| 研究実績の概要 |
The research achievement consists of three main parts. First, we proposed a novel access protocol based on the distributed queue (DQ) mechanism to tackle the massive access issue in cellular-based IoT effectively. 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 built a simulation model to validate the analytical model and the effectiveness of the proposed protocol compared to the LTE standard and conventional DQ access schemes. Second, we exploited the fact that a significant portion of devices is covered by densely deployed small-cells such that a small-cell base station (SBS) may act as a representative for its MTDs during the preamble transmission step to reduce the load on PRACH. Once the SBS succeeds, its MTDs then contend locally to send their signaling messages on the corresponding reserved uplink resources. Finally, we proposed a Dueling Deep Q-Network (DNN)-based dynamic ACB solution that explicitly considered energy consumption and controlled both the barring factor pACB and the mean barring time TACB. We showed that compared to conventional schemes that only control the barring factor, the proposed method could achieve a similar delay performance at a significantly lower energy cost. Furthermore, by adjusting a parameter representing the importance of energy performance in the reward function, our scheme could efficiently realize the tradeoff between access delay and energy consumption.
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