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研究生：	何文賢 Ho, Wen-Hsien
論文名稱：	在 CDMA/TDD 系統中對於減少干擾的時槽分配演算法之研究 A Study of Time Slot Allocation Algorithm to Avoid the Interference in the CDMA/TDD System
指導教授：	蘇賜麟 Su, Szu-Lin
學位類別：	碩士 Master
系所名稱：	電機資訊學院 - 電機工程學系 Department of Electrical Engineering
論文出版年：	2002
畢業學年度：	90
語文別：	中文
論文頁數：	52
中文關鍵詞：	分時多工技術、分碼多工擷取技術
外文關鍵詞：	CDMA, TDD
相關次數：	點閱：71 下載：1
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在 CDMA/TDD 系統中
對於減少干擾的時槽分配演算法之研究

何文賢* 蘇賜麟**

國立成功大學電機工程系碩士班通訊組

摘要

TDD系統的packet scheduling設計除了上層協定中依訊息priority考量而有不同規劃外，最主要的影響因素為TDD系統的上下傳（up/down link）通道可採用非對稱式時槽（time slot）分配，以滿足上下傳packet傳送的不同頻寬需求，這也是TDD系統與FDD系統在空中介面無線資源上最大的不同。然而此時槽分配的自由度，也讓TDD系統可能遭受FDD系統中所不會產生的多用戶干擾類型（BS-BS interference及MS-MS interference）。若此TDD系統與受干擾限制的多重擷取技術如CDMA結合，則此額外的干擾訊號將是一個重要的討論議題。

在本篇論文中，將針對CDMA/TDD系統的特性並依據細胞間不同的服務要求，分析各種情況下之Outage Probability，並利用時槽的分配，提出一個合適的機動頻道配置方法（dynamic channel assignment algorithm），以降低細胞自身及相鄰細胞間的多用戶干擾，並提高無線通訊資源使用效率。另外我們以軟體模擬來印證數學分析結果。

* 作者
** 指導教授

A Study of Time Slot Allocation Algorithm to
Avoid the Interference in the CDMA/TDD System

Wen-Hsien Ho* Szu-Lin Su**

Department of Electrical Engineering
National Cheng Kung University, Tainan,
Taiwan,R.O.C

Besides considering the priority of the messages, the most important factor that will affect the packet scheduling design of a time-division duplex (TDD) communication system is the inherent capability of unbalanced slot allocation between uplink and downlink channels. This unbalanced allocation function is the major difference on the radio resource management of the air interface between TDD and FDD (frequency-division duplex) systems. Hence, the TDD system will suffer from extra multiusers’ interference (e.g, interference of BS-BS and MS-MS) when compared to the FDD system because of the freedom of time-slot allocation. Such extra multiusers’ interference will become more important, if the TDD scheme is combined with CDMA technique, which has an interference-limited capacity.

In this thesis, according to the different traffic patterns between adjacent cells, we analyze the outage probability caused by MS-MS interference and other interference such as BS-BS, MS-BS, BS-MS interference. We propose a proper dynamic channel assignment algorithm by time slot allocation to reduce the multiusers’ interference from adjacent cells. The DCA increase the utilization of the radio resource, and then the analytic results are verified by simulation.

* The Author
** The Advisor

Contents

Abstract  ……………………………………………………………………………i 
Contents ……………………………………………………………………………ii 
List of Tables ………………………………………………………………iv 
List of Figures ……………………………………………………………  v  
INTRODUCTION  ……………………………………………………1            
1 Introduction         ……………………………………………………………1
2 Outline ……………………………………………………………………………4
UTRA TDD CHARACTERISTICS DESTRIPTION ………………………5  
1 Differences Between TDD Mode and FDDMode………………………………5            
2UTRATDDPhysicalLayer………………………………………………………6
3 Inference Between Uplink and Downlink in the TDD System……………7
4 Time Slot Allocation Strategy…………………………………8
5 Dynamic Channel Assignment………………9                                                                                     
OUTAGE PROBABILITY ANALYSIS………13 
1 AnalysisModel  ……13
2 Outage Probability Analysis             …………15
2.1 Analysis without fading channel          ………………………15
2.1.1 During the Crossed Time Slot Pair           ……………………………15
2.2 Analysis with Shadow Fading Channel                       ……22
2.2.1 During the Crossed Time Slot Pair                      ………22                                                     
2.2.2 During the Uplink Time Slot Pair                       ………26
2.2.3 During the Downlink Time Slot Pair     ……………………………29
3 Numerical Results and Discussions ……31
3.1 Numerical Results      ………31
3.2 Discussions …      32 
PROPOSED ALGORITHM & SIMULATION MODEL  …38
1 Proposed Dynamic Channel Assignment           ……………38
2 Simulation Platform     ……40
3 Simulation Results and Discussions         …………………………………43
3.1 Performance of the Proposed Algorithm   ……………………………43
3.2 Performance of the Random Allocation Algorithm                 44
3.3 Compare the Performance of the Proposed Algorithm with the Random Allocation Algorithm …………44                                                     
CONCLUSION ……………………………………………49
REFERENCE  ……………………………………………50  

List of Tables
I. Comparison of UTRA TDD and FDD Physical basic parameters   …………12
II. The performance of the random allocation algorithm                  …48
III. The optimal performance of the class B downlink channel with the proposed algorithm ……48 
List of Figures
UMTS spectrum allocation                   ……………………………2 
Example of TDD frame structure           …………………………………7
Mobile-to-mobile interference at the cell border         …10 
Base station-to-base station interference between adjacent cells …………………11
Region division of CDMA/TDD cells                            …12
The location of mobile i and mobile j in cell A and cell B ……………………14
7-a. Limit the position of mobile i in cell A                             …20
7-b. Limit the position of mobile j in cell B   …………………………………20
Average outage probability of mobile j in cell B with 4 interference users vs. the radius Rlimit of the circle in cell A and cell B …………………………………21
The locations of mobile i and mobile j in cell A and cell B ……….21
The locations of mobile i and mobile j in cell A and cell B              …35
Limit the positions of users in cell A or in cell B            …………35
Average outage probability of mobile j in cell B vs. the radius Rlimit of the circle in cell A and cell B in the shadow fading channel during the crossed time slot pair   36
Average outage probability of mobile i in cell A vs. the radius Rlimit of the circle in cell B and cell B in the shadow fading channel during the crossed time 
slot pair  ………………………………………………………36
Average outage probability of mobile j in cell B vs. the radius Rlimit of the circle in cell A and cell B in the shadow fading channel during the uplink time slot pair………………………………37
Average outage probability of mobile j in cell B vs. the radius Rlimit of the circle in cell A in the shadow fading channel during the downlink time slot pair……………37 
Example of traffic patterns in cell A and cell B                      …42
Example of the proposed algorithm case 1                         …42
Example of the proposed algorithm case 2          …42
The average outage probability of two classes calls without shadow fading channel when using the proposed algorithm case 1 ……………………………46
The average outage probability of two classes calls in the shadow fading channel (8dB variance) with the proposed algorithm case 2 …47

                                    

REFERENCE
[1]Harri Holma, Sanna Heikkinen, Otto-Aleksanteri Lehtinen, and Antti Toskala, Interference considerations for the time division duplex mode of the UMTS terrestrial radio access, “IEEE Journal on Selected Areas in Communications”, Vol. 18, No. 8, August 2000

[2]S. H. Wie and D. H. Cho, “Time slot allocation scheme based on a region division in CDMA/TDD systems”, IEEE VTC’01.

[3]A. Baier, U. C. Fiebig, W. Granzow, W. Koch, P. Teder, and J. Thielecke, “Design study for a CDMA-based third-generation mobile radio system”, IEEE J. Select. Areas Commun., Vol. 12, pp. 733-743,May 1994.

[4]D. G. Jeong, C.H. Choi, and W. S. Jeon, “Design and performance evaluation of a
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[14]S. Heikkinen, System simulations for UMTS TDD and FDD modes, Master’s thesis, Univ. Oulu, Finland/University of Edinburgh, Scotland,1999. Available from Oulu Univ. Library, P.O. Box 4000, FIN-90014 Univ. Oulu, Finland.

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校內：2003-06-25公開
校外：2004-06-25公開

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