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paging guide CDMA
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CDMA2000 1X Paging Optimization Guide Internal open
2004-10-26 All rights reserved Page i of pages 43
Document No. Product Name
Applicable for Wireless network planning Dept.
Product version
Drafted by CDMA Network Planning Dept.
Document version
CDMA2000 1X Paging Optimization
Guide
Huawei Technologies Co., Ltd.
All rights reserved
Table of Contents
1 About this Document ................................................................................................................. 3
1.1 Overview ...............................................................................................................................3
1.2 Contents ...............................................................................................................................3
2 Basic Knowledge ....................................................................................................................... 4
2.1 PCH Features .......................................................................................................................4
2.1.1 PCH Structure ............................................................................................................4
2.1.2 PCH Message ............................................................................................................6
2.1.3 MS Working Mode .....................................................................................................7
2.1.4 Fast Paging Channel .................................................................................................7
2.2 Call Flow ...............................................................................................................................8
3 Extended Bounary Paging Solution .......................................................................................... 9
3.1 Background ..........................................................................................................................9
3.2 Implementation Principle and Solutions ...........................................................................9
3.2.1 Concepts ....................................................................................................................9
3.2.2 Extended Bounary Paging Solution with a Cooperation Between MSC and BSC........................................................................................................................................... 10
3.2.3 Intra-BSC Extended Bounary Paging Solution ................................................... 12
3.2.3.1 Extended Bounary Paging Solution True LAC-based .......................... 13
3.2.3.2 Extended Bounary Paging Solution Idle Handoff-based ..................... 13
3.3 Application Background .................................................................................................. 13
3.3.1 Extended Bounary Paging Solution with a Cooperation Between MSC and BSC........................................................................................................................................... 14
3.3.2 Intra-BSC Extended Bounary Paging Solution ................................................... 16
3.4 Data Configuration ........................................................................................................... 16
3.4.1 MSC Data Configuration ........................................................................................ 16
3.4.2 BSC Data Configuration ........................................................................................ 17
3.5 Precautions ....................................................................................................................... 20
4 Optimization of BSC and BTS Paging Algorithm .................................................................... 20
4.1 Purpose .............................................................................................................................. 20
4.2 Implementation Solution .................................................................................................. 21
4.2.1 Cooperation Mechanism between BSC and BTS ............................................... 21
4.2.2 BTS Paging Scheduling Mechanism .................................................................... 23
4.2.3 GPM Combination Function .................................................................................. 24
4.3 Paging Measurement Index and Analysis ...................................................................... 26
4.4 Parameter Configurations ................................................................................................ 29
4.4.1 Default Value of F-CSCH Message Resending Parameter ................................. 29
4.4.2 Resending Times and Living Time of Paging Channel Message ...................... 31
4.4.3 L2 Acknowledgement Parameters for Access Channel Message .................... 35
4.4.4 Parameter and Function Verification ................................................................... 36
5 Application Cases .................................................................................................................... 39
Key words:
Paging channel, paging message, extended bounary paging, extended LAC,
paging algorithm, scheduling mechanism and paging measurement index.
Abstract:
This guide details the following:
The knowledge related to CDMA paging, including paging channel
message, Mobile Station (MS) working mode and call flow.
The background and implementation principle of extended bounary paging
solution cooperating with an application solution.
The data configuration and precautions during the actual application.
The VC03 paging optimization algorithm, cooperation mechanism with
BSC and BTS involved, BTS scheduling mechanism and GPM
combination strategy.
The new paging measurement indices.
Solutions to analyze the indices.
Abbreviations list:
Abbreviation Full name AC Authentication Center BCCH Broadcast Control Channel BS Base Station BSC Base Station Controller BTS Base Transceiver System CAM Channel Assignment Message CDMA Code Division Multiple Access CCM Call Control Module CI Cell Identifier DBM Data Burst Message DCH Dedicated Channel
ECAM Extended Channel Assignment Message
ESN Electronic Serial Number
ESPM Extended System Parameter Message
FCCH Forward Common Control Channel F-CSCH Forward Common Signaling
Channel
F-DSCH Forward Dedicated Signaling Channel
GPM General Paging Message GPR General Paging Response HLR Home Location Register
IMSI International Mobile Subscriber Identity
ISPAGE Inter-system Paging LAC Location Area Code LAC Layer Link Access Control Layer LAI Location Area Identifier MIN Mobile Identification Number MS Mobile Station MSC Mobility Switch Center SPU Signal Process Unit OM Order Message PCH Paging Channel RAND Random Variable SCI Syn-Capusle Indicator SIM Subscriber Identifier Module SSD Shared Secret Data TCH Traffic Channel VLR Visitor Location Register
Reference list:
1. Tan guanzhong, Huawei Technologies Co., Ltd., CBSCV100R003C03 LAC
Resending Mechanism Design Specifications.
2. Kyoung II Kim, Posts & Telecom Press, CDMA Design and Optimization..
1 About this Document
1.1 Overview
This guide details the following:
The knowledge related to CDMA paging, call flow, and BSS flow control.
The background and implementation principle of extended bounary paging
solution cooperating with an application solution.
The data configuration and precautions during the actual application.
The VC03 paging optimization algorithm, cooperation mechanism with BSC
and BTS involved, and BTS scheduling mechanism.
The new paging measurement indices.
Solutions to the problems in the actual network, the relation and analysis with
paging measurement indices.
The readers should have general knowledge about CDMA. The learner can read
the first chapters, and the last two can be a reference and guide for the skilled during
the actual network application.
1.2 Contents
CDMA20001X Paging Optimization Guide includes five parts. For details, see
the following table.
Chapter Title Content
1 About the document Introducing the contents of the document
2 Basic knowledge
Introducing paging channel features, including paging channel message and MS working mode.
Listing specific call flow so that the reader has an overall understanding about paging channel
3 Extended bounary paging solution
Introducing the background, solved problems, and application.
Detailing implementation solution and data configuration so that the
reader can understand and use the solution.
4 Optimization of BSC and BTS paging algorithm
Introducing the purpose of BSC and BTS algorithm optimization.
Detailing the cooperation mechanism and scheduling mechanism and specific measures (such as GPM combination).
Describing the new paging measurement indices in the VC03.
Providing the solutions to analyze the indices.
Providing parameter configuration during the application.
5 Application case The obtained typical cases based on actual application.
6 Annex Providing BTS.ini file in the VC03 Describing new parameters of
VC03.
2 Basic Knowledge
2.1 PCH Features
The FCCH of the CDMA 2000 1X includes pilot channel, syn. Channel and paging
channel, but the RCCH includes access channel. Wherein, dedicated WALSH code is
allocated for each FCCH. The WALSH code corresponding to paging channel ranges
from 1 to 7, and the rates of paging channel include 9600bps and 4800bps based on
the protocol. If there are no special descriptions, the rate is 9600bps. If power control
does not exist in the FCCH, a correlation must exist between the gain configurations.
For details, see CDMA2000 1X Network Planning Parameter Configuration Guide. To
support new traffic type in the subsequent protocol version, such new common
channels as FCCCH and BCCH are added to implement the function similar to paging
channel. No more descriptions are required here.
2.1.1 PCH Structure
Figure 1 PCH Structure
Maximum paging channel slot cycle
163.84s
2048 slots
Paging channel slot 0 ¡ Paging channel slot 2047Paging channel slot n
80ms
…
Paging channel half-frame Paging channel half-frame Paging channel half-frame
8 paging channel half-frames
10ms
SCI…
=1
… … …
… ..
SCI SCIPaging channelhalf-frame body
Paging channel
Half-frame body
Paging channel
Half-frame body=0 =1
Paging channel
message body
paging channel
message body
MSG_LENGTH Message body CRC
Fill inPaging channel message
8bits 30bits
0~7bits8*MSG_LENGTH
paging channel message body
Paging channel
message
Follow former
asynchronization message
Synchronization body
bits
……
Figure 1
Maximum paging channel slot cycle
163.84s
2048 slots
Paging channel slot 0 ¡ Paging channel slot 2047Paging channel slot n
80ms
…
Paging channel half-frame Paging channel half-frame Paging channel half-frame
8 paging channel half-frames
10ms
SCI…
=1
… … …
… ..
SCI SCIPaging channelhalf-frame body
Paging channel
Half-frame body
Paging channel
Half-frame body=0 =1
Paging channel
message body
paging channel
message body
MSG_LENGTH Message body CRC
Fill inPaging channel message
8bits 30bits
0~7bits8*MSG_LENGTH
paging channel message body
Paging channel
message
Follow former
asynchronization message
Synchronization body
bits
……
Figure 1
To know the paging channel, we should have a brief understanding about PCH
structure first. For details, see figure 1.
The PCH is divided into paging slots of 80ms, and each paging slot is
composed of 8 half-frames, and each half-frame is 10ms. Each half-frame starts from
Syn-Capsule Indicator (SCI) bit, and the first new message in the paging slot must
follow SCI bit. At that time, set SCI bit to 1.
PCH message is transferred on the PCH body. The PCH body includes message
body, indicating 8bit field of the whole channel body length and 30bit CRC. The lengths
of such messages as General Page Message (GPM), Channel Assignment Message
(CAM), or Order Message (OM) on the channel range from 100 to 150bit. One paging
slot includes 760bit (8 half-frames, each half-frame has 95 valid load bit, and others
are SCI bit), so it can send multiple GPMs, CAMs or OMs.
Most message body occupies one half-frame and a part of the second half-frame,
so the message body to be synchronized will waste another part of the second
half-frame. To enhance the utilization of this PCH, it is allowed only to synchronize the
first new message body within one paging slot and the subsequent message body
within the slot is attached at the back of former message body. The message filed
length of the message body indicates the start position of next message body in the
slot.
If the message body is less than 8bit from SCI bit to the end, the next message in
the slot must be synchronized. Therefore, SCI of next message must be 1 (if the
synchronization is required, set SCI to 1). The length of PCH message body must be
the integer times of byte. If not, fill in it with 0-7bit.
If multiple PCHs are constituted and alternated periodically, a slot cycle is
generated. The shortest slot cycle includes 16 slots, with the maximum length of 2048
slots. The length (T) of specific slot cycle is related to the setting of Slot_Cycle_Index
i. The relation is as follows: T=16×0.08×2i , wherein, i ranges from 0 to 11 (select 0 or
1in general).
2.1.2 PCH Message
In the CDMA system, the PCH sends the message from BS to MS and bearers
many messages, including call processing (voice and data), supplementary service
(short message), null GPM, serving redirection message, and feature notification
message. The null GPM refers to the message that does not include MS information,
indicating that all the messages in the slot are sent through the setting of related field.
In this case, MS remains more power. The messages related to calling processing
include the following:
Overhead Message or General Message: Including the information required
by the call setup, and it is updated periodically to ensure the successful call
setup. It is required to send the message once at least 1.28s, such as system
parameter message, access parameter message, neighbour list message,
CDMA channel list message and extended system parameter message.
Paging Message (GPM): Used to originate a paging to MS. When receiving call
request from MS, MSC sends a paging request message. MSC sends paging
request message through cell mode and LAC mode.
CAM/ECAM and OM: Used to exchange information with MS to complete the
call setup. BS sends the message only in a cell during the call setup.
Short Message Center (SMC) sends the SM through MSC and Data Burst
Message (DBM) of air interface from BSC to BTS. The SM can be sent through many
modes. The specific modes are set in MSC, and no more descriptions are required
here. For details, see CDMA1X Location Area Planning Guide.
2.1.3 MS Working Mode
Paging channel is divided into several slots, so slotted and unslotted working
modes are available when MS is in IDLE state.
Slotted mode: MS is awaked periodically in a special slot cycle to check the
paging message pointing at this MS. When MS works in slotted mode, it is
allowed to lower the power until pre-specified slot occurs. MS and MSC adopt
HASH function and takes MS MIN (the last 10 digits of IMSI) as the function
variable to judge when to awake the MS. At that time, the system can
determine the correct slot and performs a paging to MS through the slotted
mode. After sending all the messages on the slot, the system sends a
“–DONE” (that is, null GPM). Therefore, when MS works in slotted mode, it
does not receive the whole paging channel slot in case of being awaked. But
the MS is allowed to leave the slot to be IDLE sate.
Non-slotted mode: When MS is in IDLE state, it monitors all the paging slots,
and receives the messages on the paging slot. Obviously, when MS is
working in unslotted mode, this MS consumes the battery power too much.
Therefore, MS works in slotted mode in general. But some MSs can modify
the working mode.
2.1.4 Fast Paging Channel
To better save MS battery effectively, another channel related to the paging---fast
paging channel is added to the protocol. The rates also include 9600 and 4800bps,
and the corresponding WALSH code is 16. To save forward power, the rate of fast
paging channel should be 4800bps, and the difference between its gain and pilot‟s is
2– -5dB. The fast paging channel requires that MS should support this function, so it is
optional. Only two types of information bit are sent on the fast paging channel: Paging
indication bit and configuration change indication bit. They are sent repeatedly. At that
time, the MS working mode is consistent with that only paging channel is available.
MS monitors the fast paging channel of a special slot. If receiving the bit information
pointing at fast paging channel of this MS, MS monitors paging channel to receive the
message. When MS is in Idle state, it only monitors fast paging channel. Because MS
only receives and demodulates little information, the power can be saved.
2.2 Call Flow
The following figure shows flow chart of calling/called party, involving air interface,
Abis, and A interface. Wherein, air interface and A interface are standardized, and
they are consistent with that in the relevant protocol standard, but Abis interface is
defined by the system manufacturer. The message sent on the PCH indicates an
interactive flow of MS and system during the call setup. If the network problems are
related to the call flow, analyze the problems based on the whole call flow.
Note: BSC handles the layer-2 acknowledgement for the originating message or
paging response message of access channel. To shorten the acknowledgement
time, the modifications are performed in VC03, and BTS directly perform layer-2
acknowledgement for the above two types of messages.
HLR
Origination MsgAbis-ACH Msg Transf er(ORM)
Abis-PCH Msg Transf er(BS Ack)Base Ack Order
Abis-BTS Setup
Abis-Connect
Abis-Connect Ack
Abis-BTS Setup Ack
Abis-is-2000 FCH Fwd(Null data)Null Traff ic Data
Abis-is-2000 FCH Rvs(Idle data)
Abis-PCH Msg Transf er(ECAM)ECAM
Traff ic Channel Preamble Abis-is-2000 FCH Rvs(Preamble)
Abis-is-2000 FCH Fwd(BS Ack)Base Ack OrderIdle TCH Data Abis-is-2000 FCH Rvs(Idle Data)MS Ack Order
Abis-is-2000 FCH Rvs(Ms Ack)
Abis-is-2000 FCH Fwd(Serv ice Connect)Serv ice Connect Msg
Serv ice Connect CompleteAbis-is-2000 FCH Rvs(Ser Conn Comp)
CM Serv ice Req
Assignment Complete
Assignment Req
ACH
PCH
TCH
PCH
TCH
TCH
TCH
TCH
TCH
TCH
Pagi ng R esponse Abis-ACH Msg Transfer(PRM)
Abis-PCH Msg Transfer(Base Ack)Base Ack Order
Abis-BTS Setup
Abis-Connect
Abis-Connect Ack
Abis-BTS Setup Ack
Abis-is-2000 FCH Fwd(Null data)Null Traffic Data
Abis-is-2000 FCH Rvs(Idle data)
Abis-PCH Msg Transfer(ECAM)ECAM
Traffic Channel Preamble Abis-is-2000 FCH Rvs(Preambl e)
Abis-is-2000 FCH Fwd(Base Ack)Base Ack Order
Idle TCH Data Abis-is-2000 FCH Rvs(Idle D ata)
MS Ack Order Abis-is-2000 FCH Rvs(Ms Ack)
Abis-is-2000 FCH Fwd(Service C onnect)Service Connect Msg
Service Connect Com plete Abis-is-2000 FCH Rvs(Ser Conn C omp)
Pagi ng R esponse
Assignment Com plete
Assignment Req
Pagi ng R equestAbis-PCH Msg Transfer(GPM)GPM
Abis-IS-2000 FCH Fwd (AWIM)Alert with Info
Abis-IS-2000 FCH Rvs (MS Ack)MS Ack Order
Abis-IS-2000 FCH Rvs (Connect Order)Connect Order
Abis-IS-2000 FCH Fwd (BS Ack)BS Ack Or der Connect
CC(connection conf irm)
CC
Calling party BTS Calling party BSC MSCCalling party MS
Called party BSCCalled party BTSCalled party MS
LOCREQ (BILLID ,ORIID,DGTSDIALED)
(TRANSCAP, TAT)
Locreq (MIN ,ESN,MSC_ID ,PCSSN,ANNALIS )
(LOCALROUTINGINFO ,DMHDATA)
T)
HLR
Origination MsgAbis-ACH Msg Transf er(ORM)
Abis-PCH Msg Transf er(BS Ack)Base Ack Order
Abis-BTS Setup
Abis-Connect
Abis-Connect Ack
Abis-BTS Setup Ack
Abis-is-2000 FCH Fwd(Null data)Null Traff ic Data
Abis-is-2000 FCH Rvs(Idle data)
Abis-PCH Msg Transf er(ECAM)ECAM
Traff ic Channel Preamble Abis-is-2000 FCH Rvs(Preamble)
Abis-is-2000 FCH Fwd(BS Ack)Base Ack OrderIdle TCH Data Abis-is-2000 FCH Rvs(Idle Data)MS Ack Order
Abis-is-2000 FCH Rvs(Ms Ack)
Abis-is-2000 FCH Fwd(Serv ice Connect)Serv ice Connect Msg
Serv ice Connect CompleteAbis-is-2000 FCH Rvs(Ser Conn Comp)
CM Serv ice Req
Assignment Complete
Assignment Req
ACH
PCH
TCH
PCH
TCH
TCH
TCH
TCH
TCH
TCH
Pagi ng R esponse Abis-ACH Msg Transfer(PRM)
Abis-PCH Msg Transfer(Base Ack)Base Ack Order
Abis-BTS Setup
Abis-Connect
Abis-Connect Ack
Abis-BTS Setup Ack
Abis-is-2000 FCH Fwd(Null data)Null Traffic Data
Abis-is-2000 FCH Rvs(Idle data)
Abis-PCH Msg Transfer(ECAM)ECAM
Traffic Channel Preamble Abis-is-2000 FCH Rvs(Preambl e)
Abis-is-2000 FCH Fwd(Base Ack)Base Ack Order
Idle TCH Data Abis-is-2000 FCH Rvs(Idle D ata)
MS Ack Order Abis-is-2000 FCH Rvs(Ms Ack)
Abis-is-2000 FCH Fwd(Service C onnect)Service Connect Msg
Service Connect Com plete Abis-is-2000 FCH Rvs(Ser Conn C omp)
Pagi ng R esponse
Assignment Com plete
Assignment Req
HLR
Origination MsgAbis-ACH Msg Transf er(ORM)
Abis-PCH Msg Transf er(BS Ack)Base Ack Order
Abis-BTS Setup
Abis-Connect
Abis-Connect Ack
Abis-BTS Setup Ack
Abis-is-2000 FCH Fwd(Null data)Null Traff ic Data
Abis-is-2000 FCH Rvs(Idle data)
Abis-PCH Msg Transf er(ECAM)ECAM
Traff ic Channel Preamble Abis-is-2000 FCH Rvs(Preamble)
Abis-is-2000 FCH Fwd(BS Ack)Base Ack OrderIdle TCH Data Abis-is-2000 FCH Rvs(Idle Data)MS Ack Order
Abis-is-2000 FCH Rvs(Ms Ack)
Abis-is-2000 FCH Fwd(Serv ice Connect)Serv ice Connect Msg
Serv ice Connect CompleteAbis-is-2000 FCH Rvs(Ser Conn Comp)
CM Serv ice Req
Assignment Complete
Assignment Req
ACH
PCH
TCH
PCH
TCH
TCH
TCH
TCH
TCH
TCH
Pagi ng R esponse Abis-ACH Msg Transfer(PRM)
Abis-PCH Msg Transfer(Base Ack)Base Ack Order
Abis-BTS Setup
Abis-Connect
Abis-Connect Ack
Abis-BTS Setup Ack
Abis-is-2000 FCH Fwd(Null data)Null Traffic Data
Abis-is-2000 FCH Rvs(Idle data)
Abis-PCH Msg Transfer(ECAM)ECAM
Traffic Channel Preamble Abis-is-2000 FCH Rvs(Preambl e)
Abis-is-2000 FCH Fwd(Base Ack)Base Ack Order
Idle TCH Data Abis-is-2000 FCH Rvs(Idle D ata)
MS Ack Order Abis-is-2000 FCH Rvs(Ms Ack)
Abis-is-2000 FCH Fwd(Service C onnect)Service Connect Msg
Service Connect Com plete Abis-is-2000 FCH Rvs(Ser Conn C omp)
Pagi ng R esponse
Assignment Com plete
Assignment Req
Pagi ng R equestAbis-PCH Msg Transfer(GPM)GPM
Abis-IS-2000 FCH Fwd (AWIM)Alert with Info
Abis-IS-2000 FCH Rvs (MS Ack)MS Ack Order
Abis-IS-2000 FCH Rvs (Connect Order)Connect Order
Abis-IS-2000 FCH Fwd (BS Ack)BS Ack Or der Connect
CC(connection conf irm)
CC
Calling party BTS Calling party BSC MSCCalling party MS
Called party BSCCalled party BTSCalled party MS
Pagi ng R equestAbis-PCH Msg Transfer(GPM)GPM
Abis-IS-2000 FCH Fwd (AWIM)Alert with Info
Abis-IS-2000 FCH Rvs (MS Ack)MS Ack Order
Abis-IS-2000 FCH Rvs (Connect Order)Connect Order
Abis-IS-2000 FCH Fwd (BS Ack)BS Ack Or der Connect
CC(connection conf irm)
CC
Calling party BTS Calling party BSC MSCCalling party MS
Called party BSCCalled party BTSCalled party MS
LOCREQ (BILLID ,ORIID,DGTSDIALED)
(TRANSCAP, TAT)
Locreq (MIN ,ESN,MSC_ID ,PCSSN,ANNALIS )
(LOCALROUTINGINFO ,DMHDATA)
T)
Figure 2 Flow chart of calling/called party
3 Extended Bounary Paging Solution
3.1 Background
The following paging area bounarys are inevitable in the CDMA network:
Intra-BSC inter-LAC bounary
Intra-MSC inter-BSC bounary
Inter-MSC bounary.
Generally, the range of registration area is consistent with that of location area.
Wherein, registration area is used only for MS registration. That is, MS
originates a registration over registration area only in different registration
areas.
Location area is used only when system performs a paging to MS. It is paging
mode through which to send the range of paging message when MSC
originates a paging to MS. (CI is another paging mode.)
Because the conflict between the registration and paging in the above bounary
areas results in frequent/repeated registration or non-registration and lowers
successful paging ratio to affect network performance. MS sends the messages
on the reverse access channel during the registration, so frequent registrations
occupy the reverse access channel to affect normal call service. You can set
system parameter (such as Total-Zones or Zone-timer) related to registration in
the above bounarys to reduce the registration frequency and occupation of
reverse access channel. Meanwhile, you can adopt the special technology to
improve successful paging ratio of the above bounary.
The extended paging solutions are designed for the former two bounarys.
Inter-MSC bounary can adopt ISPAGE solution of later IS-41C recommendations.
No more descriptions are required here.
3.2 Implementation Principle and Solutions
3.2.1 Concepts
1. Extend: Enlarge and extend the paging range in case of the paging on
extended bounary.
2. True LAC: One of the cell attributes. It exists before extended bounary paging
solution is adopted. Some cells constitute the true LAC. Meanwhile, it is configured
in the LAC table of MSC, and is used for paging addressing.
3. Virtual LAC: It is used temporally during the application of extended bounary
paging solution. Some cells determine the scope defined in the BSC. It is not
configured in the LAC table of MSC.
4. Extended LAC: It includes many cells, and it can be either true one or virtual
one. Meanwhile, it is used to extend paging scope during the application of
extended bounary paging solution. If this extended LAC is virtual one, it is called
virtual LAC. Generally, the scope of virtual LAC is smaller than that of true LAC.
5. Adjacent LAC: Because extended bounary paging is extended between
adjacent LACs, extended LAC can be regarded adjacent LAC.
6. Center LAC: It is the original LAC when extended bounary paging is required,
and matched with extended LAC. Additionally, it is true LAC.
7. Extended cell: Extended LAC includes many cells, and the cell is extended
cell.
8. Bounary cell: The cell on a true LAC bounary.
3.2.2 Extended Bounary Paging Solution with a Cooperation Between MSC and BSC
This solution is implemented by MSC and BSC. An adjacent location area cell
table is added to MSC, as shown in table 1. Meanwhile, corresponding extended LAC
(adjacent LAC) is added to the location area cell table, and MSC configures extended
LAC (adjacent LAC). Wherein, extended LAC (adjacent LAC) can either belong to the
same BSC of the MSC or another BSC. Additionally, the cell scope of extended LAC
is also defined in BSC, that is, it belongs to an extended LAC by the adding of cell
attribute.
SN Field name Definition Default value Description
1 Paging LAC Index area Input is mandatory
Hex numeral.
The format and byte sequence are the same as LAI in location area cell table
2 Enable the whole The last paging is the whole
No If yes, the subsequent value is
MSC paging MSC paging (originate a paging to all the BSC of MSC)
invalid
3 Adjacent location area types
LAC or CI LAC Enumerated
4 Whether original LAC is included
Whether extended bounary paging scope includes original LAC
Yes If yes, adjacent location area cannot use CI.
5 Whether adjacent location area 1 is valid
Yes
6 Adjacent location area1
Input 4-digit hex numeral
Hex numeral 0xFFFF is an invalid value, and can be virtual LAC.(virtual LAC refers to that LAI instead of CI is configured in corresponding location area cell table).
The format and byte sequence are the same as LAI in location area cell table.
7–24 The same as 5 and 6.
6 LACs or 10 CIs adjacent location areas can be configured.
Default value must be provided. .
If adjacent location area i is “No”, valid default value is “No”.
Default value of adjacent location area: 0xFFFF
Table 1 Adjacent LAC cell
When MSC delivers a “Paging request”, query the Cell Information table of
adjacent location area to judge whether this LAC includes extended LAC (or adjacent
LAC).
If no, deliver a “Paging request” based on original LAC.
If yes, deliver a “Paging request” with corresponding extended LAC to BSC.
After receiving LAC information from MSC, BSC judges the LAC:
If this LAC is a true one, deliver a paging message based on true LAC range.
If this LAC is a virtual one, deliver a paging message based on cell range of BSC
defined virtually. The flow chart is shown in figure 3:
Figure 3 MSC delivers a “paging request”
[Note] The above functions are added to MSC side, and MSC can originate a
paging through multiple LACs/CIs. That is, MSC can carry multiple LACs or CIs for
BSC once, with the maximum of 6 LACs, and 10 CIs. In addition, MSC cannot carry
LAC and CI at the same time.
3.2.3 Intra-BSC Extended Bounary Paging Solution
The following two solutions do not require the cooperation of MSC, and are
implemented by intra-BSC automatically. To implement the following two solutions,
adjacent LAC correspondence and extended area table over idle handoff are added to
the BSC. Wherein, the former provides the correspondence between center LAC and
adjacent LAC. Obviously, center LAC and adjacent LAC belong to the same BSC, but
the latter provides the cell included in the extended LAC corresponding to a LAC (or
center LAC). Actually, this extended LAC is not put forth definitely.
[Note]
For the intra-BSC extended bounary paging solution, MSC should have originated a
paging to signaling A under the BSC, but originated a paging to signaling B and a
response is returned from signaling B. No. 20 software parameter of CCM in the
BSC controls the intra-signaling forwarding. Set 0x0 to disable the function by
default and set 0x1 to enable the function by executing command MOD SOFTPARA:
SRVMN=CCM, PRMNO=20, PRMV="0x01". Currently, actual test and verification
show that Huawei MSC can solve the above problems.
3.2.3.1 Extended Bounary Paging Solution True LAC-based
If a BSC includes several true LACs, configure adjacent LAC to be extended for
adjacent LAC correspondence during center LAC paging. Wherein, center LAC and
adjacent LAC are true LACs. MSC originates a paging based on center LAC, BSC
queries adjacent LAC correspondence to obtain the information about adjacent LAC to
be extended first, and then delivers paging messages to the LACs to implement
bounary paging function.
3.2.3.2 Extended Bounary Paging Solution Idle Handoff-based
To reduce paging traffic, and alleviate paging pressure, we obtain an extended
area with less scope over idle handoff based on the requirements of actual application
environment, and also implement extended bounary paging function. The procedures
are as follows:
1. Search the bounary cell configured under this LAC based on center LAC to
obtain bounary cell Celli;
2. Search adjacent area list set of corresponding idle handoff “Cellni+Cellmi”
based on Celli.
3. Delete Cellni of the center LAC from idle adjacent area list set “Cellni+Cellmi”.
4. Combine the repeated cells from remaining idle handoff list set “Cellmi” to
obtain final extended cell set “Cellmj”.
In this way, Cellmj constitutes the paging extended area. BSC obtains this paging
extended cell automatically, and you should configure bounary cell and adjacent
cell table of idle handoff relation in case of application.
3.3 Application Background
According to the principle and solved problem of above-mentioned extended
bounary paging solution, we determine whether to adopt the solution in the first two
bounary networks based on the paging of the two bounary areas. For details, see the
following suggestions.
3.3.1 Extended Bounary Paging Solution with a Cooperation Between MSC and BSC
If this solution is adopted, MSC should provide extended bounary paging function,
so this solution is applicable only when Huawei MSC is used. Because extended LAC
can be either true one or virtue one, concern the following:
If extended LAC is virtual one, this solution only is applicable to the
environment cooperating with Huawei BSC.
If extended LAC is true one, this solution can be applicable to the environment
cooperating with other manufacturer BSC. ,
This solution can solve intra-MSC inter-BSC bounary paging and intra-BSC
inter-LAC bounary paging. Take figure 4 for an example to illustrate the application
of solution.
Figure 4 Huawei networks with other manufacturers
Figure 4 shows the networking structure between Huawei MSC and Huawei BSC2
and other manufacturers BSC2. Wherein, LAC1, LAC2, LAC3, LAC5, LAC6 are true
LACs of two BSCs, but extended LAC7 is virtual LAC configured for BSC side. The
scopes of these LACs are defined by the real lien and broken line in figure 4, and
extended LAC7 is partial area of LAC5.
The bounary exists between Huawei BSC2 and other manufacturers BSC1, that is,
the bounary between LAC3 and LAC5. To solve the paging of this bounary, you
Huawei MSC
LAC1
LAC2 LAC3
Other manufacturers
BSC1 Huawei BSC2
LAC5 LAC6
Extended
LAC7
extend paging area after configuring extended LAC information related to LAC3 for
Huawei MSC and BSC side during the LAC3 paging.
If configure extended LAC of LAC3 as LAC5, paging area will be extended to
LAC5.
If configure extended LAC of LAC3 as extended LAC7 (virtual LAC), paging
area will be extended to extended LAC7 because the definition of extended
LAC7 is added to Huawei BSC.
Because the scope of extended LAC7 is less than that of LAC5, the paging traffic is
reduced to alleviate paging pressure of Huawei BSC.
You configure extended LAC of LAC5 as LAC3 or LAC6 for Huawei MSC to solve
the paging of bounary between Huawei BSC and other manufacturers BSC, and
Huawei intra-BSC respectively.
When you solve the paging of intra-BSC inter-LAC bounary, extended LAC can be
either true one or virtual one. Take figure 5 for an example to illustrate the
application of solution.
Figure 5 Cooperation implementation of intra-BSC inter-LAC
Figure 5 shows that LAC1, LAC2, and LAC3 are true LACs, and the scopes are
defined by the real line. But LAC4 is extended LAC, and it is virtual LAC. The scope
MSC
LAC1
Extended LAC4
LAC2 LAC3
BSC
MSC
LAC1 Extended
LAC4
LAC2 LAC3
BSC
(1) (2)
is defined by the broken line in figure 5 (1), and the dashed area is defined by broken
line in figure 5 (2).
According to extended bounary paging solution with cooperation between MSC
and BSC, you configure the information about different extended LACs of LAC3 for
MSC, and configure the cell included in this extended LAC for BSC.
If configure extended LAC as extended LAC4 in figure 5 (1), originate a paging
to extended LAC4 directly during LAC3 paging.
If configure extended LAC as extended LAC4 in figure 5 (2), originate a paging
to the area constituted by LAC3 and LAC4 during LAC3 paging.
In this way, you expand paging scope to enhance successful paging ratio of LAC3.
[Note] The above figure is only for description, and irrelevant with actual application
solution.
3.3.2 Intra-BSC Extended Bounary Paging Solution
Intra-BSC extended bounary paging solution is applicable when Huawei BSC
exists in the network only. Under other circumstances, you should adopt the above
solutions, and select the sub-solution flexibly based on actual network situation:
(1) Extended bounary paging solution over true LAC
(2) Extended bounary paging solution over idle handoff
If there are many LACs delivered by BSC, and each LAC does not include many
cells, adopt solution (1). In this way, over-large paging traffic does not occur.
If there are less LACs delivered by BSC (such as 2 LACs), but each LAC includes
many cells, adopt solution (2). In this way, you obtain extended cell set with small
scope and implement extended bounary paging function to solve the paging
intra-BSC inter-LAC bounarys.
3.4 Data Configuration
3.4.1 MSC Data Configuration
1. Extended bounary paging solution switch
Controlled by No. 87 software parameter
Bit0: Whether to enable paging optimization function.
0: No
1: Yes (default)
For MSC, enable the extended bounary paging solution by default. For details,
see M800 MSCV610R002 Software Parameter Usage Guide (new).doc.
Maintenance console command: MOD/LST SFP
2. Adjacent LAC Table
The structure is shown in table 1, and you should add the information about
adjacent LAC.
Maintenance console command: ADD/MOD/RMV/LST NEIGHBORLAC
Note:
(1) When extended bounary paging solution is adopted, LAC of BSC
delivered by MSC may include original LAC, or may not. But it is
included by default.
(2) Enable the extended bounary paging solution duirng the last
paging. For example, if there are twice for resending, the system
orignates a paging three times. The extednded bounary paging
solution is enabled duirng the third paging. If resendign does not exist
(that is only a paging), disable the extended bounary paging solution.
No. 88 software parameter controls the resending times.
(3) The extended bounary paging solution is valid only for
PagingRequest of voice/data service, so does for BSC extended
bounary paging solution.
3. LAC cell table
If extended LAC is true one, you should add the information about LAC and the
call included in LAC to LAC cell table to used in case of LAC and CI paging
modes.
If extended LAC is virtual one, you should only add virtual LAC to the LAC cell
table. In addition, between extended LAC and original LAC, and extended
LACs should not be overlapped. In this case, we avoid potential problems
because of over-large paging to the cell.
Maintenance console command: ADD/MOD/RMV/LST LAIGCI
3.4.2 BSC Data Configuration
1. Extended Mode
BSC extended mode includes the following:
0) Non-extension
1) Extension based on true LAC
2) Extension over idle handoff
3) MSC extension
(Default value: 0, that is, extended mode is the non-extension.)
So MSC enables extended bounary paging solution by default, but BSC is
performed based on the MSC mode when it is not extended by default. But BSC is not
extended, BSC judges the extended LAC sent from MSC. If this LAC is virtual one,
BSC will not deliver a paging to this virtual LAC. If this LAC is true one, BSC delivers
a paging this true LAC. Actually, MSC sends multiple true LACs.
If BSC delivers a paging to a virtual LAC, you set 3) MSC extension to the BSC
extended mode. 1) and 2) modes are used when intra-BSC implements extended
bounary paging solution automatically.
Maintenance console command: MOD/LST EBPGPARA
2. Extended Strategy
This parameter is valid only for intra-BSC extended bounary paging solution, that
is, this parameter is valid only for mode 1) and 2).1) Extension starts in case of the
paging for the first time. 2) Extension starts in case of the paging for the second
time 3) Extension starts in case of paging for the third time. Generally, we select 3).
Maintenance console command: MOD/LST EBPGPARA. For example: MOD
EBPGPARA: EXTBNDPAGEMODE=REALPAGE, STRATTIME=3
Extended mode and strategy are configured in the paging parameter table.
3. Adjacent LAC Correspondence
This table is used only intra-BSC extended bounary paging solution over true LAC,
indicating the extended relation between true LACs. One center LAC can have 6
adjacent LACs instead of repeated adjacent LACs. But one center LAC should
not have more than 2 adjacent LACs if paging traffic is considered.
Maintenance console command: ADD/MOD/RMV/LST NBRLAC.
You delete some adjacent LACs by executing command MOD NBRLAC, and only
fill “-” in the corresponding place where the parameter is located.
4. Adjacent cell table of idle handoff
It is used only when the extended mode over idle handoff is selected. Pay attention
to the change in case of the change of network structure.
5. Cell attribute
Extended LAC (virtual LAC) in the MSC extended mode and bounary cell in the
extended mode over idle handoff are expressed in the cell attributed. You set the
cell to be an extended LAC by executing a command or define the cell as a
bounary cell.
[Note]: The bounary cell may change following such network structure as new cell.
You obtain LAC corresponding cell list in the module (including the cell in the
extended LAC), extended cell table over idle handoff, and LAC, module and
signaling correspondence of the BSC, as shown in figure 6.
Maintenance console command: ADD/MOD/RMV/LST CELL
3.5 Precautions
1. Determine the extended bounary paging solution based on actual networking
environment, and configure MSC and BSC parameters correspondingly during the
paging solution with cooperation between MSC and BSC.
2. Consider the bad effect because of expansion of paging scope during the selection
of extended LAC, that is, you should pay more attention when defining extended
LAC because paging pressure and traffic increase.
3. Concern the adding and modification of larger data configuration during the
application of extended bounary paging solution.
4. Change extended LAC and extended cell scope over idle handoff of extended
bounary paging solution correspondingly in case of network expansion.
5. Concern CPU utilization of BSC SPU, BTS paging traffic measurement, and
successful MSC paging ratio during the application of extended bounary paging
solution.
4 Optimization of BSC and BTS Paging Algorithm
4.1 Purpose
The processing for paging channel message is indispensable before call flow
goes on. So the optimization for processing algorithm can perfect the whole call flow
to ensure relevant performance indices. For example, BTS instead of BSC handles
L2 acknowledgement of access channel message to shorten the acknowledgment
time.
In respect of the whole call flow, we optimize paging algorithm aims to:
Enhance reliability of paging message acceptance and utilization efficiency of
paging channel.
Ensure validity of paging message and superiority of high-level service.
Avoid affecting the normal processing of voice service because of too many
SMs to ensure the strength of the system in case of the exceptions.
4.2 Implementation Solution
4.2.1 Cooperation Mechanism between BSC and BTS
In the earlier VR03C03, message resending mechanism at LAC layer
implemented by BSC includes the following four types of messages:
Acknowledged message on the common channel
Non-acknowledged message on the common channel.
Acknowledged message on the dedicated channel.
Non-acknowledged message on the dedicated channel.
Acknowledged/non-acknowledged mode refers to that whether the L2
acknowledgement is required. In VR03C03, we modify message resending
mechanism at LAC layer, as shown below:
The messages include F-CSCH and F-DSCH.
Adjust the settings for minimum detection interval of message sending at LAC
layer, message sending times and interval at LAC layer, and acknowledged
mode or not dynamically.
Minimum detection interval of message sending at LAC layer changes from
50ms only to 10ms/20ms/30ms/40ms/50ms (default value: 20ms).
Message sending interval changes from integral times of 50ms to integral
times of 10ms/20ms/30ms/40ms/50ms (default value: Integral times of
20ms).
Messages sent on paging channel belong to F-CSCH message. For details,
see the parameter configuration in section 4.4.
No more descriptions about the messages sent on F-DSCH are required
here.
To optimize paging algorithm, ensure the effect of message resending, perform
the following:
Avoid resending BSC but send BTS in the same slot.
Discriminate message levels, perfect BTS scheduling mechanism, and
ensure stable system based on the analysis of network SM problem to add
such fields as message level, slot, message living time and resending times
to BSC and BTS interface.
BSC sends the paging message levels except those of general messages,
their living time, and resending times to BTS through Abis interface.
BTS performs relevant processing based on BTS scheduling mechanism.
Currently, message levels include the messages related to the call and unrelated
to the call. The priority of former is higher than that of latter.
The former includes GPM of voice service, GPM of circuit and packet data
service, ECAM/CAM, BS Ack Order, and other Order messages (such as
release order) and unique challenge message (such as authentication).
The latter includes DBM, GPM used to locate SM, feature notification
message, and broadcast message.
Life cycle is the living time of resending paging message in the BTS message
queue. If the living time exceeds life cycle, delete the messages from BTS
message queue. Currently, the life cycle takes 80ms as a unit.
Resending times refers to the times that BTS sends paging message repeatedly.
When resending times is set to 0, BTS does not resend the paging message.
When resending times N is more than 0, BTS sends the paging message for n+1
times.
For the acknowledged or non-acknowledged messages on PCH, see table 2.
PCH Message Acknowledged or not
Channel Assignment Message Non-acknowledged
Extended Channel Assignment Message
Non-acknowledged
General Page Message Do not belong to the two types of messages
Data Burst Message Acknowledged
Authentication Challenge Message Acknowledged
Feature Notification Message Acknowledged
Service Redirection Message Non-acknowledged
Bs Ack Order Message (ARQ sub-layer of LAC)
Non-acknowledged
Order Message Non-acknowledged
If BTS resends Bs Ack Order Message at LAC ARQ sub-layer in VC03, disable
BSC sending mechanism and it is controlled through software parameter. For details,
see the parameter configuration in section 4.4.
BTS determines whether to carry the life cycle and resending times of the message,
and the resending times and life cycle can be set in the BTS.
4.2.2 BTS Paging Scheduling Mechanism
According to the above-mentioned cooperation mechanism of BSC and BTS,
BSC transfers priority level, life cycle, and reseeding times, but BTS performs
relevant scheduling and processing. According to the priority level of paging message
and slotted or not, paging messages based on the scheduling sequence include:
General message
Slotted message related to the call, including GPM of voice and data service,
and slotted unique challenge message
Unslotted message related to the call, including CAM/ECAM, BS ACK Order,
Release Order
Slotted message unrelated to the call, including GPM and DBM to locate SM.
Unslotted message unrelated to the call
Broadcast message
The above messages are stored in corresponding queues based on the sequence
sent by BSC. For slotted messages, the queue varies with the slot. BTS schedules and
sends the paging messages on the paging slot based on scheduling sequence. If there
are no messages to send in the queue with high scheduling priority, search the
message queue with lower priority, and then send the messages.
If the messages are resent, you should transfer the message to resending queue
after it is sent once, and schedule the message when queue scheduling is completed
at the same level.
For the slotted message, the shortest scheduling period in the BTS is a slot. If
the special slot is not sent during the first slot cycle, send the corresponding
slot during the next slot cycle.
For the unslotted message, the shortest scheduling period in the BTS is a slot,
that is, the unslotted message is sent during a slot. If the slot is not sent during
the slot cycle, the shortest scheduling period is the next slot.
In addition, the living time in the queue is subject to life cycle.
Life cycle: The time when the message is sent to the queue to that the message is
deleted from the queue after the life cycle duration.
Because discriminating the priority of message related/unrelated to the call, we
ensure that:
The system can handle voice and data service normally even in the case of
SM congestion.
Normal conversation.
The system is not affected by SM to enhance strength of the system.
Configure rational life cycle and resending times to ensure the validity and
reliability of message acceptance.
4.2.3 GPM Combination Function
The above measurers are to improve the smoothness of the whole flow. But GPM
combination is to enhance the utilization efficiency of paging channel. GPM
combination is allowed impliedly in the protocol in case of GPM structure description.
GPM structure is as follows:
Field Length (bits)
MSG_TYPE („00010001‟) 8
CONFIG_MSG_SEQ 6
ACC_MSG_SEQ 6
CLASS_0_DONE 1
CLASS_1_DONE 1
TMSI_DONE 1
ORDERED_TMSIS 1
BROADCAST_DONE 1
RESERVED 4
ADD_LENGTH 3
ADD_PFIELD
Zero or more occurrences of the following page record:
PAGE_CLASS 2
PAGE_SUBCLASS 2
Page type-specific fields 38-184
RESERVED 0 - 7 (as needed)
0 or several “Page Records” are included in the structure. But “Page type-specific
fields” include the information about MS and service option. “Page records” with
different formats have different types. For example, the format of “Page type-specific
fields” is as follows:
Field Length (bits)
MSG_SEQ 3
IMSI_S 34
SPECIAL_SERVICE 1
SERVICE_OPTION 0 or 16
GPM combination means that:
Combine the MS information with the information about relevant service
option, and send them.
Original several GPMs with respective special field are sent in a GPM through
shared common field.
Enhance the utilization of paging channel.
Under the circumstance of “Page record” in a format, the utilization enhancement
result through analysis is shown below:
If N*GPM are combined, the decrease ratios of occupied bits before and after
GPM combination are as follows:
When n is set to 2, the decrease ratio is 32/128=25%.
When n is set to 3, the decrease ratio is 47/128=36.7%.
Whatever GPMs are combined, the maximum decrease ratio for paging channel
occupation is 70/128=54.7%. Generally, the GPM occupation for paging channel
is 20–30%, and the maximum decrease ratio is 11-16% after GPM combination
strategy is adopted.
When n is set to 2, the decrease ratio is 5–7.5%.
When n is set to 3, the decrease ratio is 7–11%.
This function has been implemented in VC03, and two control parameters are
available: Number of combined GPM and number of GPM search.
The former ranges from 0 to 15, that is, at most 3 GPMs are combined. If o
times are set, disable GPM combination function.
The latter is the specified queue query size in case of GPM query. Too large
queue will affect processing performance of channel board. It is set to 20 by
default.
You can configure the two parameters through .ini file (see section 4.4.3), and
optimize them after the actual network application.
4.3 Paging Measurement Index and Analysis
Paging measurement indices are added in VC03 based on actual network
application. With the implementation of following BTS traffic measurement, some
indices included in BSC traffic measurement are transferred to BTS traffic
measurement. The specific indices are as follows:
1. Occupation of sent messages related to the calls [%], including the shared
occupation of slotted message and unslotted message related to the calls.
2. Occupation of sent messages related to SM [%], including the shared occupation
of slotted message and unslotted message unrelated to the calls.
3. Occupation of all the sent messages [%]. The three indices are designed for the
occupation of paging channel.
4. PCH occupation [%] is the sum of the above three indices. Actually, there are also
SCI bit occupation and null GPM occupation. SCI bit occupation is constant, so it is
not required to consider it. But null GPM is sent until the system has no any other
messages to send, the occupation of paging channel will be up to100%. To reflect
actual message occupation in the network, you should not add null GPM
occupation. If occupation of PCH busy hour exceeds a threshold (such as 80%),
paging channel is occupied much. So the expansion for paging channel is
required.
5. Occupation of lost message related to the calls [%]=Total bytes of lost messages
related to the calls/total bytes of received messages (resent messages included)
6. Occupation of lost messages related to SM [%] =Total bytes of lost messages
unrelated to the calls (resent messages included).
7. GPM combination efficiency: The GPM combination efficiency of voice and SM is
measured respectively.
Definition: Set a measurement cycle T to 300s. If you send GPM with combination
strategy: Combine M*GPM with K times, and N*GPM are not combined, the
efficiency enhancement ratio is:
[(N+(k+1)*M)-(M+N)]/(N+(k+1)*M)=K*M/(N+(K+1)*M)
Obviously, when N is set to 0, the efficiency enhancement ratio is the maximum
(that is, K/(K+1)).
When K is se to 1, the ratio is 50%.
When K is set to 2, the ratio is 67%.
The provision of calculation formula (numerator/denominator) instead of specific
percentage during the actual implementation facilitates knowing the number of
sent GPM during a period.
The following indices are used to locate the relevant personnel of internal BTS
scheduling mechanism and detect paging scheduling mechanism. You should
not concern them in general. The indices are to grasp and understand the
information about message sent, and analyze whether the settings of queue size
and living time are appropriate. The sum of following (8), (9), (10), (11), and (13)
is the total number of slotted messages related to the call in the queue, but that of
(8), (9), (10), (11), (12), and (13) is the total number of slotted messages related
to the call before they are sent in the queue. So do for the slotted messages
unrelated to the call.
8. The number of messages sent without delay (slotted messages related to the call)
9. The number of messages sent with a delay of one slot cycle (slotted messages
related to the call)
10. The number of messages sent with a delay of two slot cycles (slotted messages
related to the call)
11. The number of messages sent with a delay of three or more slot cycles (slotted
messages related to the call)
12. The number of discarded messaged because of queue saturation (slotted
messages related to the call)
13. The number of discarded messages because living time exceeds (slotted
messages related to the call)
14. The number of messages in the queue (unslotted messages related to the call)
15. The number of messages deleted before the queue (unslotted messages related
to the call)
16. The number of discarded messages because living time exceeds (unslotted
messages related to the call)
17. The number of messages sent without delay (slotted messages unrelated to the
call)
18. The number of messages sent with a delay of two slot cycles (slotted messages
unrelated to the call)
19. The number of messages sent with a delay of two slot cycles (slotted messages
unrelated to the call)
20. The number of messages sent with a delay of three or more slot cycles (slotted
messages unrelated to the call)
21. The number of discarded messaged because of queue saturation (slotted
messages unrelated to the call)
22. The number of discarded messages because living time exceeds (slotted
messages unrelated to the call)
23. The number of messages in the queue (unslotted messages unrelated to the call)
24. The number of discarded messaged because of queue saturation (unslotted
messages unrelated to the call)
25. The number of discarded messages because living time exceeds (unslotted
messages unrelated to the call)
4.4 Parameter Configurations
4.4.1 Default Value of F-CSCH Message Resending Parameter
LAC layer resending mechanism includes two types of messages: F-CSCH
message and F-DSCH message. The latter does not belong to the content of paging
optimization. So no more descriptions are required here. For details, see Guide to
Resending Parameter at LAC Layer Provided by BSC. For the parameter setting of the
former, see table 3.
Table 3 F-CSCH Message Default Value
F-CSCH Message ID Acknowledged
mode
Sending
times at
LAC
layer
Sending interval
at LAC layer (ms)
Authentication
Challenge
Message
(AUCRM)
00001010 Acknowledged,
DB cannot be
modified
1, and
DB
cannot
be
modified
5000 (Because
the message is
not sent, the
interval is the
time that LAC
layer waits for MS
acknowledgment)
Bs Ack Order
Message(BSACKM)
11111110 Non-acknowledged,
and DB cannot be
modified
3 300
Channel
Assignment
Message(CAM)
00001000 Non-acknowledged,
and DB cannot be
modified
10 300
Data Burst
Message(DBM)
00001001 Acknowledged, and
DB cannot be
modified
1, and
DB
cannot
5000 (Because
the message is
not sent, the
be
modified
interval is the
time that LAC
layer waits for MS
acknowledgment)
Extended Channel
Assignment
Message(ECAM)
00010101 Non-acknowledged,
and DB cannot be
modified
10 300
Feature Notification
Message(FNM)
00001100 Acknowledged, and
DB cannot be
modified
1, and
DB
cannot
be
modified
5000 (Because
the message is
not sent, the
interval is the
time that LAC
layer waits for MS
acknowledgment)
Order
Message(ORDM)
00000111 Non-acknowledged 3 300
Service Redirection
Message(SRDM)
00010000 Non-acknowledged 3 300
The default values in the table are only applicable when paging living time is not
activated and BTS does not resend paging channel message. Once the function is
enabled, you should adjust the default values. For details, see table 5 in section
4.4.2.
DBM, FNM, and AUCRM are sent in the mode of slotted message. For the
setting of default value, consider the minimum paging slot cycle.
Set “Release Order” at LAC layer to Non-acknowledged, and it cannot be
changed.
Set “Bs Ack Order Messager” at LAC ARQ sub-layer to Non-acknowledged,
and it cannot be changed.
Resending times at LAC layer: 0–20.
Resending interval at LAC layer: 0–8000ms.
The maximum error of message detection mechanism is “minimum detection
interval of message sending at LAC layer". If [Sending interval]/[Minimum
detection interval of message sending at LAC layer] is not set to 0, the error may
be “minimum detection of message sending at LAC layer” because of the round
error. So you should set “Sending interval” to integral times of “Minimum detection
interval of message sending at LAC layer”. For example, if “Minimum detection
interval of message sending at LAC layer” is set to 20ms, set “Sending interval” to
20×n. This is a reference default value. You should adjust the parameters during
the actual network test to obtain the best experience value, and then submit it to
relevant Dept. for database modification.
Minimum detection interval of message sending at LAC layer: When the F-CSCH
is available, the parameter ranges from 50ms to 100ms but it is defaulted to be 100ms.
When the F-DSCH is available, the parameter ranges from 10ms to 50ms, that is, the
minimum detection interval of message sending at the LAC layer changes from 50ms
to any one of 10ms, 20ms, 30ms, 40ms or 50ms but it is defaulted to be 20ms. In this
case, the interval of message sending changes from the integral times of 50ms to
that of 10ms, 20ms, 30ms, 40ms or 50ms but it is defaulted to be that of 20ms.
Modification/query command: MOD/LST LACCTRL
Minimum detection interval of message sending at LAC layer
Modification command: MOD LACMSGINTERVAL
4.4.2 Resending Times and Living Time of Paging Channel Message
You can set resending times and living time of paging channel message based on
different messages. Wherein, maximum resending times: 15, and Unit of living time:
80ms. For the paging channel message and corresponding ID, see table 4.
Table 4
PCH ID
Channel Assignment Message 0
Extended Channel Assignment Message
1
General Page Message 2
Data Burst Message 3
Authentication Challenge Message 4
Feature Notification Message 5
Service Redirection Message 6
Order Message 7
Other message 8
Wherein, “other message” is designed for its perfectness, and it is not used
currently because of the purpose at later stage. When the living time of paging
message is activated, and BTS supports the resending of paging channel message,
set the parameter of paging channel by default. For details, see table 5.
Table 5 Parameter setting of paging channel message
F-CSCH Message Sendi
ng times
at LAC
layer
Sendin
g interval at
LAC layer
(unit: ms)
Living
time
(unit:
80ms)
Resending
time9s
Authentication
Challenge Message
(AUCRM)
1 5000 24 0
Channel Assignment
Message (CAM)
3 1000 12 3
Data Burst Message
(DBM)
1 5000 24 0
Extended Channel
Assignment Message
(ECAM)
3 1000 12 3
Feature Notification
Message (FNM)
1 5000 24 0
General Page
Message (GPM)
None None 64 0
Order
Message(ORDM)
1 0 24 2
Service Redirection
Message (SRDM)
1 0 24 2
Modification command: MOD/LST FCSCHMSGPARA
Precautions for parameter configuration:
1. The table 5 shows the following:
“None” indicates that there are no relevant parameter setting
“0” in the “Sending interval at LAC layer” column indicates that LAC resending
is not required for the message.
“1” in the “Sending times at LAC layer” and “5000” in the “Sending interval at
LAC layer” indicate that it is not required to resend this message at LAC layer.
5000(ms) indicates the time of LAC layer waits for MS answer, which is the
same as that in table 3.
“0” in the “BTS sending times” indicates that the message is resent at upper
layer instead of LAC layer of BSC and BTS.
2. The parameter setting is applicable when paging message living time is activated
and BTS paging channel message is resent. The paging message living time
function can be disabled only when “enable PCH living time” is set to 0 at the BTS
(it is caused by the matching of ABIS interface). But the paging message
resending function can be disabled not only when the resending times are set to 0
at the BTS but also “enable PCH retransmission” is set to 0 at the BTS.
3. Whether BTS supports L2 acknowledgment for access channel message,
including the following:
a. If all the BSs of BSC do not support L2 acknowledgement for reverse access
channel message, BSC sends L2 software parameter switch, and enables the switch
(that is, No. 39 software parameter of CCM. Default value: 0x00000001). At that time,
send the “Bs ACK Order Message” based on the parameter set in table 3.
b. If all the BSs of BSC support L2 acknowledgement for reverse access channel
message, disable the software parameter (that is, No. 39 software parameter of CCM.
Default value: 0x00000000). At that time, sending times and interval at LAC layer of
“Bs ACK Order Message” is invalid. For BTS, enable L2 acknowledgement switch of
access channel. For the setting of resending times and living time, see section 4.4.3.
c. If some BSs of BSC support L2 acknowledgment for reverse access channel
message, but some do not support, enable No. 39 software parameter of CCM.
To facilitate understanding living time and resending times of paging channel
message, see the following example:
If you set the sending times of ECAM at LAC layer of BSC to 3, and resenting
interval at LAC layer to1000ms, it indicates that BSC resends ECAM 3 times
at most, and resending interval is 1000ms.
If BSC receives Preamble of reserve service channel, resending the message
stops at LAC layer. When you set the living time and resending times to 12
and 3 respectively, it indicates that BTS resends the message 4 times at most
(add once for BTS), and the living time at BTS is 12×80ms=960ms. Once the
living time expires or resending completes, BTS deletes all the information
about the message.
After sending ECAM at LAC layer twice, BSC receives Preamble of reverse
service channel. In this way, BSC sends ECAM twice, but BTS sends two
cycles of ECAM (send ECAM four times at most for each cycle, and the living
time of BTS in each cycle is 960ms).
The setting of resending times should consider the effect of paging channel
occupation, but that of living time should consider the cooperation with the timers
involved in the whole call flow.
For the GPM, MSC controls resending times and interval. For details, see figure 6.
GPM living time should cooperate with paging resending interval timer T3113 of MSC,
but whose living time should be less than T3113. The living time of CAM/ECAM should
consider the cooperation with CCM_T_WT_TCH_PREAMBLE of TCH Preamble, and
should be less than this timer.
Figure 6 Simple call flow diagram
4.4.3 L2 Acknowledgement Parameters for Access Channel Message
1. L2 Acknowledgement Switch of Access Channel Message from BSC
Controlled by No. CCM39 software parameter.
Modification command: MOD SOFTPARA.
1: Enable, and 0: Disable.
The control requires the cooperation with BTS parameter.
2. L2 Acknowledgement Switch of Access Channel Message from BTS
Resending times: 2 (default value)
Living time: 16×80ms (that is, 1.28s).
You modify the above two parameters by modifying .ini file of BTS. For the file format,
see Annex 1. The specific parameters are as follows:
EnableL2AckOrderCtrl = 1; (L2 acknowledgement control: 0: Disable and 1: Enable)
L2AckOrderLivingTime = 16; (L2 acknowledgment living time: 1–255 (unit: 80ms))
L2AckOrderResendNum = 2; (L2 acknowledgement resend times: 0–15)
EnablePCHLivingTime = 1; (Enable PCH living time: 0: Disable and 1: Enable)
EnablePCHResend = 1; (Enable PCH resend: 0: Disable and 1: Enable)
GPMCombineNum = 2; (GPM combination number: 0–15)
GPMSearchNum = 20; (GPM search number: 1–100)
4.4.4 Parameter and Function Verification
Verify BSC and BTS paging optimization algorithms through the following methods:
1. Query the modified living time and resending times by executing command LST,
and view them through Abis message tool provided by BTS. For details, see Annex
2. Because the test tool is for intra-BTS use only, and intra-BTS maintains its
version, BTS relevant engineer provides on-site operation or guide for personnel
using the function.
2. View directly the GPM combination function through air interface signaling. The
case is as follows:
RecNo : 2390 : 2003-8-21 08:43:00.201 : PAGING : General Paging Message (GPM)
Record_Header, ,,
RECORD_LENGTH, 43, bytes,
LOG_CODE, 0x1007,,
MESSAGE_TIMESTAMP, 08:43:00.201,,
EXPECTED_MESSAGE_LENGTH, 31, bytes,
Message, ,,
Paging Channel Message.0, ,,
MSG_LENGTH, 31, bytes,
RESOLVE_PD, ,,
PD.0, ,,
MSG_ID, 17,,
SDU_AND_PDU_PADDING_LENGTH, 202, bits,
General Paging Message, ,,
MOB_SPECIFIC_MSG, 1,,
CONFIG_MSG_SEQ, 8,,
ACC_MSG_SEQ, 37,,
CLASS_0_DONE, 1,,
CLASS_1_DONE, 1,,
TMSI_DONE.0, 0,,
ORDERED_TMSIS.0, 0,,
BROADCAST_DONE, 1,,
RESERVED, 0,,
ADD_LENGTH, 0,,
ADD_PFIELD, 0,,
[3], ,,
PAGE_CLASS.0, Class 0 : Mobile Station Addressed,,
PAGE_SUBCLASS.0, 0,,
MSG_SEQ.0, 3,,
IMSI_S.0, ,,
IMSI_S, (009) 830-1618――――――――(1),,
IMSI_S2.0, (009),,
IMSI_S1.0, 830-1618,,
NON_IS2000_PAGE_CLASS_FIELDS.0, ,,
ADDR_MATCH.0, 0,,
SDU_INCLUDED.0, 1,,
SERVICE_OPTION.0, ,,
INCORRECT_SO, Enhanced Variable Rate Voice Service (8 kbps),,
Proprietary_Indicator.0, 0,,
Service_Option_Revision.0, 0,,
Base_Service_Option_Number.0, 3,,
PAGE_CLASS.1, Class 0 : Mobile Station Addressed,,
PAGE_SUBCLASS.1, 0,,
MSG_SEQ.0, 6,,
IMSI_S.0, ,,
IMSI_S, (078) 839-8698―――――――― (2),
IMSI_S2.0, (078),,
IMSI_S1.0, 839-8698,,
NON_IS2000_PAGE_CLASS_FIELDS.0, ,,
ADDR_MATCH.0, 0,,
SDU_INCLUDED.0, 1,,
SERVICE_OPTION.0, ,,
INCORRECT_SO, Enhanced Variable Rate Voice Service (8 kbps),,
Proprietary_Indicator.0, 0,,
Service_Option_Revision.0, 0,,
Base_Service_Option_Number.0, 3,,
PAGE_CLASS.2, Class 0 : Mobile Station Addressed,,
PAGE_SUBCLASS.2, 0,,
MSG_SEQ.0, 5,,
IMSI_S.0, ,,
IMSI_S, (078) 842-0782――――――――③,,
IMSI_S2.0, (078),,
IMSI_S1.0, 842-0782,,
NON_IS2000_PAGE_CLASS_FIELDS.0, ,,
ADDR_MATCH.0, 0,,
SDU_INCLUDED.0, 1,,
SERVICE_OPTION.0, ,,
INCORRECT_SO, Enhanced Variable Rate Voice Service (8 kbps),,
Proprietary_Indicator.0, 0,,
Service_Option_Revision.0, 0,,
Base_Service_Option_Number.0, 3,,
MSG_END_PADDING, ,,
IS2000_L2_PDU_PADDING, ,,
PDU_PADDING.0, 0,,
CRC, 631086185,,
The above GPM includes three IMSI information (such as (1) (2), and ③).
3. View and analyze BTS paging scheduling function through paging traffic
measurement.
5 Application Cases
1. The inappropriate settings for resending times and interval timer of DCH
Unacknowledged Mode message result in the MS authentication failure, and MS
cannot originate a call normally.
[Descriptions]
Set the resending times of DCH Unacknowledged Mode message at LAC
layer in an office to 5 and resending interval timer to 100ms. That is, the interval
from the first message to the last resending message is 5×100=500ms.
The authentication procedures are as follows:
1. After receiving an “Assignment Complete”, the network side originates an
authentication. At that time, a RAND is generated and the network side delivers this
RANDO to MS through an “Authentication Indication Request”.
2. After receiving MSC authentication indication, MS takes RAND delivered from
MSC, A-KEY in the SIM (actually, SSD instead of A-KEY), MIN (the last 10 digits of
IMSI), and ESN as the authentication elements to generate the authentication result
through authentication algorithm, and sends the result AUTHR1 to MSC.
3. MSC forwards the authentication elements and result from MS to HLR/AC.
4. HLR/AC takes A-KEY value of this subscriber saved in the MIN, ESN, RAND
and AC, and generates a new result AUTHR2 through the same authentication
algorithm. If AUTHR1 is consistent with AUTHR2, the authentication succeeds, and
the subscriber is a valid one. Otherwise, the subscriber is an invalid one, and will be
rejected.
The authentication includes the calling authentication and called authentication
on the traffic channel, and Unique Challenge Authentication originated by HLR when
MS is in IDLE state. Because the protocol is imperfect, and current network closes the
authentication originated by location registration, no more descriptions are detailed
here. The former authentication message (SSD Update Message) is sent in an
Unacknowledged Mode on the traffic channel, and the latter one (Unique Challenge
Message) is sent in an Acknowledged Mode on the paging channel (current network
does not support SSD Update Message on the paging channel). Meanwhile, the
detection cycle of authentication message copy sent in the Acknowledged Mode on
the DCH is 320ms.
500ms is greater than the detection time of message copy based on the
above-mentioned setting (320ms), so MS thinks a new message is sent by
mistake to send new authentication data. In this case, the two authentication
results of network side are inconsistent, and the authentication will fail.
Therefore, the resending interval of authentication message sent in an
Unacknowledged Mode on the DCH should not be greater than corresponding copy
detection cycle. The detection cycle of message copy sent in an Unacknowledged
Mode on the common channel is 2.2 second stipulated in the protocol, so the lifecycle
of authentication message sent in an Unacknowledged Mode on the common channel
should not be greater than copy detection time. Because ECAM and CAM are on traffic
channel instead of paging channel, the exceptional problems do not exist in case of
copy detection.