ity, compared to QPSK. This is in line with the within a given transmission bandwidth is the use of discussion in the previous section where it was concluded higher-order modulation, implying that the modulation that high bandwidth utilization, i.e. a high information alphabet is extended to include additional signaling rate within a limited bandwidth, in general requires alternatives and thus allowing for more bits of a higher receiver Eb/No. information to be communicated per modulation symbol. In case of QPSK modulation, i.e. the modulation 4.3.2.1 Higher-order modulation in scheme used for the downlink in the first releases of the combination with channel coding 3G mobile-communication standards (WCDMA and cdma2000), the modulation alphabet consists of four Higher-order modulation schemes such as 16QAM and different signaling alternatives. These four signaling 64QAM require, in themselves, a higher receiver Eb/No alternatives can be illustrated as four different points in for a given error rate, compared to QPSK. However, in a two-dimensional plane (see Figure 4.3-2a). With four combination with channel coding the use of higher-order different signaling alternatives, QPSK allows for up to modulation will sometimes be more efficient, that is 2 bits of information to be communicated during each require a lower receiver Eb/No for a given error rate, modulation-symbol interval. By extending to 16QAM compared to the use of lower-order modulation such as modulation (Figure 4.3-2b), 16 different signaling QPSK. This may, for example, occur when the target alternatives are available. The use of 16QAM thus allows bandwidth utilization implies that, with lower-order for up to 4 bits of information to be communicated per modulation, no or very little channel coding can be symbol interval. Further extension to 64QAM (Figure applied. In such a case, the additional channel coding that 4.3-2c), with 64 different signaling alternatives, allows can be applied by using a higher-order modulation for up to 6 bits of information 