Method and apparatus for carrier scheduling in a multi-carrier system
A method and apparatus for carrier scheduling in a multi-carrier system is provided. A terminal receives information, which indicates whether or not to perform a cross carrier scheduling process, from a base station. If it is determined, by means of said information, that the cross carrier scheduling process is to be performed, the terminal receives scheduling information about a second downlink carrier via a first downlink carrier, and receives downlink data from the second downlink carrier.
1. A method of decoding a signal for a user equipment (UE), the method comprising:
receiving, by the UE, a first control format indicator (CFI) and a second CFI from an evolved-NodeB (eNB) through a physical control format indicator channel (PCFICH);
monitoring, by the UE, a physical downlink control channel (PDCCH) that is received through a first carrier from the eNB, the PDCCH including scheduling information for a reception of a physical downlink shared channel (PDSCH); and
monitoring, by the UE, the PDSCH based on the scheduling information included in the PDCCH,
wherein the PDSCH is received through a second carrier from the eNB,
wherein the first CFI is decoded in the first carrier to determine a CFI value of each downlink component carrier,
wherein the second CFI is obtained in the second carrier to indicate a size of the PDCCH in a time domain,
wherein the first CFI and the second CFI are included in a radio resource control (RRC) message,
wherein a cross-carrier scheduling is applied for the first carrier and the second carrier,
wherein the second CFI is obtained by a specific field, which is included in downlink control information (DCI) of all downlink grant PDCCH to which the cross-carrier scheduling is applied,
wherein a starting orthogonal frequency division multiplexing (OFDM) symbol for the PDSCH in a subframe is determined based on the obtained second CFI, which indicates a number of OFDM symbols right before the starting OFDM symbol for the PDSCH,
wherein, if an index of the starting OFDM symbol for the PDSCH is equal to i, the obtained second CFI indicates an index for the number of OFDM symbols as i- 1 ,
wherein each bit size of the first CFI and second CFI is determined by an equation of log 2 X, where “X” is a number of downlink component carriers within a sub-group or a maximum index value of the downlink component carriers,
wherein a size of the specific field that obtains the second CFI is determined by the determined bit size of the second CFI, and
wherein the size of the specific field is varied for every subframe in the time domain.
2. The method of claim 1 , wherein the starting OFDM symbol for the PDSCH is placed after OFDM symbols where the PDCCH is received.
3. The method of claim 1 , wherein the first carrier and the second carrier have different frequencies from each other.
4. The method of claim 1 , wherein the scheduling information comprises a carrier indication field (CIF) which indicates the second carrier.
5. A user equipment (UE), comprising:
a radio frequency (RF) unit configured to transmit and receive a radio signal; and
a processor connected to the RF unit, the processor being configured to:
receive a first control format indicator (CFI) and a second CFI from an evolved-NodeB (eNB);
monitor a physical downlink control channel (PDCCH) that is received through a first carrier from the eNB, the PDCCH including scheduling information for a reception of a physical downlink shared channel (PDSCH); and
monitor the PDSCH based on the scheduling information included in the PDCCH,
wherein the PDSCH is received through a second carrier from the eNB,
wherein the first CFI is decoded in the first carrier to determine a CFI value of each downlink component carrier,
wherein the second CFI is obtained in the second carrier to indicate a size of the PDCCH in a time domain,
wherein the first CFI and the second CFI are included in a radio resource control (RRC) message,
wherein a cross-carrier scheduling is applied for the first carrier and the second carrier,
wherein the second CFI is obtained by a specific field, which is included in downlink control information (DCI) of all downlink grant PDCCH to which the cross-carrier scheduling is applied,
wherein a starting orthogonal frequency division multiplexing (OFDM) symbol for the PDSCH in a subframe is determined based on the obtained second CFI, which indicates a number of OFDM symbols right before the starting OFDM symbol for the PDSCH,
wherein, if an index of the starting OFDM symbol for the PDSCH is equal to i, the obtained second CFI indicates an index for the number of OFDM symbols as i- 1 ,
wherein each bit size of the first CFI and second CFI is determined by an equation of log 2 X, where “X” is a number of downlink component carriers within a sub-group or a maximum index value of the downlink component carriers,
wherein a size of the specific field that obtains the second CFI is determined by the determined bit size of the second CFI, and
wherein the size of the specific field is varied for every subframe in the time domain.
6. The UE of claim 5 , wherein the starting OFDM symbol for the PDSCH is placed after OFDM symbols where the PDCCH is received.
7. The UE of claim 5 , wherein the first carrier and the second carrier have different frequencies from each other.
8. The UE of claim 5 , wherein the scheduling information comprises a carrier indication field (CIF) which indicates the second carrier.