Question

Explain why most GSM operators evolved to UMTS as 3rd generation, and why Interim Standard 95 (IS-95) operators selected cdma2000 for their 3rd generation system.

Answer 1

most 3G services will have some type of priority implementations. In GSM a sophisticated way to handle different priority calls is already included in phase 2+, called the enhanced multi-level priority and preemption (EMLPP). UMTS can be used, e.g., to preempt calls, or to give higher access rights -superiority to higher priority calls in a saturated system.

CDMA2000 is a successor of the earlier standard IS-95 (cdmaOne), and it offers 3G mobile services as specified in IMT2000 (International Mobile Telecommunication specifications for the year 2000). CDMA2000 is backwards compatible with its predecessor IS-95, which makes the upgrade from IS-95 to CDMA2000 easy and seamless. It uses the same carrier bandwidth of 1.25 MHZ and is both circuit-switched as well as packet-switched. It can support peak data rates of up to 153 kbps in the downlink and the uplink. The access technology used in CDMA2000 is Code Division Multiple Access (CDMA) where all users share the same 1.25 MHz channel, but each user is assigned an individual pseudo-noise (PN) sequence to avoid interference.