Call Setup Success Rate (Call Resource Allocation Failures)

Counts of failed call resource assignment (CS) = Counts of assignment attempts (CS) – Counts of traffic channel

getting ready (CS)

Additional description:

CCM needs to apply all kinds of resource after receiving Assignment Request from MSC. Any failure in the period

that BSC receives the Assignment Request from the MSC until the BSC sends the ECAM/CAM message is regarded

as the Call Resource Allocation Failures. It is not the same as the total counts of congestion in the statistic of traffic

channel congestion rate. The traffic channel congestion is only the failure of radio resource assignment process, so it

is a part of the failed call resource allocations. However, the statistic traffic channel congestion rate also includes that

of handoff. Here Call Resource Allocation Failure indicates only the call setup.

Traffic Channel Congestion Rate

Counts of Request of Traffic Channel Assignment

The total counts of applying radio resource of the FCH traffic channel in the case of call, hard handoff or soft handoff.

The whole voice call process inside the BSC modules is shown in Figure 2-15. Note: The counts of requests of traffic

channel assignment are just for the RRM’s application of the radio resource, which is a part of the whole call resource

establishment process. That is to say that the traffic channel congestion is just a failure during the RRM allots radio

resource.

Figure 2-15 Call Process Flow in BSC modules

1. RRM increases the counts of the traffic channel assignment requests when receiving the

traffic channel application message CCM_RRM_FCH_REQ from CCM, as shown in Figure 2-

15.

2. When the RRM receives the message CCM_RRM_CRB_REQ and fails to allot radio

resource, the request and the failure will be counted one time respectively.

Strictly speaking, the message CCM_RRM_CRB_REQ is not a real application of traffic

channel, while the message CCM_RRM_FCH_REQ is the real one. However, because the

handling of the message CCM_RRM_CRB_REQ involves in admission control algorithm

including hard assignment, it is the permission control judgment for the module to apply carrier

CCM RRM

CCM_RRM_FCH_REQ

RRM_ CCM_FCH_REQ_REJ

and channel assignment. If it is failed, the congestion should be counted. If it is successful, the

request should not be included and will be counted later during the branch application.

The whole statistics method is when the CCM_RRM_CRB_REQ applies for the resource

successfully; the traffic channel congestion rate (the number of requests and successful

requests) will not be counted. When the application of resource fails, only the access carrier

frequency’s congestion is counted (Both request and failure are counted one time), other carried

frequency will not be counted. Please note that in case of multiple branches, the application

succeeds if there is any successful branch and fails if all the branches are failed. Counts of the

applied branches of the CCM_RRM_FCH_REQ are carried out according to the actual applied

quantity. Examples are given below:

Access carrier

Other Carriers in Radio environment Fields

Handling Result of the CCM_RRM_CRB_REQ

Handling of the CCM_RRM_FCH_REQ

Assignment activation set

Statistics

P1 P2.P3 P1, P2 and P3 are not allowed admission

--- ---One time for access carrier request, one time for failure

P1 P2.P3.P4 P1 is not allowed admission, P2 and P3 are other module’s pilots , P4 is allowed admission

P2 and P3 are not allowed admission

P4 Three times for request, one time for successful and twice for failure

Counts of Successful Traffic Channel Assignments

The total counts of successful FCH traffic channel assignments in the case of call, hard handoff or soft handoff.

BSC RRM increases this counter when call processing module applies radio resource for call/SHO/HHO success.

The actual point is: RRM sends the traffic channel establishment message RRM_CCM_FCH_REQ_CNF, as shown

in Figure 2-15.

Counts of Traffic Channel Assignment Failure (Insufficient WALSHs)

The total counts of failed FCH traffic channel assignments caused by insufficient Walsh codes.

The counter is increased when BSC RRM fails to apply the TCH resource due to insufficient WLASH code. The

actual point is: when the RRM fails to apply the WLASH code resource and sends the traffic channel rejection

message RRM_CCM_FCH_REQ_REJ. The release reason value within the RRM is 0x25 (failed code resource

assignment), as shown in Figure 2-16.

Figure 2-16 Traffic Channel Assignment Failure

Counts of Traffic Channel Assignment Failures (Insufficient Forward Power)

The total counts of failed FCH traffic channel assignments caused by insufficient forward power.

The counter is increased when BSC RRM fails to apply the TCH resource due to insufficient forward power. The

actual point is: When the RRM controls the admission; it fails to apply the forward power resource and then sends the

traffic channel rejection message RRM_CCM_FCH_REQ_REJ. The release reason value within the RRM is 0x60

(forward restricted), as shown in Figure 2-16.

Counts of Traffic Channel Assignment Failures (Insufficient Reverse Power)

The total counts of failed FCH traffic channel assignments caused by insufficient reverse power.

The counter is increased when BSC RRM fails to apply the TCH resource due to insufficient reverse power. The

actual point is: When the RRM controls the admission; it fails to apply the reverse power resource and then sends the

traffic channel rejection message RRM_CCM_FCH_REQ_REJ, as shown in Figure 2-16. The release reason value

within the RRM is 0x61 (reverse restricted). The reverse equivalent user numbers controls the reverse admission.

Counts of Traffic Channel Assignment Failures (Insufficient Channels)

Counter meaning: The total counts of failed FCH traffic channel assignments caused by insufficient CEs.

The counter is increased when BSC RRM fails to apply the TCH resource due to insufficient channel elements (CE).

The actual point is: When the RRM controls the admission; it fails to apply the CE and then sends the traffic channel

rejection message RRM_CCM_FCH_REQ_REJ, as shown in Figure 2-16. The release reason value within the RRM

is 0x62 (insufficient forward CE) or 0x63 (insufficient reverse CEs). The CE resource applied by the RRM is the logic

resource maintained by the RRM.

Counts of Traffic Channel Assignment Failures (Other)

Counter meaning: The total counts of failed FCH traffic channel assignments caused by other cases other than the

four cases mentioned above.

The counter is increased when BSC RRM fails to apply the TCH resource due to other reasons. During the

establishment of the FCH traffic channel, the RRM module encounters the failures other than forward/reverse power

failure, CE failure and WALSH failure, and then it sends traffic channel rejection message

RRM_CCM_FCH_REQ_REJ, as shown in Figure 2-16.

Traffic Channel Congestion Rate

The traffic channel congestion rate only reflects the application of the radio resource of the FCH traffic channel during

call establishment/SHO/HHO. It is different from the failure of the call resource assignment which means the failure of

the applications of all the call resources including radio resource, such as transmission and hardware resource of the

equipment.

Traffic channel congestion rate = {Counts of the requests for the traffic channel assignment – Counts of successful

traffic channel assignments} / Counts of requests for traffic channel assignments

Causes of Handoff Failure and Rollback after Handoff Failure

Causes of handoff failure include:

1) Target cell pilot coverage is not consistent with service channel coverage, and service channel signal strength in handoff is not strong enough.

2) Signal quality of target cell is not high; 3) Handoff timeout 4) Target cell resources is not available5) Maintenance interference causes the failure 6) The cell doesn't exist; 7) Voice coder rates are not matched; 8) Terrestrial resource is not available 9) Equipment or interface fault 10) Failure in case of recovering to the previous channel 11) Others

After the handoff fails, recover to the configuration status before attempting to the

handoff, and send candidate frequency measurement report or pilot strength

measurement message. The MS will switch off the relevant counter in handoff

attempt.

The transmitting of reverse supplemental channel may not be recovered.