文档介绍：后研究了分布式天线的分配问题,即所谓的传输模式选择。以多用户遍历和容量最大化为目标,提出了一种基于模式搜索的传输模式选择算法,该算法可以获得与现有算法相近的小区平均遍历和容量,但是目标函数的平均计算量却大为减小,获得了性能与计算复杂度的折中。
第四,天线单元布署位置研究。首先推导了小区中断概率的解析表达式, 然后将其作为优化目标对天线单元的布署位置问题进行了研究。提出一种基于复数编码遗传算法的天线单元布署方案。并对其进行了改进,提出一种多目标优化遗传算法,可以同时确定小区内天线单元的数量和位置。相比于现有算法, 所提出的算法具有较好的灵活性和普遍适用性,不需要预先对天线单元布署的拓扑结构做任何限制,且可以在不改变算法结构的前提下使用不同的系统性能指标作为优化目标。
关键词:分布式天线系统;信道容量;传输模式;天线布署
Abstract
The next generation wireless system is facing two great challenges, one is to transmit data at higher rates within a limited spectrum and the other is to reduce transmit power at the same time, which means higher spectrum and energy efficiencies. The existing cellular systems can not meet the aforementioned requirements, completely work architectures are needed. Some solutions to the problem are proposed, which have mon is the introducing of multiple-input multiple-output (MIMO) and munication technologies. Distributed antenna system (DAS) has attracted more and more attentions and been one of the most promising canditates for the next generation wireless systems because of its many merits in terms of coverage, power consumption and spectrum efficiency.
Though the concept of DAS first came up to stage in 1987, however, it is in recent years that the introducing of DAS architecture into the present works bining it with the advanced transmission technologies have been widely concerned and investigated, there are a great number of basic theories and corresponding key issues remain to be investigated. Theory analysis of the downlink channel capacity is carried out and the corresponding key issues are investigated in this dissertation. We focus on derivations of the analytical expressions of the channel capacity, the issues of antenna placement and transmission schemes. The main researches are summarized as follows.
Firstly, channel capacity with selection transmission and antenna selection algorithms are investigated. Detailed expressions and intensive analysis of the posite fading channel model ar