| 摘要: | 在第五代行動通訊系統（5th generation wireless communication system, 5G）新無線電（New Radio, NR）的隨機存取（random access, RA）程序中，物理隨機存取通道（physical random access channel, PRACH）將使用基於Zadoff-Chu (ZC)序列的前導格式。然而，廣泛使用的ZC序列作為RA前導具有一定的限制，限制了可以生成的前導總數，導致PRACH容量不足的問題，迫使前導的重複使用。為了解決這個問題，使用覆蓋序列的概念，提出了在文獻中兩種擴展的常振幅零自相關（constant amplitude zero auto correlation, CAZAC）序列結構，使前導容量增加，其中也有包括ZC序列，與當前的5G PRACH設計相容，也符合第三代合作夥伴計畫(3rd generation partnership project, 3GPP)的標準規格。這兩種構造都具有理想的子集結構，從而產生一個自然的蜂窩網絡序列分配，在該分配中，每個特定於單元的序列子集具有可控的低相關區域，類似於ZC序列。
本篇論文將考慮了載波頻率偏移（carrier frequency offset, CFO）和時序誤差(timing error, TE)在ZC序列與文獻中的兩種序列為具有m序列覆蓋的ZC序列(ZC sequences with m-sequence covers, ZCm)和具有Alltop序列覆蓋的ZC序列(ZC sequences with Alltop sequence covers, ZCa)進行模擬比較，從多接收天線上的檢測與估計，以及週期相關性和多樣性組合的影響等等方面評估前導序列的性能。除此之外，還探討了各個序列在峰值對平均功率比（peak to average power ratio, PAPR）和立方度量（cubic metric, CM）的性能比較分析。
;In the random access (RA) procedure of the New Radio (NR) technology in the 5th generation wireless communication system (5G), the physical random access channel (PRACH) uses a preamble format based on Zadoff-Chu (ZC) sequences. However, the widely used ZC sequences as RA preambles have certain limitations, restricting the total number of preambles that can be generated, leading to insufficient PRACH capacity and necessitating the reuse of preambles. To address this issue, the concept of covering sequences is used, and two extended constant amplitude zero auto correlation (CAZAC) sequence structures are proposed in the literature to increase preamble capacity, which include the ZC sequences and are compatible with the current 5G PRACH design, as well as compliant with the 3rd generation partnership project (3GPP) standards specifications. These two constructions both have ideal subset structures, resulting in a natural cellular network sequence allocation where each cell-specific subset of sequences has controllable low-correlation regions, similar to the ZC sequences.
This thesis considers the effects of carrier frequency offset (CFO) and timing error (TE) on ZC sequences and two types of sequences found in the literature: ZC sequences with m-sequence covers (ZCm) and ZC sequences with Alltop sequence covers (ZCa). Simulations are conducted to compare effectiveness of these sequences in terms of detection and estimation across multiple receiving antennas, evaluating the impact of periodic correlation and diversity combining. Additionally, the performance of each sequence is analyzed in terms of peak to average power ratio (PAPR) and cubic metric (CM). |
