CCE+ number allocation method and base station device
Disclosed is a CCE+ number allocation method which reduces the ACK/NACK (Acknowledgment/Negative Acknowledgment) collision probability in a mixed system containing an LTE (Long Term Evolution) system and an LTE+ (Long Term Evolution Advanced) system. A CCE (Control Channel Element)+ number is defined by selecting a number from CCE numbers of the CCE to contain PDCCH (Physical Downlink Control Channel) allocated in a resource element region constituting CCE+ where PDCCH+ is arranged. This can prevent overlapped selection of the CCE number and the CCE+ number even when the PDCCH and the PDCCH+ are simultaneously transmitted. Thus, it is possible to reduce the collision probability of ACK/NACK correlated to the CCE number and the CCE+ number.
1. A method for transmitting a control information on a control channel element (CCE), the method comprising:
mapping a first downlink control information in a first communication system to at least one of CCEs+, wherein each of the CCEs+ is comprised of resource elements and the CCEs+ are numbered respectively by CCE+ numbers that are assigned thereto; and
transmitting the first downlink control information on said at least one of the CCEs+ that are numbered by the CCE+ numbers,
wherein the CCE+ numbers are respectively assigned to the CCEs+ such that each of the CCEs+ has a CCE+ number same as a CCE number that is assigned to a CCE, that is used for a second downlink control information in a second communication system and that is comprised of the resource elements, of which said each of the CCEs+ is comprised, and
a beginning position of at least one of the CCEs+ is matched with a position obtained by multiplying an L number of CCE(s) by an integer, wherein the L is one of aggregation sizes of CCEs, which is used for the second downlink control information.
2. The method according to claim 1 , wherein M times of the CCE+ is equal to N times of CCE, where M is a natural number, N is a natural number, N>M and N/M<2.
3. The method according to claim 2 , further comprising, when an aggregation size of CCEs+ to which the first downlink control information is mapped is 1, matching a beginning position of an M number of consecutive CCEs+ with a position of a CCE having a CCE number satisfying a function of the CCF number mod N=1.
4. The method according to claim 2 , further comprising, when an aggregation size of CCEs+ to which the first downlink control information is mapped is K=2 k , matching a beginning position of a K number of consecutive CCEs+ with a position of CCE having a CCE number satisfying a function of the CCE number mod(N·K/2)=1, where k is a natural number.
5. The method according to claim 2 , further comprising, when an aggregation size of CCEs which is used for the second downlink control information is L=2 p-1 and an aggregation size of CCEs+ to which the first downlink control information is mapped is 1, matching a beginning of an M number of consecutive CCEs+ with a position of a CCE having a CCE number satisfying a function of the CCE number mod 4=1, where p is a natural number.
6. The method according to claim 2 , further comprising, when an aggregation size of CCEs which is used for the second downlink control information is mapped is L=2 p-1 and an aggregation size of CCEs+ to which the first downlink control information is mapped is K=2 k , matching a beginning position of a K number of consecutive CCEs+ with a position of a CCE having a CCE number satisfying a function of the CCE number mod(2×K)=1, where p is a natural number and k is a natural number.
7. The method according to claim 2 , further comprising, when an aggregation size of CCEs+ to which the first downlink control information is mapped is K=2 k , matching a beginning position of a K×M number of consecutive CCEs+ with a position of a CCE having a CCE number satisfying a function of the CCE number mod(4×K)−1, where k is a natural number.
8. The method according to claim 2 , wherein an aggregation size of CCEs which is used for the second downlink control information is L=2 q-1 and an aggregation size of CCEs+ to which the first control channel is mapped is K==1, M×L, where q is a natural number.
9. The method according to claim 2 , wherein N=3 and M=2.
10. The method according to claim 2 , wherein N=4 and M=3.
11. The method according to claim 1 , wherein the first communication system is a Long-Term-Evolution-Advanced (LTE+) system, and the second communication system is a LTE.
12. The method according to claim 1 , further comprising:
receiving an ACK/NACK signal, which is transmitted from a mobile station on a uplink control channel, wherein the uplink control channel is associated with said at least one of CCEs+ to which the first downlink control information is mapped.
13. The method according to claim 1 , wherein a size of the first downlink control information is greater than a size of the second downlink control information.
14. A base station apparatus transmitting a control information on a control channel element (CCE), the base station apparatus comprising:
a mapping section configured to map a first downlink control information in a first communication system to at least one of CCEs+, wherein each of the CCEs+ is comprised of resource elements and the CCEs+ are numbered respectively by the CCE+ numbers that are assigned thereto; and
a transmitting section configured to transmit the first downlink control information on said at least one of the CCEs+ that are numbered by the CCE+ numbers,
wherein the CCE+ numbers are respectively assigned to the CCEs+ such that each of the CCEs+ has a CCE+ number same as a CCE number that is assigned to a CCE, that is used for a second downlink control information in a second communication system and that is comprised of the resource elements, of which said each of the CCEs+ is comprised, and
a beginning position of at least one of the CCEs+ is matched with a position obtained by multiplying an L number of CCE(s) by an integer, wherein the L is one of aggregation sizes of CCEs, which is used for the second downlink control information.
15. The base station apparatus according to claim 14 , wherein the first communication system is a Long-Term-Evolution-Advanced (LTE+) system, and the second communication system is a LTE.
16. The base station apparatus according to claim 14 , further comprising:
a receiving section configured to receive an ACK/NACK signal, which is transmitted from a mobile station on an uplink control channel, wherein the uplink control channel is associated with said at least one of CCEs+ to which the first downlink control information is mapped.
17. The base station apparatus according to claim 14 , wherein a size of the first downlink control information is greater than a size of the second downlink control information.