摘要(英) |
LTE-MTC (Machine-Type Communication) is designed for IoT applications, compared to traditional Human-to-Human (H2H); MTC communication has several features, such as: extremely low power consumption, low mobility, lower data transmission, and non-recurring data transmission. MTC devices are more than traditional H2H devices in quantity. When the standards of MTC communication services are used for H2H communication, each layer of the architecture in mobile communication network may face the serious congestion problem.
The main research of this thesis is that a large quantities of random access collisions will occur and cause the impacts on the quality of network service when a large amounts of MTC devices try to connect with the base station at the same time; allocating 64 preambles to compete with different devices through the contention based (devices competition) and contention-free based (base station assignment). By dynamically adjusting preambles to ease the congestion and packet delay to improve the service quality of network. The so-called “dynamic adjustment” is to calculate the usage rate and estimate the carrying capacity through the usage level of preambles in base station. Two-stage and three-stage dynamic methods are proposed to evaluate whether to adjust the preambles dynamically through the carrying capacity. Then, according to the adjusted quantities of preambles, SIB parameters are modified in the base station and eNB broadcasts (pages) to the MTC devices in each cycle. Allocating preambles effectively to let the devices to compete and be assigned, eventually, it could reduce devices collision in order to improve the system performance.
The simulation part utilizes different level of MTC devices and probability of P random access. It is known from the simulation results that proposed dynamic adjustment method can reduce the random access time effectively by more than half of the random access time in which devices without dynamic adjustment. Please refer to Chapter 4 for simulation results and discussion. |
參考文獻 |
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