CDMA2000 1xEV-DO Basics

CDMA2000 1xEV-DO cell phone system is a standard that has evolved from the CDMA2000 mobile phone system and it is now firmly established in many areas of the world. The letters EV-DO sometimes referred to as EVDO stand for Evolution Data Only or Data Optimised. From the 1xEV-DO title it can be seen that it is a data only mobile telecommunications standard that can be run on CDMA2000 networks.

The concept of CDMA2000 1xEV-DO is that is a packet data only carrier - voice can be carried either by using Voice over IP, VoIP, or by using a fall-back to a CDMA2000 1X carrier. The fall-back mode is the one that tends to be used more widely as most operators have a CDMA2000 1X system in place.

CDMA2000 1xEV-DO Basics

The CDMA2000 1x EV-DO cell phone system is defined under IS-856 (TIA-856) rather than IS-2000 (TIA-2000) that defines the other CDMA2000 standards.

The EV-DO, IS-856 standard has undergone several revisions since it was first launched:

• EV-DO Release 0 (Rel. 0):   This was the first release of the EV-DO standard.
• EV-DO Revision A (Rev. A):   This revision of the standard introduced a significant increase in data rates.
• EV-DO Revision B (Rev. B):   The EV-DO Rev. B version of the standard introduced a number of updates including multicarrier operation as a software upgrade and higher order modulation with the introduction of new hardware. These two upgrades can be undertaken separately.
• EV-DO Advanced:   This software only upgrade introduced a number of smart features into the EV-DO standard.
• EV-DO Revision C (Rev.C):   This is the Ultra-Mobile Broadband standard. This is not now being pursued as the evolution from EV-DO is now to LTE for 4G services.

It can be seen that the data rates have risen considerable with successive releases and revisions of the EV-DO standard.

Data rates for CDMA2000 1xEV-DO

The CDMA2000 1xEV-DO forward channel forms a dedicated variable-rate, packet data channel with signalling and control time multiplexed into it. The channel is itself time-divided and allocated to each user on a demand and opportunity driven basis. A data only format was adopted to enable the standard to be optimised for data applications. If voice is required then a dual mode phone using separate 1X channel for the voice call is needed. In fact the "phones" used for data only applications are referred to as Access Terminals or ATs.

EV-DO tabular summary

The table below gives an overview of the capabilities of the different releases and revisions of the CDMA2000 1x EV-DO standard.

CDMA2000 1XEV-DO RELEASE / REVISION	MAX DOWNLINK DATA RATE (AVERAGE THROUGHPUT)	MAX UPLINK DATA RATE (AVERAGE THROUGHPUT)	COMMENTS
Rel. 0	2.4 Mbps (300-600 kbps)	153.4 kbps (70-90 kbps)	The first release of CDMA2000 1x EV-DO. 1.25 MHz FDD channels.
Rev. A	3.1 Mbps (600-1400kbps)	1.8 Mbps (500-800kbps)	Backwards compatible with EV-DO Rel. 0. 1.25 MHz FDD channels.
Rev. B software	9.3 Mbps	5.4 Mbps	These figures are for operation in a 5 MHz FDD channel and for the EV-DO Rev. B software upgrade. The software upgrade provides the multi-carrier facility. Figures are for the software upgrade only.
DO Rev. B hardware	14.7 Mbps	5.4 Mbps	These figures are for operation in a 5 MHz FDD channel and for the EV-DO Rev. B hardware upgrade as well as the software upgrade. The hardware upgrade allows higher order modulation (up to 64QAM) to be used.
DO Advanced	19.6 Mbps	7.2 Mbps	Figures for 4 x 1.25 MHz FDD channels

While many of the upgrades are implemented by software upgrades at the base station, new handsets, or Access Terminals, ATs are required to be able to utilise the features and data rates available. However ATs are normally replaced relatively frequently and as a result the new features are steadily taken up over time.