A method carried out by a base station for resource mapping of a physical downlink control channel, PDCCH, the method comprising: determining the number of resource sub-blocks to which a predefined number of enhanced control channel elements, eCCEs, within the PDCCH correspond, by dividing a second number of resource elements, REs, in the predefined number of eCCEs by a first number of REs in a resource sub-block in one resource block, RB wherein resource sub-blocks in one RB are formed by dividing the one RB; determining the number of RBs onto which the predefined number of eCCEs are needed to be mapped, as the number of resource sub-blocks to which the predefined number of eCCEs correspond, divided by the number of resource sub-blocks in the RB; and mapping eCCEs within the PDCCH to RBs according to the number of RBs onto which the predefined number of eCCEs are needed to be mapped; wherein: the predefined number of eCCEs is equal to the aggregation level; and locations of resource sub-blocks to which the eCCE within the PDCCH correspond are periodically cyclically shifted in each of the RBs, so that the locations of the resource sub-blocks to which the eCCEs within the PDCCH correspond are different in each of the RBs, or locations of resource sub-blocks to which the predefined number of eCCEs within the PDCCH correspond are periodically cyclically shifted in each of the RBs, so that the locations of the resource sub-blocks to which the predefined number of eCCEs within the PDCCH correspond are different in each of the RBs. determining the number of resource sub-blocks to which a predefined number of enhanced control channel elements, eCCEs, within the PDCCH correspond, by dividing a second number of resource elements, REs, in the predefined number of eCCEs by a first number of REs in a resource sub-block in one resource block, RB wherein resource sub-blocks in one RB are formed by dividing the one RB; determining the number of RBs onto which the predefined number of eCCEs are needed to be mapped, as the number of resource sub-blocks to which the predefined number of eCCEs correspond, divided by the number of resource sub-blocks in the RB; and mapping eCCEs within the PDCCH to RBs according to the number of RBs onto which the predefined number of eCCEs are needed to be mapped; wherein: the predefined number of eCCEs is equal to the aggregation level; and locations of resource sub-blocks to which the eCCE within the PDCCH correspond are periodically cyclically shifted in each of the RBs, so that the locations of the resource sub-blocks to which the eCCEs within the PDCCH correspond are different in each of the RBs, or locations of resource sub-blocks to which the predefined number of eCCEs within the PDCCH correspond are periodically cyclically shifted in each of the RBs, so that the locations of the resource sub-blocks to which the predefined number of eCCEs within the PDCCH correspond are different in each of the RBs. the predefined number of eCCEs is equal to the aggregation level; and locations of resource sub-blocks to which the eCCE within the PDCCH correspond are periodically cyclically shifted in each of the RBs, so that the locations of the resource sub-blocks to which the eCCEs within the PDCCH correspond are different in each of the RBs, or locations of resource sub-blocks to which the predefined number of eCCEs within the PDCCH correspond are periodically cyclically shifted in each of the RBs, so that the locations of the resource sub-blocks to which the predefined number of eCCEs within the PDCCH correspond are different in each of the RBs. <EOS>