CDMA2000 1xEV-DO Revision B
The Revision B (Rev B) is an evolutionary step of Rev A that consists of aggregating multiple EV-DO Rev A channels to provide higher performance for multimedia delivery, bi-directional data transmissions and VoIP-based concurrent services. The Rev B standard was published by the Third Generation Partnership Project 2 (3GPP2) under document number 3GPP2 C.S0024-B and by the Telecommunications Industry Association (TIA) and Electronics Industry Association as TIA/EIA/IS-856-B. Rev B will be commercially available in 2008.
Rev B builds on the efficiencies of Rev A by introducing the concept of dynamically scalable bandwidth. Through aggregation of multiple 1.25 MHz Rev A channels, Rev B enables data traffic to flow over more than one carrier and hence improve user data rates, latencies on both forward and reverse link. Peak data rates are proportional to the number of carriers aggregated. When 15 channels are combined within a 20 MHz bandwidth, Rev B delivers peak rates of 46.5 Mbps in forward link and 27 Mbps in the reverse link. With the 64-QAM scheme, the peak data rate in the forward link increase in a single 1.25 MHz carrier to 4.9 Mbps, an aggregated 5 MHz will deliver up to 14.7 Mbps and within 20 MHz of bandwidth up to 73.5 Mbps. By increasing the bandwidth, an operator can support more users per sector or lower their cost per megabyte to encourage longer usage. To achieve this performance, the 1.25 MHz carriers do not have to be adjacent to one another, thus giving operators the flexibility to combine blocks of spectrum from different bands. This is unique benefit of Rev B that is not available to WCDMA/HSDPA.
In addition to supporting mobile broadband data and OFDM-based multicasting, the lower latency characteristics of Rev B improve the performance of delay-sensitive applications such as VoIP, push-to-talk, video telephony, concurrent voice and multimedia and multiplayer online gaming. Rev. B also allows operators to consider the deployment of “hot zones” where the demand for data is high.