 are still under considera- tion including cdma2000 (an upgrade to cdmaOne) Wideband-CDMA (W-CDMA) Universal Wireless Communications (UWC-136) UWC-136 is based on TDMA, just like Europe's GSM, Japan's personal digital cellular (PDC) and the Digital Advanced Mobile Phone System (D-AMPS) used in the United States. Existing 2G service providers have already applied for licenses to oper- ate 3G networks around the globe. Although it's unclear what 3G technolo- gies will be adopted, the most 2.5G upgrades are GPRS and HSCSD, which is an upgrade being considered by some GSM network operators. Beyond that, EDGE modulation extensions are planned, which will enable service providers to offer even higher performance, enabling true 3G-like services. The ITU currently embraces various proposed schemes to attain the IMT-2000 3G vision. From TDMA-based 2G providers of GSM and North American dual-mode cellular (NADC) services, interim upgrades will come in the form of GPRS, HSCSD, and IS-136+, and will eventually converge at EDGE for the next throughput upgrade (to 384 Kbps) before 3G. What Is Special about EDGE? EDGE is a proposed modification to the modulation scheme utilized by GSM. EDGE is a new modulation scheme that is more bandwidth efficient than the prefiltered GMSK modulation scheme used in the GSM standard. It provides a promising migration strategy for HSCSD and GPRS. The technology defines a new physical layer: 8-PSK modulation, instead of GMSK. 8-PSK enables each pulse to carry 3 bits of information versus the GMSK 1-bit-per-pulse rate. This change will drastically increase the bit rates available to end users for the purpose of data transfer. The expecta- tion is that the enhanced modulation techniques will make it possible to maintain a good quality link by automatically adapting to the radio inter- ference conditions and thereby provide the highest possible rate. The exact implementation and technical details are still being discussed in various ETSI feasibility studies, but one can almost assume that certain f