In a possible manner, the serial numbers of the CCEs included in the control resource subset 0 are 0, 1, and 2; the serial numbers of the CCEs included in the control resource subset 1 are 3, 4, and 5; the serial numbers of the CCEs included in the control resource subset 2 are 6, 7, and 8; the serial numbers of the CCEs included in the control resource subset 3 are 9, 10, and 11. As shown in FIG. 7, the REG groups in each control resource subset are numbered. Optionally, the serial numbers of the REG groups included in CCE0 are 0, 3, and 6, the serial numbers of the REG groups included in CCE1 are 1, 4, and 7, the serial numbers of REG groups included in CCE2 are 2, 5, and 8, and the serial numbers of the REG groups included in CCE3 are 9, 12, and 15, the serial numbers of the REG groups included in CCE4 are 10, 13, and 16, the serial numbers of the REG groups included in CCE5 are 11, 14, and 17, and the serial numbers of the REG groups included in CCE6 are 18, 21, and 24, the serial numbers of the REG groups included in CCE7 are 19, 22, and 25, the serial numbers of the REG groups included in CCE8 are 20, 23, and 26, the serial numbers of the REG groups included in CCE9 are 27, 30, and 33, and the serial numbers of the REG groups included in CCE10 are 28, 31, and 34, and the serial numbers of the REG groups included in CCE11 are 29, 32, and 35. It is assumed that a PDCCH is mapped to 8 CCEs, for example, the PDCCH is mapped to the first two CCEs of each control resource subset, then the serial numbers of the CCEs occupied by the PDCCH are 0, 1, 3, 4, 6, 7, 9, 10. Optionally, the mapping sequence of the PDCCH is as shown in FIG. 7, that is, CCE0 and CCE1 in the control resource subset 0 are first occupied, then CCE3 and CCE4 in the control resource subset 1 are occupied, and next, CCE6 and CCE7 in the control resource subset 2 are occupied, and finally, CCE9 and CCE10 in the control resource subset 3 are occupied, where, in each control resource subset, the serial numbers of CCEs used to carry the PDCCH are consecutive.