在第五代（5G）移動網絡中，高數據速率和低延遲服務是被提供的。 為了滿足這兩個服務的要求，6 GHz以上的頻率是可以使用的選項之一。 然而，衰減情況是高頻系統中的一個關鍵問題，因此採用波束成型技術來克服這一問題。 對於具有波束成型的控制平面過程，需要更多時間來進行波束成型的同步和隨機接入過程。 本論文提出了一種毫米波系統中隨機接入過程的模型，並考慮了不同波束數量，不同前導碼傳輸數量的影響。 此外，我們提出了一種分析模型，通過估計接入成功概率和平均接入延遲來評估具有波束成型模型的隨機接入過程的性能。 模擬結果顯示了分析得出的性能指標的準確性。

In the fifth generation (5G) of mobile networks, high data rate and low latency services are supported. In order to fullfill these two requirements, the frequency above 6 GHz is one of options to be used. The attentuation is a critical problem in high frequency system, so beamforming technology is adopted to overcome this problem. For control plane procedure with beamforming, more time is needed to do synchronization and random access procedure with beamforming. This paper proposes a model for random access procedure in mmWave system, and shows the impact of different number of beams, different preamble transmission. Furthermore, we propose an analytical model to evaluate the performance of the random access procedure with beamforming model by estimating the access success probability and average access delay. The simulations results show the accuracy of the performance metrics derived analytically.

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X. Lin, J. Li, R. Baldemair, T. Cheng, S. Parkvall, D. Larsson, H. Koorapaty, M. Frenne, S. Falahati, A. Grövlen, K. Werner, \emph{5G New Radio: Unveiling the Essentials of the Next Generation Wireless Access Technology,}. to be published.

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M. Giordani, M. Polese, A. Roy, D. Castor and M. Zorzi, \emph{Standalone and Non-Standalone Beam Management for 3GPP NR at mmWavess,}. to be published.

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I. Ahmed et al., \emph{A Survey on Hybrid Beamforming Techniques in 5G: Architecture and System Model Perspectives,}. in IEEE Communications Surveys \& Tutorials, vol. 20, no. 4, pp. 3060-3097, Fourthquarter 2018.

T. Wang, H. Guo and L. Ruan, \emph{Low Complexity Random Access Detection for 5G Millimeter Wave Communications,}. 2018 IEEE 87th Vehicular Technology Conference (VTC Spring), Porto, 2018, pp. 1-5.

J. M. P. Arana, K. M. Saquib and Y. S. Cho, \emph{Random access preamble design for 5G millimeter-wave cellular systems with multiple beams,}. 2017 Ninth International Conference on Ubiquitous and Future Networks (ICUFN), Milan, 2017, pp. 378-380.

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R. Harwahyu, R. Cheng and C. Wei, \emph{Investigating the Performance of the Random Access Channel in NB-IoT,}. in 2017 IEEE 86th Vehicular Technology Conference (VTC-Fall), Toronto, ON, 2017, pp. 1-5.

A. G. Martín, R. P. Leal, A. G. Armada and A. F. Durán, \emph{NBIoT Random Access Procedure: System Simulation and Performance,}. in 2018 Global Information Infrastructure and Networking Symposium (GIIS), Thessaloniki, Greece, 2018, pp. 1-5.

3GPP TR 38.912, \emph{Study on New Radio (NR) access technology,}. ver.15.0.0, Jun. 2018.

3GPP TR 38.211, \emph{NR;Physical channels and modulation,}. ver.15.4.0, Dec. 2018.

3GPP TR 38.213, \emph{NR;Physical layer procedures for control,}. ver.15.4.0, Dec. 2018.

3GPP TR 38.214, \emph{NR;Physical layer procedures for data,}. ver.15.4.0, Dec. 2018.

3GPP TR 38.321, \emph{NR;Medium Access Control (MAC) protocol specification,}. ver.15.4.0, Dec. 2018.

3GPP TR 38.331, \emph{NR;Radio Resource Control (RRC) protocol specification,}. ver.15.4.0, Dec. 2018.