MULTIPLE ACCESS FOR BROADBAND WIRELESS NETWORKS Beyond 3G: Wideband wireless Data Access based on OFDM and dynamic Packet assignment Justin Chuang and Nelson Sollenberger, AT&T Labs-Research ABSTRACT sion capabilities, increasingly demanding Internet applications and user expectations have emerg The rapid growth of wireless voice sub- Experience with laptop computers and personal scribers, the growth of the Internet, and the digital assistants(PDAs) has shown that many Icreasing use of portable computing devices end users desire their portable equipment to pro- rapidly over the next few years. Rapid progress cations they enjoy at their desks with fer in digital and RF technology is making possible compromises. Experience with wireless access has highly compact and integrated terminal devices, demonstrated the singular importance of ere data software is making wireless Internet access access. Wireless packet data access in macrocell- more user-friendly and providing more value. lar environments at peak rates beyond 2 Mb/s is Transmission rates are currently only about 10 likely to be needed in the near future to provide kb/s for large cell systems. Third-generation users with an application environment with few wireless access such as WCDMA and the evolu- compromises from fixed environments. Chal ion of second-generation systems such as lenges for the high-speed wireless data access TDMA IS-136+, EDGE, and CDMA IS-95 will future are transmission speeds at 100-1000 times provide nominal bit rates of 50-384 kb/s in existing rates; costs of a few cents per minute for macrocellular systems. [1 This article discusses access; RF power transmission efficiency that is packet data transmission rates of 2-5 Mb/s in 10-20 dB better than existing systems; and sub- macrocellular environments and up to 10 Mb/s stantially increased spectral efficiency in microcellular and indoor environments as a Two important business drivers for comple complementary service to evolving second-and mentary packet data access at speeds above 2 hird-g tion wireless D Mb packet assignment for high-efficiency resource Integration of wireless data services across management and packet admission; OFDM macrocellular, microcellular, and private the physical layer with interference suppression, indoor systems, and with other services d fre diversity;as·High efficiency well as smart antennas to obtain good power Wireless service providers pay dearly to acqui and spectral efficiency are discussed in this pro- spectrum. Efficiency of spectrum usage is always posal. Flexible allocation of both large and a strong factor in a decision on wireless technol small resources also permits provisioning of ogy Spectrum efficiency becomes crucial for services for different delay and throughput very high-speed data services(e. g,>2 Mb/s) requirements. By taking advantage of improvements in digital signal processing(DSP)and radio frequency INTRODUCTION (RF) technologies, orthogonal frequency-divi- sion multiplexing(OFDM) provides the possibil- wireless Internet access is expected to grow rapid- ity to provide 2 Mb/s packet data at a cost an ly, because of the maturing of digital cellular, with a spectrum efficiency that allow wireles portable computing, and fixed Internet technolo- providers to compete with wireline carriers for gies Data transmission rates are growing rapidly data services Integrated services also provid in fixed networks with the use of wavelength-divi- significant billing advantages for both customers sion multiplexing(WDM) in backbone fiber net- and service providers. Based on customers' pref works and the introduction of cable modems and erences, telecommunications companies such high-speed digital subscriber line(HDSL) technol- AT&T are moving in the direction of delivering ogy in the fixed access networks In parallel with tegrated services which cover local residential the expanding availability of high-speed transmis- and business, long distance, and both wireline 0163-68040010002000IEEE IEEE Communications Magazine. July 200078 IEEE Communications Magazine • July 2000 Beyond 3G: Wideband Wireless Data Access Based on OFDM and Dynamic Packet Assignment 0163-6804/00/$10.00 © 2000 IEEE ABSTRACT The rapid growth of wireless voice sub￾scribers, the growth of the Internet, and the increasing use of portable computing devices suggest that wireless Internet access will rise rapidly over the next few years. Rapid progress in digital and RF technology is making possible highly compact and integrated terminal devices, and the introduction of sophisticated wireless data software is making wireless Internet access more user-friendly and providing more value. Transmission rates are currently only about 10 kb/s for large cell systems. Third-generation wireless access such as WCDMA and the evolu￾tion of second-generation systems such as TDMA IS-136+, EDGE, and CDMA IS-95 will provide nominal bit rates of 50–384 kb/s in macrocellular systems. [1] This article discusses packet data transmission rates of 2–5 Mb/s in macrocellular environments and up to 10 Mb/s in microcellular and indoor environments as a complementary service to evolving second- and third-generation wireless systems. Dynamic packet assignment for high-efficiency resource management and packet admission; OFDM at the physical layer with interference suppression, space-time coding, and frequency diversity; as well as smart antennas to obtain good power and spectral efficiency are discussed in this pro￾posal. Flexible allocation of both large and small resources also permits provisioning of services for different delay and throughput requirements. INTRODUCTION Wireless Internet access is expected to grow rapid￾ly, because of the maturing of digital cellular, portable computing, and fixed Internet technolo￾gies. Data transmission rates are growing rapidly in fixed networks with the use of wavelength-divi￾sion multiplexing (WDM) in backbone fiber net￾works and the introduction of cable modems and high-speed digital subscriber line (HDSL) technol￾ogy in the fixed access networks. In parallel with the expanding availability of high-speed transmis￾sion capabilities, increasingly demanding Internet applications and user expectations have emerged. Experience with laptop computers and personal digital assistants (PDAs) has shown that many end users desire their portable equipment to pro￾vide essentially the same environment and appli￾cations they enjoy at their desks with few compromises. Experience with wireless access has demonstrated the singular importance of widespread coverage and anywhere/anytime access. Wireless packet data access in macrocellu￾lar environments at peak rates beyond 2 Mb/s is likely to be needed in the near future to provide users with an application environment with few compromises from fixed environments. Chal￾lenges for the high-speed wireless data access future are transmission speeds at 100–1000 times existing rates; costs of a few cents per minute for access; RF power transmission efficiency that is 10–20 dB better than existing systems; and sub￾stantially increased spectral efficiency. Two important business drivers for comple￾mentary packet data access at speeds above 2 Mb/s are: • Integration of wireless data services across macrocellular, microcellular, and private indoor systems, and with other services • High spectrum efficiency Wireless service providers pay dearly to acquire spectrum. Efficiency of spectrum usage is always a strong factor in a decision on wireless technol￾ogy. Spectrum efficiency becomes crucial for very high-speed data services (e.g., > 2 Mb/s). By taking advantage of improvements in digital signal processing (DSP) and radio frequency (RF) technologies, orthogonal frequency-divi￾sion multiplexing (OFDM) provides the possibil￾ity to provide > 2 Mb/s packet data at a cost and with a spectrum efficiency that allow wireless providers to compete with wireline carriers for data services. Integrated services also provide significant billing advantages for both customers and service providers. Based on customers’ pref￾erences, telecommunications companies such as AT&T are moving in the direction of delivering integrated services which cover local residential and business, long distance, and both wireline Justin Chuang and Nelson Sollenberger, AT&T Labs-Research MULTIPLE ACCESS FOR BROADBAND WIRELESS NETWORKS