LTE, LTE-Advanced and WiMAX: Towards IMT-Advanced Networks

Signaling for Bandwidth Requests and Grants

The setup, management and release of a radio bearer are carried out by the MME on the S1 interface. This is an addition of other functionalities required for bandwidth requests and grants signaling such as resource management and admission control. The setup release and management of a dedicated radio bearer are different from those made for a default bearer, as will be shown in the following sections.

Figure 12.1 Dedicated bearer activation. Reproduced by permission of © 2010 3GPP. Further use is strictly prohibited.

Dedicated Bearer

Dedicated Bearer Activation

The activation of dedicated radio, shown in Figure 12.1, bearer takes place as follows:

1. The PDN GW sends a Create Dedicated Bearer Request message (I MSI, PTI, EPS Bearer QoS, TFT, S5/S8 TEID, LBI, Protocol Configuration Options) to the Serving GW. The LBI is the Linked EPS Bearer Identity (LBI) of the default bearer.
2. The Serving GW sends the Create Dedicated Bearer Request (I MSI, PTI, EPS Bearer QoS, TFT, S1-TEID, LBI, Protocol Configuration Options) message to the MME. If the UE is in ECM-IDLE state, the MME will trigger the Network Triggered Service Request from Step 3. In such a case, Steps 4-7 may be combined into a Network Triggered Service Request procedure or be performed individually.
3. The MME selects an EPS Bearer Identity that has not yet been assigned to a UE. The ...