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博碩士論文 etd-0806101-182401 詳細資訊
Title page for etd-0806101-182401
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
系所名稱
Department
畢業學年期
Year, semester
語文別
Language
學位類別
Degree
頁數
Number of pages
48
研究生
Author
指導教授
Advisor
召集委員
Convenor
口試委員
Advisory Committee
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
統計
Statistics
本論文已被瀏覽 5675 次,被下載 19
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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