How QCI Allocation in LTE ie. which QCI for which services?

Question

LTE provides different QoS for a given application by putting it into the different bearer. each bearer has its own QCI (QoS Class Identifier) which introduce a particular service for a particular application. Now the question is why QCI got introduced in LTE i.e. what was the problem with earlier approach.

Answer 1

LTE network uses different type of bearers with each different QCI value to support different kinds of data transmission. IP network can treat different kinds of IP packets differently by using ToS (type of service) but at the eNodeB over the air different treatment is achieved by using different QCI bearers.

Refer following link to get the details on different kinds of QCI bearers.
http://www.sharetechnote.com/html/Handbook_LTE_QCI.html

Answer 2

QCI is gotten from ToS field using a specific mapping process using TFT and SDF filters. It allocates the level of priority of the packets among EPS nodes and link of the network. There is another metric accompanied with QCI, which is ARP defined the QoS level of the bearer itself. There are 12 specific QCIs in LTE-APro R13 and the rest left to be defined by the network operator.