Bearers for Quality of Service

1. Understanding 3GPP BearersLTE / HSPA / EPC‘knowledge nuggets’Neil Wiffen - nwiffen@red-banana.orgMore free downloads at www.red-banana.orgPublic Seminar details – www.4g-seminar.com

2. Bearers for Quality of Service QoS Characteristics QoS Characteristics QoS Characteristics Traffic class, bit rate, delivery order, reliability, delay characteristics, priority etc.

3. UMTS Bearer Service External Bearer Service Local Bearer Service Radio Access Bearer Service Core Network Bearer Service Radio Bearer Service Iu Bearer Service Backbone Bearer Service UTRA FDD/TDD Service Physical Bearer Service UMTS Bearer Hierarchy Terminal Equipment Mobile Equipment UTRAN Core Network Edge Node Core Network Gateway Terminal Equipment End to End Service

4. UMTS Bearer Components RNC CN node Iu Signalling bearer Signalling Radio Bearers CS Radio Access Bearer (RAB) MSC CS Data bearer CS Radio Bearers PS Radio Access Bearer (RAB) SGSN PS Radio Bearer PS Data bearer PS Radio Access Bearer (RAB) SGSN PS Radio Bearer PS Data bearer

5. EPS Bearer Hierarchy S-GW P-GW Application Peer UE e-NB End-to-end Service EPS Bearer E-RAB S5/S8 Bearer Radio Bearer S1 Bearer LTE-Uu S1 S5/S8 SGi E-UTRAN EPC

6. IP-Connectivity Access Network Internet GERAN, UTRAN, EUTRAN GPRS CN, UMTS CN, EPC SGSN, S-GW GGSN, P-GW IMS Platform BTS, Nb, eNb Intranet IP-CAN IP-PDN

7. IP-CAN Bearers SGSN GGSN PS-RAB GTP-Tunnel IP-CAN Bearer (PDP Context) S-GW P-GW LTE-Bearer GTP–Tunnel IP-CAN Bearer (EPS Bearer) Interconnect / Roaming support required SGSN S-GW P-GW GTP–Tunnel PS-RAB GTP-Tunnel (EPS Bearer) IP-CAN Bearer

8. LTE Connection components SDFs E-RABs IP Flow(s) IP-CAN Bearer PCRF MME GTP Tunnel(s) GTP Tunnel(s) RBs PGW SGW ISP / Transit Networks(s) Application Server Application / SP EDGE Router MNO EDGE Router SCTP Association GTP-C Tunnel MNO Domain SPR HSS

9. Radio Bearer (RB) • Radio Bearer • L2 service provided for transfer of info on the Air Interface • Describes L2 processes per bit-stream (flow) • Different QoS requirements supported by different RBs • Example • Flow A requires low latency but can tolerate packet loss of 10-2 • Flow B has less stringent latency requirements, but can only tolerate a packet loss of 10-6 • Flow A and B must be supported by 2 separate Radio Bearers

10. LTE Radio Bearer categories • Signalling Radio Bearers (SRB) • SRB0 is for RRC messages • Using the CCCH logical channel • SRB1 is for RRC / NAS messages • Used prior to the establishment of SRB2 • Using DCCH logical channel • NAS messages may be piggybacked inside RRC messages • All messages are Integrity Protected and Ciphered after security activation • SRB2 is for NAS messages • Using DCCH logical channel • May be contained in RRC messages, but with no RRC control content • All messages are Integrity Protected and Ciphered after security activation • Lower priority then SRB1 • Data Radio Bearers (DRB) • Carry User Plane content on the Air Interface

11. Radio Bearers SRB1 (RRC / NAS messages on DCCH) SRB0 (RRC messages on CCCH) Used for RRC connection setup DRB1 (User content with QoS ‘A’ on DTCH1) Multiple SRBs/DRBs to support on-going user connection SRB2 (NAS messages on DCCH) DRB2 (User content with QoS ‘B’ on DTCH2)

12. Bearer Mapping DRBs Mapped to / from S1 Bearers SRB RRC messages Interpreted by UE / ENB S1 GTP Tunnels (S1 Bearers) S5/S8 GTP Tunnels (S5/S8 Bearers) MME PGW SGW SCTP Association S1 Bearers Mapped to/from S5/S8 Bearers GTP-C Tunnel SRB NAS messages Mapped to SCTP association Interpreted by UE / MME

13. QoS and TFT EPS Bearer with defined QoS UL Traffic Flow Aggregates DL Traffic Flow Aggregates UL QoS managed by ENB ‘router’ UL / DL QoS managed by ENB scheduler SGW PGW UL TFT DL TFT RB ID  S1 TEID S1 TEID  S5/S8 TEID UL TFT  RB ID RB ID  S1 TEID S1 TEID  S5/S8 TEID S5/S8 TEID  DL TFT Packet Filters - applied to each uplink IP-datagram (QoS control) Packet Filters - applied to each downlink IP-datagram (QoS control) DL QoS managed by SGW ‘router’