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論文名稱 Title |
Code Merge : 一個應用於WCDMA OVSF碼之動態頻道配置法 Code Merge Scheme (CMS) :A Dynamic Scheme for Allocating OVSF Codes in WCDMA |
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系所名稱 Department |
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畢業學年期 Year, semester |
語文別 Language |
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學位類別 Degree |
頁數 Number of pages |
48 |
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研究生 Author |
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指導教授 Advisor |
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召集委員 Convenor |
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口試委員 Advisory Committee |
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口試日期 Date of Exam |
2001-07-24 |
繳交日期 Date of Submission |
2001-08-06 |
關鍵字 Keywords |
寬頻分碼多工、動態頻寬配置、正交 Orthogonal, Dynamic Channel Allocation, WCDMA |
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統計 Statistics |
本論文已被瀏覽 5675 次,被下載 19 次 The thesis/dissertation has been browsed 5675 times, has been downloaded 19 times. |
中文摘要 |
中文摘要 WCDMA是一種第三代的無線通訊系統,它能提供高速的傳輸速度以及不同流速的服務,可以改善現階段無線通訊系統頻寬不足的問題,一些先進國家已積極的投入第三代無線通訊系統的研發當中。 WCDMA採用長度可動態調整的OVSF碼以作為其展頻碼,靠著配置不同長度的OVSF碼可以用以調整分配給使用者的傳輸速率,藉由OVSF碼的樹狀分佈,我們可以討論出一個更有效率的頻寬配置方法以減少使用者被拒絕傳輸要求的機會以及使用中的展頻碼被重新配置的可能性,這可以改善系統的整體效能,我們可由模擬的結果看到我們提出的方法所展現出的較佳效果。 |
Abstract |
Abstract Wideband-CDMA (WCDMA) is a kind of third-generation wireless communication system. It can provide multi-rate services and fast transmission with wideband technology. To improve the solution of no enough wireless bandwidth currently, the 3G communication systems have been researched and developed in several leading countries recently. WCDMA adopts a kind of new spreading codes named Orthogonal Variable Spreading Factor codes (OVSF codes) that have advantages of dynamically variable rates and keeping orthogonality. OVSF codes can provide different data transmission rates by assigning codes with different lengths. By building a code tree, we can discuss some better schemes to assign available data rate. In this paper, we propose an efficient channel assignment scheme that can decrease the call blocking rate and complexity of channel reassignment procedure. Based on the properties of the binary code tree, we use code merge scheme to decrease channel reassignment rate and call blocking rate. This will efficiently improve the performance of channel assignment and spectral efficiency. Simulation results show that the proposed scheme has expected results. |
目次 Table of Contents |
Index Abstract Content 1. Introduction…………………………………………………………………………1 2. Specifications of WCDMA System………………………………………………...4 2.1 3G Communication System………………………………………………….4 2.2 Direct-Sequence Code Division Multiple Access(DS-CDMA)………….6 2.3 Call Admission……………………………………………………………….6 2.4 The Definition of OVSF Codes………………………………………………8 2.5 Dynamic Channel Assignment……………………………………………...11 2.6 Code Assignment Scheme…………………………………………………..13 3. Relative Code Reassignment Schemes…………………………………………….15 3.1 Code Exchange Scheme…………………………………………………….15 3.2 Optimal Dynamic Code Assignment Scheme………………………………18 4. Our Proposed Code Reassignment Scheme: Code Merge Scheme………………..21 4.1 The Least Number of Unused Codes……………………………………….21 4.2 The Distribution of Unused Codes in the Code Tree……………………….21 4.3 Code Merge Scheme………………………………………………………..22 4.4 Why we replace “Sort” with “Merge”?……………………………………..26 4.5 Analysis of Complexity in Code Exchange Scheme and Code Merge Scheme…………………………………………………………………….29 5. Simulation…………………………………………………………………………33 5.1 Simulation Environment and Parameters…………………………………...33 5.2 Blocking Probability with Code Exchange Scheme and Code Merge scheme…………………………………..………………………….35 5.3 The Number of Reassignment with Code Exchange Scheme and Code Merge Scheme……………………………………………………....40 6. Comparison of Three Algorithms………………………………………………....45 7. Conclusions and Future Work……………………………………………………..47 References……………………………………………………………………………48 |
參考文獻 References |
[1] R. Prasad and T. Ojanpera, “An Overview of CDMA Evolution Toward Wideband CDMA”, IEEE Communications Surveys, 1998. [2] TR 25.922, ”Radio Resource Management Strategies”, 3GPP, v3.1.0, March, 2000. [3] Ray-Guang Cheng and Phone Lin, ”OVSF Code Channel Assignment for IMT-2000”, Vehicular Technology Conference Proceedings, 2000. VTC 2000-Spring Tokyo. 2000 IEEE 51st, Volume: 3, 2000, Page(s): 2188 –2192. [4] Thit Minn and Kai-Yeung Siu, “Dynamic Assignment of Orthogonal Variable-Spreading-Factor Codes in W-CDMA”, Selected Areas in Communications, IEEE Journal on, Volume: 18, NO. 8, Aug. 2000, Page(s): 1429 -1440. [5] F. Adachi, M. Sawahashi, and K. Okawa, ”Tree-structured generation of orthogonal spreading codes with different lengths for forward link of DS-CDMA mobile radio”, Electron. Lett., Volume: 33, Jan, 1997,Pages(s): 27-28. [6] Biing-Chwan Liu, “Efficient Channelization Code Assignment Schemes for 3GPP”, 2000. [7] Federal Standard 1037C homepage: http://www.its.bldrdoc.gov/fs-1037/fs-1037c.htm |
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