The evolution of 3G will open the door of the wireless local loop (WLL) to PSTN and public data network access, while providing more convenient control of applications and network resources. It will also provide global roaming, service portability, zone-based ID and billing, and global directory access. The 3G technology is even expected to support seamless satellite interworking. One of technical requirements for cdma2000 includes cdmaOne backward compatibility for voice services, vocoders, and signaling structure, as well as for privacy, authentication, and encryption capabilities. 3G systems promise to deliver wireless voice services with wireline quality levels, along with the speed and capac-ity needed to support multimedia and high-speed data applications. Location-based services, on-board navigation, emergency assistance, and other advanced services will also be supported. There are two phases of cdma2000 i.e.,
- Phase one of the cdma2000 effort, also known as 3G1X, employs 1.25 MHz of band-width and delivers a peak data rate of 144 kbps for stationary or mobile applications.
- Phase two of cdma2000, called 3G3X, will use 5 MHz bandwidth and is expected to deliver a peak data rate of 144 kbps for mobile and vehicular applications, and up to 2 Mbps for fixed applications. industry insiders predict that the 3G3X phase will eventually yield up to 1 Mbps for each traffic or Walsh channel.
By aggregating two channels, users can achieve the 2-Mbps peak data rate targeted for 1MT-2000. The primary difference between phase one and phase two of cdma2000 is bandwidth and resulting throughput speed, or peak data rate capability. Phase two will introduce advanced multimedia capabilities and lay the foundation for popular 3G voice services and vocoder, such as voice over IP. Since the 3GIX and 3G3X standards essentially share the same baseband radio elements, operators can take a major step toward full 3G capabilities by implementing 3GIX. cdma2000 phase two will include detailed descriptions of signal protocols, data management, and expected upscale requirements for moving from 5 MHz to 10 MHz, and 15-MHz radios in future interactions. By migrating from the current 1S-95 CDMA air interface technology to 3GIX of the cdma2000 standard, operators can achieve a twofold increase in radio capacity and ability to handle up to 144 kbps of packet data. Phase one capabilities of cdma2000 include a new physical layer for IX and 3X 1.25 MHz channel sizes, support for multicarrier forward link 3X options, and definitions for the IX and 3X numerology. Operators will also enjoy voice service enhancements that will produce twice the voice capacity of cdmaOne.