网络　；参考：《西安电子科技大学》2014年博士论文

【摘要】：为了适应不同的通信环境和不断增长的用户业务需求，无线通信技术相继经历了从第一代到第四代的演进，异构无线网络成为无线通信网络发展的必然趋势，其异构性体现在：(1)多种接入技术和接入网共同部署，(2)多层低功率小基站与宏蜂窝基站重叠覆盖，(3)业务类型逐渐多样化，业务分布随时间和空间而变化，(4)无线终端随着认知技术的发展而呈现多频多模的发展趋势。然而，支持无线通信的频谱资源是有限的，传统的频谱固定分配方法造成了资源“紧缺”和“浪费”的矛盾现象。因此在当前的异构无线网络环境下，按业务分布的变化周期进行频谱资源动态分配的研究显得尤为重要，本文对其中的频谱分配算法以及与其息息相关的干扰管理和干扰控制进行了系统的研究。具体内容如下： 1.研究了基于克隆选择优化的频谱动态分配算法。首先，针对不同接入网的基站在重叠覆盖区域造成的干扰，基于基站分布拓扑构造了干扰图和基站干扰矩阵。接着，针对不同接入网对应的不同粒度的信道之间的重叠关系，进一步构造了信道图和信道干扰矩阵。基于基站干扰矩阵和信道干扰矩阵，以相互干扰的基站不能被分配同频信道为约束条件，将频谱分配建模为非线性约束0-1整数规划问题，进而提出了基于克隆选择优化的频谱分配算法，包括在算法步骤中设计了适用于该问题的抗体编码方式，并针对干扰约束条件而增加了抗体修正操作。仿真结果表明，所提算法相比于基于贪婪算法的频谱分配，增加了网络频谱效益，提高了频谱资源利用率。 2.针对每种接入网由六边形小区无缝覆盖的异构无线网络场景，研究了空域干扰约束下的频谱动态分配算法。首先提出基于空域干扰约束的干扰控制模型：对位于小区内某位置的用户而言，将单一接入网中采用固定频谱分配时该用户受到的小区间干扰设置为该用户的最大干扰门限，控制频谱动态分配过程中该用户接收到的干扰不超过此最大干扰门限；进一步限制小区内满足干扰约束的区域(i.e.用户的潜在位置)比例达到基站的覆盖率要求。基于此干扰控制模型，建模并设计两种启发式算法求解频谱分配优化问题，提出了空域干扰约束下的频谱动态分配算法。仿真显示，该算法能在增加网络频谱效益的同时，提高基站的频谱需求满足率。 3.关注基站位置不规则分布的异构无线网络场景，提出了确保覆盖概率的频谱动态分配算法。在仅考虑平均路径损耗的信道条件下，考虑小区内用户的空间分布及不同业务的比例，将用户SINR(signal to interference plus noise ratio)性能巧妙地转化为小区基站的覆盖性能，提出基于覆盖概率的干扰控制模型，从保证基站的覆盖性能出发，达到保证小区内任意位置的用户SINR要求的目的。基于此干扰控制模型，建模频谱分配优化问题，并基于图着色理论提出确保覆盖概率的频谱动态分配算法。与已有算法相比，所提算法能够有效控制基站间干扰，在满足用户SINR门限要求的前提下，增加频谱复用，进而提高网络频谱效益。 4.研究了阴影衰落信道条件下的确保覆盖概率的频谱动态分配算法。忽略背景热噪声，考虑到阴影衰落因子服从对数正态分布，首先近似计算了干扰信号强度以及用户SIR(signal to interference ratio)的概率密度函数，进而分析在阴影衰落信道条件下确保覆盖概率的干扰控制模型，并基于此干扰控制模型，建模和求解频谱分配问题。仿真显示，该算法能够增加频谱复用，提高网络频谱效益，，并且在实际信道环境中能有效控制基站之间的干扰和满足用户的SIR要求。 5.在由宏蜂窝和家庭基站组成的双层异构网络中，将频谱资源划分为若干资源块，研究了基于队列状态的资源块分配。首先考虑到基站端为每个下行链路的用户业务设置独立的有限长队列缓存，以避免缓冲队列长度无限增大、保持网络系统稳定为目标，依据李雅普诺夫稳定性理论，建模资源块分配优化问题。接着根据用户业务的缓冲队列状态和基站间干扰关系构造加权干扰图，在将资源块分配优化问题转化为最大加权独立集问题的基础上，提出基于队列状态的资源块分配算法。仿真结果表明，所提算法可以有效匹配资源块和业务队列，保证队列系统稳定，提高系统吞吐量。
[Abstract]:In order to adapt to different communication environment and growing user service requirements , wireless communication technology has experienced the evolution from the first to fourth generations . The heterogeneous wireless networks have become the inevitable trend of the development of wireless communication networks .

1 . The frequency spectrum dynamic allocation algorithm based on clonal selection optimization is studied . Firstly , the interference pattern and the base station interference matrix are constructed on the basis of the base station distribution topology for the interference caused by the base stations in different access networks . Then , the spectrum allocation algorithm based on the base station interference matrix and the channel interference matrix can not be allocated to the non - linear constraint 0 - 1 integer programming problem . The simulation results show that the proposed algorithm increases the spectrum efficiency of the network and improves the utilization rate of the spectrum resources compared with the spectrum allocation based on the greedy algorithm .

2 . Aiming at the heterogeneous wireless network scenario seamlessly covered by hexagonal cells in each access network , the spectrum dynamic allocation algorithm under the constraint of space domain interference is studied . Firstly , an interference control model based on space interference constraint is put forward : for a user located at a certain location in the cell , the inter - cell interference of the user is set to the maximum interference threshold of the user , and the interference received by the user in the dynamic allocation process of the control spectrum does not exceed the maximum interference threshold ;
Based on the interference control model , two heuristic algorithms are modeled and designed to solve the spectrum allocation optimization problem , and a spectrum dynamic allocation algorithm under the constraint of space domain interference is proposed . Simulation shows that the algorithm can improve the spectrum efficiency of the network while increasing the spectrum demand satisfaction rate of the base station .

3 . Aiming at the heterogeneous wireless network scenario of irregular distribution of base station location , a spectrum dynamic allocation algorithm to ensure coverage probability is proposed . Based on the interference control model , the interference control model based on coverage probability is proposed .

4 . The spectrum dynamic allocation algorithm is studied under the condition of shadow fading channel to ensure coverage probability . The probability density function of interference signal intensity and signal to interference ratio is firstly approximate to calculate the probability density function of signal to interference ratio under the condition of shadow fading channel , and then the spectrum allocation problem is modeled and solved under the condition of shadow fading channel . Simulation shows that the algorithm can increase spectrum reuse , improve network spectrum benefit , and can effectively control interference between base stations and meet the SIR requirements of users in real channel environment .

5 . In a double - layer heterogeneous network composed of macro cell and home base station , the spectrum resources are divided into a plurality of resource blocks , and the resource block allocation based on the queue state is studied .

【学位授予单位】：西安电子科技大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN92

【参考文献】