fication for the system was IS95A, but its performance was later upgraded under IS95B. Apart from voice it also carries data at rates up to 14.4 kbps for IS95A and under IS95B data rates of up to 115 kbps are supported. Table 10.1 continued System Generation Channel Access Comments spacing CDMA2000 1X 1.25 MHz This system supports both voice and data capabilities within a standard 1.25MHz CDMA channel. CDMA2000 builds on cdmaOne to provide an evolution path to 3G. The system doubles the voice capacity of cdmaOne systems and also supports high speed data services. Peak data rates of 153 kbps are currently achievable with figures of 307 kbps quoted for the future, and 614 kbps when two channels are used. CDMA2000 1xEV-DO 1.25 MHz The EV-DO stands for Evolution Data Only. This is an evolution of CDMA 2000 that is designed for data only use and its specification is IS 856. It provides peak data rate capability of over 2.45 Mbps on the forward or downlink, i.e. from the base station to the user. The aim of the system is to deliver a low cost per megabyte capability along with an always on connection costed on the data downloaded rather than connection time. CDMA2000 1xEV-DV 1.25 MHz This stands for Evolution Data and Voice. It is an evolution of CDMA2000 that can simultaneously transmit voice and data. The peak data rate is 3.1 Mbps on the forward link. The reverse link is very similar to CDMA2000 1X and is limited to 384 kbps. 5 MHz CDMA/ Universal Mobile Telecommunications System. Uses Wideband CDMA (W-CDMA) with one 5 MHz channel for both voice and data, providing data speeds up to 2 Mbps. TD-SCDMA 1.6MHz Time Division Synchronous CDMA. A system developed in China to establish their position on the cellular telecommunications arena. It uses the same bands for transmit and receive, allowing different timeslots for base stations and mobiles to communicate. Unlike other 3G systems it uses a time division duplex (TDD) system. 254 Newnes Guide to Radio and Communications Technology (FDMA). Another uses different timeslo