A communications apparatus and method are provided. The communications method for an apparatus capable of Carrier Aggregation (CA), wherein the apparatus includes a plurality of processing engines and antennas, includes the steps of determining whether the apparatus is configured in a single component carrier for a first group of the antennas, and activating a second group of the antennas when the apparatus is configured in the single component carrier. T the first group of antennas are configured for a first part of the processing engines and the second group of antennas are configured for a second part of the processing engines, and the first part of the processing engines and the second part of the processing engines share a MIMO detector.