CA stands for "Carrier Aggregation" or "Carrier Aggregation" in the context of LTE -A.
With respect to lte point of view, an eNodeB can deploy with maximum of 20Mhz bandwidth. Sometime, it may bottleneck for a lte eNodeB while providing high data rate for all the users.
LTE advance has provided couple of new concepts, CA is one of them.
By using, CA multiple carrier or channel can be aggregated and can have more room or space as compare to LTE. I read from somewhere that up to 5 channels of each 20 Mhz bandwidth, can be aggregated . So this way, an eNodeB can have 100 Mhz space to operate on it and of course better service can be provided with more space.
As per my knowledge, 3 types of carrier or channel aggregations are defined.
1. For Intra-band contiguous channels
2. For Intra-band non-contiguous channels.
3. For Inter-band channels
