CDMA and OFDM - The Convergence of Wireless Mobile Services

By Setyo Budianto

Up until the end of the 20th century, there was a fairly clear division between the cellular industry and other telecommunication industries which offered basic telephone, television, radio, computer and Internet services. Most mobile operators used second generation (2G) digital wireless technologies to enable voice communications and limited data services, while most wireline, cable and satellite systems provided the bulk of the other telecommunication services. In spite of its initial limitations, cellular communications has been a tremendous success, surpassing fixed line connections worldwide in 2001,just 12 years after its market introduction. This has been especially evident in developing markets where, due to its lower deployment costs and greater network flexibility, wireless technologies have become the primary means of communication for millions of people, spurring the economic and social development of these markets.

Since the beginning of the 21st century, there has been a dramatic shift in the market dynamics of telecommunications services. With the introduction of third generation (3G) IMT-2000 technologies based on CDMA, wireless operators have been able to offer high-quality voice services as well as broadband Internet access and multimedia services, blurring the boundaries between the telecom industries. Service providers and regulators across both developed and developing markets have been quick to adopt and promote the technologies. As a result, a tremendous momentum has been built behind the deployment and adoption of the 3G CDMA services. In the 7 years since its introduction in 2000, over 460 operators have launched CDMA2000 and WCDMA systems surpassing a half a billion users by September 2007. The adoption of 3G mobile broadband technologies, such as CDMA2000 1xEV-DO and HSPA, has also accelerated, reaching 270 commercial systems serving more than 100 million users in 165 countries.

Yet again, the wireless industry stands at the crossroads of selecting capabilities and services to take it well into the future. These new dimensions include: the proliferation of voice, video, television, broadband Internet and value-added data services; integration amongst wireless and fixed networks to enable the seamless delivery of these services over multiple networks; improved user experience and economics, and; convergence of industries such as telecommunications, information and broadcasting.

The next-generation of IMT systems based on CDMA and Orthogonal Frequency Division Multiple (OFDM) technologies, along with OFDM-based broadcast technologies such as DVB-H, FLO and ISDB-T, will be key enablers of this transition. In particular, CDMA2000 EV-DO Revision B (Rev. B), HSPA+, Ultra Mobile Broadband (UMB), Long Term Evolution (LTE), and Mobile WiMAX (802.16m) are capable of providing the performance characteristics that will support multi-megabit-per-second data delivery to users, carrier-grade VoIP and other real-time and broadband intensive applications (Figure 1).

With significant market momentum and large economies of scale and scope, 3G CDMA technologies will continue to be the leading platform for mobile communications, including next-generation broadband services, well beyond the year 2020. Nevertheless, some incumbent operators and new service providers are considering the purchase of additional spectrum and deployment OFDM-based systems.

Regardless of the operator's approach and existing technology roadmap, it is becoming evident that a "one network fits all" strategy will not suffice in future competitive markets. Selecting alternate technologies will be very dependent upon an operator's unique set of circumstances, including market opportunities, assigned licenses, available spectrum, previous technology selections, vendor relationships and propensity for risk. In other words, service providers will choose the path and technologies that best meets their market and economic requirements.

From its inception, the CDMA technology roadmap has provided operators with technology-leading performance capabilities and a time-to-market advantage. Thanks to CDMA's forward-and-backward compatible technology upgrades within the 1.25 MHz CDMA radio channel, CDMA operators have benefited from the favorable economics of an evolutionary "in-band" solution. As a result they have been able to deploy new technologies and value-added services throughout their entire network much faster than their competitors.

The CDMA2000 family of technologies is strongly positioned to remain a vital component of the convergence revolution. With the commercial availability of CDMA2000 1xEV-DO Revision A(Rev. A) in 2006 and multi-carrier EV-DO, or EV-DO Revision B (Rev. B) in 2008 to provide additional capacity via a simple software upgrade, CDMA2000 operators will be able to offer multi-megabit-per-second average data rates to individual users while leveraging the large economies of scale and scope that the CDMA2000 industry offers.

OFDM-based solutions will be built-out over time as the demand for high-capacity broadband services grows and wider bandwidth spectrum becomes available. Meanwhile, 3G CDMA solutions will coexist with these higher-bandwidth OFDM-based solutions until OFDM-based technologies are fully capable of delivering an equivalent or better value proposition to the end user, including ubiquitous coverage, compelling broadband services, carrier-grade VoIP replacing circuit-switched voice services, affordable devices, global roaming and an improved profitability for operators.

It is expected that the coexistence of CDMA and OFDM-based solutions will persist well beyond 2020. Until then, 3G CDMA-based solutions will remain the core business for hundreds of operators. Once the adoption criteria are met, the more than 3-4 billion wireless subscribers in the world will begin migrating to the newer generation of wireless technologies. With an ever increasing subscriber base, the migration process is lengthening.

The "one technology fits all" approach will not suffice in the future competitive telecommunications market. Instead, operators will leverage the most appropriate technology for a particular application or service. Bluetooth will support the personal area network, NFC will enable mobile commerce, Wi-Fi will satisfy local area network connectivity, GPS will enable presence and location-based services, 2G and 3G cellular technologies will provide ubiquitous voice and broadband data services, and OFDM-based technologies will provide large amounts of bandwidth for backhaul, broadcast and broadband applications in "hot-zones."

For most operators, 3G CDMA-based technologies will be more than sufficient for their voice and broadband data requirements for the at least a decade. For those operators that require higher amounts of bandwidth especially in high-traffic areas, OFDM-based technologies offer certain economic benefits and will enable them to complement their services, features and coverage. In most instances, however, 3G CDMA will remain the leading and most economical platform for the delivery of mobile broadband services.

OFDM-based solutions will be built-out over time as the demand for broadband services grows and spectrum becomes available. Mass adoption of these wide-bandwidth OFDM-based solutions will take years, as coverage is expanded and economies of scale are built. Meanwhile, CDMA2000 will continue to be the core business for hundreds of operators for well over a decade and play a key role in the future of the wireless industry.