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研究生:陳泊澄
研究生(外文):Po-Cheng Chen
論文名稱:SoftHandoffHandlingBasedontheDelayedresourceReservationScheme
論文名稱(外文):Soft Handoff Handling Based on the Delayed resource Reservation Scheme
指導教授:蔡榮宗蔡榮宗引用關係
指導教授(外文):Jung-Tsung Tsai
學位類別:碩士
校院名稱:國立臺灣師範大學
系所名稱:資訊教育研究所
學門:教育學門
學類:專業科目教育學類
論文種類:學術論文
論文出版年:2002
畢業學年度:90
語文別:英文
論文頁數:43
中文關鍵詞:soft handoffresource reservationDelayed Resource Reservation
外文關鍵詞:soft handoffresource reservationDelayed Resource Reservation
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Abstract
Soft handoff is an exclusive feature of CDMA system that is able to improve the quality of seamless roaming communication services. This thesis investigates resource reservation schemes effectively to use soft handoff techniques to handle call-handover service without much sacrificing system capacity utilization. In particular, the proposed algorithm exploits the spirit of delayed resource reservation schemes to tightly control the timing to reserve resources such that the waste of unnecessary resource reservations is statistically reduced. This feature is achieved through utilizing a mechanism to estimate the speed and direction of mobility by the user itself and delaying issuing a resource reservation request for some moment according to the estimation. Specifically, the mechanism facilitates resolving issues on ``whether to reserve or not to reserve” when an active mobile station moves into the radio coverage areas of two or more cells. Furthermore, the proposed scheme yields an advantage of no extra hardware requirement for implementation in mobile stations for the required power control mechanism is an essential part of CDMA systems.
Performance data for system evaluation are all obtained from simulations. The soft handoff failure ratio, the new call blocking ratio, and the total handoff dropping ratio from using a static resource reservation scheme based on a fixed power threshold and from using the proposed delayed scheme are both obtained, illustrated and compared. We found that the proposed scheme is able to reduce new call blocking ratio and handoff dropping ratio while keep the soft handoff failure probability almost unchanged.

Abstract
Soft handoff is an exclusive feature of CDMA system that is able to improve the quality of seamless roaming communication services. This thesis investigates resource reservation schemes effectively to use soft handoff techniques to handle call-handover service without much sacrificing system capacity utilization. In particular, the proposed algorithm exploits the spirit of delayed resource reservation schemes to tightly control the timing to reserve resources such that the waste of unnecessary resource reservations is statistically reduced. This feature is achieved through utilizing a mechanism to estimate the speed and direction of mobility by the user itself and delaying issuing a resource reservation request for some moment according to the estimation. Specifically, the mechanism facilitates resolving issues on ``whether to reserve or not to reserve” when an active mobile station moves into the radio coverage areas of two or more cells. Furthermore, the proposed scheme yields an advantage of no extra hardware requirement for implementation in mobile stations for the required power control mechanism is an essential part of CDMA systems.
Performance data for system evaluation are all obtained from simulations. The soft handoff failure ratio, the new call blocking ratio, and the total handoff dropping ratio from using a static resource reservation scheme based on a fixed power threshold and from using the proposed delayed scheme are both obtained, illustrated and compared. We found that the proposed scheme is able to reduce new call blocking ratio and handoff dropping ratio while keep the soft handoff failure probability almost unchanged.

Table of Contents
Abstract…………………………………………………………………….……….....i
Acknowledgement…………………………………………………………………...iii
Table of Contents…………………………………………………………………….iv
List of Figures……………………………………………………...………………...vi
List of Tables………………………………………………………………....……...vii
Chapter 1 Introduction…………………………………………….……………..1
1.1 Introduction……………………………………………………………1
1.2 Background and related work…………………………………………3
1.3 Objective………………………………………………………………5
1.4 Thesis Organization…………………………………………………...6
Chapter 2 System Model.….……………………………………..………………7
2.1 System Architecture…………………………………………………...7
2.1.1 CDMA Cellular system model…………………………………..7
2.1.2 Traffic Model………………………………………………...…12
2.2 Static Reservation Scheme…………………………………………...14
2.3 Delayed Resource Reservation Scheme……………………………...15
2.3.1 Mobility Estimation and Power changing ratio………………...15
2.3.2 A Mobility-based Resource Reservation strategy……………...18
2.3.3 Delay Function…………………………………………………19
2.3.4 Initial Reservation……………………………………………...20
2.4 Resource Reservation Scheme……………………………………….20
Chapter 3 Simulation Model……………………………...……………………25
3.1 Topology……………………………………………………………..25
3.2 Traffic Model………………………………………………………...26
3.3 Operation Algorithm…………………………………………………26
3.3.1 New Call (MS)…………………………………………………27
3.3.2 Handoff Call (MS)……………………………...……………...28
3.3.3 Requests handling(BS)…………………………………………29
Chapter 4 Numerical Data………………………………………………...…… 31
4.1 Traffic Patterns……………………………………………………….31
4.4.1 Uni-direction vs. Two-direction……………………………….31
4.1.2 High speed vs. Low speed…………………………………...…35
4.2 Reservation Life Time………………………………………………..36
4.3 Initial Reservation……………………………………………………38
Chapter 5 Conclusion and Future work …………………….………………....41
5.1 Conclusion……………………………………………………………41
5.2 Future work…………………………………………………………..42
Reference…...………………………………………………………………..………43
List of Figures
Figure 2-1 A radio coverage area is divided into three concentric ring areas.…...11
Figure 2-2 Three power level thresholds, ………………..11
Figure 2-3 The calling activity of MS……………………………………………12
Figure 2-4 The transition diagram of user mobility in three states……………....13
Figure 2-5 An array of each channel state…………….…………………………21
Figure 2-6 State transition diagram of the entry in channel array…..…..……….22
Figure 3-1 A ring topology………………………………………………………25
Figure 3-3 The algorithm in MS to to process new call requests….………….….27
Figure 3-3 The algorithm in MS to delay the processing of handoff calls…...….28
Figure 3-4 Reservation handling in BS………………………………………….29
Figure 3-5 Handoff algorithm in BS………………………………………….….30
Figure 4-1 Performance of both schemes in uni-direction pattern………………32
Figure 4-2 Performance of both schemes in two-directions pattern……………..34
Figure 4-3 performance of both schemes fo MSs moving in two-direction pattern and very high speed.…………………………………………...……..36
Figure 4-4 Performance of both schemes for different reservation life time...…..37
Figure 4-5 Performance of both schemes with initial reservation……………….39
List of Tables
Table 4-1 the percentage of improvement by using delayed schemes………….33
Table 4-2 the percentage of improvement by using delayed schemes in two direction pattern…..………………………………………………….35
Table 4-3 the percentage of improvement by using delayed schemes in very high speed pattern…………………………………………………………36
Table 4-4 the percentage of improvement by using delayed schemes in various reservation life time………………………………………………….38
Table 4-5 the percentage of improvement by using delayed schemes with initial reservations…………………………………………………………..40

[Reference]
[1] S.S Pappaport, “Blocking, hand-off and traffic performance for cellular communication systems with mixed platforms,” IEE Proceedings, Vol. 140, No. 5, October 1993.
[2] S. L Su et al., “Performance analysis of soft handoff in CDMA cellular systems,” IEEE J. Select. Areas Commun., vol. 14, pp. 1762-1769, Dec. 1996
[3] M. H. Chiu and M. Bassiouni, “Predictive schemes for handoff prioritization in cellular networks based on mobile position,” IEEE Journal on Selected Area in Communication. Vol. 18, No 3. Mar. 2000
[4] J. Hou, Y. Fang, and A. N. Akansu, “Mobility-based channel reservation scheme for wireless mobile networks,” IEEE WCNC, 2000, Vol. 2, page(s): 527-531.
[5] J. T. Tsai, “A prioritized handoff local-packing distributed dynamic channel allocation algorithm for cellular networks,” IEEE GLOBECOM, San Francisco, December 2000.
[6] F. Yu and V. C. M. Leung, “Mobility-based predictive call admission control and bandwidth reservation in wireless cellular networks,” IEEE Infocom 2001.
[7] W. S. Soh and H. S. Kim, ”Dynamic guard bandwidth scheme for wireless broadband networks,” IEEE Infocom 2001.
[8] J. W. Chang, and D. K. Sung, “Adaptive channel reservation scheme for soft handoff in DS-CDMA cellular system,” IEEE Transaction on Vehicular Technology, Vol. 50, No. 2, March 2001.
[9] J. T. Tsai, “Delayed resource reservation for handoff handling in wireless communications,” unpublished.

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