Wi-Fi uses CSMA/CA protocol for channel access and CSMA/CA includes physical layer clear channel assessment (CCA) that makes busy if sening any signal in current channel. Therefore, two nodes will never transmit simultaneously. In LTE Carrier Aggregation, there is no such limitation because a channel can be accessed by multi-users.

There are other details. You can get more information from following links:

http://www.4gamericas.org/files/1214/4648/2397/4G_Americas_LTE_Aggregation__Unlicensed_Spectrum_White_Paper_-_November_2015.pdf

https://arxiv.org/pdf/1402.0454.pdf

https://arxiv.org/pdf/1510.01392.pdf

You might want to look through some of these presentations.

http://www.3gpp.org/news-events/3gpp-news/1603-lte_in_unlicensed

LTE carrier aggregation, including possibly aggregating LTE carriers in the unlicensed spectrum, treats the aggregated LTE carriers as one wide LTE channel. Whereas if LTE offloads traffic to WiFi, that is a separate link, using the WiFi protocol for access, IP routing, and so on. And, importantly perhaps, the cellular carrier will not make revenue off the WiFi session, as the cellular carrier might make if the aggregtaed link were another LTE channel, or even LTE-U (LTE over the unlicensed spectrum).

HI 

Attachment here will help you

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