Modulation Scheme used in downlink channel in LTE?

Question

What are the modulation schemes used for the Downlink Channel in LTE?

Answer 1

There are 3 modulation schemes are used in lte .
1. QPK
2. 16 QAM
3. 64 QAM

Based on the Channel Quality Indicaiton reported by UEs to eNB. Enodeb MAC scheduler chooses appropriate modulation scheme to send data. As usual if radio conditions are good scheduler would like to send more data(more bits over the one resource element) so it will use 64 QAM. Similarly for other two. I am just telling about PDSCH which is mainly used for data so modulation schemes varies. But some channels like PDCCH and PBCH are in LTE system which mainly focus on reliable delivery of control data UE/UEs,so QPSK is used to send control information.

Comments

For Data Transmission : QPSK, 16QAM, 64QAM for PDSCH, PMCH
For Normal Control Information : QPSK for PDCCH, PCFICH, PBCH
For HARQ : BPSK for PHICH

Answer 2

Modulation scheme used in DL are QPSK, 16QAM And 64 QAM. Depending on the radio condition as main criteria it is decided.