Inter-band, non-contiguous

Inter-band carrier aggregation refers to the aggregation of two or more LTE channels in separate LTE Frequency Bands. The term non-contiguous refers to the fact that a spectrum gap exists between all LTE Frequency Bands, and therefore no inter-band aggregation can be treated as a single enlarged channel.

Unsurprisingly this form of CA is the most complex, requiring significant eNB hardware changes to implement.