In the December 6 and December 20 editions of Mobile & Wireless UPDATE, I looked at several features of third-generation (3G) wireless networks and what this emerging technology will mean for carriers and users alike. To wrap up this series, I want to examine existing wireless technology and the migration path that most carriers will probably use to get to 3G. Because I don't have room to discuss all carriers here, I'll focus on the primary US-based carriers. Most European carriers will follow the Global System for Mobile Communication (GSM) path, and most carriers in the Asia and Pacific region will either use GSM or Code Division Multiple Access (CDMA).
As I mentioned last time, two main technology standards are emerging for 3G wireless networks. Both standards are based on CDMA technology for sharing spectrum—one uses CDMA2000 and the other uses Wideband CDMA (WCDMA)/Unified Mobile Telephony System (UMTS). CDMA-based technology has advantages over current Time Division Multiple Access (TDMA)-based technology because CDMA uses a code, rather than a dedicated time slot, to split the spectrum. Of course, splinter technologies exist; for example, the Japanese carrier NTT DoCoMo is currently rolling out a different 3G technology called Freedom of Multimedia Access (FOMA), which is based on WCDMA, but I doubt that the phones will work transparently with 3G technologies. Most carriers worldwide will use CDMA2000 or WCDMA/UMTS technology and not FOMA.
So what direction will carriers take when migrating to 3G? To begin, Qualcomm and the current 2G CDMA carriers will use CDMA2000 technology. To get to CDMA2000, carriers must first move to Radio Transmission Technology (1xRTT). 1xRTT is a 2.5G step that uses 1.25MHz of spectrum and allows data speeds as fast as 144Kbps. To implement full 3G wireless networks, carriers will implement CDMA2000 3xRTT technology to allow speeds as fast as 432Kbps (3 x 144Kbps). This step requires three 1.25MHz bands of spectrum. Carriers that can use three different spectrum bands will have an advantage, especially in the US market, which has tight limitations on the availability of spectrum for 3G use.
Most GSM carriers are moving toward WCDMA/UMTS. WCDMA/UMTS uses 5MHz of spectrum for all 3G services. Current GSM networks are based on TDMA, and carriers moving toward WCDMA/UMTS are moving away from TDMA. Current GSM carriers will first move to general packet radio service (GPRS), with speeds as fast as 112Kbps, and possibly move to Enhanced Data for GSM Evolution (EDGE), which increases data speeds beyond 112Kbps, before migrating fully to WCDMA/UMTS in the next few years. One disadvantage of WCDMA/UMTS is that it requires a full 5MHz of spectrum (hence the name wideband), which can't be broken up into smaller spectrum bands.
Here's a summary of the main technologies that carriers are using, as well as the carriers' migration paths to 3G:
- GSM (e.g., VoiceStream, Cingular) -> GSM/GPRS/EDGE -> WCDMA/UMTS
- TDMA/CDPD (e.g., AT&T Wireless) -> GSM/GPRS/EDGE -> WCDMA/UMTS
- IDEN (e.g., Nextel) -> Unknown Migration Path (Possibly CDMA2000)
- CDMA (e.g., SprintPCS, Verizon) -> CDMA2000 1xRTT -> CDMA2000 3xRTT
As you can see, carriers have many options. In the United States, carriers will start implementing 3G in 2002. From the user's perspective, knowing that 3G will provide better coverage, more reliable calls, full voice and data integration, and higher bandwidth for wireless data applications is important.
Finally, I hope everyone has a happy and successful 2002. Stay tuned for the latest information about mobile and wireless technologies and as always, if you want to hear about a specific topic, let me know. In the next regular edition of Mobile & Wireless UPDATE on January 17, I'll look at several solutions for mobile and wireless monitoring and administration of Windows-based servers and enterprise systems.
