2003 Fiscal Year Final Research Report Summary
Improved OFDM-CDMA System coping with the Near-Far Problem
| Project/Area Number |
14550349
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
情報通信工学
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
SAKANIWA Kohichi Tokyo Institute of Technology, Graduate School of Science & Engineering, Professor, 大学院・理工学研究科, 教授 (30114870)
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| Co-Investigator(Kenkyū-buntansha) |
HASEGAWA Hiroshi Tokyo Institute of Technology, Graduate School of Science & Engineering, Associate Professor, 大学院・理工学研究科, 助手 (40323802)
SHIBUYA Tomoharu Tokyo Institute of Technology, National Institute of Multimedia Education, Associate Professor, メディア教育開発センター, 助教授 (20262280)
YAMADA Isao Tokyo Institute of Technology, Graduate School of Science & Engineering, Associate Professor, 大学院・理工学研究科, 助教授 (50230446)
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| Project Period (FY) |
2002 – 2003
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| Keywords | mobile communication / multi-user / multiple access / near-far problem / OFDM / fading / equalizer |
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| Research Abstract |
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.)
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Research Products
(5 results)
