The ARP priority level determines the order in which a congested network (LTE's eNodeB) should satisfy requests to establish or modify a bearer, with level 1 receiving the highest priority.
The pre-emption capability field determines whether a bearer can grab resources from another bearer with a lower priority and might typically be set for emergency services. Similarly, the pre-emption vulnerability field determines whether a bearer can lose resources to a bearer with a higher priority.
AS you know we have limited amount of air resources which must be shared among multiple users who use the network with various kinds of subscription schemes ,some are high priority user and other are normal user in order to provide best service to users the congestion control scheme must be used.
