s a one-to-one mapping between the E-RAB and an EPS bearer. A data radio bearer transports the packets of an EPS bearer between a UE and the eNB. When a data radio bearer exists, there is a one-to-one mapping between this data radio bearer and the EPS bearer/E-RAB. An S1 bearer transports the packets of an E-RAB between an eNB and an S-GW. An S5/S8 bearer transports the packets of an EPS bearer between a Serving GW and a PDN GW. A UE stores the mapping between an uplink packet filter and data radio bearer to create the binding between the service data flow and the data radio bearer in the uplink. The P-GW stores the mapping between the downlink packet filter and S5/S8a bearer to create the binding between a service data flow and the S5/S8a bearer in the downlink. The eNB stores a one-to-one mapping between the data radio bearer and the S1 bearer to create the binding between the data radio bearer and the S1 bearer in both the uplink and downlink. Appendix A: Proportional fair scheduling algorithm The S-GW stores a one-to-one mapping between the S1 bearer and the S5/S8a bearer to create the binding between the S1 bearer and the S5/S8a bearer in both the uplink and downlink. Each EPS bearer/E-RAB (GBR and non-GBR) is associated with the following bearer-level QoS parameters: QoS Class Identifier (QCI): a metric that is used as a reference to access node-specific parameters that control bearer-level packet forwarding function, e.g., scheduling weights, admission thresholds, queue management thresholds, link layer protocol configuration, etc., that have been pre-configured by the network operator. Allocation and Retention Priority (ARP): the primary purpose of ARP is to decide whether a bearer establishment/modification request can be accepted or needs to be rejected in the case of resource limitations. In addition, the ARP can be used by the eNB to decide which bearers to drop during special resource limitations. Each GBR bearer is additionally associated with the bit rate that can be expected to be provided by a GB