| 研究実績の概要 |
The research achievement consists of two main parts. First, we propose a novel access protocol based on the distributed queue (DQ) mechanism to effectively tackle the massive access issue in the cellular-based IoT. A new method to avoid the DQ's inherent over-division problem by letting the base station first roughly probes the number of colliding devices in a random-access opportunity. We also develop an analytic model to accurately estimate the average access delay of the proposed protocol in the massive scenarios. We then build a simulation model to validate the analytic model as well as the effectiveness of the proposed protocol in comparison with the LTE standard and conventional DQ access schemes.
Second, we propose a novel time- and energy-efficient identification protocol for dense RFID systems for massive IoT. The protocol is designed based on a conventional M-ary collision tree, where tags involving a collision are classified into other M subtrees. We also incorporate a newly designed transmission mechanism, by which each tag only responds to the reader by a small number of bits for a collision detection. The mechanism relies on a collision window supported by tag cardinality estimation, and the Manchester encoding, which is common in RFID systems. Thanks to that, the number of bits transmitted by tags can be significantly reduced, which improves the overall system performance in terms of both time and energy consumption. Theoretical analysis and computer simulation are performed and the obtained results confirm the effectiveness of the proposed protocol.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
1: 当初の計画以上に進展している
理由
The project progressed more smoothly than initially planned thanks to the fact that we can quickly recruit research assistants (PhD students) and therefore, can start the project early. We also maintain the project progress weekly meeting to confirm work status and quickly address any arising issues.
With these facts and situations, the project is progressed more smoothly than the original plan, in terms of both research implementation and result dissemination. In AY2018, we have published three journal articles and two conference papers.
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| 今後の研究の推進方策 |
We continue working on improving the design and thus, the performance in terms of both energy efficiency and delay, of both the newly proposed DQ-based random-access protocols for MTC devices and the identification protocols. More specifically, we focus on improving the design of protocols in the case there are different access priorities. In addition, we also look at new mechanisms to improve the delay performance of the proposed procols and to use the resources more effectively.
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