· The purpose of the UE requested bearer resource allocation procedure is (for an UE) to request an allocation of bearer resources for a traffic flow aggregate.
· The UE requests a specific QoS demand (QCI) and optionally sends a Guaranteed Bit Rate (GBR) requirement for a new traffic flow aggregate.
· If accepted by the network, this procedure invokes a dedicated EPS bearer context activation procedure or an EPS bearer context modification procedure.
· If there is a PDN connection for emergency bearer services established, the UE shall not request additional bearer resources for this PDN connection.
· The UE initiates this procedure by sending a BEARER RESOURCE ALLOCATION REQUEST message to the MME and starts the timer T3480.
· The UE shall include the IE Linked EPS bearer identity and set it as the EPS bearer identity of the default EPS bearer associated with the requested bearer resource.
· The UE shall set the TFT operation code in the Traffic flow aggregate IE to "Create new TFT".
· In the Required traffic flow QoS IE, the UE shall indicate a QCI (QoS Class Identifier) and, if the UE also includes a GBR, the additional GBR required for the traffic flow aggregate.
· If the bearer resource allocation request is accepted by the network, the MME shall send either an ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST or MODIFY EPS BEARER CONTEXT REQUEST message with a PTI value received in the BEARER RESOURCE ALLOCATION REQUEST message.
· If the UE doesn’t receive response to the BEARER RESOURCE ALLOCATION REQUEST message before the expiry of the timer T3480, the UE shall resend this message and reset/restart T3480. This retransmission is repeated four times, i.e. on the fifth expiry of T3480, the UE shall abort the procedure, release the PTI allocated for this activation.
· The Protocol Configuration Options IE is included in the BEARER RESOURCE ALLOCATION REQUEST message if the UE wishes to transmit (protocol) data (e.g. configuration parameters, error codes or messages/events) to the network.
· The UE shall include the IE Device Properties in this message if the UE is configured for NAS signalling low priority
Reference 3GPP TS 24.301
Example: BEARER RESOURCE ALLOCATION REQUEST message
Hi Kumar, Nice post. I have few doubts, please clarify.
ReplyDelete1. Does EPS bearer id =0 represent NULL value for the EPS bearer id?
2. And what does Linked EPS Bearer id indicate? Shall the UE need to fill default EPS bearer id for all Bearer Resource Allocation Requests?
3. Last one. It is possible to create Dedicated bearer(s) along with the Default bearer during the ATTACH procedure itself.. right? Then can you please mention which ESM message should be present in the ESM container IE of the ATTACH message. (For normal ATTACH, the ESM container contains PDP CONNECTIVITY REQUEST.)