Hey members,
Hope you are safe and doing great.
So today we are talking about Carrier Aggregation(CA).
What is Carrier Aggregation?
LTE Advanced Carrier Aggregation, CA, is one of the key techniques used to enable the very high data rates of 4G to be achieved.
Carrier aggregation is a technique used in wireless communication to increase the data rate per user, whereby multiple frequency blocks (called component carriers) are assigned to the same user.
The maximum possible data rate per user is increased the more frequency blocks are assigned to a user. The sum data rate of a cell is increased as well because of a better resource utilization
Carrier aggregation, CA requires many different features to be implemented to enable it to operate effectively, as the two channels are likely to have very different characteristics, especially if they are on different bands.
Carrier aggregation is supported by both formats of LTE, namely the FDD and TDD variants. This ensures that both FDD LTE and TDD LTE are able to meet the high data throughput requirements placed upon them.
Types of Carrier Aggregation:
Depending on the positions of the component carriers three cases of carrier aggregation are distinguished:
- The case where the component carriers are contiguous in the same frequency band is called intra-band contiguous carrier aggregation.
- If the component carriers are in the same frequency band but are separated by a gap the carrier aggregation is called intra-band non-contiguous.
- The most complex case is when the component carriers lie in different frequency band. This is called inter-band carrier aggregation applied to heterogeneous networks.
There is no difference between these three cases from a baseband perspective. However, the complexity from an RF point of view is increased in the case inter-band carrier aggregation.
LTE carrier aggregation basics:
The target figures for data throughput in the downlink is 1 Gbps for 4G LTE Advanced. Even with the improvements in spectral efficiency it is not possible to provide the required headline data throughput rates within the maximum 20 MHz channel. The only way to achieve the higher data rates is to increase the overall bandwidth used. IMT Advanced sets the upper limit at 100 MHz, but with an expectation of 40 MHz being used for minimum performance. For the future it is possible the top limit of 100 MHz could be extended.
It is well understood that spectrum is a valuable commodity, and it takes time to re-assign it from one use to another in view - the cost of forcing users to move is huge as new equipment needs to be bought. Accordingly as sections of the spectrum fall out of use, they can be re-assigned. This leads to significant levels of fragmentation.
LTE carrier aggregation bandwidth classes:
There is a total of six different carrier aggregation, CA bandwidth classes which are being defined.
LTE CARRIER AGGREGATION BANDWIDTH CLASSES
CARRIER AGGREGATION AGGREGATED TRANSMISSION NUMBER OF COMPONENT CARRIERS
BANDWIDTH CLASS BW CONFIGURATION
