EV-DO Rev. B
- CDMA2000 1xEV-DO Rev. B overview detailing the technology behind the scheme and the advantages it offers.
CDMA2000 1xEV-DO Rev. B is an enhanced for of the CDMA2000 1xEV-DO standard that provides much high data download rates than the previous forms of EV-DO, as well as enhancing efficiency of the system for operators.
The EV-DO Rev B enhancements have been launched on a number of networks, although users need the Rev B handsets or dongles to be able to take advantage of the improvements.
Although there are a number of changes that are included in the EV-DO Rev B updates, speeds up to 14.7 Mbps can be achieved in the downlink
EV-DO Rev B basics
The EV-DO Rev B upgrade to the standard CDMA2000 EV-DO scheme incorporates a number of changes over the Rev A system. These enable the system to provide a much higher level of performance, allowing more effective operation for video streaming, gaming and other high data applications.
The main updates to the system to achieve the required EV-DO Rev B performance are:
- Carrier aggregation / carrier bundling: the specification for EV-DO Rev B enables carriers to be aggregated to enable higher data rates to be carried. Typically it is envisaged that two or three carriers will be aggregated in view of the spectrum limitations, but more can be added if required. Carrier aggregation improves the peak data rates for individual users to be increased along with the average throughput rates. This is because of the statistical nature of the data capacity usage and the creation of a larger data pipe.
- Higher order modulation: The EV-DO Rev B standard allows the use of higher order modulation - up to 64QAM - this enables higher data rates to be achieved.. This can be used where the link quality is sufficiently good to allow the use of this modulation, otherwise lower order modulation schemes are used.
- Reduced latency: Using a technique called Statistical Multiplexing across the aggregated carriers the level of latency is reduced. The technique uses the multiple carriers and resulting additional capacity to reduce packet wait times. This improves the level of latency for sensitive services such as gaming, video telephony, remote console sessions and web browsing.
- Hybrid frequency re-use: EV-DO Rev B utilises a system known as hybrid frequency re-use. This provides a reduction in levels of interference from the adjacent sectors especially to users at the edge of the cell. It has the effect of increasing the data rates that can be provided.
- Improved support for asymmetric data flow: One of the major issues with any system using paired frequency spectrum is the asymmetric data flow - more data flows in the downlink than in the uplink. The EV-DO Rev B has additional support to enable more efficient utilisation of the resources.
EV-DO Rev B performance
CDMA2000 EV-DO Rev B provides some significant increases in performance over the previous versions of EV-DO.
|EV-DO Release / Revision||Downlink data rate (peak)||Uplink data rate (peak)||Channel configuration|
|Rel. 0||2.4 Mbps||153 kbps||1.25 MHz FDD|
|Rev. A||3.1 Mbps||1.8 Mbps||1.25 MHz FDD|
|Rev. B (Multi-Carrier only)||9.3 Mbps||5.4 Mbps||5 MHz FDD|
|Rev. B (MC + H/W upgrade)||14.7 Mbps||5.4 Mbps||5 MHz FDD|
EV-DO Rev B migration
The migration from Rev A to EV-DO Rev. B can be undertaken in two stages. This approach was adopted to provide operators with the most effective upgrade path for their individual requirements. These two stages or phases are outlined below:
- Rev. B software upgrade: The main upgrade in this section is the multi-carrier facility.
- Rev. B hardware upgrade: The main upgrade in this section is the move to 64QAM to provide higher data rates on each channel when link conditions are suitable.
By Ian Poole
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