摘要
随着移动通信技术的迅速发展,第三代移动通信系统已全面步入商用,TD-SCDMA移动通信系统作为我国第一个拥有自主知识产权的国际电信标准,更是受到了国内外的普遍关注。由于使用了一系列先进的通信技术,该系统在系统性能、容量和制造成本上都显示出了明显的优势。
本文简单介绍了移动通信的发展概况,对TD-SCDMA系统及其使用的智能天线技术和动态信道分配技术进行了综述,由此引出对信道空分复用SDMA的讨论。文中给出了SDMA的概念,实现方案及工作链路,重点讨论了实现SDMA后,系统容量及业务阻塞率的改善情况。对于SDMA系统的容量,我们讨论了几种增大系统容量的方式,并以香农公式为基础,对干扰和多径条件下SDMA系统容量的计算公式进行推导,通过与使用全向天线、定向天线等进行比较,证明使用智能天线的SDMA系统可以明显提升系统容量。对于业务阻塞率,我们以FD和DL两种简单的信道空分复用方案为基础,通过分析其状态转移过程,对其业务阻塞率的计算公式进行了分析推导和仿真比较。
由于智能天线的波达方向估计DOA是信道是否可以实现空分复用的一个重要参数,文中对智能天线及其波达方向估计也有简单的介绍,对其常见的DOA算法进行了仿真研究。文章最后研究了目前普遍使用的基于载干比的空分信道模型,以FD和DL方案为基础,结合智能天线讨论的结果,提出了一种相对随机的信道空分复用机制。该随机方案避免了在FD和DL方案中对信道测量和分配的排序,根据信道载干比和DOA估计提供的用户空间信息来分配信道,将用户均匀的分布于各信道。通过对随机方案的业务阻塞率和系统容量等进行理论推导和仿真,证明了该方案的合理性。
文章最后对全文进行总结,指出了文中的不足之处。提出了从基站侧对发送信号进行编码实现信道空分复用的研究设想。
With the rapid development of mobile communication technology, the third generation mobile communication system is fully used.TD-SCDMA mobile communication system as China's first international telecommunications standards of independent intellectual property rights attracted extensive attention at home and abroad.The system uses a series of advanced communications technology so that it has a distinct advantage in performance, capacity and manufacturing costs.
This paper describes the development of mobile communication and give a detailed overview of the TD-SCDMA system with the use of smart antenna technology and radio resource management which lead to the discussion of the channel spatial reuse (SDMA). In the paper ,we presents the concept ,implementation scheme and working link of SDMA,especially focus on the inprovement of capacity and service blocking probability then achieved SDMA. For the system capacity, we discussed several ways to increase it and derived the SDMA system capacity with multi-angle-multi-path based on the Shannon formula. With both theoretical analysis and simulation ,we find that compared with omnidirectional antenna and cell sectorisation,the use of smart antenna can improve the system capacity obviously.For the service blocking probability, we give two simple channel spatial reuse scheme FD and DL scheme, analysis and simulates the blocking probability by analyzing the state transition process.
As the DOA estimation of smart antenna is an important parameter to decide if the channel spatial reuse can be achieved,we also give a brief introduction of smart antenna and DOA estimation.We studied the common DOA algorithm like dely-add,CAPON,MUSIC and ESPRIT,compared them with the use of simulation software. In the final ,we studied the widely used channel allocation model based on the carrier to interference ratio.Compared with FD and DL scheme,we proposed a random scheme of our own.The system capacity and business blocking probability of the random scheme is carried out with a detailed theoretical analysis and simulation. The study and compare we did proved that the scheme we proposed is in reason and can assign the traffic more uniformly.
At last, we gave a summary of the entire paper and show the short of it.Then,give an idea of making space dicvision multiplexing by coding the user information at the base station.
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