Standard revisions

There have been several revisions of the standard, starting with Revision 0 (Rev. 0). This was later expanded upon with Revision A to support Quality of Service (to improve latency) and higher rates on the forward link and reverse link. Later in 2006 Revision B was published, that among other features includes the ability to bundle multiple carriers to achieve even higher rates and lower latencies (see TIA-856 Rev. B). The upgrade from EV-DO Rev. A to EV-DO Rev. B involves a software update to the cell site modem, and additional equipment for the new EV-DO carriers. Existing cdma2000 operators may also have to retune some of their existing 1xRTT channels to other frequencies, since Rev. B requires all DO carriers be within 5 MHz.