3G Evolution of GSM, IS-136, and PDC systems

Introduction:
The 3G evolution of GSM, IS-136, and PDC systems refers to the transition from second-generation (2G) technologies to third-generation (3G) technologies in these respective systems. The advent of 3G brought significant advancements in terms of data transfer speeds, capacity, and multimedia capabilities.

Explanation:
The correct option among the given choices is option 'A', which is W-CDMA (Wideband Code Division Multiple Access). W-CDMA is the technology that led to the 3G evolution of GSM, IS-136, and PDC systems. Here is a detailed explanation:

1. GSM (Global System for Mobile Communications):
GSM is a 2G digital cellular technology that was widely used for voice communication. However, it had limited data transfer capabilities. To enhance data transfer speeds and introduce multimedia capabilities, GSM evolved into 3G using W-CDMA technology.

2. IS-136 (Interim Standard-136):
IS-136, also known as D-AMPS (Digital Advanced Mobile Phone System), is a 2G TDMA (Time Division Multiple Access) technology used primarily in North America. Similar to GSM, IS-136 systems also needed an evolution to support higher data rates and multimedia applications. W-CDMA provided the necessary upgrade to enable 3G capabilities.

3. PDC (Personal Digital Cellular):
PDC is a 2G TDMA technology used in Japan. As with GSM and IS-136, PDC systems also required an upgrade to meet the growing demand for faster data transfer and multimedia services. W-CDMA was the chosen technology for the 3G evolution of PDC systems.

4. W-CDMA (Wideband Code Division Multiple Access):
W-CDMA is a 3G technology that uses a wider bandwidth and a different modulation scheme compared to 2G technologies like GSM, IS-136, and PDC. It provides higher data transfer rates, improved capacity, and better support for multimedia applications. W-CDMA was standardized by the International Telecommunication Union (ITU) for the 3G evolution of various 2G systems worldwide.

Conclusion:
In conclusion, the 3G evolution of GSM, IS-136, and PDC systems was achieved using W-CDMA technology. W-CDMA provided the necessary enhancements in terms of data transfer speeds, capacity, and multimedia capabilities, allowing these 2G systems to transition into the 3G era.