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All rights reserved. Passing on and copying of this document,
use and communication of its contents not permitted without
written authorization from Alcatel.
EVOLIUM Base Station SubsystemIntroduction to GPRS & E-GPRS QoS Monitoring /
B9
TRAINING MANUAL3FL11829ABAAWBZZA ed 1 January 2006
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Safety Warning
Both lethal and dangerous voltages are present within the equipment. Do not wear conductive jewellery while working on the equipment.Always observe all safety precautions and do not work on the equipment alone.
Caution
The equipment used during this course is electrostatic sensitive. Please observe correct anti-static precautions.
Trade Marks
Alcatel and MainStreet are trademarks of Alcatel.
All other trademarks, service marks and logos (Marks) are the property of their respective holders including Alcatel. Users are notpermitted to use these Marks without the prior consent of Alcatel or such third party owning the Mark. The absence of a Mark identifier isnot a representation that a particular product or service name is not a Mark.
Copyright
This document contains information that is proprietary to Alcatel and may be used for training purposes only. No other use or transmissionof all or any part of this document is permitted without Alcatels written permission, and must include all copyright and other proprietarynotices. No other use or transmission of all or any part of its contents may be used, copied, disclosed or conveyed to any party in anymanner whatsoever without prior written permission from Alcatel.
Use or transmission of all or any part of this document in violation of any applicable Canadian or other legislation is hereby expresslyprohibited.
User obtains no rights in the information or in any product, process, technology or trademark which it includes or describes, and isexpressly prohibited from modifying the information or creating derivative works without the express written consent of Alcatel.
Alcatel, The Alcatel logo, MainStreet and Newbridge are registered trademarks of Alcatel.
All other trademarks are the property of their respective owners. Alcatel assumes no responsibility for the accuracy of the informationpresented, which is subject to change without notice.
2004 Alcatel. All rights reserved.
Disclaimer
In no event will Alcatel be liable for any direct, indirect, special, incidental or consequential damages, including lost profits, lost business orlost data, resulting from the use of or reliance upon the information, whether or not Alcatel has been advised of the possibility of suchdamages.
Mention of non-Alcatel products or services is for information purposes only and constitutes neither an endorsement nor arecommendation.
Please refer to technical practices supplied by Alcatel for current information concerning Alcatel equipment and its operation.
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PROGRAM
1 Role of the BSS in GPRS QoS Monitoring
2 Recalls on the Main BSS GPRS Telecom Procedures3 Description of the Main BSS GPRS QoS Counters and
Indicators
4 Detection of the Main BSS GPRS QoS Problems
5 Analysis of the Main BSS GPRS QoS Problems
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1 Role of the BSS in GPRS QoS monitoring
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1 Role of the BSS in GPRS QoS MonitoringSession Presentation
> Objective: to be able to describe the role of the BSS in the End-user GPRS QoS and the dependencies between Global
(BSS+GSS) and BSS GPRS QoS on one hand and betweenBSS GSM and GPRS QoS on the other hand
> Program:
1.1 Distinction between BSS/BSS+GSS/End-user GPRS QoS
1.2 Implementation of GPRS QoS profiles at BSS level
1.3 Source of information for GPRS QoS monitoring1.4 Dependencies between BSS GSM and GPRS QoS
1.5 Impact of GMM/SM signaling on BSS QoS interpretation
1.6 Indicators Classification
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1 Role of the BSS in GPRS QoS monitoring
1.1 Distinction between BSS/BSS+GSS/End-user GPRS
QoS
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1.1 Distinction between BSS/BSS+GSS/End-user GPRSQoSDifferent Levels of QoS GGSN
GPRSGPRS
BackboneBackbone
PacketPacket
DataData
NetworkNetwork
Gb
SGSN
A935
MFS
BSC
Ater
B
T
S
Abis
BSS
BSS+GSS QoS
Gn GiUmR
BSS QoS
End-user QoS
TETE
> 3 types of QoS are involved in the overall analysis of the GPRS QoS :
Radio QoS
It must be considered from the R interface to the Gb interface. It belongs mainly to the radio environment as wellas the proper functioning of the PCU implemented inside the BSS.
It is defined in terms of throughput, service precedence, RLC reliability mode, transfer delay.
GPRS QoS
It must be considered from the R interface (MS access to the GPRS) to the Gi interface (exit from the GPRSNetwork).
It includes the Radio QoS and the GSS QoS.
It is defined in terms of service precedence, transfer delay, mean and peak throughputs and reliability.
End-User QoS
This is the QoS as the user feels it.
It includes the GPRS QoS as well as the QoS of the external networks and their connection to the GPRS GSS. Even if it does not belong to the operator, it should still be monitored as it can generate customer complaints.
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1.1 Distinction between BSS/BSS+GSS/End-user GPRSQoSDependencies between QoS levels
End-user QoS
BSS+GSS QoS
BSS QoS
> A bad BSS GPRS QoS (Radio QoS) will lead to a bad GPRS QoS and a bad End-user QoS.
> A bad End-user performance can be due to a bad GSS behaviour without any BSS GPRS QoS degradation.
> A bad End-user QoS can also be due to a bad PDN performance.
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1.1 Distinction between BSS/BSS+GSS/End-user GPRSQoSImpact of UE
> Different data applications are multiplexed over the GPRS radio
layers: FTP, WEB/HTTP, WAP, MMS, etc
> Data applications have very different traffic characteristics
(amount of data, duration between LLC PDUs) leading to
different ways of triggering radio layers algorithms
> Therefore Parameters setting in the GPRS network will lead to
different performance according to the service
> A bad end-user QoS can also be due to the setting of TE protocol layers parameters which can not have optimal values to get thebest GPRS performance.
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1.1 Distinction between BSS/BSS+GSS/End-user GPRSQoSImpact of UE : example
> Data applications use TCP/IP protocol layers which have a
great impact on the end-user QoS
(*)
First IP router Last IP ro
GTP
relay
SNDCP
BSSGPRLC BSSGP
relay
relay
SNDCPPPP
FTP
TCP
IP
PPP
LLC
RLC
MAC
RF
MAC
RF
NS
L1
NS
L1
LLC UDP
IP-Gn
L2
L1
UDP
IP-Gn
L2
L1
IP
relay
IP
GTP
IP
relay
IP
relay
IP
UmR
Gb
Gn GiTE (PC,PDA )
MS
BSS
SGSN
GGSN
Possible repartition on the end to end path of the TCP flight si ze
TCP data segment
TCP acknowledgement
(*) this graphical representation is used toexpress the fact that many data segments arecurrently waiting to be transmitted on therepresented link and are stored in buffers of thedevice handling the link . It doesnt mean thatsimultaneous segments are being transmitted.
FTP above TCP/IP layers
> A bad end-user QoS can also be due to the setting of TE protocol layers parameters which can not have optimal values to get thebest GPRS performance.
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1.1 Distinction between BSS/BSS+GSS/End-user GPRSQoSUnderstand BSS GPRS QoS> GPRS QoS is not an isolated topic:
It is necessary to use GSM indicators in order to complete the
analysis of GPRS QoS
It is necessary to use GSM counters in order to complete the
analysis of the impact of GPRS traffic on GSM QoS
> The BSS QoS does not allow to have a complete
understanding of the end to end QoS seen by the user
Indeed, upper protocol layers (TCP for example) have a great
impact on the global QoS
The GSS also has a great impact on the global QoS
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1 Role of the BSS in GPRS QoS monitoring
1.2 Implementation of GPRS QoS profiles at BSS level
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Location services Traffic Conditions Itineraries Nearest Restaurant,
Cinema, Chemist,Parking;, ATM ...
Fun Games (Hangman, Poker, Quiz, ) Screen Saver Ring Tone Horoscope Biorhythm
MediaAlways-on
M-commerce
Mobile Office Voice (!)
E-mail Agenda IntraNet/InterNet Corporate Applications Database Access
Transportation Flight/train Schedule
reservation
Verticalapplication
Traffic Management
Automation
Mobile branches
Health
Music Downloading of
music files orvideo clips
News(general/specific) International/National News Local News Sport News Weather Lottery Results Finance News Stock Quotes Exchange Rates
Physical on-line shopping on-line food
Non physical on-line Banking Ticketing Auction Gambling Best Price e-Book
Directories Yellow/White Pages International Directories Operator Services
1.2 Implementation of GPRS QoS Profiles at BSS LevelData Services
> Different services can be found in the 3 categories:
Teleservices provide the full capabilities for communications by means of a terminal equipment, network functions andpossibly functions provided by dedicated centers.
Multimedia teleservices support the transfer of several types of information.
M-commerce:
Non-physical = electronic goods (e-banking, e-flight ticketing, etc).
Physical = electronic payment of physical goods (food, supplies, hardware, etc).
> Retrieval services
Provide the capability of accessing information stored in data base centers. The information is sent to the user on demand only. Anexample of one such service in the Internet's World Wide Web (WWW).
> Messaging services
Offer user-to-user communication between individual users via storage units with store-and-forward mailbox, and/or messagehandling (e.g., information editing, processing and conversion) functions;
> Conversational services
Provide bi-directional communication by means of real-time (no store-and-forward) end-to-end information transfer from user touser. An example of such a service is the Internet's Telnet application;
> Tele-action services
Characterized by low data-volume (short) transactions, for example credit card validations, lottery transactions, utility meterreadings and electronic monitoring and surveillance systems.
> Distribution services
Characterized by the unidirectional flow of information from a given point in the network to other (multiple) locations. Examples mayinclude news, weather and traffic reports, as well as product or service advertisements;
> Dispatching services
Characterized by the bi-directional flow of information from a given point in the network (dispatcher) and other (multiple) users.Examples include taxi and public utility fleet services;
> Conferencing services
Provide multi-directional communication by means of real-time (no store-and-forward) information transfer between multiple users.
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1.2 Implementation of GPRS QoS Profiles at BSS LevelQoS Requirements - Exercise
> Different applications require different QoS
Exercise: find qualitatively the QoS requirements of the following
data services
+: low sensitivity, ++: medium, +++: high
Service Tra nsfer Delay Throughput Relia b il i ty
web
video streaming
ftp
location based advertising
audio streaming
email
wap
fax
e-commerce
interactive gamesSMS
> Data applications have very different traffic characteristics (amount of data, duration between LLC PDUs) leading to differentways of triggering radio layers algorithms. This has a direct impact on the follow-up of some QoS indicators at OMC-R level:number of DL/UL TBF establishment requests, DL/UL TBF duration, coding scheme distribution.
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> 5 GPRS QoS attributes in the R97/98 standard:
Precedence Class: relative importance of service under
congestion; 3 values are defined Delay Class: total delay measured between the R or S point
and the Gi interface; 4 values are defined
Reliability Class: mainly linked to Ack / Not Ack modes at RLC
and LLC levels and within the backbone network; 5 values are
defined
Peak Throughput Class: measured at the Gi and R reference
points;9 values, ranging from 8 Kbit/s up to 2048 Kbit/s
Mean Throughput Class: measured at the Gi and R reference
points; 19 values, ranging from Best Effort up to 111 Kbit/s
1.2 Implementation of GPRS QoS Profiles at BSS LevelR97/98 GPRS QoS Profile
> Precedence classes: high, normal, low
> Delay classes: class 1 (average delay
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> ETSI R97 principles:
GPRS QoS is negotiated between the MS and the SGSN, at
PDP context activation
The BSS is not involved in QoS negotiation
No absolute QoS can be guaranteed by the BSS
The SGSN and the GGSN play the main role in QoS
management
> But the BSS should be able to do its best...
1.2 Implementation of GPRS QoS Profiles at BSS LevelETSI Principles
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GGSN
GPRSGPRS
BackboneBackbone
PacketPacket
DataData
NetworkNetwork
Gb
SGSN
A935
MFS
BSC
Ater
B
T
S
Abis
BSS
GPRS QoS
Gn GiUmR
Radio QoS
User QoS
TETE
1.2 Implementation of GPRS QoS Profiles at BSS LevelQoS Profile at BSS Level
> Throughput: not managed by Alcatel BSS. Best effort is supported.
> Service precedence: partly managed by Alcatel BSS.
> RLC reliability mode: managed by the BSS.> Transfer delay: not managed by Alcatel BSS. Best effort is supported.
> See next pages for details.
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1.2 Implementation of GPRS QoS Profiles at BSS LevelThroughput
> Throughput:
Defines the data throughput requested by the user
Specified on:
The DL path: in the DL BSSGP PDU header
The UL path: peak throughput class in Packet resource request(2-phase access)
Not taken into account by the BSS
The allocation strategy consists in trying to allocate to the MS as
many PDCHs as supported by its multislot class if known
> Throughput:
The PDCH available throughput (in terms of RLC/MAC blocks) is shared equally between all MSs allocated on it. TheBSS tries periodically to offer the best throughput to a TBF in case it has a sub-optimal allocation. It corresponds to thedirection of the bias and a better allocation is available.
The operator can limit the maximum number of PDCHs allocated to a TBF through the O&M configuration.
The maximum throughput that can be served to an MS is limited to n x 20 Kbit/s for a GPRS MS or n x 59.2 Kbit/s for anEGPRS MS, in case of good radio conditions (no retransmission), n being limited by the upper multislot class supportedby the network (n=5).
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1.2 Implementation of GPRS QoS Profiles at BSS LevelDelay
> Delay:
Defines the end-to-end transfer delay incurred in the
transmission of SDUs through the GPRS network
Specified on:
The DL path: through the PDU lifetime which indicates the latesttime at when the PDU must be completely transmitted
The UL path: peak throughput class in Packet resource request(2-phase access)
Best effort is supported by the BSS:
The PDU lifetime is taken into account for a DL LLC PDU
As many TSs as requested according to the MS Multislot Class
are allocated if possible
> Transfer delay:
This includes the radio channel access delay (on the uplink) or radio channel scheduling delay (on the downlink), the
radio channel transit delay (uplink and/or downlink paths) and the GPRS-network transit delay (multiple hops). It does notinclude transfer delays in external networks.
Delay is measured between the R or S (for MS) and Gi (for FS) reference points when applied to "MS to Fixed Station(FS)" or "FS to MS" transmissions.
The PDU lifetime is expected to be configured by the SGSN according to the GPRS transfer delay class of the associatedPDP context
In DL: case of unavailability of either traffic resources (TFI, TAI, throughput) or PDCH resources, DL TBF establishmentsrequests are queued and served according to the PDU lifetime.
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1.2 Implementation of GPRS QoS Profiles at BSS LevelReliability
> Reliability:
Defines the transmission characteristics that are required by an
application in terms of SDU loss probability, duplication of SDU,
mis-sequencing of SDU or corruption of SDU
Implemented at BSS level as RLC Acknowledged (Ack) mode or
RLC Not acknowledged (Nack) mode
Specified on
The DL path: in the DL BSSGP PDU header
The UL path: in Packet resource request (2-phase access)
Default mode: Ack
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1.2 Implementation of GPRS QoS Profiles at BSSLevel
Alcatel QoS Offer - R97/98 QoS Compliance
ETSI R97/98 QoS attributes Alcatel Of fer
Precedence classMean throughput
classDelay class Resulting QoS class
(4) Best Effort
1, 2 or 3
1,. 2 or 3
1,. 2 or 3
1,. 2 or 3
any
(3) Low priority
Normal, High priority
(2) Normal priority
(1) High priority
any
any
Best Effort
specified, except BE
specified, except BE
Best-Effort
Best-Effort
Best-Effort
Normal
Premium
Reliability class: as required by the MS
BE = Best-Effort
> The QoS attributes are associated with a PDP context performed by an R97/98 MS.
> The five QoS parameters of the standard define more than 60 combinations! This is too much and must be simplified:
Too complex to implement,
Many of the combinations have no meaning!
The standard "allows" simpler QoS implementations.
- = any value.
In green, the main criterion for the definition of the resulting QoS.
> Alcatel implementation: 3 QoS classes are defined:
Best effort: Inexpensive, comparable to the Internet (no commitment). Ideal for foraging on the internet.
Normal: Comparable to an intranet.
Premium: Expensive, high performance.
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> 4 UMTS QoS classes in the R99 standard (traffic
classes):
Conversational class
video conference
Streaming class
live video retransmission
Interactive class
web browsing
Background class
email, SMS
1.2 Implementation of GPRS QoS Profiles at BSS LevelR'99 UMTS QoS Classes
Delay
sensitiv
e
+
-
Data
Integrity
sensitiv
e
-
+
> Conversational class:
The most well known use of this scheme is telephony speech (e.g., GSM). But with the Internet and multimedia, a
number of new applications will require this scheme, for example voice over IP and video conferencing tools.
Real time conversation is always performed between peers (or groups) of live (human) end users. This is the onlyscheme where the required characteristics are strictly given by human perception.
> Streaming class:
When the user is looking at (listening to) real time video (audio) the scheme of real time streams applies. The real timedata flow is always aiming at a live (human) destination. It is a one way transport.
> Interactive class:
When the end user, that is either a machine or a human, is on line requesting data from a remote equipment (e.g., aserver), this scheme applies.
Examples of human interaction with the remote equipment are: web browsing, data base retrieval, server access.Examples of machines interaction with the remote equipment are: polling for measurement records and automatic database enquiries (tele-machines).
> Background class:
When the end user, that typically is a computer, sends and receives data files in the background, this scheme applies.
Examples are background delivery of E-mails, SMS, download of databases and reception of measurement records.
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1.2 Implementation of GPRS QoS Profiles at BSS LevelAlcatel QoS Offer - R97/98 QoS Mapping into R'99 QoS
Traffic handling priorityR'99 Traffic class R97/98 Bearer QoS class
Premium
Premium
Premium
Normal
Normal
conversational
streaming
interactive
interactive
interactive
-
-
1
2
3
Best Effortbackground -
> There is a mapping between R'99 Traffic class and Alcatel QoS
class
> The mapping of R97/98 QoS attributes to R'99 QoS is applicable in the following cases:
hand-over of PDP context from GPRS R97/R'98 SGSN to GPRS R'99 or UMTS SGSN.
when an R'99 MS performs a PDP context activation in an R'99 SGSN with an R'97/98 GGSN.
When GGSN respond to the PDP Context Activation, mapping of the changed R97/98 QoS attributes received from
the GGSN to R99 QoS attributes is performed in the serving SGSN.
when the SGSN has received an R97/98 QoS subscribed profile, but the MS is R'99.
> The mapping of R'99 QoS attributes to R'97/98 QoS is applicable in the following cases:
the PDP context is handed over from GPRS R'99 to R'97/R'98.
when an R'99 MS performs a PDP context activation in an R'99 SGSN while the GGSN is R'97/98.
In this case the SGSN shall perform mapping of the R99 QoS attributes to the R97/98 QoS attributes;
when the SGSN sends user data to the BSS for an R'99 MS.
when the SGSN has received R'99 QoS subscribed profile but the MS is R'97/98.
in the new SGSN, during an inter-SGSN RA_update procedure, or an inter-system change, on receipt of the R'99 QoS
attributes from the old SGSN.
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1 Role of the BSS in GPRS QoS monitoring
1.3 Source of information for GPRS QoS monitoring
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1.3 Source of Information for GPRS QoS MonitoringTrace User Data Transfer
> Transmission plane
MAC
GSM-RF
LLC
RLC
IP/X25
SNDCP
application
MS
MAC
UmMFS
RLC
relay
BSSGP
NS
L1bis
NS
L1bis
BSSGP
Gb
LLC
SGSN
SNDCP GTP
L2
L1
IP
UDP/TCP
relay
GSM-RFrelay
Abis/Ater
L1-GCHL2-GCH
L1-GCHL2-GCH
BTS
AirInterfacetraces
GCHtraces
Gbtraces
> Interfaces traces are of good complementary information but expensive:
used for problem investigation
used when lack of PM counters
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1.3 Source of Information for GPRS QoS MonitoringEnd-User QoS
> End-user performances are obtained through measurements
carried out for different end-user services:
Ping
FTP
WAP
WEB (HTTP)
Traces must be performed at both Air interface and Applicationlevels
> These performances must be interpreted with a maximum of
information concerning the context of the measurements Use of a database to register performance results
> FTP tests:
Static cell measurements:
DL transfer of an uncompressible file of 500 KB size UL transfer of an uncompressible file of 200 KB size
Drive measurements:
DL transfer of an uncompressible file of 1MB minimum size
UL transfer of an uncompressible file of 200 KB minimum size
> PING Tests:
Series of 100 pings
> HTTP tests:
Static cell and drive measurements:
HTTP browsing of an html page of 400 KB minimum size
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1.3 Source of Information for GPRS QoS MonitoringEnd-User QoS Measurements Results
> Applications server accessibility (PING)
Server accessibility success rate
Round Trip Time (RTT) in seconds per ping command
> FTP
FTP session success rate
Application layer throughput in kbit/s per file
> WAP
WAP gateway access time
WAP page download success rate
Application throughput
> HTTP (WEB) WEB page download success rate
Application throughput
> MMS tests:
MMS emission success rate
MMS notification success rate MMS reception success rate
MMS time to send
Time to receive the MMS notification
Time to retrieve the MMS
>Optional RLC/MAC statistics during end-user QoS tests:
CS distribution : % of CSx RLC blocks and total time of CSx usage
CS changes: number of CS changes per minute
Retransmissions: % of RLC blocks retransmitted
BLER: % of RLC blocks in error
> Usually QoS indicators giving throughput or time values are provided with 4 detailed indicators:
minimum
maximum
average
standard deviation
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1.3 Source of Information for GPRS QoS MonitoringGSS QoS
> Counters:
in the SGSN
in the GGSN
in the HLR
> Traces:
BSS-SGSN interface (Gb)
GGSN-PDN interface (Gi)
intra-GSS interface (Gn)
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1.3 Source of Information for GPRS QoS MonitoringBSS QoS
> Counters:
in the MFS (specific to GPRS)
in the BSC (in relation to GSM)
> Traces:
Air interface (Um)
Ater interface (GCH)
MFS-BSC interface (GSL)
BSS-SGSN interface (Gb)
Tool chain = OMC-R+NPA+RNO
Trace MS + Agi lent NITRO
Protocol analyzer + COMPASS
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1.3 Source of Information for GPRS QoS MonitoringBSS QoS Measurements Principles
BTSInternet/Intranet
SGSN GGSNMFSBSCFire-wall
OtherPLMNPacket domain
Core network
GnGbAterAbis
Physical layer
RLC/ MAC layer
IP layer
Appl ication layer SERVERe.g.
FTP, HTTPGPRSMS
Sagem
OT190
Measurement
Trace SW
Agilent
E6474A
Appl icati on
Presentation
Session
Physical
Transport
Data Link
OSI Layer
Network
LLC layer
BTSInternet/Intranet
SGSN GGSNMFSBSCFire-wall
OtherPLMNPacket domain
Core network
GnGbAterAbis
Physical layer
RLC/ MAC layer
IP layer
Appl ication layer SERVERe.g.
FTP, HTTPGPRSMS
Sagem
OT190
Measurement
Trace SW
Agilent
E6474A
Appl icati on
Presentation
Session
Physical
Transport
Data Link
OSI Layer
Network
LLC layer
Protocol
Analyzer
K1205
AMI CompassGNNettest
OMC-R network stat istics
with OMC-Rnetwork counters
Gb Statistics
GPRS Air
Interface
Statistics
>For the Air interface trace:
Use of a too old or too new mobile can be risky
Reference mobiles are Sagem (OT290), Motorola (T280), NOKIA ( 6230)Use of a PC preferably with Windows 2000
Use of the Agilent software E6474A Nitro
Use of end-user QoS monitoring tool (DEUTRIP, DMS)
>For the GCH, GSL, Gb interface trace:
Use of a protocol analyzer with the Alcatel BSCGP stack
The reference analyzer is Tektronix K1205 v2.40
Use of a post-processing tool
The reference tool is COMPASS GPRS
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1 Role of the BSS in GPRS QoS monitoring
1.4 Dependencies between BSS GSM and GPRS QoS
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1.4 Dependencies between BSS GSM and GPRS QoSImpacts
GSM QoS
GPRS QoS
> Bad radio conditions like coverage or interference problems degrading GSM QoS also provoke BSS GPRS QoS problems.
> Bad BSS GPRS performance is not always correlated to GSM QoS problems:
Congestion can be due to a lack of resource specific to GPRS. A low throughput can be due to a bad setting of radio algorithms specific to GPRS .
> On the other hand GPRS traffic can induce or worsen GSM QoS performance:
PS traffic can increase CS congestion.
PS signaling using CCCH channels can induce a PS AGCH and/or PCH overload and eventually an SDCCH congestion.
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Time allowed:
10 minutes
1.4 Dependencies between BSS GSM and GPRS QoSExercise
Among the following list of typical problems in aGSM network:
Find the ones having an impact on BSSGPRS QoS
Typical BSS GSM pr oblem Impact on BSS GPRS QoS
Coverage
Interference
path unbalanced at cell fringe
TRX HW degradation
Abis MW problem
A interface congestion
SDCCH congestion
TCH congestion
Rate of LU/call too high
Handover failure too high
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1.5 Impact of GMM/SM Signaling on BSS QoS InterpretationGMM/SM Signaling Load
> There are a lot of GPRS signaling message in case of:
cell update
RA update (Normal, Periodic)
> There are less GPRS signaling message in case of :
GPRS attach
GPRS detach
PDP context activation
PDP context de-activation
> BSS GPRS QoS indicators must be carefully interpreted knowing that TBFs are used for both data and signaling transfer.
> Gb traces might be needed for a better understanding of QoS problems.
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1 Role of the BSS in GPRS QoS monitoring
1.6 Indicators Classification
> This chapter is also valid for B7 release.
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1.6 Indicators Classification
> Traffic Load
> Quality Of Service
Evaluation of the rate of success or failure per interface : (Radio, AterMux, Gb)
or per telecom procedure:
TBF UL/DL establishment, UL/DL Data transfer, radio resource
allocation or re-allocation
> Resource Availability and Usage
Abis interface (abis nibbles)
AterMux interface (GCH, LapD) Gb interface (PVC, Bearer Channel)
GPU object (CPU and DSP usage)
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1.6 Indicators Classification
BSCGP Interface
GB Interface
Control and Traffic
Channels
Ressource
Allocation
Data Transfer
TBF
Establishment
Traffic Load
Ressource
Allocat ion
Data Transfer
TBF
Establishment
Global QoS
DSP
CPU
Gb Interface
Ater Interface
Abis Interface
Resource
Availabil ity
GPRS
Indicators
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2 Recalls on the Main BSS GPRS TelecomProcedures
B9
> This chapter is a summary of GPRS basics. It is also valid for B7 release.
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2 Recalls on the Main BSS GPRS TelecomProcedures
2.1 GPRS Logical Channels
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2.1 GPRS Logical Channels
PDCH
Master PDCH Slave PDCH
PBCCH PCCCH
PDTCH PACCH
PTCH PTCCH
Primary MPDCH
PPCH PAGCH
Secondary MPDCH
physical channel
control channel
traffic channel
signaling associated control channel
logical channel category
logical channel
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2 Recalls on the Main BSS GPRS TelecomProcedures
2.2 TBF: Data Transfer Procedure between the MS and the
BSS
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2.2 TBF Data Transfer Procedure between the MS and theBSSRadio Resources
> Temporary Block Flow (TBF): unidirectional flow of databetween the MS and the MFS for the transfer of one or more
LLC PDUs> Radio resources allocated to a TBF are:
DL TBF:
UL TBF:
PDCH 1
B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11
PDCH 2
B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11
PDCH 3
B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11
TBF with TFI = 5 TBF with TFI = 17 TBF with TFI = 24
> A Temporary Block Flow is a temporary, unidirectional physical connection across the Um interface, between one mobile and theBSS. The TBF is established when data units are to be transmitted across the Um interface. It is released as soon as thetransmission is completed.
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2.2TBF Data Transfer Procedure between the MS and theBSSTBF Phases
> The TBF procedure can be split as represented below
> During an on-going TBF (progress) in one direction, a TBF inthe other direction can be established quicker than usually
establishment progress release
Radio resources to be
used during the data
transfer are reserved by
the BSS and areassigned to the MS
Data transfer through
RLC blocks
transmission
Radio resources are
freed
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> In order to establish a DL TBF faster the release of a UL TBF
can be delayed
T_DELAYED_FINAL_PUAN is the time during which a DL TBF
can be established using the UL TBF radio resources before theyare freed
UL TBF
2.2 TBF Data Transfer Procedure between the MS and theBSSUL TBF, Delayed Final PUAN without extended UL TBF
establishment progress release
T_DELAYED_FINAL_PUAN
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> The release of a DL TBF is delayed after all the DL RLC blocks
have been transferred in order to be able to:
establish a UL TBF faster
resume the DL data transfer (new LLC PDU coming from the
SGSN) without having to establish a new DL TBF
DL TBF
2.2 TBF Data Transfer Procedure between the MS and theBSSDL TBF, Delayed DL TBF Release
progress release
T_NETWORK_RESPONSE_TIME
TBF active TBF delayed
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> A DL TBF can be re-established faster during a short time after
a DL TBF release using the radio resources of the previous TBF
It is possible because the MS still monitors the radio resources
during timer T3192 after the DL TBF has been released
DL TBF
2.2 TBF Data Transfer Procedure between the MS and theBSSDL TBF, Fast Establishment
release
T3192
TBF active TBF delayed
Fast DL TBF
establishment
on PACCH
possible
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> After T3192, a DL TBF has to be established on Control
Channels:
faster during DRX_TIMER_MAX when the MS is in Non-DRX
mode
slower afterwards when the MS is in DRX mode
DL TBF
2.2 TBF Data Transfer Procedure between the MS and theBSSDL TBF, Establishment in DRX Mode
TBF release
DRX_TIMER_MAX
TBF active
TBF delayed
T3192
on PCH
or PPCH
of MS paging group
DL TBF establishment
possible
on AGCH
or
any PPCH
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2 Recalls on the Main BSS GPRS TelecomProcedures
2.3 Gb: BSSGP Protocol and Frame
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2.3 Gb: BSSGP Protocol and FrameL1bis
> Bearer Channels
L1
NS (SNS)
NS (NSC)
BSSGP
MFS
L1
NS (SNS)
NS (NSC)
BSSGP
SGSN
Gb interface
PCM BC i
BC j
PCM
BC y
BC x
> The Gb physical interface is made up of one or more 64-Kbit/s channels on one or more physical lines at 2048 Kbit/s.
> Both individual 64-Kbit/s and n*64-Kbit/s channels are supported by the MFS.
> A Bearer Channel (BC) is an n*64-Kbit/s channel (1 n 31).
> NB: among the 16 PCM links offered per PCU, only 8 are dedicated to the Gb interface, 4 for the upload and 4 for thedownload. The maximum point-to-point transfer capacity over the Gb interface in one direction is then 31*64 Kbit/s*4 = 8192Kbit/s.
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2.3 Gb: BSSGP Protocol and FrameNetwork Service 1/3
> The Sub-Network Service (SNS) sub-layer is dependent on the
transmission network and manages Permanent Virtual
Channels (PVCs)
L1
NS (SNS)
NS (NSC)
BSSGP
MFS
L1
NS (SNS)
NS (NSC)
BSSGP
SGSN
Frame Relay NetworkPVCa
DLCIx
PVCm
DLCI
PVCb
DLCI
y
PVCn
DLCI
Gb interface
> Concept of PVC:
A PVC is a synchronous access line, semi-permanent connection.
The PVC allows the multiplexing on a BC. It is not an end to end link between the MFS and the SGSN.
At MFS side a PVC is identified by its Data Link Connection Identifier (DLCI) which is independent from the one definedat SGSN side. DLCI 0 is used for signaling.
There is one PVC per BC.
> The SNS layer, layer 2.1 in the OSI model, offers the Frame Relay technology. The NSC layer, layer 2.2 in the OSI model,offers the point to point data transfer in both directions.
> The PVC standards are not specific to GPRS. Please refer to the Frame Relay Forum organization, the ITU-T and ANSI(T1S1.1 workshop) specifications.
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2.3 Gb: BSSGP Protocol and FrameNetwork Service 3/3
> Concept of NSE:
A Network Service Entity (NSE) groups several NS-VCs (at least
2 NS-VCs per NSE) = the NSE corresponds to the resources of
one GPU
The concept of NSE is useful for the load sharing between the
different NS-VCs: the NS-VCs of the NSE are shared by the BVC
associated to the NSE
The NSE is identified by an NSEI which has an end-to-end
significance over the Gb interface
NSVC
NSVCi=11
NSVC
NSVCi=12L1
NS (SNS)
NS (NSC)
BSSGP
PCU
NSE
NSEi = 1
> Note: for MM purposes, the SGSN needs a 1:1 correspondence between the NSEI and the RAI.
Physical layer
SNS sub-layer
NSC sub-layer
BVCBSSGP layer
Cell
BSS
BVC
Cell
2 Mbit/s
BC BC
PVC PVC
NS-VC NS-VC
NSE
BVC
Cell
BVC
Cell
2 Mbit/s
BC BC
PVC PVC
NS-VC NS-VC
NSE
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SNS
NSC
BSSGP
SGSN
2.3 Gb: BSSGP Protocol and FrameBSSGP
> BSSGP Virtual Connection (BVC): end to end link between the
MFS and the SGSN
L1
SNS
NSC
BSSGP
MFS
L1
Gb interface
NSVC
BVCi=1
BVCi=2
BVCi=n BVCi=1
BVCi=2
BVCi=n
> Two types of BVC:
point-to-point BVC dedicated to the PS traffic of one cell (BVCi 0).
signaling BVC (BVCi=0) which is the signaling circuit of all the point to point BVCs of one NSE (GPU).
> For NM reason, the duplet BVCi/NSEi must be unique within an SGSN.
> To activate a new cell in an SGSN, it is only needed to add a new BVCi in an NSEi. No update of the NSEi information isnecessary.
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NSE2
SGSN
NSE1NSE1
NSE2
F.RF.RNetworkNetwork
PCM
2.3 Gb: BSSGP Protocol and FrameGb Interface - Manageable Entities
PCM
PCM
BVCI=2
BVCI=
1BVCI=3
BVCI=5
BVCI=
6
BVCI=
4
BSC1
BSC2
GPRS Core Network sideBSS side
BC PCMBCPVC
BC BCPVC
NSVC1
NSVC2
PCM
PCM
PCM
BC PCMBCPVC
BC BCPVC
NSVC3
NSVC4
BVCI=2BVCI=2
BVCI=1BVCI=1
BVCI=3BVCI=3
BVCI=5BVCI=5
BVCI=4BVCI=4
BVCI=6BVCI=6
> Dimensioning rules:
Gb inter face
Max. number of Gb interface physical links
per GPUnGb nGb+ nAter(mux)16 where nAter(mux)
Max. number of Frame Relay bearer
channels per physical link31
Max. number of Frame Relay bearer
channels per GPU board124
Max. number of BVCs per GPU board 265 Limit due to the number of cells per BSS(264) + one signalling BVC (1)
Number of signalling BVCs per GPU 1 1 NSE is defined per GPU
Ater inter face
Maximum number of 64 kbit/ s signalling
channels (GSL) per GPU
4
Number of Ater(mux) PCM links between
one GPU and one BSC
nAte r(m u
x)
nGb+ nAtermux16
Atermux sharing granularity for PS traffic g g can be set to:100 % AterMux, or
75 % AterMux, or
25 % AterMux, or
12.5 % Atermux for GPRS traffic
Max. number of BSSs per MFS 22
Max. number of GPUs per MFS 30
Max. number of BSS per GPU board 1
Max. number of cells per MFS 20 00
Max. number of TBFs per GPU 96 0
Maximum number of GPU boards per BSS 6
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2.3 Gb: BSSGP Protocol and FrameGb Interface - Protocol Model and Entities
SGSNPacket Control Unit function
(PCU)
BSS GPRS Protocol
(BSSGP)BSS GPRS Protocol
(BSSGP)
Network Service Control
(NSC)Network Service Control
(NSC)
BVCI=BVCI=
22BVCI=BVCI=
11BVCI=3BVCI=3
BVCI=5BVCI=5
BVCI=BVCI=
66
BVCI=BVCI=
44
BSC1
BSC2
GPRS Core Network sideBSS side
Sub-Network Service
(SNS)
Physical layer
Sub-Network Service
(SNS)
Physical layer
Frame Relay
BVC
NS-VCNSE
PVCBC
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2.3 Gb: BSSGP Protocol and FrameBSSGP Frame
> One BSSGP PDU includes one and only one LLC PDU
GPRS Traffic or signalingTLLIBVCI
LLC frame
BSSGP frame
LLC header
BSSGP header
LLC payload
> In case of data traffic the LLC PDU contains an SNDCP PDU.
> In case of signaling, the LLC PDU contains a GMM or an SM message.
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3 Description of the Main BSS GPRS QoS Countersand Indicators B9
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3 Detection of the Main BSS GPRS QoSCounters/IndicatorsSession Presentation
> Objective: to be able to interpret the BSS GPRS QoS indicators
attached to each BSS GPRS procedure or algorithm having an
impact on QoS and to interpret the BSS GPRS PM counters
used in the computation formulae of QoS indicators
> Program:
3.1 Data Transfer Establishment
3.2 Data Transfer Progress
3.3 Data Transfer Release
3.4 MS Sessions / Transfers
3.5 Resource Usage
3.6 CS and MCS Adaptation
3.7 Cell Reselection
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3 Detection of the Main BSS QoSCounters/Indicators
3.1 Data Transfer Establishment
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3.1 Data Transfer EstablishmentTBF Establishments
Data Transfer
establishment
UL TBF establishment DL TBF establishment
MS in PIM MS in PTM MS in PIM MS in PTM
MS in MM Ready s tate MS in MM Standby s tateMS in MM Ready s tate
on CCCH on PCCCH
2-Phase 2-Phase
on CCCH on PCCCH
Non-DRX Non-DRX
UL TBF
running
DL TBF
running
T3192
running
1-Phase1-Phase
PS Paging
DRX DRX
> There are 5 types of UL TBF establishment:
1. 1-phase access on CCCH : when the MS is in Packet Idle Mode and no PCCCH is available in the cell and the MS does
not need more than 1 PDCH and wants to transfer blocks in RLC acknowledge mode.
2. 2-phase access on CCCH : when the MS is in Packet Idle Mode and no PCCCH is available in the cell and the MSneeds more than 1 PDCH or wants to transfer blocks in RLC unacknowledge mode.
3. 1-phase access on PCCCH : when the MS is in Packet Idle Mode and a PCCCH is available in the cell and the MSdoes not need more than 1 PDCH and wants to transfer blocks in RLC acknowledge mode.
4. 2-phase access on PCCCH : when the MS is in Packet Idle Mode and a PCCCH is available in the cell and the MSneeds more than 1 PDCH or wants to transfer blocks in RLC unacknowledge mode.
5. During a DL TBF: when the MS is in Packet Transfer Mode in DL.
> There are 6 types of DL TBF establishment:
1. On CCCH DRX mode: when the MS is in Packet Idle Mode and no PCCCH is available in the cell and the MS islistening to all PCH channels of its CS paging group.
2. On CCCH Non-DRX mode: when the MS is in Packet Idle Mode and no PCCCH is available in the cell and the MS islistening to all AGCH channels.
3. On PCCCH DRX mode: when the MS is in Packet Idle Mode and a PCCCH is available in the cell and the MS islistening to all PPCH channels of its PS paging group.
4. On PCCCH Non-DRX mode: when the MS is in Packet Idle Mode and a PCCCH is available in the cell and the MS islistening to all PPCH channels of its PCCCH channel.
5. During a UL TBF: when the MS is in Packet Transfer Mode in UL.
6. When T3192 is running: when a DL TBF has been released at the MS side and before the previously used radioresources are released (at T3192 expiry).
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P49
3.1 Data Transfer EstablishmentUL TBF Establishment 1-Phase Access on CCCH,Success
MS BTS BSC MFS
TA calculation
RACH Channel request (TA)
(EGPRS Packet)
Channel request
AGCH
Immediate assignment
Channel assignment UL (IA)PDCH, TFI, USF, TAI, TA, CS
(MCS, EGPRS window size)MS switches
on assigned
PDCH USF Scheduling
PDTCH
USF Scheduling
RLC data block
PACCH
Packet UL Ack/Nack
PDTCH
TLLI, TFI
T_USF_Scheduling_AGCH
expiry
P62c
P30cContention
resolution
T_GPRS_ASSIGN_AGCH
RLC data block
TLLI, TFI
Packet UL Ack/Nack
P62d
GPRS EGPRS
P30d
GPRS EGPRS
GCH allocation
Channel required
(TA)
Imm. assign. command
> In case a Channel Request or an EGPRS Packet Channel Request is received from the mobile station, an ImmediateAssignment message is sent to the MS assigning the radio resources.
In case a Channel Request is received on a RACH, the BSS does not know the multislot class of the MS.Consequently, the Alcatel BSS assigns only one PDCH to the MS.
In case an EGPRS Packet Channel Request message is received from the mobile station, the EGPRS multislot class ofthe MS is known by the BSS. However only one PDCH is allocated due to the limitation of the Immediate Assignmentmessage.
if the PDCH is allocated on a non-EGPRS capable TRX an Immediate Assignment message in GPRS mode issent to the MS including the PDCH id, the USF value, the TFI value, the TAI value, the TA value, and the GPRScoding scheme to be used.
If the PDCH is allocated on an EGPRS capable TRX, an Immediate Assignment message in EGPRS mode issent to the MS including the PDCH id, the USF value, the TFI value, the TAI value, the TA value and theEGPRS modulation and coding scheme to be used.
> Timers
T_USF_scheduling_AGCH: Time between the sending of the Assignment Command message to the BTS and thescheduling of the first UL block on the PDCH. This internal MFS timer is always expiring in order to leave time to theMS to switch from a CCCH to a PDCH time slot.
T_GPRS_ASSIGN_AGCH T_USF_scheduling_AGCH: Started at T_USF_scheduling_AGCH expiry, stopped whenreceiving the first UL block from the MS.
T_GPRS_ASSIGN_AGCH = 0.8 s (default value) but computed as a function of the CCCH configuration in thecell. It cannot be set at the OMC-R level.
T_USF_scheduling_AGCH = 0 ms (default value). It cannot be set at OMC-R level.
> T_GPRS_ASSIGN_AGCH" is the HMI name of "T_ul_assign_ccch" present in BSS telecom parameters catalogue
> A contention resolution procedure is used in order to avoid that two MS sending a Channel Request at the same time use thesame allocated radio resource to send data.
Each MS sends its TLLI in the first RLC Data Block.
The TLLI of the MS chosen by the BSS is present in the Packet UL Ack/Nack from the MFS.
The other MS will stop using the radio resource when receiving the Packet UL Ack/Nack with another TLLI .
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3.1 Data Transfer EstablishmentUL TBF Establishment 2-Phase Access on CCCH,Success
MS BTS BSC MFS
RACH
Channel request
(TA)
(EGPRS Packet)
Channel request
AGCHImmediate assignment PDCH id, TBF starting time,
TA, 1 (multiple) block(s)
MS switches
on assigned
PDCHs
PACCHPacket resource request
Packet UL assignmentPACCH
Packet resource request
Packet UL assignmentTLLI, PDCHs, USFs, TFI, TAI, TA,
CS
(MCS, EGPRS window size)PDTCHUSF Scheduling USF Scheduling
TLLI, MS Radio Access Capability, QoS
(Additional Radio Access Capability)
RLC data block
PDTCH
P49
T_GPRS_ASSIGN_AGCH
T_ACK_WAIT
Contention
resolution
RLC data block
MS switches
on allocated
RLC block(s)
T3168
P62c P62d
GPRS EGPRS
P30c P30d
GPRS EGPRS
GCH allocation
GCH allocationTA calculation
Channel required
(TA)
Channel assignment UL (IA)Imm. assign. command
> A 2-phase access is initiated in one of the following cases:
When a GPRS MS wants to use the TBF to send user data in RLC unacknowledged mode.
When a GPRS or EGPRS MS wants to precise QoS parameters (e.g., Peak_Throughput_Class, Radio_Priority).
When a GPRS MS wants to provide the BSS with its multislot class in case of an uplink access done on CCCH.
When an GPRS MS wants to establish the TBF to send user data in RLC acknowledged mode and the amount of data tosend takes more than 8 RLC/MAC blocks (Note 1 and Note 2).
If the EGPRS PACKET CHANNEL REQUEST is not supported in the cell (Note: the Alcatel BSS always supports theEGPRS PACKET CHANNEL REQUEST), when an EGPRS MS wishes to send user data or signaling data.
If the EGPRS PACKET CHANNEL REQUEST is supported in the cell, when an EGPRS MS wants to use the TBF tosend user data in RLC unacknowledged mode.
If the EGPRS PACKET CHANNEL REQUEST is supported in the cell, when an EGPRS MS wants to establish the TBFto send user data in RLC acknowledged mode and the amount of data to send takes more than 8 RLC/MAC blocks (Note3 and Note 4).
Note 1: The number of blocks must be calculated assuming channel coding scheme CS-1.Note 2: The mobile station can also request a 1-phase access.Note 3: The number of blocks must be calculated assuming modulation and channel coding scheme MCS-1.Note 4: If the cell is EGPRS capable, the mobile station can also request 1-phase access.
> The MS Radio Access Capability IE includes the Multislot class of the MS as well as the QoS required for the transfer
> Timers
T_GPRS_ASSIGN_AGCH, controls the duration between (EGPRS Packet) Channel Request message and the UL radioblock allocated to the MS.
T_ACK_WAIT: Started when the first UL block is scheduled to the MS, stopped when receiving the first UL block.
T_ACK_WAIT = 1.2 s (default value). It cannot be set at OMC-R level.
T3168: MS timer started when sending the Packet Resource Request message and stopped when receiving the PacketUL Assignment. It is broadcast in the SI13 message.
T3168 = 1 s (default value). It can be set at the OMC-R level but 1 s is the minimum value.
> .
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3.1 Data Transfer EstablishmentUL TBF Establishment 1-Phase Access on PCCCH,Success
MS BTS BSC MFS
TA calculationPRACH (4 A.B.)
(EGPRS)
Packet Channel request
MS switches
on assigned
PDCHs
Packet UL assignment
PAGCH
Packet UL assignment
PDCHs, USFs, TFI, TAI, TA, CS (MCS, EGPRS
window size)
PDTCHUSF Scheduling USF Scheduling
RLC data block
T_ACK_WAIT
PDTCH
RLC data block
Contention
resolution
TLLI, TFI
PACCH
Packet UL Ack/Nack
TLLI, TFI
Packet UL Ack/Nack
(EGPRS)
Packet Channel request
(TA)
(EGPRS) Multislot class
P30a P30d
GPRS EGPRS
P62a P62d
GPRS EGPRS
GCH allocation
(EGPRS)
Packet Channel request
(TA)
> Possible causes for the one phase access for GPRS:- 1-phase access (MS multislot class provided)- Short access (less than 8 RLC blocks)
- Paging response- Cell update- MM procedures (GPRS Attach, GPRS Detach, RA update)- Single block without TBF establishment
- Note: The access indicating Single Block Without TBF Establishment is supported by the Alcatel BSS: such an access isused by the MS to report a Packet Measurement Report message or a Packet Cell Change Failure message in PacketIdle Mode
> Possible causes for the one phase access for EGPRS:- 1-phase access- Short access- signaling
> A EGPRS mobile provides both its GPRS multislot class and its EGPRS multislotclass. If the TBF can not be established inEGPRS mode it will then be established in GPRS mode if possible. In this case the EGPRS multislot class is used by the BSS toallocate the corresponding number of PDCHs. If the GPRS multislot class is higher than the EGPRS one then the TBF is acandidate for a subsequent radio resource re-allocation to extend the number of PDCHs.
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3.1 Data Transfer EstablishmentUL TBF Establishment 2-Phases Access on PCCCH,Success
MS BTS BSC MFS
TA calculation
MS switches
on assignedPDCHs
PACCHPacket resource request
Packet UL assignment
PACCHPacket UL assignment
TLLI, PDCHs, USFs, TFI, TAI, TA,
CS(MCS, EGPRS window size)PDTCH
USF Scheduling USF Scheduling
Packet resource requestTLLI, MS Radio Access Capability, QoS
(Additional Radio Access Capability)
T_ACK_WAIT
Contention
resolution
RLC data block
PDTCH
RLC data block
MS switches
on allocated
RLC block(s)
PRACH (4 A.B.)
(EGPRS)
Packet Channel request
Packet UL assignment
PAGCH
Packet UL assignment
T_UL_Assign_PCCCH
PDCH id, TBF starting time, TA, 1(multiple) block(s)
(EGPRS) Multislot class
T3168
P62a P62d
GPRS EGPRS
P30a P30d
GPRS EGPRS
PDCH & GCH
allocation
(EGPRS)
Packet Channel request
(TA)
(EGPRS)
Packet Channel request
(TA)
> Timer: T_UL_ASSIGN_PCCCH controls the duration between (EGPRS) Packet Request message and the UL radio blockallocated to the MS.
T_UL_ASSIGN_PCCCH = 0.4 s (default value). It can be set at the OMC-R level.
> 2-phase access is used when the MS wants specific QoS attribute values to be taken into account (e.g., RLC Nack mode).
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3.1 Data Transfer EstablishmentUL TBF Establishment during a DL TBF, Success
MS BTS BSC MFS
P30b
T_ACK_WAIT
DL transfer
RLC data block, pollingRLC data block
PDTCH
Packet DL Ack/Nack
PACCH(EGPRS) Packet DL Ack/Nack with Channel request
Packet UL assignment
PACCH
Packet UL assignment
PDCHs, USFs, TFIUL,TAI, CS (MCS, EGPRS window size)
P62b
T3168
PDTCH
USF Scheduling USF Scheduling
RLC data block
PDTCH
RLC data block
GPRS EGPRS
GPRS EGPRS
GCH allocation
> This scenario corresponds to a UL TBF establishment in PTM without re-allocation of the on-going DL TBF.
> The Packet UL Assignment message is repeated N_SIG_REPEAT times because if the MS has not decoded the Packet UL
Assignment then the MS tries again to establish the UL TBF only after T3168 expiry. N_SIG_REPEAT = 1 (default value). It cannot be set at the OMC-R level. Therefore the Packet UL Assignment is sent 2
times in a row.
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Time allowed:
30 minutes
3.1 Data Transfer EstablishmentUL TBF Establishment, Exercise
Exercise 1: Identify the type of UL TBFestablishment procedure among the providedtraces 1, 2, 3, 4, 5
Exercise 2: Using the trace 2 , find how manyTBFs are established and when?
Exercise 3: Using the trace 2, identify thevalues of:
TFIUL TFIDL PDCHs allocated for the UL TBF
B9
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3.1 Data Transfer EstablishmentUL TBF Establishment, Failures
UL TBF establishment FAILURE
BSS Resource
Congestion Radio pb BSS pb Gb pb
Radio
congestion
GPU DSP
congestion
Ab is
congestion
GPU with CPU
overload
B9
Ater
congestion
Too many TBF
DSP with CPU
in load state
NewB9
NewB9
NewB9
> Note:GPU congestion means that the maximum capacity of at least one DSP on the GPU is reached in terms of resourcesGCH and/or PDCH
A lack of Ater resources occurs when there is not enough Ater nibbles to serve the UL TBF request.A lack of Abis transmission resources occurs when there is not enough Abis nibbles to serve the UL TBF request.
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3.1 Data Transfer EstablishmentUL TBF Establishment, Failures, BSS ResourceCongestion
MS BTS BSC MFS
RACH
(EGPRS Packet)
Channel request
AGCH
Immediate assignment rejectImm. assign. command
(Imm. assign. Reject) Wait indication
No resource available
(radio+Ab is+Ater+Toomany TBF+DSP+
GPU+GPU-CPU)
P27+P105j+P105h+P10
5l+P204+P105d+P105f(EGPRS)
Packet Channel
request
PAGCH or PACCH
Packet access reject Packet access reject
Wait indication
or Packet resource request
or Packet DL Ack/Nack with
Channel request
or Packet resource request
or Packet DL Ack/Nack with
Channel request
Channel request (TA)Channel required
(TA)
(EGPRS)
Packet Channel request
(TA)
or Packet resource request
or Packet DL Ack/Nack with
Channel request
(EGPRS)
Packet Channel request
(TA)
Channel assignment UL
(Imm. assign. Reject)
Packet access reject
B9
No resource available
(radio+Abis+Ater+Toomany TBF+DSP+
GPU+GPU-CPU)
Modified
B9
Modified
B9
> The first scenario corresponds to:
the impossibility to allocate the resources for a UL TBF establishment 1-phase access on CCCH.
the impossibility to allocate the UL block(s) for a UL TBF establishment 2-phase access on CCCH.
> The second scenario corresponds to:
the impossibility to allocate the resources for a UL TBF establishment 2-phase access on CCCH.
the impossibility to allocate the resources for a UL TBF establishment 1-phase access on PCCCH.
the impossibility to allocate the UL block(s) or the resources for a UL TBF establishment 2-phase access on PCCCH.
the impossibility to allocate the resources for a UL TBF establishment during a DL TBF.
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3.1 Data Transfer EstablishmentUL TBF Establishment on CCCH, Failures, Radio
MS BTS BSC MFS
RACHChannel request + TA
(EGPRS Packet)
Channel request
AGCHImmediate assignmentPDCH, TFI, USF, TAI, TA, CS
(MCS, EGPRS window size)
USF Scheduling
PDTCH
USF Scheduling
RLC data block
PDTCHT_GPRS_ASSIGN_AG
CH expiryP28
Packet UL assignment
PACCH
Packet UL assignment
TLLI, PDCHs, USFs, TFI, TAI, TA,CS
(MCS, EGPRS window size)PDTCHUSF Scheduling USF Scheduling
T_ACK_WAI
T expiry
P28
Channel required
(TA)Channel assignment UL (IA)
Imm. assign. command
> The first scenario corresponds to:
a radio failure occurring during a UL TBF establishment 1-phase access on CCCH.
> The second scenario corresponds to:
a radio failure occurring during a UL TBF establishment 2-phase access on CCCH.
> If the contention resolution fails, the MS will try to establish the UL TBF up to 4 times.
> The radio problems counted are usually due to interference or bad coverage
but Abis microwave transmission problems or some BSS problems (RSL overload) can be counted as radio problems.
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3.1 Data Transfer EstablishmentUL TBF Establishment on PCCCH, Failures, Radio
MS BTS BSC MFS
PRACH (4 A.B.)
(EGPRS)
Packet Channel
request
Packet UL assignment
PAGCH
Packet UL assignment
PDCHs, USFs, TFI, TAI, TA, CS (MCS, EGPRSwindow size)
PDTCHUSF Scheduling USF Scheduling
P28T_ACK_WAI
T expiry
(EGPRS) Multislot class
PDTCH
RLC data block
Packet UL assignmentPACCH
Packet UL assignmentTLLI, PDCHs, USFs, TFI, TAI, TA, CS
(MCS, EGPRS window size)
PDTCHUSF Scheduling USF Scheduling
P28T_ACK_WAI
T expiry
(EGPRS)
Packet Channel request
(TA)
(EGPRS)
Packet Channel request
(TA)
> The first scenario corresponds to:
a radio failure occurring during a UL TBF establishment 1-phase access on PCCCH.
> The second scenario corresponds to:
a radio failure occurring during a UL TBF establishment 2-phase access on PCCCH.
> The radio problems counted are usually due to interference or bad coverage
but Abis microwave transmission problems or some BSS problems (RSL overload) can be counted as radio problems.
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3.1 Data Transfer EstablishmentUL TBF Establishment during a DL TBF, Failures, Radio
MS BTS BSC MFS
P28
DL transfer / Active or Delayed phase
RLC data block, pollingRLC data block
PDTCH
Packet DL Ack/Nack
PACCH(EGPRS) Packet DL Ack/Nack with Channel request
Packet UL assignment
PACCH
Packet UL Assignment
PDCHs, USFs, TFIUL,TAI, CS (MCS, EGPRS window size)
T3168
PDTCH
USF Scheduling USF Scheduling
T_ACK_WAI
T expiry
> If a DL TBF re-allocation is triggered upon a UL TBF establishment and if the DL TBF re-allocation fails due to a radio problemthen counter P28 is also incremented.
> The radio problems counted are usually due to interference or bad coverage
but Abis microwave transmission problems or some BSS problems (RSL overload) can be counted as radio problems.
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> Problem at Gb interface level
When the CELL is in the operational state disabled in the BSS
O&M problem
> Problem at BSS level
which is not linked to Congestion, Radio, Gb no specific counter
3.1 Data Transfer EstablishmentUL TBF Establishment, Failures, Gb, BSS
MS MFS SGSN
>
Cell identity
Cell BVC
unavailable
P66
> A problem at BSS level can be linked to a Hardware or a Software failure .
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3.1 Data Transfer EstablishmentDL TBF Establishment on CCCH, MS in Ready State
MS BTS BSC MFS LLC PDU
PDCH, TFI, TAI, (EGPRS)Immediate assignment
PCH/AGCH (DRX/Non-DRX)
Packet DL assignment, polling
PDCHs, TFI, TAI, (EGPRS window size)PACCH
Packet DL assignment
PACCH (4 A.B.)
Packet control AckPacket control AckTA calculation
Timing Advance / Power control
PACCH
TA / PC
PDTCH
RLC data block
MS
switches
on
assigned
PDCH
P91f,
P91c
T3190
t_assign_agch_pacc
h
t_assign_pch_pacch
expiry & restart
P90f,
P90c
P91g
GPR
SEGPR
S
P90g
GPR
S EGPR
S
P53c,
P49
GCH allocation
Channel assignment UL (IA)Imm. assign. command
> If the MFS does not receive the Packet Control Ack message from the MS:
it sends again the Packet Downlink Assignment message up to MAX_GPRS_ASSIGN_PCH_RETRANS if the MS is inDRX mode or up to MAX_GPRS_ASSIGN_AGCH_RETRANS if the MS is in Non-DRX mode.
if the Maximum number of retransmission of Packet Downlink Assignment message is reached then the MFS restartsthe whole DL TBF establishment procedure up to MAX_DL_RETRANS times.
MAX_GPRS_ASSIGN_PCH_RETRANS = 3 (default value)
MAX_GPRS_ASSIGN_AGCH_RETRANS = 3 (default value)
MAX_DL_RETRANS = 3 (default value)
The other establishment attempts of the same TBF are not counted, only the first attempt is counted.
> Timers
T_GPRS_ASSIGN_AGCH: controls the reception of the Packet Control Ack message from the MS in Non-DRX mode.
T_GPRS_ASSIGN_AGCH = 0.8 s (default value) but computed as a function of the CCCH configuration in thecell. It cannot be set at the OMC-R level.
T_GPRS_ASSIGN_AGCH" is the HMI name of "T_ul_assign_ccch" described in the BSS telecom parameters
catalogue.
T_GPRS_ASSIGN_PCH: controls the reception of the Packet Control Ack message from MS in DRX mode.
T_GPRS_ASSIGN_PCH = 1.4 s (default value) but computed as a function of the BS_PA_MFRMS CCCHparameter in the cell. It cannot be set at the OMC-R level.
T_GPRS_ASSIGN_PCH" is the HMI name of "T_dl_assign_ccch" described in the BSS telecom parameterscatalogue.
t_assign_agch_pacch: is the time the MFS waits for the Packet Control Ack message after having sent the PacketDownlink Assignment message to the MS in Non-DRX mode before repeating the Packet Downlink Assignmentmessage.
Its value is computed as T_GPRS_ASSIGN_AGCH / (MAX_GPRS_ASSIGN_AGCH_RETRANS + 1).
t_assign_pch_pacch: is the time the MFS waits for the Packet Control Ack message after having sent the PacketDownlink Assignment message to the MS in DRX mode before repeating the Packet Downlink Assignment message.
Its value is computed as T_GPRS_ASSIGN_PCH / (MAX_GPRS_ASSIGN_PCH_RETRANS + 1).
T3190: if this timer expires, the MS returns into Packet Idle Mode.
T3190 = 5s (default value).
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3.1 Data Transfer EstablishmentDL TBF Establishment on PCCCH , MS in Ready State
MS BTS BSC MFS LLC PDU
PPCH
(first/paging group)
Packet DL assignment, polling
PDCHs, TFI, TAI, (EGPRS window size)
Packet DL assignment
PACCH (4 A.B.)
Packet control AckPacket control AckTA calculation
Timing Advance / Power control
PACCH
TA / PC
PDTCH
RLC data blockT3190
P90d,
P90a
MS
switches
on
assigned
PDCH
T_ACK_WAIT
T_ACK_WAIT_DRX_PCCCH
P91g
GPRS
EGPRS
P91d,
P91a
P90g
GPRSEGPRS
GCH allocation
> If the MFS does not receive the Packet Control Ack message from the MS:
the MFS restarts the whole DL TBF establishment procedure up to MAX_DL_RETRANS times.
MAX_DL_RETRANS = 3 (default value) The other establishment attempts of the same TBF are not counted, only the first attempt is counted.
> Timers
T_ACK_WAIT: controls the reception of the Packet Control Ack message from the MS in Non-DRX mode.
T_ACK_WAIT = 1.2 s (default value). It cannot be set at the OMC-R level.
T_ACK_WAIT_DRX_PCCCH: controls the reception of the Packet Control Ack message from the MS in DRX mode.
T_ACK_WAIT_DRX_PCCCH = 2.5 s (default value). It cannot be set at the OMC-R level.
T3190: if this timer expires, the MS returns into Packet Idle Mode.
T3190 = 5 s (default value)
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T3190
PACCHTA/PC
TA/PC
PDTCHRLCdatablo
ckRLCdatablo
ckPACCHTA/PC
TA/PC
PDTCHRLCdatablo
ckRLCdatablo
ck
3.1 Data Transfer EstablishmentDL TBF Establishment during a UL TBF
MS BTS BSC MFS
UL transfer
PacketDLassignment
PACCH
PacketDLassignment,po
lling
PDCH(s),TFIDL,TA
I,(EGPRS
window size)
P91b
P90b
T_ACK_WAITPacketcontrolAckPacketcontrolAck
RRBP
LLC PDU
PDTCHRLCdatablo
ck
RRBP
+
40 ms
GCH allocation
> This scenario corresponds to a DL TBF establishment in PTM without re-allocation of the on-going UL TBF.
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semantic
0
1
The SDU contains signaling (e.g., related to GMM)
The SDU contains data
coding
T bit coding
3.1 Data Transfer EstablishmentDL TBF Establishment, Radio Resource Optimization
MFS
BSSGP PDUn PDCHs
allocated
according to
MS multislotclass
SGSN
(QoS profile, LLC PDU)
Only 1 PDCH allocated
n PDCHs allocated
according to
MS multislot class
8
octet 1
octet 2.2a
octet 3-4
octet 5
IEI
Length Indicator
Peak bit rate provided by the network, coded as
the value part in Bucket Leak Rate/R IE/ GSM 08.18 a)
7 6 5 4 3 2 1
SPARE C/R T A Precedence
QoS Profile IE from BSSGP message GSM 08.18
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Time allowed:
30 minutes
3.1 Data Transfer EstablishmentDL TBF Establishment, Exercise
Exercise 1: Identify the type of DL TBFestablishment procedure among the providedtraces 6, 6bis and 8
Exercise 2: identify trace 6bis if the DL TBF isestablished for data or signaling transfer
B9
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3.1 Data Transfer EstablishmentDL TBF establishment, failures
DL TBF establishment FAILURE
BSS
Resource
Congestion
Radio pb BSS pb Gb pb
Radio congestion
GPU DSP
congestion
Ater congestion
GPU CPU
congestion
Ab is congestion
Too many TBF
NewB9
NewB9
B9
CPU_LOAD
NewB9
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> BSS resource congestion: radio (PDCH, TAI, TFI), Ater, GPU
> Problem at Gb interface level
When the CELL is in the operational state disabled in the BSS
O&M problem
3.1 Data Transfer EstablishmentDL TBF Establishment, Failures, BSS Resource Cong,Gb
MFS
LLC PDUsNo resource available:(radio+Abis+Ater+DSP+CPU)+ CPU_LOAD +too
many TBFsP14+ P105i+
P105g+P105c+P105e+P203+
P105k
SGSN
LLC Discarded
MFS
LLC PDUs
Cell BVC unavailable
P65
SGSN
LLC Discarded
B9
Modified
B9
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> Radio problem
> Problem at BSS level
what is not Congestion, Radio, Gb
no specific counter
3.1 Data Transfer EstablishmentDL TBF Establishment, Failures, Radio
MSBTS BSC MFS
Packet control Ack
t_assign_agch_pacch expiry
or t_assign_pch_pacch expiry
or T_ACK_WAIT expiry
or T_ACK_WAIT_DRX_PCCCHexpiry
for the last attempt of the same DL
TBF establishment
Packet DL assignment, polling
PDCHs, TFI, TAI, (EGPRS window size)
Packet DL assignment
PACCH or