第五代行動通訊(5G)現今發展越來越成熟，國際電信聯盟(International Telecommunication Union, ITU)將5G的應用定義為三大場景：超可靠低延遲通訊(Ultra-reliable and Low Latency Communications, uRLLC)、增強型行動頻寬(Enhanced Mobile Broadband, eMBB)和大規模機器型通訊(Massive Machine Type Communications, mMTC)，其中uRLLC強調低延遲高可靠的傳輸，eMBB注重於傳輸速度以及傳輸數據量，當兩種不同類型的設備存在於共同的環境下時，如何分配資源使得彼此有更好的效能也是一大重點，無論是哪種類型的裝置，當有資料需要上傳時，都會需要經過隨機存取程序和基地台進行連線，但一個基地台能夠提供的Preamble數量是有限的，因此有大量的裝置同時進行隨機存取程序時，會發生碰撞而影響到傳輸的效能。
本論文將Preamble分成三組，提出uRLLC Priority Dynamic Allocation、eMBB Priority Dynamic Allocation和Reserved Dynamic Allocation三種不同動態調整Preamble數量的方法進行模擬實驗，其實驗方法為每隔一段時間觀察系統內不同裝置使用Preamble的情況，推出下一段時間內該如何分配各組的Preamble數量，透過對Preamble數量動態調整來提高不同類型的傳輸效能。
從模擬結果可得uRLLC Priority Dynamic Allocation方法可以更有效的利用各組的Preamble，並且提升裝置的成功率。eMBB Priority Dynamic Allocation方法因優先處理eMBB裝置而導致於uRLLC裝置的效能大幅度的下降。Reserved Dynamic Allocation證明了兩種不同裝置類型共存的環境下，適當的保留資源給uRLLC是必須的。

The fifth generation mobile communication (5G) is becoming more and more mature. The International Telecommunication Union (ITU) defines the application of 5G as three scenarios: Ultra-reliable and Low Latency Communications (uRLLC), Enhanced Mobile Broadband (eMBB) and Massive Machine Type Communications (mMTC). uRLLC emphasizes low-latency and highly reliable transmission. eMBB focuses on the number of transmissions and the amount of data transmitted. How to allocate resources to make each other have better performance when two different types of devices coexist is a key point. When the devices has data to upload it will need to go through random access procedure. The fetch program is connected to the base station. but the number of Preambles that a base station can provide is limited. Therefore, when a large number of devices random access at the same time.Collisions will occur and the transmission performance will be affected.
This paper divides the Preambles into three groups and proposes three different methods of dynamically adjusting the number of Preambles: uRLLC Priority Dynamic Allocation, eMBB Priority Dynamic Allocation and Reserved Dynamic Allocation. Observes the use of Preambles by different devices in the system at regular intervals and adjust them in the next period of time. Allocating and adjusting the number of Preambles in each group to improve the transmission performance of different types by dynamically.
From the simulation results, it can be seen that the uRLLC Priority Dynamic Allocation method can more effectively utilize the Preamble of each group and improve the success rate of the devices. eMBB Priority Dynamic Allocation causes the performance of the uRLLC device to drop significantly due to the priority processing of the eMBB device. Reserved Dynamic Allocation proves that in an environment where two different device types coexist, it is necessary to properly reserve resources for uRLLC devices.

[1] "Study on Scenarios and Requirements for Next Generation Access Technologies," 3GPP TR 38.913 (Rel.16), 07 2020.
[2] ITU-R, "M.2083 : IMT Vision - Framework and overall objectives of the future development of IMT for 2020 and beyond," 9 2015.
[3] "Technical Specification Group Radio Access Network ; NR;Physical channels and modulation," 3GPP TS 38.211 (Rel.16), 1 2021.
[4] [Online]Available:https://www.sharetechnote.com/html/5G/5G_FrameStructure.html
[5] "User Equipment (UE) radio transmission and reception; Part 1: Range 1 Standalone," 3GPP TS 38.101 (Rel.16), 7 2020.
[6] "NR and NG-RAN Overall description; Stage-2," 3GPP TS 38.300 (Rel.16), 1 2021.
[7] "Radio Resource Control (RRC);Protocol specification," 3GPP TS 38.331(Rel.15), 1 2020.
[8] [Online]Available:https://github.com/wjhgh04/lte_study/blob/master/%E6%B7%B1%E5%85%A5%E7%90%86%E8%A7%A3LTE-A.pdf
[9] Yan Liu, Yansha Deng, Maged Elkashlan, Arumugam Nallanathan, and George K. Karagiannidis, "Analyzing Grant-Free Access for uRLLC Service," IEEE Journal on Selected Areas in Communications, vol. 39, no. 3, March, 2021.
[10] Jayashree Thota and Adnan Aijza, "On Performance Evaluation of Random Access Enhancements for 5G uRLLC", 2019 IEEE Wireless Communications and Networking Conference (WCNC)
[11] Yifan Chen, Guohui Wang, Huiyue Yi, Wuxiong Zhang, "Priority-based Distributed Queuing Random Access Mechanism for mMTC/uRLLC Terminals Coexistence", 2021 IEEE 93rd Vehicular Technology Conference (VTC2021-Spring)
[12] Seokjae Moon and Jang-Won Lee, "Integrated Grant-Free Scheme for uRLLC and mMTC," IEEE 5G World Forum (5GWF), 2020.
[13] Jie Liu, Mamta Agiwal, Miao Qu, Hu Jin, "Online Control of Preamble Groups With Priority in Massive IoT Networks", IEEE Journal on Selected Areas in Communications, vol. 39, no. 3, March 2021.