| Budget Amount *help |
¥3,610,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥510,000)
Fiscal Year 2007: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
Fiscal Year 2006: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2005: ¥700,000 (Direct Cost: ¥700,000)
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| Research Abstract |
In recent years, a lot of researchers have studied ubiquitous networks that allow all users to access information of any kind at any time, from anywhere. In those networks, LEO (Low Earth Orbit) satellite networks are expected to play a key role, mainly due to their low propagation delay. The purpose of this research is to study fundamental technologies in nest generation LEO satellite networks which have high affinity with the Internet. We researched the four following fundamental technologies as originally planned:
1. LEO satellites communicate directly with ground terminals. Since LEO satellites move quickly, handover occurs frequently and mobility management packets are generated often. As a result, radio resources are wasted. So, we proposed a low-cost mobility management technology based on geographic information and LEO satellite orbit.
2. If TCP/IP is applied to LEO satellite networks, efficiency and fairness are difficult to achieve due to propagation delay and other phenomenon. So we proposed a high efficiency and fairness emphasizing protocol. This protocol enables calculation of a suitable data rate with predicting round trip time by satellite hop counts.
3. To propose a security technology on LEO satellite networks, we proposed a scheme that reduces the impact of routing attack on ad-hoc networks. We need to extend this scheme for LEO satellite networks in the future.
4. We proposed a traffic control scheme that enables neighboring satellites to explicitly exchange information on their congestion status. In this scheme, traffic load is distributed so as not to concentrate it on any certain satellite.
The above proposed schemes serve as a foundation for the next generation LEO satellite network system, and will contribute largely to the implementation of a seamless network environment. Therefore, the purpose of this research was accomplished.
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