What is Carrier Aggregation?

Carrier Aggregation is a key technology in LTE-Advanced system (also called 4G+). In order to meet the requirements of single user peak rate and system capacity improvement, one of the most direct ways is to increase the system transmission bandwidth. Therefore, LTE Advanced system introduces a technology to increase the transmission bandwidth, that is, CA (Carrier Aggregation) technology. 

Types of Carrier Aggregation

The easiest way to arrange aggregation would be to use contiguous component carriers within the same operating frequency band (as defined for LTE), so called intra-band contiguous. 
This might not always be possible, due to operator frequency allocation scenarios. 
For non-contiguous allocation it could either be intra-band, i.e. the component carriers belong to the same operating frequency band, but have a gap, or gaps, in between, or it could be inter-band, in which case the component carriers belong to different operating frequency bands

For more information about Carrier Aggregation, please refer to Carrier aggregation - Wikipedia

How it works on TP-Link LTE Gateway Routers/MiFi?

As we mentioned above, Carrier Aggregation is a key technology in LTE-Advanced system (also called 4G+). LTE-Advanced means the UE category is cat6 or higher, so all LTE Cat4 product don’t support carrier aggregation such as TL-MR6400, Archer MR200, M7200, M7350 etc.

For TP-Link LTE Advanced devices, please refer to the following table:

Note: 2CA or 3CA means it supports aggregating up to 2 or 3 carriers at most.

Carrier Aggregation is enabled by default for LTE Advanced devices, when connecting to LTE network, the TP-Link device will report its own carrier aggregation capability to the network, and then the network side allocates frequency band resources, and the allocation of resources depends entirely on the network side.

Q&A

Q1. Which LTE band does TP-Link LTE device supports? Does it support all band combinations for carrier aggression?
Please check the supported bands and also Carrier Aggregation band combinations on the specification page of the product. For example, here is Archer MR600 V3 Specification
As you can see, the Carrier Aggregation band combinations are listed as well, not all combinations are supported, for example, even though it supports 4G band 1 and also band 40, but it doesn’t support band 1+band 40 for carrier aggregation.

 
Q2. Why my TP-Link LTE Advanced device doesn’t work on 4G+, or only work on one single band?
Please refer to Carrier Aggregation or 4G+ doesn’t work properly on LTE Advanced Router for troubleshooting.

Q3. I selected two LTE bands manually, why does only one band display on status page?
Selecting LTE bands manually is to inform the network side which band(s) we would like to use, but whether and how the band will aggregate is decided by the network side, so it is normal that only one band is working when you select two or more bands manually.

You could also try other band combinations that are supported by both the device and your ISP.
If the two or more bands you selected are not supported by your ISP, 4G will not work at all.

Q4. Band shows 1,1 on my TP-Link LTE Advanced device, does it mean 4G or 4G+?

It means 4G+ network. 1,1 means it successfully aggregated two carriers within the same band 1, which is intra-band aggregation(either contiguous or non-contiguous). As long as it aggregates two or more carriers, it will show 4G+.

Q5. I selected one band manually, why it actually works on another band?
A: The manual band selection is only for 4G, if there is no 4G signal in the area or the 4G band you selected is not supported by your SIM card, the router will fall back to 3G if you are using 4G Preferred network mode, thus the 3G band might be different from your manually selected 4G band.
You could check Network Type on Advanced->Status page to verify whether it is on 4G LTE or WCDMA (3G).

If you don’t want it to fall back to 3G, please change the network mode from “4G Preferred” to “4G Only”.