Method for transceiving downlink control information in a wireless access system and apparatus therefor
The present invention relates to a method for transceiving downlink control information in a wireless access system that supports an enhanced physical downlink control channel (e-PDCCH), and to an apparatus for the method. More particularly, the method comprises the steps of: precoding downlink control information using a precoding matrix set in a terminal; and transmitting the precoded downlink control information to the terminal via the e-PDCCH using multiple antennas, wherein the e-PDCCH is multiplexed with a PDSCH in a first slot of a subframe in which the downlink control information is transmitted.
1. A method of transmitting downlink control information by a base station in a radio access system supporting an enhanced physical downlink control channel (e-PDCCH) transmitted in a state of being multiplexed with a physical downlink shared channel (PDSCH), the method comprising:
precoding the downlink control information using a precoding matrix set in a user equipment (UE);
transmitting the precoded downlink control information to the UE via the e-PDCCH which is multiplexed with the PDSCH in a first slot of a subframe, and
transmitting to the UE a second slot of the subframe with a greater modulation and coding scheme (MCS) level than a MCS level of the first slot,
wherein a first codeword is allocated to the downlink control information when the downlink control information includes information related to uplink,
wherein a second codeword is allocated to the downlink control information when the downlink control information includes information related to downlink, and
wherein a null symbol or a predetermined reference modulation symbol is inserted to a modulation symbol having a smaller symbol length such that modulation symbols from the first codeword and the second codeword have equal bit sizes before the precoding.
2. The method of claim 1 , further comprising performing joint channel coding with respect to a plurality of pieces of downlink control information to generate one coded bit.
3. The method of claim 1 , wherein the downlink control information is precoded based on a cell-specific reference signal (CRS) or a demodulation reference signal (DMRS).
4. The method of claim 3 , further comprising transmitting the information regarding the precoding matrix to the UE when the downlink control information is precoded based on the CRS.
5. The method of claim 3 , wherein, when the downlink control information is precoded based on the DMRS, the downlink control information is precoded using a precoding matrix used in a most recent PDSCH or physical downlink control channel (PDCCH) transmitted to the UE.
6. A method of receiving downlink control information in a radio access system supporting an enhanced physical downlink control channel (e-PDCCH) transmitted in a state of being multiplexed with a physical downlink shared channel (PDSCH), the method comprising:
receiving downlink control information precoded using a precoding matrix set in a user equipment (UE) from a base station via the e-PDCCH which is multiplexed with the PDSCH in a first slot of a subframe; and
performing decoding in order to detect the downlink control information,
receiving a second slot of the subframe which is transmitted by the base station with a greater modulation and coding scheme (MCS) level than a MCS level of the first slot,
wherein a first codeword is allocated to the downlink control information when the downlink control information includes information related to uplink,
wherein a second codeword is allocated to the downlink control information when the downlink control information includes information related to downlink, and
wherein a null symbol or a predetermined reference modulation symbol is inserted to a modulation symbol having a smaller symbol length such that modulation symbols from the first codeword and the second codeword have equal bit sizes.
7. The method of claim 6 , wherein the downlink control information is precoded based on a cell-specific reference signal (CRS) or a demodulation reference signal (DMRS).
8. The method of claim 7 , further comprising receiving the information regarding the precoding matrix from the base station when the downlink control information is precoded based on the CRS,
wherein the decoding is performed using the information regarding the precoding matrix.
9. The method of claim 7 , wherein, when the downlink control information is precoded based on the DMRS, the decoding is performed using a precoding matrix used in a most recent PDSCH or physical downlink control channel (PDCCH) transmitted from the base station.