TDD/CDMA 無線電系統下鏈容量分析 徐永昇、李金椿
E-mail: [email protected]
摘 要
本文係探討一簡單型TDD/CDMA下鏈系統的基地台及行動台的干擾時間比例與系統容量，並加入護衛時間以避免行動台 發生必須同時發射及接收的情況，其中一TDMA時框只包含發射及接收各一時槽。由於行動台為平均分佈於細胞內，在下 行鏈路中，行動台距基地台越遠，其接收到的訊號-干擾比(SIR)越低。我們取兩點位於細胞邊緣，所受到的干擾較為嚴重 處來分析其受干擾情形，再以通訊中斷率為標準，分析其系統容量。無線通道只考慮了路徑損失和遮蔽效應，而多路徑影 響則假設可由其它訊號處理方法加以補償。 關於干擾方面，我們發現細胞半徑限制在小於3750公尺時，同細胞其它用戶不 會對目標行動台造成干擾，而細胞外的干擾則只有鄰近基地台造成的干擾，由於細胞半徑限制在小於3750公尺，使得鄰近 基地台的干擾時間比例相當的小。在細胞半徑為500、1000、3000公尺時，系統分別可容納29、29、29個使用者。我們可 以觀察到當細胞半徑小於3750公尺時，通訊中斷率不會受到細胞半徑的影響。
關鍵詞 : TDD/CDMA、干擾時間比例、通訊中斷率、容量、細胞半徑 目錄
第一章 緒論．．．．．．．．．．．．．．．．．．．．．1 第二章 行動無線通訊簡介．．．．．．．．．．．．．．
．4 2.1 行動無線通道．．．．．．．．．．．．．．．4 2.1.1 路徑損失．．．．．．．．．．．．．．5 2.1.2 遮蔽效應．
．．．．．．．．．．．．．6 2.1.3 多重路徑衰變．．．．．．．．．．．．7 2.1.3.1 瑞雷分佈．．．．．．．．．．．8 2.1.3.2 萊斯分佈．．．．．．．．．．．8 2.2 蜂巢網行動通訊系統．．．．．．．．．．．．9 2.3 蜂巢網組織與架構．
．．．．．．．．．．．．12 第三章 TDD和CDMA系統．．．．．．．．．．．．．13 3.1 雙工系統．．．．．．．．
．．．．．．．．13 3.2 多重存取系統．．．．．．．．．．．．．．．15 3.2.1 劃頻多重存取的技術．．．．．．．．
．15 3.2.2 劃時多重存取的技術．．．．．．．．．16 3.3 展頻技術．．．．．．．．．．．．．．．．19 3.3.1 虛擬雜訊 序列．．．．．．．．．．．20 3.3.2 處理增益．．．．．．．．．．．．．22 3.4 CDMA系統．．．．．．．．．．．
．．．．24 3.5 TD-WCDMA系統．．．．．．．．．．．．．24 3.5.1 通道結構．．．．．．．．．．．．25 3.5.2 展頻
．．．．．．．．．．．．．．27 第四章 TDD/CDMA無線電系統下鏈容量分析．．．．．28 4.1 護衛時間與細胞半徑．
．．．．．．．．．．．28 4.2同細胞的用戶干擾．．．．．．．．．．．．30 4.3緊鄰基地台干擾．．．．．．．．．．
．．．．30 4.3.1 干擾時間比例．．．．．．．．．．．31 4.3.2 干擾強度．．．．．．．．．．．．．32 4.3.2.1 行動台位 於A點．．．．．．．．33 4.3.2.2行動台位於B點．．．．．．．．38 4.4緊鄰行動台干擾．．．．．．．．．．．．．
．41 4.5細胞外總干擾量．．．．．．．．．．．．．49 4.6 TDD/CDMA的通訊效能Eb/I0．．．．．．．．50 4.7通訊容 量分析．．．．．．．．．．．．．．53 第五章 結論．．．．．．．．．．．．．．．．．．．．56 參考文獻．．．．
．．．．．．．．．．．．．．．．．．57 參考文獻
[1] R. J. Sanchez, “CDMA digital cellular overview and field trials results,” Technologies for Wireless Applications Diqest, pp. 37-43, Feb. 1995.
[2] O. Momtahan, H. Hashemi, “A comparative evaluation of DECT, PACS, and PHS standards for wireless local loop applications,” Personal Communications, IEEE, Vol. 7, Issue 3, PP.35-41, June 2000.
[3] R. Esmailzadeh, M. Nakagawa, and A. Jones, “TDD-CDMA for the 4-th generation of wireless communications,” IEEE Wireless Communications, vol. 10, no. 4, pp. 8-15, Aug. 2003.
[4] A. Samukic, “UMTS Universal mobile telecommunication system: Development of standards for third generation,” IEEE Transaction on Vehicular Technology, vol. 47, no. 4, pp. 1976-1983, Nov. 1998.
[5] T. Ojanpera and R. Prasad, “An overview of air interface multiple access for IMT -2000/UMTS,” IEEE communication Magazine, vol. 36, no. 9, pp. 82-95, Sep. 1998.
[6] E. Dahlman, B. Gudmundson, M. Nilsson, and J. Skold, “UMTS/IMT-2000 based on wideband CDMA,” IEEE communication Magazine, vol. 36, no. 9, pp. 70-80, Sep. 1998.
[7] E. Dahlman, B. Belling, J. Knutsson, F. Ovesjo, M. Persson, and C. Roobol, “WCDMA-The radio interface for future mobile multimedia communications,” IEEE Transaction on Vehicular Technology, vol. 47, no. 4, pp. 1105-1118, Nov. 1998.
[8] K. Tachikawa, “A perspective on the evolution of mobile communication,” IEEE Communication Magazine, vol. 41, no. 10, pp. 66-73, Oct.
2003.
[9] Y. Kim, B. J. Jeong, J. Chung, C.-S. Hwang, J. S. Ryu, K.-H. Kim and Y. K. Kim, “Beyond 3G: Vision, requirements, and Enabling Technologies,” IEEE Communication Magazine, vol. 41, no. 3, pp. 120-124, Mar. 2003.
[10] Huaming Wu, Weidong Li, Youzheng Wang, and Jing Wang, “WCDMA-TDD for Multimedia Mobile Communication,” State Key Lab.
on Microwave & Digital Communications. Department of Electronic Engineering, Tsinghua University.
[11] Xingyao Wu, Lie-Liang Yang and Hanzo, L., “Uplink capacity investigations of TDD/CDMA,” IEEE 55th VTC, vol. 2, pp. 997-1001, 6-9 May 2002.
[12] Miao Qingyu, Wang Wenbo, Yang Dacheng and Wang Daqing, “An analysis of the interference in the TDD/CDMA system,” TENCON 2000. vol. 1, pp. 333-337, 24-27 Sep. 2000.
[13] D. Li, “The perspectives of Large Area Synchronous CDMA Technologies,” IEEE Communication Magazine, vol. 41, no. 3, pp. 114-118, Mar. 2003.
[14] Mugen Peng, Biao Huang and Wenbo Wang , “TDD/CDMA capacity loss due to adjacent channel interference in the macro environment employing smart antenna techniques,” 2004 Asia-Pacific Radio Science Conference, pp. 146-149, 24-27 Aug. 2004.
[15] Jiang Chang, Wenbo Wang and Dacheng Yang, “Investigation of a combined power control scheme for a time-division duplex CDMA system,” The 2000 IEEE Asia-Pacific Conference on Circuits and Systems, pp. 46-49, 4-6 Dec. 2000.
[16] 李金椿, 崔德高, 曾平一, 徐永昇, “TDD/CDMA之上鏈數據流量分析,” Fourth Conference on Communication Applications, CCA Procceding, pp. 208-214, 北台技術學院, March, 2006.
[17] 陳俊男, “Performance analysis for multi-rate transmission in W-CDMA,” Ch2&3,大葉大學, 2002.
[18] J. L. Dornstetter and D. Verhulst, “Cellular efficiency with slow frequency hopping: Analysis of the digital SFH900 mobile system,” IEEE J.
Sel. Area Commun., vol. 5, no. 5, pp. 835-848, Jun. 1987.
[19] R. Steele [Ed], “Mobile Radio Communication,” Pentech Press, 2002.
[20] P. Jung, P. W. Basier and A. Steil, “Advantages of CDMA and spread spectrum techniques over FDMA and TDMA in cellular mobile radio applications,” IEEE Transactions on Vehicular Technology, vol. 4, pp. 357-364, 1993.
[21] L. A. Gerhardt, “Spread Spectrum Communication,” NATO AGARD Lecture Series, no. 58, Jul. 1973.
[22] D. J. Torrieri, “Performance of direct-sequence system with long pseudo noise sequence,” IEEE J. Sel. Area Commun., vol. 10, no. 4, pp.
770-781, May 1992.
[23] R. Steele, C. C. Lee and P. Gould, “GSM CdmaOne and 3G Systems, ” John Wiley & Sons, 2001.
[24] W.C.Y Lee, “Overview of cellular CDMA,” IEEE Transactions, vol. 40, Issue 2, pp. 291-302, May 1991.
[25] C.-C. Lee, C.-H. Wang and C.-H. Yang, “Performance of the W-CDMA in multi-path fading channels,” 2003 International Conference on Informatics, Cybernetics, and Systems, 14-16 Dec., Kaohsiung, Taiwan, 2003.
