分碼多重進接 (CDMA) 已經成為第三代行動通訊系統之核心技術。相對於分時多重進接與分頻多重進接系統之硬式容量，分碼多重進接系統之系統容量是軟式容量。明確地說，在分碼多重進接系統中，只要干擾位準低於某一預先設定之臨限值，則新用戶可被允入。因此，連結允入控制 (CAC) 在 CDMA 系統中扮演重要之角色，因為 CAC 直接控制用戶之人數且當一連結抵達時決定是否該連結要受到允入或拒絕。CAC 應設計成為可同時保證通信品質 (GoS) 與服務品質 (QoS)。基本上，存在二種CAC 可應用於CDMA 系統： 以人數為基礎之 CAC (NCAC) 與以干擾為基礎之 CAC (ICAC)。本篇論文將針對NCAC 與ICAC來探討如何設計CAC 以同時滿足QoS 與GoS 要求。首先，我們研究多重細胞之影響。明確地說，不同於某些先前研究假設交遞抵達速率無關於其他參數，我們考慮交遞抵達速率決定於新連結結抵達速率與其他系統系統參數。第二，我們研究保護通道對於降低交遞失敗機率與改善通信品質之影響。第三，細胞停留時間與連結服務時間被假設成為hyper-exponential 分佈，而非 exponential 分佈。因此，我們研究細胞停留時間與連結服務時間之方差對於GoS與QoS之影響。最後，我們考慮支援二種服務之系統：語音與數據。交遞佇列與保護通道被用來給與交遞連結高於新連結之優先權。此種系統對於QoS之影響受到研究。為了進行效能分析，針對容量臨限值與建議之CAC方法，我們推導適當之多維馬可夫鏈模型與計算相關效能量度之數學解析方法。感興趣之效能量度是當做GoS之新連結阻塞機率，交遞失敗機率與加權機率；與當做QoS之通訊品質喪失機率。

Code division multiple access (CDMA) has been the core technology for the third-generation mobile communication systems. In contrast to the hard capacity of TDMA and FDMA systems, that of CDMA systems is soft capacity. Specifically, in CDMA systems, new users can be accepted as long as the interference level is below some threshold. Call admission control (CAC) thus plays a very important role in CDMA systems because it directly controls the number of users and determines whether to admit or reject a call upon its arrival. CAC must be designed to guarantee both grade of service (GoS) and quality of service (QoS). Basically, there are two types of CAC schemes for CDMA systems: number-based CAC (NCAC) and interference-based CAC (ICAC). In this thesis, for both NCAC and ICAC, we study the issue of how to design a CAC scheme satisfying both QoS and GoS requirements. First, we study the effect of multiple cells by allowing the handoff call arrival rate to depend on the new call arrival rate and other system parameters. Second, we study the effect of guard channels on lowering handoff failure probability and improving GoS. Third, the distributions of both dwell times and call durations are hyper-exponential distributions, instead of exponential distribution. Thus, we study the effect of the variances of cell dwell time and call duration on GoS and QoS. Finally, we consider systems supporting two types of service: voice and data. Both handoff queue and guard channel are utilized to give handoff calls priority over new calls. The effect of such a system on QoS is studied. For the performance analysis, we derive appropriate multi-dimensional Markov chain models and analytical methods to compute the performance measures for the capacity threshold and the proposed CAC scheme. The performance measures of interest are new call blocking probability, handoff failure probability, and weighted probability for GoS, and loss probability of the communication quality for QoS.

[1] T. S. Rappaport, Wireless Communications: Principles and Practice, Prentice Hall, 1996.
[2] J. Zhang, J. Huai, R. Xiao and B. Li, “Resource Management in the Next-Generation DS-CDMA Cellular Networks,” IEEE Wireless Commun., Aug. 2004, pp. 52-58.
[3] C.-J. Ho, JA Copeland, C.-T. Lea and GL. Stuber, “On Call Admission Control in DS/CDMA Cellular Networks,” IEEE Trans. Veh. Tech., vol. 50, no. 6, Nov. 2001, pp. 1328-1343.
[4] L. Jorguseski, E. Fledderus, J. Farserotu and R. Prasad, “Radio Resource Allocation in Third-Generation Mobile Communication Systems,” IEEE Commun. Mag., Feb. 2001, pp. 117-123.
[5] L. Wang and W. Zhuang, “Call Admission Control for Self-Similar Data Traffic in Cellular Communication,” IEEE Globecom'03, San Francisco, Dec. 2003, pp. 982-986.
[6] J. Zhang, J. W. Mark and X. Shen, “ Joint Packet- and Call-level Soft Handoff in CDMA Wireless Cellular Networks,” IEEE PIMRC'2003, pp. 2485-2489.
[7] Y. Ishikawa and N. Umeda, “Capacity Design and Performance of Call Admission Control in Cellular CDMA systems,” IEEE J. Select. Areas Commun., vo1. 15, no. 8, pp. 1627-1635, Oct. 1997.
[8] R. P. Narrainen and F. Takawira, “Performance Analysis of Soft Handoff in CDMA Cellular Networks,” IEEE Trans. Veh. Tech., vol. 50, no. 6, Nov. 2001, pp. 1507-1517.
[9] D. Kim and Y. Chang, “Performance of Prioritized Call Admission Strategies in Cellular CDMA Systems with Limited Receiver Processors,” IEEE Conf. Wireless Commun. Networking, no. 1, Sept. 2000, pp. 522-526.
[10] D. Hong and S. S. Rappaport, “Traffic Model and Performance Analysis for Cellular Mobile Radio Telephone Systems with Prioritized and Nonprioritized Handoff Procedures,” IEEE Trans. Veh. Tech., vol. VT-35, Aug. 1986, pp. 77-92.
[11] I. Koo and K. Kim, “Erlang Capacity of Voice/Data DS-CDMA Systems with Prioritized Services,” IEEE Trans. Commun., vol. E84-B, no. 4, Apr. 2001, pp. 716-726.
[12] Y. Fang and I. Chlamtac, “A New Mobility Model and Its Application in the Channel Holding Characterization in PCS Networks,” IEEE Infocom’99, New York, Mar. 1999.
[13] M. A. Marsan, G. Ginella, R. Maglione and M. Meo, “Performance Analysis of Hierarchical Cellular Networks with Generally Distributed Call Holding Times and Dwell Times,” IEEE Trans. Wireless Commun., vol. 3, no. 1, Jan. 2004, pp. 248-257.
[14] M. Soroushnejad and E. Geraniotis, “Multi-Access Strategies for an integrated Voice/Data CDMA Packet Radio Network,” IEEE Trans. Commun., vol. 43, no. 234, Feb./Mar./Apr. 1995, pp. 934-945.
[15] Y. Ma, J. Han and K. S. Trivedi, “Call Admission Control for Reducing Dropped Calls in CDMA Cellular System,” Computer Communications, 2001.
[16] S. Shin, C. H. Cho, and D. K. Sung, “Interference Based Channel Assignment for DS-CDMA Cellular Systems,” IEEE Trans. Veh. Tech., vol. 48, no. 1, Jan. 1999, pp. 233-239.
[17] N. Dimitriou and R. Tafazolli, “Quality of Service for Multimedia CDMA,” IEEE Commun. Mag., Jul. 2000, pp.88-94.
[18] A. M. Viterbi and A. J. Viterbi, “Erlang Capacity of a Power Controlled CDMA System,” IEEE J. Select. Areas Commun., vol. 11, no. 6, Aug. 1993, pp. 892-900.
[19] J. Zhang, J. W. Mark, X. Shen, “A Novel Resource Reservation Scheme for Handoff in CDMA Wireless Cellular Networks,” IEEE WCNC’03, Mar. 2003, pp. 2069-2074.
[20] I. Koo, S. Bahng, and K. Kim, “Resource Reservation in Call Admission Control Schemes for CDMA Systems with Non-uniform Traffic Distribution among Cells,” IEEE VTC, 2003, pp. 438–441.
[21] ETSI/RES3, “A Guide to DECT feature,” RES3(92)21, Feb. 1992.