PCRF not deployed in LTE network

Hello everone.
Could someone tell me if you do not deploy PCRF in LTE network, what are deficiency?

I’ve heard normal policy enforcement can be done by PGW.

I think PCRF plays a vital role in between EPC and up network for IP data flow and used to charge based on subscribe plan and define a QoS.
In LTE network solutions we need PCRF for policy change rules…
Correct me if i wrong…

You need to PCRF to control the QoS of the LTE data services. On one side, this is the QoS needed to manage the transport and transmission networks. On the other side it can also be something closer to the users like uplink and downlink data speed.

You also need the functions of the PCRF to make VoLTE work.

It should be deployed , the main functionality of PCRF is the QOS coordination between external PDN and EPC so it connected via Rx+ interface to external data network PDN .
this function can be used to check and modify QOS associated with a SAE bearer setup from ot to request stetup of SAE bearer from PDN .
this QOS mangment resembles the policy and charging control frame work introduced for IMS with UMTS Release 6.