technology discussed here can provide rates with robust performance that is not ach ble in second-or third- generation technologies r,it is a less mature technology th requires more research and development effort 160 邮业 CoNCLUSIONS erference suppressio Peak bit rates of 2-5 Mb/s are likely to be desir- interference suppression able for future packet wireless data service for Internet applications with widespread macrocell- Adaptive modulation will where/anytime access maximum efficiency and allow for the more limit ed transmit levels of portable terminals The 5 MHz channelization discussed can cket data bit rates of 2-5 Mb/s in macrocellular 1000 environments in a complementary ket data Delivered bit rate per cell(kb/s) mode Bit rates up to 10 Mb/s can be supported in microcellular and indoor environments using Figure 8. Average delay of the delivered packets as a function of the through ace-time coding with two transmit and two put per base stati receive antennas Space-time coding may also be applicable in macrocellular environments. Private indoor systems should probably use unlicensed 16V. Tarokh, N Seshadri, and A.R. Calderbank,"Space- spectrum for hig igh-speed wireless data access, because of the need for large amounts of spec- Performance cr vol.44,Mar.1998 trum and emerging wireless LAN standards, [7Y(Geoffrey)Li and N R Sollenberger, "Adaptive based on OFDM. Dynamic packet assignment, erference, " IEEE Trans. Commun., vol. 47, no. 2, Feb 999,pp.217-2 OFDM physical layer, adaptive modulation and [8]GJ Pottie, "System Design oding, space-time coding and interference sup- techniques to provide wideband OFDM packet 9]J.C.-. and N.R. Sollen be wireless data access in macrocellular and micro Resource Allocation for wireless pack pplication to Advanced Cellular Intern cellular environments. The target bit rates are JSAC, voL. 16, no. 6, Aug. 1998, pp. 82 ubstantially higher than what third-generation stems can achieve in macrocellular environ BIOGRAPHIES nents, and can reduce the gap between wireline andwirelessdataratesandapplications.AreasJusTInC-L.HUANGFustin@research.att.com)receiveda for further study include receiver structures and implementations, resource assignment, and Qos provisioning for mixed services, as well as many he was with GE Corporate Research and Development, Sch other issues not discussed here obile dy, New York, where he studied personal and ACKNOWLEDGMENTS Bellcore(now Telcordia Technologies), Red Bank, New Jer- The concepts in this article are based on the work 993 to 1996 he was with the electrical and Electron and ideas of a number of colleagues within AT&T Engineering Department of the Hong Kong University of Greenstein contributed to concepts on microcells. tions ing June 1996 he returned to the United States and Len Cimini and Ye li contributed to the oFdm joined AT&T Labs-Research in New Jersey, where he is now techniques that were discussed. Vahid Tarokh, a technology leader in the Wireless Systems Research Nambi Seshadri, and Rob Calderbank contribut- Department, involved in creating technologies to provide ed to space-time coding concepts. Hong Zhao reliable services on wireless platt contributed to concepts for applications and tor for Wireless Communications for IEEE Transactions requirements for high-speed data services Communications. He is a member of phi Kappa phi REFERENCES NELSONSoLLENBERGER(FI(nelson@research.att.com)heads t at at&t. h [1]T. oj [2]L. J. Cimini, Jr, "Analysis and Simulation of a Digital rocessing, system architectures, and radio link techniques 7.Juy1985pp.665-75 [3] L.J. Cimini, Jr, J. C-L. Chuang, and N. R Sollenberger (ae, boh ind electrica en ineerin t from 1979 threse Advanced Cellular Internet Service, "IEEE Commun. 1986 he was a member of the cellular radio developme Mag,oct.1998,pp.1509 where he investigated EDGE with Wideban I5I roy so ora tioe MTM e Thes Mal ale A ce s scheme of thait department tfom iss to 1995. At ellcore he. (UTRA), ETSI SMG2, London, U.K., June 23-27, 1997 munications System. In 1995 he joined AT&T IEEE Communications Magazine. Jul 87IEEE Communications Magazine • July 2000 87 technology discussed here can provide high peak rates with robust performance that is not achiev￾able in second- or third-generation technologies. However, it is a less mature technology that requires more research and development effort. CONCLUSIONS Peak bit rates of 2–5 Mb/s are likely to be desir￾able for future packet wireless data service for Internet applications with widespread macrocel￾lular coverage to enable anywhere/anytime access. Adaptive modulation will be important to achieve maximum efficiency and allow for the more limit￾ed transmit power levels of portable terminals. The 5 MHz channelization discussed can support packet data bit rates of 2–5 Mb/s in macrocellular environments in a complementary packet data mode. Bit rates up to 10 Mb/s can be supported in microcellular and indoor environments using space-time coding with two transmit and two receive antennas. Space-time coding may also be applicable in macrocellular environments. Private indoor systems should probably use unlicensed spectrum for high-speed wireless data access, because of the need for large amounts of spec￾trum and emerging wireless LAN standards, including the IEEE 802.11 standard at 5 GHz based on OFDM. Dynamic packet assignment, an OFDM physical layer, adaptive modulation and coding, space-time coding and interference sup￾pression, and smart antennas are proposed as techniques to provide wideband OFDM packet wireless data access in macrocellular and micro￾cellular environments. The target bit rates are substantially higher than what third-generation systems can achieve in macrocellular environ￾ments, and can reduce the gap between wireline and wireless data rates and applications. Areas for further study include receiver structures and implementations, resource assignment, and QoS provisioning for mixed services, as well as many other issues not discussed here. ACKNOWLEDGMENTS The concepts in this article are based on the work and ideas of a number of colleagues within AT&T as well as others. Lek Ariyavisitakul and Larry Greenstein contributed to concepts on microcells. Len Cimini and Ye Li contributed to the OFDM techniques that were discussed. Vahid Tarokh, Nambi Seshadri, and Rob Calderbank contribut￾ed to space-time coding concepts. Hong Zhao contributed to concepts for applications and requirements for high-speed data services. REFERENCES [1] T. Ojanpera and R. Prasad, “An Overview of Air Inter￾face Multiple Access for IMT-2000/UMTS,” IEEE Com￾mun. Mag., vol. 36, no. 9, Sept. 1998, pp. 82–95. [2] L. J. Cimini, Jr., “Analysis and Simulation of a Digital Mobile Channel Using Orthogonal Frequency Division Multiplexing,” IEEE Trans. Commun., vol. COM-33, no. 7, July 1985, pp. 665–75. [3] L. J. Cimini, Jr., J. C.-I. Chuang, and N. R. Sollenberger, “Advanced Cellular Internet Service,” IEEE Commun. Mag., Oct. 1998, pp. 150–9. [4] J. C.-I. Chuang et al., “High-Speed Wireless Data Access based on Combining EDGE with Wideband OFDM,” IEEE Commun. Mag., Nov. 1999, pp. 92–8. [5] Sony Corporation, “BDMA, The Multiple Access Scheme Proposal for the UMTS Terrestrial Radio Air Interface (UTRA),” ETSI SMG2, London, U.K., June 23–27, 1997. [6] V. Tarokh, N. Seshadri, and A. R. Calderbank, “Space￾Time Codes for High Data Rate Wireless Communica￾tions: Performance Criterion and Code Construction,” IEEE Trans. Info. Theory, vol. 44, Mar. 1998, pp. 744–65. [7] Y. (Geoffrey) Li and N. R. Sollenberger, “Adaptive Antenna Arrays for OFDM Systems with Co-Channel Interference,” IEEE Trans. Commun., vol. 47, no.2, Feb. 1999, pp. 217–29. [8] G. J. Pottie, “System Design Choices in Personal Com￾munications,” IEEE Pers. Commun., vol. 2, no. 5, Oct. 1995, pp. 50–67. [9] J. C.-I. Chuang and N. R. Sollenberger, “Spectrum Resource Allocation for Wireless Packet Access with Application to Advanced Cellular Internet Service,” IEEE JSAC, vol. 16, no. 6, Aug. 1998, pp. 820–29. BIOGRAPHIES JUSTIN C.-I. CHUANG [F] (justin@research.att.com) received a B.S. degree (1977) from National Taiwan University, and M.S. (1980) and Ph.D. (1983) degrees from Michigan State University, all in electrical engineering. From 1982 to 1984 he was with GE Corporate Research and Development, Sch￾enectady, New York, where he studied personal and mobile communications. From 1984 to 1993 he was with Bellcore (now Telcordia Technologies), Red Bank, New Jer￾sey, as a member of the Radio Research Department. From 1993 to 1996 he was with the Electrical and Electronic Engineering Department of the Hong Kong University of Science and Technology (HKUST), where he established the teaching and research program in wireless communica￾tions. In June 1996 he returned to the United States and joined AT&T Labs-Research in New Jersey, where he is now a technology leader in the Wireless Systems Research Department, involved in creating technologies to provide reliable services on wireless platforms. He continues to serve as an adjunct professor of HKUST. He is the Area Edi￾tor for Wireless Communications for IEEE Transactions on Communications. He is a member of Phi Kappa Phi. NELSON SOLLENBERGER [F] (nelson@research.att.com) heads the Wireless Systems Research Department at AT&T. His department performs research on next-generation wireless systems concepts and technologies, including high-speed transmission methods, smart antennas and adaptive signal processing, system architectures, and radio link techniques to support wireless multimedia and advanced voice ser￾vices. He received his Bachelor’s degree from Messiah Col￾lege (’79) and his Master’s degree from Cornell University (81), both in electrical engineering. From 1979 through 1986 he was a member of the cellular radio development organization at Bell Laboratories, where he investigated spectrally efficient analog and digital technologies for sec￾ond-generation cellular radio systems. In 1987 he joined the radio research department at Bellcore, and was head of that department from 1993 to 1995. At Bellcore he investigated concepts for PACS, the Personal Access Com￾munications System. In 1995 he joined AT&T. ■ Figure 8. Average delay of the delivered packets as a function of the through￾put per base station. Average delay of delivered packets (ms) Delivered bit rate per cell (kb/s) 80 40 160 120 200 0 0 1000 2000 3000 No beamforming, no interference suppression Beamforming, no interference suppression No beamforming, interference suppression Beamforming, interference suppression