[ EPS bearer ]
- Basics
Packet filters: function usually packet transfer process to allow or prevent them through. To complete packet filtering, we must set up rules to specify which types of data packets are allowed to pass through and which types of data packets will be blocked.
The TFT (Traffic Flow Template) : template transport stream, is associated with the EPS bearer to a set of packet filters , filter template into an uplink UL TFT (UpLink TFT) filtering templates and downlink DL TFT (DownLink TFT).
UL TFT is a set of uplink packet filter , DL TFT is a group of downlink packet filters . Each dedicated bearer is associated with a TFT.
By mapping the UL TFT UE data for transmission on the uplink carrier associated TFT, P-GW through the DL TFT mapping to the downlink data transmission on the associated bearer TFT.
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EPS bearer
The EPS : Evolved Packet the System, Evolved Packet System.
May be considered EPS = UE (User Equipment, user equipment) + LTE (access network portion 4G) + EPC (Evolved Packet Core, Evolved Packet Core)
EPS bearer (EPS Bearer): one or more traffic between the UE and the P-GW data stream SDF (Service Data Flow) logic polymerization , including Radio Bearer, S1 Bearer, and S5 / S8 Bearer.
Description:
1) UE UL TFT by mapping uplink data to a EPS bearer;
2) PDN GW by mapping the downlink data DL TFT to a EPS bearer;
3) to transmit data on the air interface between the eNodeB and the UE through Radio Bearer. Radio Bearer EPS bearer and one correspondence.
4) to transfer data between the eNodeB and the S-GW through S1 Bearer;
5) An E-RAB (E-UTRAN Radio Access Bearer) refers to the Radio Bearer, and S1 Bearer associated therewith;
6) to transfer data between S-GW and the PDN GW through the S5 / S8 Bearer;
7) UE saved uplink filter (uplink packet filter) and the mapping between Bearer Radio;
8) PDN GW holds the filter downstream (downlink packet filter) and a mapping between the S5 / S8 Bearer;
9) S-GW to save the mapping between S1 Bearer and S5 / S8 Bearer.
- The carrier is divided into: default bearer (default) and dedicated bearer (Dedicated)
EPS system while performing the Attach, for the user to establish a default bearer, which ensure basic service requirements. During the existence of the PDN connection default bearer context remains active, so, give UE to provide "always on" IP connection.
Dedicated bearer context indicates additional bearer between the UE and the PDN. Dedicated bearer always has an associated default bearer. Dedicated bearer may be released, it does not affect the default bearer. Imparting specified by a TFT (transport flow template Traffic Flow Template) and QoS (Quality of Service), to be completed by a dedicated bearer specific business.
