What is the meaning of multiple PDN connectivity in LTE and UMTS?

Question

Can there be inter PDN handover in LTE or UMTS if yes then please explain the procedure.

Answer 1

UE can connect to multiple PDN at a time. If UE is connected multiple PDN, it mean UE have multiple IP(One IP correspond to one PDN). UE is required multiple PDN connectivity when existing PDN is not able to fulfill UE requirement.

Comments

can you tell how UE can connect to multiple pdns at a time?if 1 pdn not fulfilling requirement we have to connect to other pdn but ue can connect to 1 pdn at a time na plz clarify me

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Suppose UE is attached with LTE n/w and a default bearer is created. So UE have connected with one PDN(apn) and have one IP. If UE want to make voice call in LTE and IMS server is connected with different PDN then UE needs to connect with IMS PDN to make voice call. UE will make PDN connectivity request with IMS PDN(apn). This will lead to create one other default bearer with IMS PDN and UE will get one other IP as well.
So now UE have two IP and both IP can be used by UE at same time.

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UE can connect to multiple PDNs at a time. It depends upon the type of service user wants to access. Few examples of PDNs are Internet, IMS, MMS etc. UE will be configured with one default bearer for each connected PDN. So there's a one-to-one mapping between the count of default bearers and PDNs connected with a UE. When any new dedicated bearers are configured in a particular PDN later, it will be configured as a Dedicated EPS bearer which will be mapped to default EPS bearer of that PDN using 'Linked EPS bearer id' field. So there is one-to-many relationship between default and dedicated bearers of a pdn. Dedicated bearers can be released individually. But when UE wants to disconnect itself from a particular PDN, eNodeB will only specify the default bearer id of that pdn in RRC Connection Reconfiguration message. UE's higher layer will itself delete all other dedicated bearers associated with this default bearer.