| Project/Area Number |
10450148
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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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 | Meijo University (2000)
Nagoya University (1998-1999) |
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Principal Investigator |
OGAWA Akira School of Science and Technology, Meijo University Professor, 理工学部, 教授 (20204068)
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| Co-Investigator(Kenkyū-buntansha) |
OKADA Hiraku Center for Information Media Studies, Nagoya University, Assistant Professor, 情報メディア教育センター, 助手 (50324463)
YAMAZATO Takaya Center for Information Media Studies, Nagoya University, Associate Professor, 情報メディア教育センター, 助教授 (20252265)
KATAYAMA Masaaki Graduate School of Engineering, Nagoya University, Associate Professor, 工学研究科, 助教授 (60185816)
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| Project Period (FY) |
1998 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥5,900,000 (Direct Cost: ¥5,900,000)
Fiscal Year 2000: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1999: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1998: ¥3,800,000 (Direct Cost: ¥3,800,000)
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| Keywords | CDMA ALOHA System / Access Control / Multimedia / Mobile Communications / Throughput / Quasi-Synchronous Spreading Code / Interference Cancellation / マルチメディアサービス / アクセス制御方式 / スループット解析 / CDMA ALOHA / マルチパス フェージング / 遠近問題 |
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| Research Abstract |
The object of this research is to study on various access control schemes for CDMA ALOHA that can provide high efficiency under practical environments. The CDMA ALOHA is considered promising for simple and efficient multimedia mobile communications.
We have developed a model with which the system performance can be evaluated, and studied on the access control schemes capable of maintaining high efficiency even in the presence of fading and near-far problems. As a result, It was shown that access controlling in accordance with the distance from a base station with a rake receiver and simple transmit power control can provide high efficiency.
We have also developed a method for evaluating the performance of multimedia CDMA systems in which there coexist voice and data channels having different required quality of service, and proposed an access control scheme such that the traffic is controlled with a threshold determined by the total numbers of users for telephone service and data service, and with another threshold determined only by the number of data users. We have also proposed another scheme that can improve the throughput of data packet without degradation in the performance of telephone service, utilizing the random access feature of data packet service.
To reduce the amount of multiple access interference, we have studied the application of the quasi-synchronous code sequence to CDMA slotted ALOHA, and clarify its effectiveness using the binary quasi-synchronous code sequence that can be easily generated. As another mean to reduce the effect of multiple access interference, we have analyzed the relationship between cross correlation and noise enhancement accompanied by a decorrelating detector with respect to a synchronous CDMA system, and proposed a interference canceller based on MMSE criterion, applied to the CDMA unslotted ALOHA system.
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