Adaptive Modulation & Coding[AMC]

Adaptive Modulation & Coding[AMC]

Variable spreading factor and power control that are used in WCDMA are replaced by adaptive modulation  and coding in HSDPA

In WCDMA downlink power control dynamics is 20dB while in uplink it is 70dB.

DL power control dynamics is limited by intra-cell interference (interference between parallel codes).

As a result transmitted power to users near the cell centre in unnecessary high.

In HSDPA adaptive modulation and coding selects higher order modulation and low coding rate for users near the cell centre => less radio resources are needed for those users and less interference is generated. Also significantly higher data rates are available for users near the cell centre.