When a new service accesses the network, NodeB credit resource–based admission is optional.
7.4.1 NodeB Credit
CE is used to measure the channel demodulation capability of the NodeBs. On the RNC side, it is referred to the NodeB credit. On the NodeB side, it is the channel element.
The resource of one equivalent 12.2 kbit/s AMR voice service, including 3.4 kbit/s signaling on the Dedicated Control Channel (DCCH), is defined as one CE. If there is only 3.4 kbit/s signaling on the DCCH, one CE is consumed. Channel elements provide either uplink or downlink capacity for services. There are two kinds of CE. One is uplink CE supporting uplink services, and the other is downlink CE supporting downlink services. Therefore, one 12.2 kbit/s AMR voice service consumes one uplink CE and one downlink CE.
The principles of NodeB credit–admission control are similar to those of power-based admission control, that is, to check in the local cell, local cell group (if any), and NodeB whether the remaining credit can support the requesting services.
For details about local cell, local cell group, and capacity consumption law, refer to the 3GPP TS 25.433.
According to the capacity consumption laws of common and dedicated channels, the
Controlling RNC (CRNC) debits the amount of the credit resource consumed from or credits the amount to the Capacity Credit (CC) of the local cell (or local cell group, if any) based on the SF. The specific scenarios are the addition, removal, and reconfiguration of the common and dedicated channels.
If the UL CC and the DL CC are separate, they are maintained separately in the local cell or local cell group.
If the UL CC and DL CC are not separate, only the global CC is maintained in the local cell or local cell group.
The consumption laws of CEs and the relation between CE and credit are listed in Table 7-12 and Table 7-13.
For the DCH service, the RNC uses the MBR to calculate the SF and searches Table 7-12 for the number of consumed CEs.
For the HSUPA service, if the HsupaCeScheduleSwitch is on, the RNC uses the GBR to calculate the SF; if this switch is off, the RNC uses the MBR to calculate the SF. Then, the RNC searches Table 7-13 for the number of consumed CEs.
Table 7-12 Consumption of credits related to SF for the DCH service Direction Rate
(kbit/s) SF Number of CEs
Consumed Corresponding Credits Consumed
UL 3.4 256 1 2
13.6 64 1 2
8 64 1 2
16 64 1 2
32 32 1.5 3
64 16 3 6
128 8 5 10
144 8 5 10
256 4 10 20
384 4 10 20
DL 3.4 256 1 1
13.6 128 1 1
8 128 1 1
16 128 1 1
32 64 1 1
64 32 2 2
128 16 4 4
144 16 4 4
256 8 8 8
384 8 8 8
Table 7-13 Consumption of credits related to SF for HSUPA services Direction Rate (kbit/s) SF Number of CEs
Consumed Corresponding Credits Consumed
UL 8 64 1 2
UL 16 64 1 2
Issue Error! Unknown Error! Unknown document property 17 Direction Rate (kbit/s) SF Number of CEs
Consumed Corresponding Credits Consumed
UL 32 32 1 2
UL 64 32 1 2
UL 128 16 2 4
UL 144 16 2 4
UL 256 8 4 8
UL 384 4 8 16
UL 608 4 8 16
UL 1450 2SF4 16 32
UL 2048 2SF2 32 64
UL 2890 2SF2 32 64
UL 5760 2SF2+2SF4 48 96
As listed in Table 7-12 and Table 7-13, for each data rate and service, the number of UL credits is equal to the number of UL CEs multiplied by 2. This is because the RESOURCE STATUS
INDICATION message over the Iub interface supports only integers. For example, a UL 32 kbit/s PS service consumes 1.5 CEs. Then, the number of corresponding UL credits consumed is 3, an integer, which can be carried in the RESOURCE STATUS INDICATION message.
There is no capacity consumption law for HS-DSCH in 3GPP TS 25.433, so certain credits are reserved for HSDPA RAB, and credit admission for HSDPA is not needed.
7.4.2 Procedure of Admission Decision Based on NodeB Credit
When a new service tries to access the network, the admission decision based on NodeB credit is implemented as follows:
For an RRC connection setup request, the credit resource–based admission is successful if the current remaining credit resources of the local cell, local cell group (if any), and NodeB are sufficient for RRC connection setup.
For a handover service, the credit resource–based admission is successful if the current remaining credit resources of the local cell, local cell group (if any), and NodeB are sufficient for the service.
For other services, the RNC has to ensure that the remaining credit of the local cell, local cell group (if any), and NodeB does not exceed the value of UlHoCeResvSf (for the uplink) or DlHoCeCodeResvSf (for the downlink) after admission of the new services.
The CE capabilities at the levels of local cell, local cell group, and NodeB are reported to the RNC through the NBAP_AUDIT_RSP message over the Iub interface.
- The CE capability of local cell level indicates the maximum capability in terms of hardware that can be used in the local cell.
- The CE capability of local cell group level indicates the capability obtained after the license and hardware are taken into consideration.
- The CE capability of NodeB level indicates the number of CEs allowed to use as specified in the license.
If the UL CC and DL CC are separate, the credit resource–based admission is implemented in the UL and DL, respectively.
If the UL CC and DL CC are not separate, the credit resource–based admission is implemented based on the total CC.