網際網路的豐富資源以及多媒體服務的大受歡迎，刺激了寬頻網路的發展，建置寬頻網路深入到每個家庭，整合通訊、電腦及資訊，建立網路桃花源是世人的理想；使用者莫不期待高品質、高可靠度以及高速的通訊系統來有效率的擷取網際網路資源。在許多解決方案中，儘管已經有將高速傳輸實現在雙絞線上的非對稱數位用戶迴路(ADSL)，或是擴充現有有線電視網路的混合光纖同軸電纜(HFC)等有線方案，但是在有線基礎建設不足的區域或是對於新加入競爭的業者而言，無線的解決方案具備了建置時程短以及成本低廉之優勢，因此仍然獲得了網路以及服務提供業者的青睞。寬頻無線接取網路，區域多點分配系統 Local Multipoint Distribution System (LMDS) 這種固定式的無線傳輸系統為一工作於28G Hz之雙向數位式細胞式系統；因為影像傳輸需極寬之頻寬，使得系統需密集的重複使用頻率，因此同頻干擾成為影響系統效能的關鍵因素，又由於用戶使用高指向性之天線，此種干擾造成信號衰減之區域，端視干擾台之位置。
為確實分析在微波頻段之通道效應，本論文首先討論降雨衰減與植被去極化之影響，結果顯示提出之優質的細胞建置規劃可獲致較佳之系統效能。因此運用細胞工程方法(cellular engineering methodologies), 結合區域多點傳輸系統特殊條件，例如雙極化高指向性天線的使用，我們提出細胞群交錯的概念來建置此一固定式網路，並考慮其於分時多工進接與分碼多工進接系統之應用；模擬結果顯示所提出新的細胞架構能有效的降低同頻干擾的影響，且具有極大之基地台配置彈性，同時，由於僅需做好頻道規劃，無須增加硬體設備之額外投資，因此比典型的細胞建置擁有更佳之成效。

The rapid growth of the Internet has increased the demand for broadband services. Users expect high quality, reliability and high-speed communication systems that allow easy access to this resource. Solutions, such as the x-digital subscriber line (x-DSL), which aims at high-bit-rate transmissions over twisted pairs as well as an extension of the existing cable television networks, known as hybrid fiber coaxial (HFC), appears very promising. An alternative technique, the wireless approach to the last mile access is attractive to network operators and service providers because of its reduced deployment time and cost compared to the construction of a wired infrastructure.
LMDS, which typically operates at millimeter-wave frequencies above 20 G Hz, is a two-way digital cellular system that offers a wireless access method to broadband interactive services for point-to-multipoint distribution. In this fixed broadband wireless access network, each cell is divided into multiple sectors, with each served by a sector antenna collocated within the hub. Users supported in these systems employ highly directional antennas and signal polarization to communicate with the hub station. The major advantage of using directional terminal antennas is that a large portion of the interference is attenuated by the antenna front-to-back ratio.
The system performance is limited by the signal strength over individual radio links and the amount of co-channel interference. Besides the severe attenuation of precipitation in millimetre wave band should be considered in link budget calculation, the effect of antenna and depolarisation also should be integrated into the co-channel interference calculation, since dual-polarized LMDS system is proposed to increase spectrum efficiency and high gain antenna is used to reduce interference.
Using cellular engineering methodology, an interleaved cellular pattern, that exploits the high-directivity of the subscriber antenna, is proposed. A cluster-interleaved cellular pattern is proposed by interleaving the cell clusters. The proposed cellular system can be easily developed and without making any additional equipment investment. The coverage performance was investigated by considering high signal propagation impairment for the Taiwan area.
A new cellular architecture, termed extended interleaved twisted cell (EITC),reduces the co-channel interference experienced by users located in strong interference regions. The proposed structure delivers the advantages of the interleaved cell, which manipulates the spectral efficiency of fixed broadband wireless networks. This work presents a new cell structure that combines extended cluster planning to eliminate co-channel interference by exploiting the terminal directional antenna for system deployment. The main benefit of this novel design lies in the directivity of the terminal directional antennas. This allows flexible hub deployment. The extended interleaved twisted cell is simple to implement and requires no extra equipment cost.
A dual-polarized multimode CDMA based LMDS with hexagonal cell architecture is investigated. Various cellular architectures for improving the system performance are discussed. A novel cellular pattern that exploits the interleaving scheme is proposed to reduce the impact of inter-cell interference to enhance the power of the multimode CDMA scheme in this fixed wireless network. By managing the channel polarization used in the service area, no extra equipment investment is required and better system performance is obtained.
Rain attenuation and foliage depolarization play important roles in system deployment. Developing better cellular architecture is an economical approach to enhance spectrum efficiency for LMDS. Results show that the proposed novel cellular system achieves greater improvement for system coverage performance.

[1] D.R. Amitava, “ Bringing home the Internet,” IEEE SPECTRUM, Vol. 36, pp. 32-38, March 1999.
[2] P. Mahonen, T. Saarinen, Z. Shelby and, L. Munoz, “Wireless Internet over LMDS: architecture and experimental implementation,” IEEE Communications Magazine, Vol. 39, pp. 126-132, May 2001.
[3] A. Nordbotten, “ LMDS systems and their application,” IEEE Communications Magazine, Vol. 38, pp. 150-154, June 2000.
[4] G.M. Stamatelos and D.D. Falconer, “ Millimeter Radio Access to Multimedia Service via LMDS,” in Proceedings of Global Telecommunications Conference,1996, pp.1603-1607.
[5] B. Cornaglia, R. Santaniello, E. Leonardi, R.L. Cigno, M. Meo, F. Neri and D. Saracino, “ LMDS System: A Possible Solution for Wireless ATM Access Networks,” in Proceedings of IEEE International Conference on ATM, 1998, pp.41-50.
[6] R.C. Flint, D.D. Zenobio, G. Santella, M. Celidonio and B. Vucetic, “ The CABSINET Project: A Flexible Cellular Broadband Architecture,” in Proceedings of International Zurich Seminar on Broadband Communications, Accessing, Transmission, Networking. 1998, pp.149-154.
[7] I. Frigui and J. Schellenberg, “ Providing Effective Internet Services in the MMDS, LMDS MVDS Environment,” in Proceedings of International Broadcasting Convention, September 1997, pp. 898-94.
[8] P.B. Papazian, G.A. Hufford, R. J. Achatz and R. Hoffman, “Study of The Local Multipoint Distribution Service Radio Channel,” IEEE Transactions on Broadcasting, vol.43, pp.175-184, June 1997.
[9] D.A. Gray, “A Broadband Wireless Access System at 28 G Hz” in Proceedings of Wireless Communication Conference, 1997, pp. 1-7
[10] V.I. Roman, “Frequency Reuse and System Deployment in Local Multipoint Distribution Service” IEEE Personal Communications, pp. 20 –27, 1999.
[11] M. Gagnaire,“ An Overview of Broad-Band Access Technologies,” IEEE Proceeding, Vol. 85, No. 12, pp.1958-1972, 1997.
[12] H. Sari, “ Some Design Issues in Local Multipoint Distribution Systems,” in Proceedings of International Symposium on Signals, Systems, and Electronics, 1998, pp. 13 –19.
[13] H. Bolcskei, A.J. Paulraj, K.V.S. Hari, R.U. Nabar and W.W. Lu, “ Fixed Broadband Wireless Access: State of The Art, Challenges, and Future Directions,” IEEE Communication Magazine, pp. 100-108, 2001.
[14] O. Andrisano, V. Tralli and R. Verdone, “Millimeter Waves for Short-Range Multimedia Communication System”, IEEE Proceeding, vol. 86, pp1383-1401, July 1998.
[15] T.K. Fong, P.S. Henry, K.K. Leung, X. Qiu, N.K. Shankaranarayanan, “ Radio Resource Allocation in Fixed Broadband Wireless Networks,” IEEE Transactions on Communication, Vol.46, pp.806-817, June.1998.
[16] K.K. Leung and A. Srivastava “ Dynamic Allocation of Downlink and Uplink Resource for Broadband Services in Fixed Wireless Networks,” IEEE Journal on Selected Areas in Communications , Vol.17, pp.990-1006, May.1999.
[17] S. Farahvash and M. Kavehrad, “Assessment of Cochannel Interference in Fixed Wireless Cellular Systems,” in Proceedings of Radio and Wireless Conference, 1999, pp. 13 –16.
[18] G. Redaelli, S. Marsili, G. Coppola and G. Girila, “ Performance Evaluation and Link Budget Analysis for 42 GHz Local Multipoint Distribution Systems,” in Proceedings of Global Telecommunications Conference 1997, pp. 2630-2636.
[19] A.Kajiwara, “ LMDS Radio Channel Obstructed by Foliage,” in Proceedings of IEEE International Conference on Communications, 2000. Vo. 3, pp.1583 -1587.
[20] D.A. Gray, “Optimal Hub Deployment for 28 GHz LMDS Systems” in Proceedings of Wireless Communications Conference, 1997, pp. 18 –22.
[21] C.H. Lee; B.Y. Chung; S.H. Lee “Dynamic Modulation Scheme In Consideration of Cell Interference for LMDS” in Proceedings of International Conference on Communication Technology, 1998, vol. 2, pp. 1-5.
[22] N. Morinaga, M. Nakagawa and R. Kohno, “ New Concepts and Technologies for Achieving Highly Reliable and High-capacity Multimedia Wireless Communications Systems,” IEEE Communication Magazine, pp. 34-40, January 1997.
[23] H.R. Anderson, “ Simulations of Channel Capacity and Frequency Reuse in Multipoint LMDS Systems,” in Proceedings of IEEE Radio and Wireless Conference, 1999, pp.9-12.
[24] S.W. Wang and S.S. Rappaport, “ Signal-to-Interference Calculations for Balanced Channel Assignment Patterns in Cellular Communications System,” IEEE Transactions on Communications, vol. 37, pp. 1077 –1087, October 1989.
[25] S.W. Wang and S.S. Rappaport, “ Signal-to-Interference Calculations for Corner-Excited Cellular Communications System,” IEEE Transactions on Communications, vol. 39, pp. 1886 –1896, December 1991.
[26] L.C. Wang, K.K. Leung, “ A High-capacity Wireless Network by quad-sector Cell and Interleaved Channel Assignment,” IEEE Journal on Selected Areas in Communications, pp. 472-480, March 2000.
[27] O.W. Ata, H. Seki and A. Paulraj, “ Capacity Enhancement in Quad-Sector Cell Architecture with Interleaved Channel and Polarization Assignments,” in Proceedings of IEEE International Conference on Communications, 2001, pp.2317-2321.
[28] I. Islam and S. Hossain, “ Optimum Cell-site Positioning Model for Cellular Network by Grid Line Shifting Method,” in Proceedings of the IEEE Region 10 Conference, pp.2317-2321.
[29] S. Faruque, “ Science, Engineering and Art of Cellular Network Deployment,” in Proceedings of The Ninth IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, 1998, pp.313-317.
[30] O.C. Yue, “ Design Trade-Offs in Cellulaar/PCS Systems,” IEEE Communications Magazine, pp. 146-152, September 1996.
[31] William C.Y. Lee, “ Elements of Cellular Mobile Radio Systems,” IEEE Transactions on Vechicular Technology, Vol.35, pp.48-56, May.1986.
[32] G.K. Chan, “ Effects of Sectorization on the Spectrum Efficiency of Cellular Radio Systems” IEEE Transactions on Vehicular Technology, Vol.41, pp.217-225, Aug.1992.
[33] L.C. Wang, G.L. Stuber and C.T. Lea, “ Architecture design, frequency planning, and performance analysis for a microcell/macrocell overlaying system,” IEEE Transactions on Vehicular Technology, no. 4, pp. 836-848, 1997.
[34] B.C. Jones and D.J. Skellern, “Derivation of Cochannel and Adjacent Channel Reuse Ratio Distributions in DCA Cellular Systems,” IEEE Transactions on Vehicular Technology, vol. 49no. 1, pp. 50-62, 2000.
[35] Q.T. Zhang, “ Bridging the Gap Between Dynamic and Static Methods for Cell Planning,” IEEE Transactions on Vehicular Technology, no. 5, pp. 1224-1230, 1997.
[36] R. Pattuelli and V. Zingarelli, “ Precision of the Estimation of Area Coverage by Planning Tools in Cellular Systems,” IEEE Personal Communication, pp. 50-53, June 2000.
[37] J.F. Arnaud,” Frequency Planning for Broadcast Service in Europe,” IEEE Proceedings, vol. 68, pp1515-1522, December 1980.
[38] K.I. Kim, “CDMA Cellular Engineering Issues,” IEEE Transactions on Vehicular Technology, vol. 42, no. 3, pp. 345-350, August 1993.
[39] H. Seki, O.W. Ata and A. Paulraj, “ Effect of Customer Premises Directional Antennas on Fixed Wireless Access System in the Downlink Multipath Channel,” in Proceedings of IEEE International Conference on Communications 2001, pp. 2312-2316.
[40] G.L. Stuber, Principles of Mobile Communication, Kluwer Academic, 2001.
[41] A.R. Johnson, “ Frequency Planning and System Design of Wide-area Coverage Cellular Radio Systems,” in Proceedings of 3rd AFRICON Conference, 1992
pp. 162 –165.
[42] T.M. Ko, “ A frequency selective insertion strategy for fixed channel assignment,” IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, 1994 pp. 311 –314.
[43] P.F. Delli , N.P. Magnani, V. Palestini, F. Sestini, “ Application of dynamic channel allocation strategies to the GSM cellular network, ” IEEE Journal on Selected Areas in Communications, vol. 15, pp. 1558-1567, Oct. 1997.
[44] K. Kennedy, E. de Vries, P. Koorevaar, “ Performance of a distributed DCA algorithm under inhomogeneous traffic modelled from an operational GSM network ” IEEE Conference on Vehicular Technology, 1998, pp. 1085 -1090.
[45] N.E. Daly, T.C. Tozer, D.A.J. Pearce, D. Grace and A.G. Burr, “ Capacity Effects on Terrestrial Broadband Wireless Access Networks, Operating in the LMDS Frequency Band, During Rainfall Conditions,” in Proceedings of Vehicular Technology 2000, pp. 2444 –2448.
[46] J.T.Ong, Y.K. Choo, S.P.Zhang, “Rain Rate and Attenuation Prediction Model for Singapore” in Proceedings of Ninth International Conference Antennas and Propagation, 1995, pp. 81 –84.
[47] W.L. Flock, Propagation Effects on Satellite Systems as Frequencies Below 10 G Hz, NASA Reference Publication, 1987.
[48] S.M.R. Jones and P.A. Watson, “ Attenuation and Countermeasures in Millimeter-wave Point-to-multipoint Networks,” Radio Science, vol. 28, no. 6, pp. 1057-1069, 1993.
[49] H. Vasseur, “Degradation of Availability Performance in Dual-Polarized Satellite Communication System” IEEE Transactions on Communications, vol.48, no. 3, pp. 465-472, March. 2000.
[50] R.L. Olsen, “ Cross Polarization During Clear-air Conditions on Terrestrial Links: A Review,” Radio Science, vol. 16, no. 5, pp. 631-647, 1981.
[51] R.L. Olsen, “ Cross Polarization During Precipitation on Terrestrial Links: A Review,” Radio Science, vol. 16, no. 5, pp. 761-779, 1981.
[52] K.V. Cartwright, P.F. Duvoisin, S.T. Hsieh and E.P. Williamson, “ Steady-State Performance of the Adaptive MLD Receiver in Dual-Polarized 16-QAM Systems with Crosstalk,” in Proceedings of Energy and Information Technologies in the Southeast IEEE, 1989, pp.911-918.
[53] M.K. Tsay and F.T. Wang, “A Study of Fixed Wireless Cellular System Operating at Ka Band,” in Proceedings of Asia-Pacific Conference on Communications, Tokyo, Japan, September 2001, pp. 288-291.
[54] V. Erceg, L.J. Greenstein, S.Y. Tjandra, S.R. Parkoff, A. Gupta B. Kulic, A. A. Julius and R. Bianchi, “An Empirically Based Path Loss Model for Wireless Channels in Suburban Environments,” IEEE Journal on Selected Areas in Communications, vol. 17, pp. 1205-1211, July 1999.
[55] G. Durgin, T.S. Rappaport, Hao Xu “Measurements and Models for Radio Path Loss and Penetration Loss In and Around Homes and Trees at 5.85 GHz,” IEEE Transactions on Communications, vol. 46, pp. 1484 –1496, Nov. 1998.
[56] X. Hao, T.S. Rappaport, R.J.Boyle, J.H. Schaffner, “Measurements and Models for 38-GHz Point-to-Multipoint Radiowave Propagation,” IEEE Journal on Selected Areas in Communications, volume. 18, March 2000, pp. 310 –321.
[57] J. D. Parsons, The Mobile Radio Propagation Channel. John Wiley & Sons, 1991
[58] J.W.F.Goddard, M.Thurai, “Radar-derived Path Reduction Factors for Terrestrial Systems” in Proceedings of Tenth International Conference on Antennas and Propagation, vol. 2, 1997, pp. 218 –221.
[59] ITU-R P.530, Propagation Data and Prediction Methods Required for the Design of Terrestrial Line-of-Sight Systems.
[60] R. K. Crane, “ Prediction of Attenuation by rain,” IEEE Transactions on Communications, no. 9, pp. 1717-1733, 1980.
[61] A. Disssanayake, J. Allnutt and F. Haidara, “ A Prediction Model that Combines Rain Attenuation and Other Propagation Impairments along Earth-Satellite Paths,” IEEE Transactions on Antenna and Propagation., no. 10, pp. 1546-1559, 1997.
[62] S.P. Shih and Y.H. Chu, “ Ka Band Propagation Experiments of Experimental Communication Payload (ECP) on ROCSAT-1 – Preliminary Results,” TAO, pp. 145-164, 1999.
[63] A. Paraboni, G. Masini and A. Elia, “ The Effect of Precipitation on Microwave LMDS Networks – Performance Analysis Using a Physical Raincell Model,” IEEE Journal on Selected areas in Communications, no. 3, pp. 615-619, 2002.
[64] F.T. Wang and M.K. Tsay, “Twisted Sector Cellular in Fixed Broadband Networks,” in Proceedings of the 7-th Asia-Pacific Conference on Communication, Tokyo, Japan, September 2001, pp. 533 –537.
[65] L.C. Wang, G.L, “ A New Cellular Architecture Based on an Interleaved Cluster Concept,” IEEE Transactions on Vehicular Technology, no. 6, pp. 1809-1818, 1999.
[66] M.D Yacoub, A.F. de Toledo, P.R.C. Gomez, P.J.E. Jeszensky and E.B.R. Feris, “ Reuse Pattern for Microcellular Networks,” International Journal of Wireless Information Networks, no. 1, pp. 1-7, 1999.
[67] Air Interface for Fixed Broadband Wireless Access System, Sept.2000.
[68] H. Stellakis et al., "Reverse link performance of wireless local loop CDMA systems," IEEE Commun. Lett., vol. 4, pp.49-51, Feb. 2000.
[69] H. Sari, “ A Multimode CDMA scheme with Reduced Intercell Interference for LMDS Networks,” in Proceedings of Broadband Communications Conference, 2000, pp. 307 -312.
[70] H. Sari, "A Multimode CDMA Scheme with Reduced Intercell Interference for LMDS Networks," IEEE Journal on Selected Areas in Communications, vol. 19, pp 1316-1323, July. 2000.
[71] W. S. Kim, “ New Frequency Planning of CDMA System for Adaptive Traffic Control,” in Proceedings of 48th IEEE Vehicular Technology Conference, 1998, pp. 1351-1355.
[72] M. K. Tsay and F. T. Wang, “A Dual-polarized Multimode CDMA Based Local Multipoint Distribution System Cellular,” accepted by IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences.
[73] M. K. Tsay and F. T. Wang, “ Cellular Architecture on CDMA Based LMDS, ” accepted by International Symposium on Communication Systems, Networks and Digital Signal Processing, Staford, England, July, 2002.
[74] K. C. Chen, M. K. Tsay, “ Radio propagation characteristics at Ka and Ku band ”, prepared NSC Report, 2002.
[75] J. G. Proakis, Digital Communication. McGraw-Hill, 1989.
[76] Skolnik, M. Ivan, Introduction to Radar Systems, McGraw-Hill, 1978.
[77] C.A. Balanis, Antenna Theory-Analysis and Design, 1982.
[78] H.J. Im, W. Hwang, S. Choi and H. Kim, “Performance Analysis of A Smart Antenna System Utilizing a Test-bed Implemented on A DSP Board,” in Proceedings of Asia-Pacific Microwave Conference, 2000, pp. 799 –803.
[79] M. Chryssomallis, “ Smart Antenna,” IEEE Antenna and Propagation Magazine, no. 3, pp. 129-136, 2000.
[80] R.D. Murch and K.B. Letaief, “ Antenna System for Broadband Wireelss Access,” IEEE Communications Magazine, pp. 76-83, April 2002.
[81] S. Kurosaki, M. Hiraki and S. Aikawa, “ A Smart Multiple Sector Antennas Control Technique for A High-speed ATM Wireless Access System Using 25 GHz Band,” in Proceedings of Vehicular Technology Conference, 1999 IEEE, pp. 458–462.
[82] R.C. Bernhardt, “ Macroscopic Diversity in Frequency Reuse Radio Systems,” IEEE Journal on Selected Areas in Communications, Vol.SAC-5, pp.862-870, June.1987.
[83] D. Lee and C. Xu, “The Effect of Narrowbeam Antenna and Multiple Tiers on System Capacity in CDMA wireless Local Loop,” IEEE Communication Magazine, pp. 110-114, September 1997.