geran ur13 zgb-03!02!003 dynamic configuration of sdcch feature guide (v4)_v1.0
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GERAN UR13 ZGB-03!02!003 Dynamic Configuration of SDCCH Feature Guide (V4)_V1.0TRANSCRIPT
ZGB-03-02-003 Dynamic
Configuration of SDCCH
Feature Guide
ZGB-03-02-003 Dynamic Configuration of SDCCH
ZTE Confidential Proprietary 1
ZGB-03-02-003 Dynamic Configuration of SDCCH
Version Date Author Reviewer Notes
V1.00 2014/01/22 Shu Yan Gu Yuhui First edition
© 2014 ZTE Corporation. All rights reserved.
ZTE CONFIDENTIAL: This document contains proprietary information of ZTE and is not to be disclosed or used
without the prior written permission of ZTE.
Due to update and improvement of ZTE products and technologies, information in this document is subjected to
change without notice.
ZGB-03-02-003 Dynamic Configuration of SDCCH
2 ZTE Confidential Proprietary
TABLE OF CONTENTS
1 Feature Attribute ............................................................................................... 4
2 Overview ............................................................................................................ 4
2.1 Feature Introduction ............................................................................................. 4
2.2 License Control .................................................................................................... 5
2.3 Correlation With Other Features .......................................................................... 5
3 Technical Description ....................................................................................... 6
3.1 Algorithms for Dynamic SDCCH Configuration .................................................... 7
3.1.1 Descriptions of the Parameters Involved in the Algorithms ................................... 7
3.1.2 Dynamic SDCCH Configuration Standards and Idle TCH Selection Policies ........ 7
3.1.3 SDCCH Decrease and SDCCH Selection Principles ............................................ 8
4 Parameters ......................................................................................................... 9
5 Related Counters and Alarms ........................................................................ 10
5.1 Related Counters ............................................................................................... 10
5.2 Related Alarms .................................................................................................. 12
6 Engineering Guide .......................................................................................... 12
6.1 Application Scenario .......................................................................................... 12
6.2 Feature Activation Procedure ............................................................................. 12
6.3 Feature Validation Procedure............................................................................. 14
6.4 Feature Deactivation Procedure ......................................................................... 14
6.5 Impact on the Network ....................................................................................... 14
7 Abbreviation .................................................................................................... 14
8 Reference Document ....................................................................................... 15
ZGB-03-02-003 Dynamic Configuration of SDCCH
ZTE Confidential Proprietary 3
FIGURES
Figure 6-1 GSM Logical Configuration ...............................................................................13
Figure 6-2 GSM Cell Configuration ....................................................................................13
TABLES
Table 2-1 License Control List ............................................................................................ 5
Table 4-1 Parameter List .................................................................................................... 9
Table 5-1 Counter List .......................................................................................................10
ZGB-03-02-003 Dynamic Configuration of SDCCH
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1 Feature Attribute
BSC version: [ZXG10 iBSC V6.50.20]
BTS version: [Independent of the BTS hardware platform]
Attribute: [Basic]
Involved NEs:
NE Name Related or Not Special Requirement
MS √ None
BTS √ None
BSC √ None
iTC - None
MSC - None
MGW - None
SGSN - None
GGSN - None
HLR - None
“√”: involved
“-”: not involved
2 Overview
2.1 Feature Introduction
Dynamic SDCCH configuration means the dynamic conversion of TCH to SDCCH if
there are insufficient SDCCH resources but relatively sufficient TCH channel resources
available in the current serving cell. This feature is used to mitigate the shortage of
SDCCH resources and improve the channel utilization rate.
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2.2 License Control
Table 2-1 License Control List
Feature ID Feature Name License
Control Item
Configured
NE Unit
ZGB-03-02-003 Dynamic Configuration
of SDCCH None None None
2.3 Correlation With Other Features
1. Required Features
None
2. Mutually Exclusive Features
None
3. Affected Features
Generally, a BCCH carrier is configured with some static SDCCHs for service application,
and the system also provides flexible SDCCH configuration, which means that static
SDCCHs are configured on ordinary carriers other than the BCCH carrier. Dynamic
SDCCH configuration means the conversion of TCH to SDCCH.
This feature correlates with other features as follows:
ZGB-03-02-001 Support of SDCCH/4 and SDCCH/8
ZGB-03-02-002 Flexible SDCCH Configuration
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6 ZTE Confidential Proprietary
3 Technical Description
Dynamic SDCCH configuration is a policy adopted by the network to allocate channel
resources. If there are no sufficient SDCCH resources available in the current serving
cell, this feature can make full use of the idle TCH resources by converting one idle TCH
to eight SDCCHs to relieve SDCCH congestion.
With dynamic SDCCH configuration enabled, the network periodically checks the
number of idle SDCCHs in the cell based on the SDCCH scanning period set by the
module parameters. If the number of idle SDCCHs is less than the dynamic SDCCH
conversion threshold set by the network, and both the total number of idle TCHs in the
cell and the number of idle TCHs in the first sub-cell are more than four, or the total
number of idle TCHs is more than the number of carriers in the cell, the network selects
randomly one idle TCH and converts it to eight SDCCHs. Similarly, upon the completion
of a dynamic SDCCH conversion, the network continues the conversion of TCH to
SDCCH if the SDCCHs are occupied immediately and the network detects that the
conversion conditions are satisfied when checking periodically the number of idle
SDCCHs in the cell. There is a restriction that one carrier is allowed to be configured with
up to three SDCCHs during a dynamic SDCCH conversion. Therefore, dynamic SDCCH
conversion is related to the planned static SDCCHs. If more than three static SDCCHs
have been planned for a carrier, dynamic SDCCH conversion is impossible on this carrier,
and the network selects another carrier in the cell on the same frequency band with the
BCCH carrier and then attempts a dynamic SDCCH conversion. Version V6.20.200e of
the BSC solves this problem that there is no maximum number of converted SDCCHs on
one carrier.
If the shortage of SDCCH resources in the network is mitigated after a period of time, and
the SDCCH resources are relatively idle for some time, or in other words, the number of
SDCCHs is more than the sum of 8 and the dynamic SDCCH conversion threshold, the
network re-converts the eight SDCCHs back to one TCH and then the dynamic SDCCH
configuration flow is ended. The above-mentioned period of time can be set through the
SDCCH-to-TCH conversion delay in the background. This operation is helpful to prevent
frequent conversions between SDCCH and TCH, which may otherwise cause undesired
consumption of network resources. It should be noted that the SDCCH-to-TCH
conversion occurs only on the cells that generate dynamic SDCCH conversions. In
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addition, only the TCHs that have been originally converted to SDCCHs can be
converted back to TCHs.
3.1 Algorithms for Dynamic SDCCH Configuration
3.1.1 Descriptions of the Parameters Involved in the Algorithms
bCanSdcchDyn: It indicates whether dynamic SDCCH configuration is allowed and is
obtained from BSC parameters.
CanSdcchDyn: It indicates whether dynamic SDCCH configuration is allowed and is
obtained from cell parameters.
byMinSdcch: TCH-to-SDCCH conversion threshed, obtained from module parameters
MIN_TCH: minimum number of TCHs in a cell (4)
MIN_SDCCH: minimum number of SDCCHs in a cell (8)
byTimeToTch: SDCCH-to-TCH conversion delay, obtained from module parameters
scanSDCCH: scanning period
Of channel combination types, TCH/F is the most widely used for implementation
feasibility and convenience.
3.1.2 Dynamic SDCCH Configuration Standards and Idle TCH Selection
Policies
The control process collects statistics on channel occupation in each cell based on the
scanSDCCH period. These statistics mainly involve the number of idle TCHs and the
number of idle SDCCHs.
In accordance with the dynamic SDCCH standards, dynamic TCH-to-SDCCH
configuration is started in a cell when the cell meets the following conditions:
1. Dynamic SDCCH configuration is allowed, that is, the values of bCanSdcchDyn (for
the module) and ScanSdcchDyn (for the cell) are both TRUE.
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2. The number of idle SDCCHs in the cell is smaller than the byMinSdcch threshold.
3. The difference between the total number of idle TCH/Fs and the total number of idle
reserved TCH/Fs in the cell, and the total number of idle TCH/Fs in the first sub-cell
are both larger than MIN_TCH or the total number of TRXs in the cell.
The policies of selecting an idle TCH/F during the configuration are as follows:
1. The network selects a TCH on the same frequency band as the BCCH carrier. For
example, if the BCCH carrier is in P-GSM, it is not allowed to select an E-GSM or
R-GSM extended frequency point or 1800M TCH.
2. The network selects a static TCH/F first, and then a dynamic TCH/F.
3. The network selects a TCH with the worst interference.
4. The network selects a TCH from the first sub-cell.
The converted TCH timeslot is included in the conversion queue.
3.1.3 SDCCH Decrease and SDCCH Selection Principles
If it is detected that a cell meets certain conditions, an SDCCH-to-TCH conversion starts
and the SDCCH is selected from the timeslots configured as SDCCHs derived from
TCH/Fs.
The principles to decrease the number of SDCCHs are as follows (the initial value of S is
equal to byTimeToTch):
1. If the number of idle SDCCHs in a cell is equal to the sum of MIN_SDCCH and
byMinSdcch, no action is required.
2. If the number of idle SDCCHs in a cell is smaller than the sum of MIN_SDCCH and
byMinSdcch, S+ = 12 is selected (not more than byTimeToTch).
3. If the number of idle SDCCHs in a cell is larger than the sum of MIN_SDCCH and
byMinSdcch, S- = 3 is selected.
If S is smaller than or equal to 0, an SDCCH-to-TCH conversion is triggered one time.
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4 Parameters
Table 4-1 Parameter List
Manage
d
Object
Logic
Name Parameter Description Value Range Unit
Defaul
t
Value
Reco
mmen
ded
Value
BSC,CE
LL
Dynami
c
Configur
ation
SDCCH
This parameter indicates
whether dynamic SDCCH/TCH
conversion is enabled in the
BSC. The network can
dynamically perform
conversions between SDCCH
and TCH when this function is
enabled. Another prerequisite
of successful dynamic
DCCH/TCH conversion in a cell
is that this function is also
enabled in the cell.
0:No
1:Yes None 0 1
BSC Scan
SDCCH
This parameter indicates the
period of scanning idle
SDCCHs when the dynamic
SDCCH/TCH conversion
function is enabled in a cell.
After the dynamic SDCCH/TCH
conversion function is enabled
in a network, the network scans
SDCCHs at the period
specified by this parameter to
find the number of idle
SDCCHs for determining
whether to convert SDCCH
back to TCH.
10~1000 100ms 100
BSC
TCH->S
DCCH
Limit
This parameter specifies the
threshold that triggers a
TCH-to-SDCCH conversion in
a cell where SDCCH dynamic
configuration is enabled. When
2~64 None 4
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Manage
d
Object
Logic
Name Parameter Description Value Range Unit
Defaul
t
Value
Reco
mmen
ded
Value
the number of idle SDCCHs is
lower than this threshold, a
TCH to- SDCCH conversion is
performed.
BSC
SDCCH
->TCH
Delay
This parameter is used to
enable dynamic SDCCH
configuration function in the
cell. After TCH is dynamically
converted to SDCCH channel
and SDCCH channel is idle, to
prevent from frequent channel
conversion, a time limit will be
added for the conversion from
SDCCH channel to TCH
channel. During this limit,
SDCCH channel cannot be
converted to TCH channel.
0~24 None 0
BSC
Minimu
m Tch
reserve
d for
dynamic
SDCCH
If dynamic SD conversion is
enabled, the conversion
TCH->SDCCH requires
checking the number of idle
TCHs in the cell and No. 1
sub-cell. If the number is
greater than MinTch, the
switchover is allowed.
1~64 None 0
5 Related Counters and Alarms
5.1 Related Counters
Table 5-1 Counter List
Counter ID Name
ZGB-03-02-003 Dynamic Configuration of SDCCH
ZTE Confidential Proprietary 11
C901250001 Number of SDCCH seizure attempts for
assignment(Times)
C901250002 Number of SDCCH seizure success for
assignment(Times)
C901250003 Number of SDCCH seizure failure for
assignment(Times)
C901250004 Number of SDCCH seizure attempts for
handover(Times)
C901250005 Number of SDCCH seizure success for
Handover(Times)
C901250006 Number of SDCCH seizure failure for handover(Times)
C901250007 Number of SDCCH allocation attempts for
assignment(Times)
C901250008 Number of SDCCH allocation success for
assignment(Times)
C901250009 Number of SDCCH allocation failure for
assignment(Times)
C901250010 Number of SDCCH allocation attempts for
handover(Times)
C901250011 Number of SDCCH allocation success for
handover(Times)
C901250012 Number of SDCCH allocation failure for
handover(Times)
C901250013 Number of SDCCH assignment attempts(Times)
C901250014 Number of SDCCH assignment success(Times)
C901250015 Number of SDCCH assignment failure(Times)
C901250016 Number of SDCCH handover attempts(Times)
C901250017 Number of SDCCH handover success(Times)
C901250018 Number of SDCCH handover failures with the handover
failure message returned from MS(Times)
C901250019 Number of SDCCH handover failure without the
handover failure message returned from MS(Times)
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5.2 Related Alarms
This feature has no related alarm.
6 Engineering Guide
6.1 Application Scenario
A short message group sends a large number of location update messages and
therefore occupies SDCCH resources.
The multi-paging mode configured on the network side consumes large amount of
SDCCH resources.
A dynamic SDCCH conversion should be activated for the cells at the edge of the
location area because there are many location updates.
A dynamic SDCCH conversion is needed if SDCCHs are congested while TCHs are idle.
6.2 Feature Activation Procedure
1. In the configuration resource tree, select Modify Area > Managed Element and
double click GSM Logical Configuration, see the following figure.
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Figure 6-1 GSM Logical Configuration
2. In the configuration resource tree, select Modify Area > Managed Element > GSM
Logical Configuration > Cell Information Configuration, double click GSM Cell
Configuration, and configure Dynamic configuration SDCCH, see the following
figure.
Figure 6-2 GSM Cell Configuration
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6.3 Feature Validation Procedure
Test Item Dynamic SDCCH
Prerequisite 1. The CN is in good condition.
2. The BSC is operating properly.
3. The SDR is operating properly.
4. The default cell configuration and parameter
configurations are correct in the BSC.
5. The MSs are ready for the test.
6. The radio environment is good.
Steps 1. On the GSM Cell Configuration tab, set
CanSdcchDyn to YES.
2. On the GSM Logical Configuration tab, set Dynamic
config SDCCH to Yes, Scan SDCCH to 10, and
TCH->SDCCH limit to 2.
3. Block all SDCCHs in the cell.
4. The MS makes a call in the cell and holds on.
5. Check the configuration of Cell Channel Management
in dynamic data management.
Expected Result 1. The call can be established in the cell.
2. In cell channel management, the number of converted
SDCCHs can be calculated correctly.
6.4 Feature Deactivation Procedure
This feature is enabled with the switches at the cell level and the BSC level, and disabled
at the cell level or the BSC level.
6.5 Impact on the Network
When this feature is enabled, network congestion on SDCCHs can be greatly relieved.
7 Abbreviation Abbreviation Full Name
ZGB-03-02-003 Dynamic Configuration of SDCCH
ZTE Confidential Proprietary 15
3GPP 3rd Generation Partnership Project
SDCCH Stand-Alone Dedicated Control Channel
GSM Global System for Mobile communications
BSC Base Station Controller
BTS Base Transceiver Station
MS Mobile Station
MSC Mobile Switching Centre
8 Reference Document
ZXUR 9000 GSM (V6.50.20) Base Station Controller Performance Counter Reference
ZXUR 9000 GSM (V6.50.20) Base Station Controller Radio Parameter Reference