Universal Cellular Engineering - Technology


	Overview



	GSM



	GPRS



	EDGE



	TETRA



	UMTS/WCDMA



	CDMA

CDMA

CDMA
Code Division Multiple Access

Overview
CDMA is a "spread spectrum" technology, allowing many users to occupy the same time and frequency allocations in a given band/space. As its name implies, CDMA assigns unique codes to each communication to differentiate it from others in the same spectrum. In a world of finite spectrum resources, CDMA enables many more people to share the airwaves at the same time than do alternative technologies.

cdmaOne describes a complete wireless system based on the TIA/EIA IS-95 CDMA standard, including IS-95A and IS-95B revisions. It represents the end-to-end wireless system and all the necessary specifications that govern its operation. cdmaOne provides a family of related services including cellular, PCS and fixed wireless (wireless local loop).

CDMA2000 represents a family of ITU-approved, IMT-2000 (3G) standards and includes CDMA2000 1X and CDMA2000 1xEV technologies. They deliver increased network capacity to meet growing demand for wireless services and high-speed data services. CDMA2000 1X was the world's first 3G technology commercially deployed (October 2000).

Specifications

Frequency Bands	Frequency Range	Duplex
Band Class 0	824.0 – 849.0 MHz(uplink) 869.0 – 893.0 MHz (downlink)	45 MHz
Band Class 1	1850.0 – 1910.0 MHz (uplink) 1930.0 – 1990.0 MHz (downlink)	80 MHz
Band Class 2	872.0 – 915.0 MHz (uplink) 917.0 – 960.0 MHz (downlink)	45 MHz
Band Class 3	887.0 – 925.0 MHz (uplink) 832.0 – 870.0 MHz (downlink)	45 MHz
Band Class 4	1750.0 – 1780.0 MHz (uplink) 1840.0 – 1870.0 MHz (downlink)	90 MHz
Band Class 5	411.0 – 483.0 MHz (uplink) 421.0 – 494.0 MHz (downlink)	10 MHz
Band Class 6	1920.0 – 1980.0 MHz (uplink) 2110.0 – 2170.0 MHz (downlink)	90 MHz
Channel spacing	30 kHz
Channel Bandwidth	1.2288 MHz
Modulation	QPSK (forward link) OQPSK, HPSK (reverse link)
Chip Rate	1.2288 Mcps
Access format	CDMA
Speech	Digital transmission with one out of several possible vocoders: QCELP (8 kbit/s) (quadrature code excited linear prediction) EVRC (8 kbit/s) (enhanced variable rate codec) ACELP (13 kbit/s) (algebraic code excited linear prediction)
Power control	Up to 800 power control commands per second changing the level in increments of 1 dB.