Implementation Options

The original proposal from 3GPP2 to the ITU was based on the assumed need to fill 5
MHz of RF bandwidth. This could be achieved either by increasing the spreading ratio,
as in SR3DS (direct sequence) shown in Figure 3.28, or by putting three CDMA2000
1.25 MHz channels together (SR3MC).
In practice, CDMA2000 is not being implemented into 5 MHz channels, and higher
data rates are being achieved by using higher-level modulation schemes (8 PSK and
16-level QAM) in 1.25 MHz RF channels—the variant known as 1xEV.