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4 Flow ControlAbout This Chapter
4.1 Overview
This topic describes flow control. The flow control function enables the BSS to decrease the
access traffic flow. This ensures the smooth processing of services.
4.2 Availability
This topic describes the availability of flow control. The realization of flow control depends on
the cooperation of related hardware, software, and configuration parameters.
4.3 ImpactThis topic describes the impact of flow control on system performance and on other features.
4.4 Technical Description
The technical description of flow control consists of the causes, measures, and algorithms of
flow control.
4.5 Implementation
The implementation of flow control refers to configuring flow control.
4.6 Maintenance Information
This topic describes the alarms and counters related to flow control.
4.7 References
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4.1 Overview
This topic describes flow control. The flow control function enables the BSS to decrease the
access traffic flow. This ensures the smooth processing of services.
Definition
When the system traffic flow or load exceeds the design specifications, the BSS system performs
flow control to reduce the service connections or forbid some OM based on priorities. This
ensures the smooth processing of primary services and enables the system to restore to the normal
state within a short period of time.
Flow control can be classified into two types:
l Traffic flow control
Traffic flow control is an overload precaution. The traffic flow control function enables the
system to monitor the message arrival rate and take measures to ensure the stable running
of the system.
l System congestion control
System congestion control is an overload protection measure. The system congestion
control function enables the system to control the message arrival rate when the system is
overloaded. Thus, the system load is reduced.
Purposes
Under the specific system capacity and load, the BSC can normally provide services. When thetraffic flow exceeds the design specifications of the BSC, flow control should be performed to
ensure the following functions:
l The BSC runs normally and provide services.
l The BSC provides optimal services.
l The BSC provides differentiated services based on the QoS policies.
Terms
Terms Definition
Message arrival rate Message arrival rate indicates the number of specified messages
received by the BSC in a unit time.
Abbreviations
None.
4.2 Availability
This topic describes the availability of flow control. The realization of flow control depends onthe cooperation of related hardware, software, and configuration parameters.
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Network Elements Involved
Table 4-1 lists the NEs involved in flow control.
Table 4-1 NEs involved in flow control
MS BTS BSC MSC MGW SGSN GGSN HLR
NOTE
l : not involved
l : involved
Software Releases
Table 4-2 describes the versions of GBSS products that support flow control.
Table 4-2 GBSS products and related versions
Product Version
BSC BSC6000 V900R001C01 and later releases
BTS BTS All the releases
MiscellaneousThe realization of flow control requires the cooperation of the MSC and the BTS.
l The MSC can process Overload messages and Load Indication messages on the A interface.
The MSC can process Overload messages and Load Indication messages sent by the BSC
according to the 3GPP 48008 protocol. When the BSC is overloaded, the MSC should
reduce the number of messages sent to the BSC.
l The BTS can process the Overload, CCCH Load Indication, and CBCH Load Indication
messages on the Abis interface.
When the BTS is overloaded, it can send flow control messages (such as Overload messages
and CCCH Load Indication messages) on the Abis interface to the BSC to inform the BSCof the BTS load conditions.
4.3 Impact
This topic describes the impact of flow control on system performance and on other features.
Impact on System Performance
Flow control requires the system to measure the system load and message arrival rate in real
time. The measurement has impacts on the system performance.
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Impact on Other Features
Flow control has the following impacts on other features:
l When the flow control takes effect, some system OM functions may be forbidden and some
service flow may be controlled. For example, debug logs cannot be outputted, or sometracing messages may be limited.
l When the flow control takes effect, some functions cannot be used. For example, the
SDCCH dynamic adjustment function is forbidden.
l When the flow control takes effect, the BSC may discard some access request messages,
for example, access request messages sent by MSs, paging messages, incoming BSC
handover request messages.
4.4 Technical Description
The technical description of flow control consists of the causes, measures, and algorithms offlow control.
4.4.1 Flow Control Measures
This topic describes why the BSS performs flow control and the flow control measures taken
by the BSC.
4.4.2 Flow Control Algorithms
This topic describes the flow control algorithms involved in flow control.
4.4.1 Flow Control Measures
This topic describes why the BSS performs flow control and the flow control measures takenby the BSC.
The causes that lead to system overload are as follows:
l Internal causes
Internal causes such as OM in batches or internal exceptions may increase system
processing loads or exhaust key system resources.
l External causes
Excessive traffic flow from other NEs may lead to the BSS overload. For example, the
MSC sends a large number of paging messages within a short period of time, or a large
numberof MSs send or resend access request messages simultaneously. All this increases
the traffic flow and processor load of the BSC and exhausts key system resources. Thus,the BSS is overloaded.
The BSC uses various flow control measures to avoid network overload. When the network is
overloaded, the traffic flow can be reduced significantly. This ensures the smooth processing of
primary services and enables the system to restore the normal state within a short period of time.
The BSC has the following flow control measures:
l Flow control of message arrival rates
l Flow control on LAPD links
l Traffic flow control on the Um interface
l Cell traffic flow control
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l Internal flow control
l OM flow control
4.4.2 Flow Control Algorithms
This topic describes the flow control algorithms involved in flow control.
4.4.2.1 Flow Control of Message Arrival Rates
This topic describes the flow control of message arrival rates. The flow control of message arrival
rates enables the BSC to receive only a certain number of messages in a statistical period
4.4.2.2 Flow Control on LAPD Links
This topic describes the flow control on LAPD links. The flow control on LAPD links is
classified into DL flow control and UL flow control.
4.4.2.3 Traffic Flow Control on the Um Interface
This topic describes the traffic flow control on the Um interface. The traffic flow control on theUm interface involves the BTS processor overload, paging channel overload, and cell broadcast
channel overload.
4.4.2.4 Cell Flow Control
This topic describes cell flow control. To enable the cell flow control, each cell has a state
machine for cell flow control. The flow control of one cell is independent of the other cells.
4.4.2.5 Internal Flow Control
This topic describes the internal flow control. The BSC performs flow control on key system
resources such as messages and CPU usage. This ensures that the primary services run normally
and the BSS gradually restores the normal capacity and load when the traffic flow exceeds the
capacity and flow specifications.
4.4.2.6 OM Flow Control
This topic describes the OM flow control. The GBAM and service boards determine whether to
perform OM or whether to send OM messages to other boards based on relevant information.
Flow Control of Message Arrival Rates
This topic describes the flow control of message arrival rates. The flow control of message arrival
rates enables the BSC to receive only a certain number of messages in a statistical period
The MSC sends a large number of paging messages within a short period, or a large number of
MSs send or resend random access request messages. These paging messages or access messages
increase the BSC load, exhaust key system resources, and thus overload the BSC.
In this case, the BSC controls the message arrival rates of the paging messages on the A interface
and of the random access request messages on the Abis interface. When the message arrival rate
control function is enabled, the BSC monitors the paging messages on the A interface and the
random access request messages on the Abis interface, and calculates in real time the message
arrival rates.
l If the calculated message arrival rate is lower than the configured message arrival rate, the
system does not enable the message arrival rate control function.
l If the calculated message arrival rate in a specified unit time is higher than the configured
maximum message arrival rate, the system directly discards the messages the number ofwhich exceeds the maximum allowed number.
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In the message arrival rate control function, the parameters such as whether to start message
arrival rate control, the statistical period, and the number of messages in a statistical period are
configurable. The parameters are as follows:
l Start Pg Arrival Ctrl Pg State Period
l Pg Max Message Number In Period
l Start Channel Request Arrival Ctrl
l Channel Request Stat Period
l Channel Request Max Message Number In Period
l CPU usage threshold of XPUT channel required flow control in critical congestion
Flow Control on LAPD Links
This topic describes the flow control on LAPD links. The flow control on LAPD links is
classified into DL flow control and UL flow control.
The flow control on LAPD links over the Abis interface enables the system to control the number
of messages (including paging messages and access request messages) sent on the Abis interface
based on the message arrival rates and system load. Thus, the requirements for signaling load
and system load on LAPD links are met. This ensures the smooth operations of call services.
The DL flow control on LAPD links refers to controlling the number of paging messages. The
UL flow control on LAPD links refers to controlling the number of random access request
messages.
DL Flow ControlIf the rate that the BSC sends messages to the LAPD links is greater than the rate that the messages
on the Abis interface are sent to the BTS, DL messages are buffered in the I frame queue or are
even discarded. Thus, the length of the I frame queue should be calculated and flow control
should be performed.
The parameters of DL flow control on LAPD links are as follows:
l Flow Control End Threshold
l Flow Control Start Threshold
UL Flow Control
If a large number of random access request messages are sent on the LAPD links on the Abis
interface, the traffic flow of the system is greatly increased. Thus, the LAPD links are overloaded.
To avoid this case, the BSC controls the message arrival rate of random access request messages
sent by the BTS. If the actual message arrival rate exceeds a configured rate, the BSC discards
some of the random access request messages based on the configured flow control data.
The parameters ofthe UL flow control on LAPD links are as follows:
l Ra Max Count Percent Period
l Ra Check Period (50 ms)
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Traffic Flow Control on the Um Interface
This topic describes the traffic flow control on the Um interface. The traffic flow control on the
Um interface involves the BTS processor overload, paging channel overload, and cell broadcast
channel overload.
The traffic flow control on the Um interface is controlled by the BSC based on the load reports
sent by the BTS.
BTS Processor Overload
When a TRX processor in the BTS is overloaded, the BTS sends an Overload message to the
BSC with the cause value Processor Overload and the overloaded TRX.
On receiving the Overload message, the BSC starts the TRX overload timer and sets the state
of the overloaded TRX to the overload state. In this case, the BSC stops assigning the SDCCHs
and TCHs of the TRX. It also stops the SDCCH dynamic adjustment and reconversion.
If the TRX runs normally after the TRX overload timer expires, the BSC can perform channelassignment and SDCCH dynamic adjustment.
If the TRX overload timer does not expire (the TRX is in the overload state) and the BSC again
receives an Overload (processor overload) message related to the TRX, the BSC restarts the
TRX overload timer and sets the TRX to the overload state.
Paging Channel Overload
The network can locate a called MS by paging the MS in its location area. Then, the MS requests
access to the network.
If many paging messages are sent on the Um interface, PCHs may be overloaded. In this case,the BTS sends the BSC a CCCH Overload Indication message, indicating that the PCHs of the
current cell are overloaded.
On receiving the CCCH Overload Indication message, the BSC sends an Overload message to
the BSC with the overload cause CCCH Overload. The Overload message also indicates the
overloaded cell.
After receiving the Overload message, the MSC reduces paging messages sent to the BSC.
The flow control related to paging channel overload is a basic function of the BSS and does not
require data configurations.
Cell Broadcast Channel OverloadThe BSC supports the cell broadcast short message function. Cell broadcast short messages are
sent on the CBCHs on the Um interface.
Based on the loads of the CBCHs on the Um interface, the BTS sends the CBCH Load Indication
messages to the BSC. The CBCH Load Indication messages indicate whether the CBCH is
overloaded or underloaded.
If the CBCH Load Indication message indicates that the CBCHs of the current cell are
overloaded, the BSC does not send cell broadcast message to the cell in a period of N*1.883
seconds. Assume that N is the delay value that is indicated in the CBCH Load Indication message.
If the CBCH Load Indication message indicates that the CBCHs of the current cell areunderloaded and indicates the number N, the BSC determines how many cell broadcast messages
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can be sent. Assume that N is the number of cell broadcast messages that can be sent to the
current cell, M is the number of cell broadcast messages that need to be sent, and S = Min {M,
N}. The number of cell broadcast messages that can be sent by the BSC to the BTS is S.
The flow control related to cell broadcast messages does not require data configurations, but
requires the system to support cell broadcast short messages.
NOTE
The minimum interval of two consecutive cell broadcast messages is 1.883 seconds.
Cell Flow Control
This topic describes cell flow control. To enable the cell flow control, each cell has a state
machine for cell flow control. The flow control of one cell is independent of the other cells.
Cell flow control is performed to avoid the following conditions:
l When a large number of MSs simultaneously send location update requests (channel
requests), the BSC sends a large number of Immediate Assignment messages or Immediate
Assignment Reject messages to the BTS. Thus, the BTS is overloaded and the transmission
queue of AGCHs overflows.
l After sending a channel request message, the MS retransmits the channel request message
if it does not receive a real-time response from the network. When an Immediate
Assignment message is discarded, the MS cannot use the activated signaling channel, which
is not released until the relevant timer expires. Thus, the signaling channel is wasted.
After the BSC receives a channel request message, there is no available channel to be assigned.
In this case, cell flow control is triggered.
The cell flow control function uses the double timer mechanism to adjust the flow control level.
The double timer mechanism is described in the 3GPP 48058 protocol. When a cell is initialized,
the flow control level of the cell is zero and the flow control state is Idle state. Timers T1 and
T2 are not running. Table 4-3 describes the transfer of the flow control states.
Table 4-3 Transfer of the flow control states
Current State Event Action Next State
Idle state The current cell has
no available channel.
The flow control
level is increased by
one. Start timers T1and T2.
Timers T1 and T2 are
running.
Timers T1 and T2 are
running.
The current cell has
no available channel.
Take statistics of
traffic.
Timers T1 and T2 are
running.
Timer T1 expires. No action is
performed.
Timer T2 is running.
Timer T2 is running. The current cell has
no available channel.
The flow control
level is increased by
one. Start timers T1
and T2.
Timers T1 and T2 are
running.
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Current State Event Action Next State
Timer T2 expires. The flow control
level is decreased by
one. If the flow
control level after the
decrease is greater
than zero, restart
timer T2.
The flow control
level is decreased by
one. The flow control
level after the
decrease is zero.
Timer T2 is running.
Idle state
Cell flow control has six levels: 0 to 5.
l Level 0 indicates the normal state.
l Level 5 indicates the most serious flow control state.
When the flow control level changes, the BSC modifies the parameters MS MAX Retrans and
Tx-integer in the system message and retransmits the system message. The new system message
requests the MS to reduce channel request messages and to increase the interval of sending
channel request messages. Table 4-4 describes the flow control measures that are taken when
the cell flow control level changes.
Table 4-4 Cell flow control level
Adjustment ofCell FlowControl
MS MAX Retrans Tx-integer
01 Min(4, initial configuration) If the flow control level is smaller
than 4, set the flow control level
to 4.
12 Min(2, current value) If the flow control level is smaller
than 7, set the flow control level
to 7.
23 Min(2, current value) If the flow control level is smaller than 10, set the flow control level
to 10.
34 1 If the flow control level is smaller
than 13, set the flow control level
to 13.
45 1 The flow control level is 15.
54 1 The flow control level is Max(13,
initial configuration)
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Adjustment ofCell FlowControl
MS MAX Retrans Tx-integer
43 Min(2, initial configuration) The flow control level is Max(10,
initial configuration)
32 Min(2, initial configuration) The flow control level is Max(7,
initial configuration)
21 Min(4, initial configuration) The flow control level is Max(4,
initial configuration)
10 Initial configuration Reset to initial configuration.
The Immediate Assignment Reject message sent by the BSC to an MS indicates the time that
the MS should wait before retransmitting a channel request message. The time depends on theflow control level. The higher the flow control level is, the longer the MS should wait. Table
4-5 lists the mapping between the flow control level and the length of timer T3122.
Table 4-5 Mapping between the flow control level and the length of timer T3122
Cell Flow Control Level Length of Timer T3122 (Second)
0 10
1 30
2 90
3 130
4 170
When configuring the cell flow control, you should set the Abis-interface flow control timers
T1 and T2. Timer T1 and T2 work together to determine the cell flow control level. When the
cell flow control level changes, the parameters MS MAX Retrans and Tx-integer in the system
message are modified. The parameters of timers T1 and T2 are as follows:
l Abis Flow Control Timer 1 (s)
l
Abis Flow Control Timer 2 (s)NOTE
When setting timers T1 and T2, ensure that the length of timer T1 should be smaller than that of timer T2.
Internal Flow Control
This topic describes the internal flow control. The BSC performs flow control on key system
resources such as messages and CPU usage. This ensures that the primary services run normally
and the BSS gradually restores the normal capacity and load when the traffic flow exceeds the
capacity and flow specifications.
The BSC monitors in real time the usage of key system resources, performs calculation, andcompares the calculation results with thresholds. In this way, the BSC determines the current
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flow control level and the discard proportion of random access request messages and paging
messages.
The internal flow control function enables the system to sample the number of resources used
by all messages. Then the number serves as an input of a low pass filter, the output of the low
pass filter is the average number (avg) of resources used by each system message. Through thefiltering, burst flow under normal conditions can be filtered and congestion can be detected.
NOTE
At present, the low pass filter in use is a WIN_SIZE-point rectangular window filter. The filter calculates
the average value of recent WIN_SIZE points input to obtain the current output.
The average message usage (avg) is used to determine the system load. The system message
usage changes rapidly, as shown in Figure 4-1. If the system message usage is directly used to
determine the system load, a tiny traffic burst may trigger the internal flow control, that is, the
internal flow control is triggered under normal conditions. If the flow control function is enabled
frequently, normal calls are rejected and call loss occurs. Thus, the system processing capability
is underused. Smoothing (low pass filter) filters tiny burst flow. When congestion occurs, themessage queue is long and average message usage (avg) continually increases. At last, the traffic
flow exceeds the flow control begin threshold.
Figure 4-1 BSS internal flow control
Th2
Th1
t
Assume that avg is the average system message usage, Th1 is the internal flow control discard
begin threshold, Th2 is the internal flow control discard all threshold, and P is the message
discard probability. Figure 4-2 shows the calculation of P.
l If avg < Th1, then P = 0.
l If Th1 avg
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Figure 4-2 Calculation of P
P
avgTh1 Th2
When the BSC receives paging messages on the A interface or random access request messages
on the Abis interface, it discards some of these messages based on P.
The internal flow control levels are calculated based on P and are classified into 12 levels: level0 through level 11.
l Level 0 indicates that internal flow control is not required.
l Level 11 indicates the most serious flow control state.
The BSS limits some auxiliary functions based on the internal flow control levels. Table 4-6
lists the auxiliary functions related to the internal flow control levels.
Table 4-6 Auxiliary functions related to the internal flow control levels
Control Item Flow Control Level
Level 01
Level 23
Level 45
Level67
Level 89
Level 1011
Cell frequency scan - Inhibit Inhibit Inhibit Inhibit Inhibi
t
Normal information
- Inhibit Inhibit Inhibit Inhibit Inhibi
t
Normal log - Inhibit Inhibit Inhibit Inhibit Inhibi
t
Call resource check - Inhibit Inhibit Inhibit Inhibit Inhibit
Forced handover - - Inhibit Inhibit Inhibit Inhibi
t
Switching candidate
query
- - - Inhibit Inhibit Inhibi
t
Channel allocation
queue function
- - - - Inhibit Inhibi
t
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Control Item Flow Control Level
Level 01
Level 23
Level 45
Level67
Level 89
Level 1011
Radio resource
indication processing
(interference band)
- - - - Inhibit Inhibi
t
Call preemption - - - - Inhibit Inhibi
t
Channel conversion - - - - - Inhibi
t
Conversion between
traffic channel and
signaling channel
- - - - - Inhibi
t
The parameters of the internal flow control are as follows:
l Internal Flow Control Allowed
l Internal Flow Control Discard Begin Threshold
l Internal Flow Control Window Size
l Internal Flow Control Discard All Threshold
OM Flow ControlThis topic describes the OM flow control. The GBAM and service boards determine whether to
perform OM or whether to send OM messages to other boards based on relevant information.
The system monitoring processes in the GBAM and service boards monitor in real time key
system resources such as the CPU usage and system message resources, and then calculate the
usage of these resources and the flow control level of each board. Then, these flow control levels
are used to control the flow of log messages and signaling tracing messages.
The flow control level of each service board is broadcast to other boards through periodical
message broadcasts among the GBAM and serviceboards. A board determines whether to
perform OM or send OM messages to other boards based on its flow control level and the flow
control levels of other boards received from periodical message broadcasts.
By default, the OM flow control of the BSC uses hierarchical flow control and has multiple flow
control thresholds (ThSt). For each flow control level, the BSC performs relevant operations.
l If the value of a flow control source is smaller than ThSt1, the flow of the flow control
source is not controlled.
l If the value of a flow control source is greater than ThStn, all the flow control sources are
discarded.
l If the value of a flow control source is between ThSt1 and ThStn, the flow of the flow
control source is controlled based on its flow control level.
Figure 4-3 shows the relations between the OM flow control levels and the flow controlthresholds.
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Figure 4-3 Relations between the OM flow control levels and the flow control thresholds
Not overload state
Serious overload
stateBegin overload state
1 2
3
4
When the flow control level reaches level 2, the BSS controls the flow of the signaling tracing
messages.
4.5 Implementation
The implementation of flow control refers to configuring flow control.
4.5.1 Configuring Flow Control
This topic describes how to configure flow control on the BSC6000 Local Maintenance
Terminal.
4.5.1 Configuring Flow Control
This topic describes how to configure flow control on the BSC6000 Local Maintenance
Terminal.
Procedure
Step 1 On the Management Tree tab page of the BSC6000 Local Maintenance Terminal, right-clickBSC6000, and then choose Configure BSC Attributes on the shortcut menu. A dialog box is
displayed, as shown in Figure 4-4.
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Figure 4-4 Configure BSC Attributes dialog box
Step 2 Click the Flow Control Data tab. Set the relevant parameters, as shown in Figure 4-5 andFigure 4-6.
Figure 4-5 Configuring flow control data (1)
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Figure 4-6 Configuring flow control data (2)
Step 3 Click the BSC Timer tab. Set the parameters, as shown in Figure 4-7.
Figure 4-7 Configuring BSC timer
Step 4 Click the Software Parameters tab. Set flow control data of LAPD links, as shown in Figure4-8.
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Figure 4-8 Configuring software parameters
Step 5 Set Flow Control Start Threshold and Flow Control End Threshold.
1. On the Management Tree tab page of the BSC6000 Local Maintenance Terminal, right-
click the target TRX, and then choose Configure TRX Attributes on the shortcut menu.
A dialog box is displayed, as shown in Figure 4-9.
Figure 4-9 Configure TRX Attributes dialog box
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2. Select the target TRX, and then clickSet TRX Attributes. A dialog box is displayed, as
shown in Figure 4-10.
Figure 4-10 Configure TRX Attributes dialog box
3. Click the RSL Setting tab, and then set Flow Control Start Threshold and Flow Control
End Threshold.
----End
4.6 Maintenance Information
This topic describes the alarms and counters related to flow control.
Alarms
Table 4-7 lists the alarms related to flow control.
Table 4-7 Alarms related to flow control
Alarm ID Alarm Name
201 Internal Flow Control Level Changed
202 Internal Flow Control Released
101 MSC Overload
21001 LAPD Link Congestion
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Counters
Table 4-8 describes the counters related to flow control.
The cell flow control is performed through a double-timer mechanism:
l If a trigger event occurs when timer T1 is running, the trigger event is ignored.
l When a trigger event occurs, if timer T1 is not running, the flow control level is increased
by one unless it reaches the highest level. At the same time, timers T1 and T2 (T2 > T1)
are started.
If timer T2 expires, the flow control level is decreased by one. If the flow control level is not
zero after the decrease, timer T2 is restarted.
Table 4-8 Counters related to flow control
Counter Description
Increaes of Flow Control Levels This counter indicates the number of times the trigger
event occurs when T1 stops and the flow control does
not reach the highest level.
Decreases of Flow Control Levels The counter indicates the number of times timer T2
expires.
Ignored Trigger Events This counter indicates the number of times that trigger
events occur when timer T1 is running.
Highest Level Delays This counter indicates the number of times trigger events
occur when timer T2 is running and the flow control level
is the highest level.
SM Pagings Discarded on LAPD
Link
This counter indicates the number of discarded short
message (SM) pagings on the LAPD link.
CS Pagings Discarded on LAPD
Link
This counter indicates the number of discarded CS
pagings on the LAPD link.
PS Pagings Discarded on LAPD
Link
This counter indicates the number of discarded PS
pagings on the LAPD link.
MSG CCCH LOAD IND (RACH)
Messages Sent on Abis Interface
The counter indicates the number of times that the BSC
receives CCCH Load Indication messages with the cause
value UL CCCH (RACH) Overload from the BTS.
MSG CCCH LOAD IND (PCH)
Messages Sent on Abis Interface
The counter indicates the number of times the BSC
receives CCCH Load Indication messages with the cause
value DL Circuit Service CCCH (PCH) Overload from
the BTS.
PACKET CCCH LOAD IND
Messages Sent on Abis Interface
This counter indicates the number of times the BSC
receives Packet CCCH Load Indication messages in a
statistical period.
MSG ABIS OVERLOAD (CCCH
OVERLOAD) Messages Sent on
Abis Interface
This counter indicates the number of times the BSC
receives Overload messages with the cause value CCCH
Overload in a statistical period.
HUAWEI BSC6000 Base Station Subsystem
BSS Feature Description 4 Flow Control
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Counter Description
MSG ABIS OVERLOAD
(PROCESSOR OVERLOAD)
Messages Sent on Abis Interface
This counter indicates the number of times the BSC
receives Overload messages with the cause value TRX
Processor Overload in a statistical period.
4.7 References
l 3GPP 48.058 Base Station Controller - Base Transceiver Station (BCS-BTS) Interface
Layer 3 Specification
l 3GPP 48.008 Mobile Switching Centre - Base Station system (MSC-BSS) Interface Layer
3 Specification
4 Flow Control
HUAWEI BSC6000 Base Station Subsystem
BSS Feature Description
4-20 Huawei Technologies Proprietary Issue 01 (2007-09-05)