Quiz Entry - updated: 2026.07.14
What is the history of CDMA technology, and which standard body chose it for UMTS?
CDMA was originally proposed by Qualcomm in 1993 for US mobile standards, and ETSI selected Wideband-CDMA (W-CDMA) as the air interface for UMTS (3G) in January 1998.
Timeline:
| Date | Event |
|---|---|
| July 1993 | Qualcomm proposes CDMA for the North American mobile standard — becomes IS-95 (cdmaOne) |
| 1995 | ANSI standardizes J-STD-008 CDMA for PCS (Personal Communications Services) |
| January 1998 | ETSI selects Wideband-CDMA (W-CDMA) in FDD mode as the UMTS air interface |
| Spring 2002 | First commercial 3G UMTS network launches in Japan |
Why CDMA won over TDMA for 3G:
- Higher capacity — CDMA can serve more users per cell than TDMA because of frequency reuse factor 1 (all cells use the same frequency)
- Soft handover — devices can communicate with multiple base stations simultaneously during handover
- Variable data rates — easily supports different speeds by assigning more or fewer codes
- Inherent security — the spread signal looks like noise without the correct code
Key players: Qualcomm invented and patented core CDMA technology. Their patents were so fundamental that every 3G phone in the world paid Qualcomm royalties, making it one of the most profitable patent portfolios in technology history.
Go deeper:
IS-95 / cdmaOne technology basics (Electronics Notes) — how Qualcomm's DSSS proposal became the first commercial CDMA cellular standard, and its IS-95A → IS-95B → cdma2000 path into 3G.- Code-division multiple access (Wikipedia) — the IS-95 / cdmaOne and W-CDMA lineage and the spread-spectrum principle behind them (kept for the diagram carousel).