What is EPS Bearer in LTE?

What is EPS Bearer in LTE?

• EPS is a connection-oriented transmission network and, as such, it requires the establishment of a “virtual” connection between two endpoints (e.g. a UE and a PDN-GW)
• This virtual connection is called an “EPS Bearer”
• It provides a “bearer service”, i.e. a transport service with specific QoS attributes.
• The QoS parameters associated to the bearer are: QCI, ARP, GBR and AMBR
• A data radio bearer transports the packets of an EPS bearer between a UE and an 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 eNodeB and a Serving GW. 
  An S5/S8 bearer transports the packets of an EPS bearer between a Serving GW and a PDN GW. 
  The QoS parameters associated to the bearer are: QCI, ARP, GBR and AMBR.
  
  • A low priority signaling (message) bearer (SRB1)
  • A high priority signaling (message) bearer (SRB2)
  • A data radio bearer (DRB), i.e. a bearer for IP packets