Improved OFDM-CDMA System coping with the Near-Far Problem

改进的 OFDM-CDMA 系统应对近远问题

基本信息

批准号：
14550349
负责人：
SAKANIWA Kohichi
金额：
$ 2.24万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14550349/
关键词：
mobile communication multi-user multiple access near-far problem OFDM fading equalizer

项目摘要

In multi-user mobile communication system, a combination of CDMA (Code Division Multiple Access) and OFDM (Orthogonal Frequency Division Multiplexing) techniques is widely as techniques providing an efficient and robust communication system for fading channel. It is also well known that multi-user mobile communication systems need to consider the near-far problem due to signal power difference between each user and the base station. The near-far problem can occur in (1) up links (from each user to the base station) and (2) down links (from the base station to each user).The near-far problem in the up links has been well studied in the past and power control technique is widely employed to get uniform receiving power from every user at the base station. The power control by the base station for the down links, on the other hand, is recently proposed to provide homogeneous QoS (Quality of Service) to all user in the cell. In both cases, the receiver should be designed by assuming the difference of each user's signal power to provide a higher system performance.In this research, we propose a design method of a multi-user receiver which employ a fading equalizer optimizing the system performance by taking the difference of each user's signal power into account. By the proposed design method, it has been shown that a higher performance receiver can be obtained compared to the conventional methods. Moreover, if we add a couple of IML (iterative maximum likelihood) decoding further big improvement can be obtained over the conventional corresponding methods.(A journal paper including the final research results was requested to be revised by the reviewers the transaction. Now the revised version is resubmitting.)

在多用户移动通信系统中，CDMA（代码部门多访问）和OFDM（正交频分多路复用）技术的组合广泛，因为技术为褪色通道提供了有效且强大的通信系统。众所周知，多用户移动通信系统需要考虑由于每个用户和基站之间的信号功率差而引起的近乎快速问题。近乎快速的问题可能发生在（1）UP链接（从每个用户到基站）和（2）向下链接（从基站到每个用户）。过去的UP链接中的近战问题在过去进行了很好的研究，并且功率控制技术已被广泛使用，可从基站的每个用户获得统一的接收电源。另一方面，基本站的电源控制供下链路进行DOWN链接，最近提议为单元中的所有用户提供均匀的QoS（服务质量）。在这两种情况下，都应通过假设每个用户信号功率的差异来设计接收器以提供更高的系统性能。在这项研究中，我们提出了一种多用户接收器的设计方法，该方法采用褪色的均衡器来通过考虑每个用户信号功率的差异来优化系统性能。通过提出的设计方法，已经表明，与常规方法相比，可以获得更高的性能接收器。此外，如果我们添加一些IML（迭代最大可能性）解码可以比传统的相应方法获得进一步的重大改进。（（包括最终研究结果在内的期刊论文，要求审阅者修订交易。现在，修订后的版本已重新提交。）