(E)GPRS BASICS & KNOWLEDGE SHARING(E)GPRS BASICS & KNOWLEDGE SHARING
(E)GPRS OBJECTIVES
“2G Data EXPLAIN”
Main topics
• Basic GSM/GPRS/EDGE data network functionality
Concepts
• (E)GPRS = GPRS & EDGE
• EGPRS = EDGE
(E)GPRS - ContentFunctionality
• NE & interfaces
• Protocol stack
• TBF, Session Management, Mobility Management
Base Station Subsystem (BSS)
• Modulation (Air interface),
• EDAP and PCU (Resource allocation)
• Gb
SW and HW Releases
This material describes the Nokia (E)GPRS System with the following SW and HW releases:
• BSS SW:• BSS10.5, 11.0 and 11.5 and S12.0
• BSC variants with PCU1:• BSCi, BSC2, BSC2i, BSC3i
• BTS versions:• Talk, PrimeSite, MetroSite, UltraSite
• SGSN• SG5.0
CONTENT :- 1
Introduction
• Network Architecture and Interfaces
• Mobile Classes
• Network Protocols
• Multiframe and Header Structure
• Air Interface Mapping – Physical and Logical Channel
Procedures
• State and Mobility Management
• GPRS Attach/Detach
• Routing Area
• Session Management (PDP context)
• Temporary Block Flow
•RLC/MAC Header
•TBF Establishment
MSCHLR/AuCEIR
BSCBTSUm
PSTNNetwork
GSM & (E)GPRS Network Architecture
PCU
EDAPGb
Gateway GPRSSupport Node(GGSN)
Charging Gateway (CG) Local
AreaNetwork
Server
Router
Corporate 1
Server
Router
Corporate 2
Datanetwork(Internet)
Datanetwork(Internet)
Billing System
Inter-PLMNnetwork
GPRSINFRASTRUCTURE
BorderGateway (BG)
Lawful InterceptionGateway (LIG)
GPRSbackbo
nenetwork
(IP based)
Serving GPRSSupport Node(SGSN)
SS7Network
PAPU
(E)GPRS Network Elements and Primary Functions
SGSN• Mobility Management• Session Management• MS Authentication• Ciphering• Interaction with
VLR/HLR• Charging and
statistics• GTP tunnelling to
other GSNs
GGSN• Session
Management• GTP tunnelling to
other GSNs • Secure interfaces
to external networks
• Charging & statistics
• IP address management
Charging Gateway
• CDR consolidation
• Forwarding CDR information to billing center
Border Gateway• Interconnects
different GPRS operators' backbones
• Enables GPRS
roaming• Standard Nokia IP
router family
Domain Name Server• Translates IP host names to IP
addresses (DNS Resolution)• Makes IP network configuration
easier• In GPRS backbone SGSN uses
DNS to get GGSN and SGSN IP addresses (APN Resolution)
• Two DNS servers in the backbone to provide redundancy
Legal Interception Gateway• Enables authorities to intercept
subscriber data and signaling• Chasing criminal activity• Operator personnel has very
limited access to LI functionality• LI is required when launching the
GPRS service
GSM and (E)GPRS Interfaces
Gf
D
Gi
Gn
GbGc
CE
Gp
Gs
Signaling and Data Transfer InterfaceSignaling Interface
MSC/VLR
TE MT BSS TEPDN
R Um
GrA
HLR
Other PLMN
SGSN
GGSN
Gd
SM-SCSMS-GMSCSMS-IWMSC
GGSN
EIR
SGSN
Gn
(E)GPRS Interfaces
Gf
D
Gi
C
E
Gp
Gs
Signaling and Data Transfer InterfaceSignaling Interface
MSC/VLRTE BSS
TEPDN
R Um
Gr
HLR
Other PLMN
GGSN
Gd
SM-SCSMS-GMSCSMS-IWMSC
EIR
GnLAN
SW / IP BB
DNS CG LIG
Gn Ga
Gc
A
Gb
MT
SGSN SGSN GGSN
Gn
Gn Gn
Optional
GMSK & 8-PSK - Phase State Vectors
22,5° offset to avoid zero crossing
GMSK
8PSK(0,0,1)
(1,0,1)
(0,0,0) (0,1,0)
(0,1,1)
(1,1,1)
(1,1,0)
(1,0,0)
Time
Envelope (amplitude)
Time
Envelope (amplitude)
(0,0,1)
(1,0,1)
(d(3k),d(3k+1),d(3k+2))=
(0,0,0) (0,1,0)
(0,1,1)
(1,1,1)
(1,1,0)
(1,0,0)
8-PSK Modulation
EDGE GSM + EDGE Modulation 8-PSK, 3bit/sym GMSK, 1 bit/sym Symbol rate 270.833 ksps 270.833 ksps Bits/burst 348 bits
2*3*58 114 bits 2*57
Gross rate/time slot 69.6 kbps 22.8 kbps
• 8-PSK (Phase Shift Keying) has been selected as the new modulation added in EGPRS
• 3 bits per symbol
• 22.5° offset to avoid origin crossing (called 3/8-8-PSK)
• Symbol rate and burst length identical to those of GMSK
• Non-constant envelope high requirements for linearity of the power amplifier
• Because of amplifier non-linearities, a 2-4 dB power decrease back-off (BO) is typically needed, Nokia guaranteed a BO of 2 DB for BTS
3/8
Phase states transitionsto avoid zero-crossing
GMSK and 8PSK BurstsdB
t
- 6
- 30
+ 4
8 µs 10 µs 10 µs 8 µs
(147 bits)
7056/13 (542.8) µs 10 µs
(*)
10 µs
- 1+ 1
(***)
(**)
10 8 10 10 8 10 t (s)
dB
-30
(*)
-6
+2,4
+4
-20
-2
(***)
(**)
2 2 22
7056/13 (542,8)s
(147 symbols)
0
GMSK Burst
8PSK Burst
Phase state vector diagram•Amplitude is not fixed•Origin is not crossed•Overshooting
8-PSK Modulation – Back-off Value
• Since the amplitude is changing in 8-PSK the transmitter non-linearities can be seen in the transmitted signal
• These non-linearities will cause e.g. errors in reception and bandwidth spreading.
• In practice it is not possible to transmit 8-PSK signal with the same power as in GMSK due to the signal must remain in the linear part of the power amplifier
Peak to Average of 3,2 dB
Pin
Pout
Back Off= 4 dB
Compression point
Peak to Average of 3,2 dB
Pin
Pout
Back Off= 4 dB
Compression point
• The back-off value is taken into account in link budget separately for UL / DL and bands: 900/850, 1800/1900)
• Too high MCA (8PSK) can lead to unsuccessful TBF establishment, if the MS is on cell border with low signal level (so the back-off is taken into account) and / or low C/I
Burst Structure
• Burst structure is similar with current GMSK burst, but term 'bit' is replaced by 'symbol'
• Training sequence has lower envelope variations
• Seamless switchover between timeslots
• In case of max output power only, back-off applied to 8-PSK
TSL1 TCH
GMSK
TSL2 TCH
GMSK
TSL3 TCH
GMSK
TSL4 TCH
GMSK
TSL5 PD T CH 8 - PSK / GMSK
TSL6 PD T CH 8 - PSK / GMSK
TSL7 PD T CH 8 - PSK / GMSK
TSL0 BCCH GMSK
P (dB)
t ( us )
EDGE Signal
1 2 3 4
1. Spectrum of Unfiltered 3pi/8 8psk modulation.
2. Filtered to fit GSM bandwidth.
3. Constellation after filtering: error vectors introduced.
4. Constellation after receiver Edge (equalised) filtering
GPRS Coding Schemes
• GPRS provides four coding schemes: CS-1, CS-2 and with PCU2 CS-3, CS-4
• PCU1 and 16 kbit/s Abis links support CS-1 and CS-2, the Dynamic Abis makes it possible to use CS-3 and CS-4
• Each TBF can use either a fixed coding scheme (CS-1 or CS-2), or Link Adaptation (LA) based on BLER
• Retransmitted RLC data blocks must be sent with the same coding as was used initially
Coding Scheme
Payload (bits)per RLC block
Data Rate (kbit/s)
CS1 181 9.05
CS2 268 13.4
CS3 312 15.6
CS4 428 21.4
More Data =
Less Error Correction
Nokia GPRSPCU1
•CS1 & CS2 – Implemented in all Nokia BTS without HW change
•CS3 & CS4 – S11.5 (with PCU2) and UltraSite BTS SW CX4.1 CD1 (Talk is supporting CS1 and CS2)
Data
Err
or
Corr
ect
ion
GPRS Coding Schemes
Nokia GPRSPCU2
CS-1
CS-2
CS-3
57 57 57 57 57 57 57 57
456 bits
MAC
USF BCS +4
puncturing
rate a/b convolutional coding
CS-1 CS-2 CS-3
RLC/MAC Block Size: 181 268 312
Block Check Sequence: 40 16 16
Precoded USF: 3 6 6
1/2 ~2/3 ~3/4
length: 456 588 676
0 132 220
Data rate (kbit/s): 9.05 13.4 15.6
interleaving
MAC
USF BCS
RLC/MAC Block Size: 428
BCS Size: 16
Precoded USF: 12
Data rate (kbit/s): 21.4
CS-4
20 ms
GPRS Coding Schemes
EGPRS Modulation and Coding Schemes
EGPRS modulation and coding schemes:
Scheme Modulation Data rate kb/s
MCS-9 59.2
MCS-8 54.4
MCS-7 44.8
MCS-6 29.6 27.2
MCS-5
8PSK
22.4
MCS-4 17.6
MCS-3 14.8 13.6
MCS-2 11.2
MCS-1
GMSK
8.8
Ref: TS 03.64
EGPRS Data Treatment Principle in RF Layer
User data
"Additional info" that does not require extra protection
Header part, robust coding for secure transmission
Adding redundancy
Puncturing of the coded info
BSC
BTS
• Class C Packet only (or manually switched between GPRS and speech modes)
• Class B Packet and Speech (not at same time) (Automatically switches between GPRS and speech modes)
• Class A Packet and Speech at the same time(DTM is subset of class A)
(E)GPRS Mobile Terminal Classes
(E)GPRS Multislot ClassesType 1
Multislot Classes 1-12- Max 4 DL or 4 UL TSL (not at same time)- Up to 5 TSL shared between UL and DL- Minimum 1 TSL for F Change- 2-4 TSL F Change used when idle
measurements required
Multislot Classes 19-29- Max 8 downlink or 8 uplink
(not required at same time)- 0-3 TSL F Change
Multislot Classes 30-45 (Rel-5)- Max 5 downlink or 5 uplink (6 shared)- Max 6 downlink or 6 uplink (7 shared)
Type 2
Multislot Classes 13-18- simultaneous receive & transmit- max 8 downlink and 8 uplink (Not available yet, difficult RF design)
DL
UL
DL
UL
1 TSL for F Change
1 TSL for Measurement
DL
UL
GPRS implementation
• GPRS/EGPRS capable terminals are required
• GPRS territory is required in BTS
• Packet Control Units (PCUs) need to be implemented in BSCs
• Gb interface dimensioning
• GPRS packet core network dimensioning
• If CS3&CS4 will be implemented following units/items are required• PCU2 with S11.5 BSC SW
• Dynamic Abis Pool (DAP)
• EDGE capable TRXs
• UltraSite and MetroSite BTS SW support
EGPRS Implementation
• Can be introduced incrementally to the network where the demand is
• EGPRS capable MS
• Network HW readiness/upgrade (BTS and TRX)
• TRS capacity upgrade (Abis and Gb!)
• Dynamic Abis
GMSK coverage
8-PSK coverage
AA-bis
Gb
Gn
BTS
BTS
BSC
SGSNGGSN
MSC
More capacity in interfaces to support higher data usage
EDGE capable TRX, GSM compatible
EDGE capable terminal, GSM compatible
EDGE functionality in the network elements
Create a BCF
Create a BTS
Attach BTS to RAC
Enable EGPRS (EGENA/Y)
Define GPRS and EGPRS parameters
Enable GPRS (GENA/Y)
Create a TRX with DAP connection
Create handover and power control parameters
The steps to create radio network objects
Enabling (E)GPRS
RAC= Routing Area code
Create the dynamic Abis pool
Disable the GPRS in the cell
Lock the TRX
Delete the TRX to be connected to Dynamic Abis pool
Create a TRX which uses the dynamic Abis pool
All the TRXs that will be using EGPRS in the BTS must be attached to a dynamic Abis pool
Unlock the TRX
Enable EGPRS in the BTS (EGENA/Y)
Enable GPRS in the cell (GENA/Y)
Unlock the BTS
Lock the BTS
The steps to enable the (E)GPRS in BSC
Enabling (E)GPRS
To be considered:• When the TRX has been created with EDAP defined at BSC and EGPRS feature is enabled,
the TRX must be attached to EDAP on the BTS side also not to fail the configuration of BCF
• EDAP in BSC must be inside the TSL boundaries defined in the BTS side• When modifying EDAP the size of EDAP in the BTS has to be the same as the size of EDAP in the
BSC
• Creating, modifying or deleting of EDAP in the BSC will cause a territory downgrade/upgrade procedure to all territories served by the PCU in question
• The ongoing EGPRS/GPRS connections will pause and resume immediately
• The maximum EDAP size is 12 timeslots
• EDAP must be located on the same ET-PCM line as TRX signaling and traffic channels
• There are no specific commissioning tests concerning EDAP
• EDAP must be located on the same BCSU as Gb interface
Enabling (E)GPRS
(E)GPRS Protocol Architecture
L1
L2
IP
UDP
GTP
USERPAYLOAD
GGSN
L1
L2
IP
GPRS Bearer
GGSN
Relay
IP
GPRS IP Backbone
L1
L2
IP
GTP
L1bis
NW sr
BSSGP
SNDCP
LLC UDP
SGSN
Relay
Gn
Internet
L1
L2
IP
TCP/UDP
APP
Gi
User information transferUser information transfer
LLC
SNDCP
IP
TCP/UDP
APP
RLC
MAC
GSM RF
MS
RLC
MAC
GSM RF
BSSGP
NW sr
L1bis
BSS
Ciphering and reliable link
Um Gb
Compression, segmentation
FIXED HOST
(E)GPRS Logical Channels
GPRS Air Interface Logical Channels
CCCHCommon Control Channels
DCHDedicated Channels
PCHPaging CH
AGCHAccess Grant CH
RACHRandom Access CH
Existing GSM Channels(Shared with GPRS Signaling in GPRS Release 1)
PACCHPacket Associated
Control CHPDTCH
Packet Data TCH
NEW GPRS Channels
Functionality - Content
Introduction
• Network architecture and Interfaces
• Mobile classes
• Network Protocols
• Multiframe and header structure
• Air interface mapping – physical and logical channel
Procedures
• State and Mobility Management
• GPRS Attach/Detach
• Routing Area
• Session Management (PDP context)
• Temporary Block Flow
•RLC/MAC Header
•TBF Establishment
(E)GPRS Procedures - Content
• Mobility Management and State Management• Mobile States
• GPRS attach
• GPRS detach
• Routing Area
• Session Management• PDP context activation
• Temporary Block Flow• RLC/MAC Header
• TBF establishment
GPRS Mobility Management - Mobile States
MS location not known, subscriber is not reachable by the GPRS nw.
IDLE READY
STANDBY
READY Timer expiry
MOBILE REACHABLE Timer expiry
Packet TX/RX
GPRS Attach/Detac
h
MS location known to Routing Area level. MS is capable to being paged for point-to-point data.
MS location known to cell level. MS is transmitting or has just been transmitting. MS is capable of receiving point-to-point data.
Attach Procedure
• The GPRS Attach procedure establishes a GMM context. This procedure is used for the following two purposes:
• a normal GPRS Attach, performed by the MS to attach the IMSI for GPRS services only
• a combined GPRS Attach, performed by the MS to attach the IMSI for GPRS and non-GPRS services
• Attach procedure description• MS initiates by sending Attach Request
• If network accepts Attach Request it sends Attach Accept• P-TMSI, RAI
• If network does not accept Attach request it sends Attach Rejected
• MS responds for Attach Accept message with Attach Complete (only if P-TMSI changes)
Detach Process
• GPRS Detach procedure is used for the following two purposes:• a normal GPRS Detach
• a combined GPRS Detach (GPRS/IMSI detach, MS originated)
• MS is detached either explicitly or implicitly:• Explicit detach: The network or the MS explicitly requests detach.
• Implicit detach: The network detaches the MS, without notifying the MS, a configuration-dependent time after the mobile reachable timer (MSRT) expired, or after an irrecoverable radio error causes disconnection of the logical link
Routing Area
The Routing Area Update procedure is used for the followings:
• a normal Routing Area Update
• a combined Routing Area Update
• a periodic Routing Area Update
• an IMSI Attach for non-GPRS services when the MS is IMSI-attached for GPRS services.
• Routing Area (RA)• Subset of one, and only one Location Area (LA)
• RA is served by only one SGSN
• For simplicity, the LA and RA can be the same
• Too big LA/RA increases the paging traffic, while too small LA/RA increases the signaling for LA/RA Update
Routing Area Location
Area (LA)
Routing Area (RA)
SGSN
MSC/VLR
GS Interface
• Bad LA/RA border design can significantly increase the TRXSIG on LA/RA border cells causing the cell-reselection outage to be longer
• LA/RA border should be moved from those areas where the normal CSW and PSW traffic is very high
•PDP Context (Packet Data Protocol): Network level information which is used to bind a mobile station (MS) to various PDP addresses and to unbind the mobile station from these addresses after use
•PDP Context Activation• Gets an IP address from the network• Initiated by the MS• Contains QoS and routing information enabling data transfer between MS and
GGSN• PDP Context Activation and Deactivation should occur within 2 seconds
Session Management - Establishing a PDP Context
PDP Context Request
155.131.33.55
MSC
PSTNNetwork
GPRSINFRASTRUCTURE
HLR/AuCEIR
Gateway GPRSSupport Node(GGSN)
Domain Name Server (DNS)
GPRSbackbo
nenetwork
(IP based)
PDP Context Activation - 11. MS sends "Activate PDP Context Request" to SGSN
2. SGSN checks against HLR
Datanetwork(Internet)
Datanetwork(Internet)
Access Point
SS7Network
APN= "Intranet.Ltd.com" 2.
Serving GPRSSupport Node(SGSN)
Access Point Name = Reference to an external packet data network the user wants to connect to
BSCBTSUm
1.
MSC
PSTNNetwork
GPRSINFRASTRUCTURE
HLR/AuCEIR
PDP Context Activation - 2Finding the GGSN
3. SGSN gets the GGSN IP address from DNS
4. SGSN sends "Create PDP Context Request" to GGSN
Datanetwork(Internet)
Datanetwork(Internet)
SS7Network
4.
Serving GPRSSupport Node(SGSN)
GPRSbackbo
nenetwork
(IP based)
3.
Domain Name Server (DNS)
Gateway GPRSSupport Node(GGSN)
Access Point
BSCBTSUm
DNS (Domain Name System) = mechanism to map logical names to IP addresses
MSC
GPRSINFRASTRUCTURE
HLR/AuCEIR
PSTNNetwork
PDP Context Activation - 3Access Point Selection
Access Point Name refers to the external network the subscriber wants to use
Datanetwork(Internet)
SS7Network
Serving GPRSSupport Node(SGSN)
GPRSbackbo
nenetwork
(IP based)
Domain Name Server (DNS)
Gateway GPRSSupport Node(GGSN)
Access Point
APN="Intranet.Ltd.com"
Datanetwork(Internet)
BSCBTSUm
MSC
PSTNNetwork
GPRSINFRASTRUCTURE
HLR/AuCEIR
Datanetwork(Internet)
Datanetwork(Internet)
Access Point
APN="Intranet.Ltd.com"
Domain Name Server (DNS)
SS7Network
5.
Serving GPRSSupport Node(SGSN)
GPRSbackbo
nenetwork
(IP based)
6.
Gateway GPRSSupport Node(GGSN)
BSCBTSUm
User (dynamic) IP address allocated
5. GGSN sends "Create PDP Context Response" back to SGSN
6. SGSN sends “Activate PDP Context Accept“ to the MS
PDP Context Activation - 4Context Activated
Temporary Block Flow
Temporary Block Flow (TBF):• Physical connection where multiple mobile stations can share one or more traffic
channels – each MS has own TFI• The traffic channel is dedicated to one mobile station at a time (one mobile station is
transmitting or receiving at a time)• Is a one-way session for packet data transfer between MS and BSC (PCU)• Uses either uplink or downlink but not both (except for associated signaling)• Can use one or more TSLs
Comparison with circuit-switched:• normally one connection uses both the uplink and the downlink timeslot(s) for traffic
In two-way data transfer:• uplink and downlink data are sent in separate TBFs - as below
BSBSCC
Uplink TBF (+ PACCH for downlink TBF)
Downlink TBF (+ PACCH for uplink TBF)
PACCH (Packet Associated Control Channel): Similar to GSM CSW SACCH
TLLI / TBF Concept
TBF (TFI + TSL)
MS SGSN GGSN
Internet or Intranet
GPRS CORE
BSS
TBF (RLC / MAC Flow)
TBF (LLC Flow)
PCUBTS
TLLI (SNDCP Flow)
P-TMSI
HLRVLR
IMSITMSI
Multiple Mobiles and Downlink Transmission
TFI2
TFI5
TFI3
TFI2
MSs
BTS
The TFI included in the Downlink RLC Block header indicates which Mobile will open the RLC Block associated with its TBF
RLC Data Block
• Several mobiles can share one timeslot
• Maximum of 7 Mobiles are queued in the Uplink
• Mobile transmissions controlled by USF (Uplink State Flag) sent on DL (dynamic allocation)
TS 1
TS 2
TS 3
Uplink State Flag
• Mobile with correct USF will transmit in following Uplink block
• Timeslot selected to give maximum throughput
New MS
Multiple Mobiles and Uplink Transmission
Multiple Mobiles and Uplink Transmission
USF = 1
USF = 2
USF = 3
USF = 3
MSs
BTS
RLC Data Block
The USF included in the Downlink RLC Block header identifies which Mobile will transmit in the following Uplink RLC Block
(E)GPRS Resource Allocation - Content
Territory method
• Default and dedicated territory
• Free TSLs
TSL Allocation
• Scheduling with priority based QoS
Territory Method
TRX 1
TRX 2
BCCH TS TS TS TS TS TSSDCCHBCCH TS TS TS TS TS TSSDCCHBCCH TS TS TS TS TS TSSDCCH
TS TS TSTS TSTS TS TSTS TSTS TS TS TSTS TS TSTS
TS
TS
= (E)GPRS Territory/Dedicated capacity
= CSW Territory
TS= (E)GPRS Territory/Additional capacity
BCCH= Signaling
TS = Free TSL for CSW
TS= (E)GPRS Territory/ Default capacity
Territory border
EDAP, PCU and Gb Functionality - Content
EDAP
• Abis vs. Dynamic Abis
• Channels carried on EDAP
• EDAP limits
• Abis PCM structure
PCU
• PCU procedures
• PCU types and limits
Gb
• Gb protocols
• Gb over FR
• Gb over IP
Abis Basic Concepts – PCM frame (E1)
One 64 kbit/s (8 bits) channel in PCM frame is called timeslot (TSL)One 16 kbit/s (2bits) channel timeslot is Sub-TSLPCM frame has 32 (E1) or 26 (T1) TSLs
One Radio timeslot corresponds one 16 kbit/s Sub-TSL (BCCH, TCH/F etc.) and one TRX takes two TSLs from Abis
0 MCB LCB123456789
101112131415161718 TCH 0 TCH 1 TCH 2 TCH 319 TCH 4 TCH 5 TCH 6 TCH 7202122232425 TRXsig2627 BCFsig28293031 Q1-management
One TRX has dedicated TRXsig of 16, 32 or 64 kbit/s.
48 kbit/s isnot allowed.
One BCF has dedicated BCFsig (16 or 64 kbit/s) for O&M
TRX1
Q1-management needed if TRS management under BSC
MCB/LCB required if loop topology is used
AbisBTS BSC
(E)GPRS Dynamic Abis Pool – EDAP Introduction• Fixed resources for signaling and
voice• Dynamic Abis pool (DAP) for data
• Predefined size 1-12 PCM TSL per DAP
• DAP can be shared by several TRXs in the same BCF (and same E1/T1)
• Max 20 TRXs per DAP• Max 480 DAPs per BSC• DAP + TRXsig + TCHs have to be
in same PCM• UL and DL EDAP use is
independent• DAP schedule rounds for each
active Radio Block• Different users/RTSLs can use
same EDAP Sub-TSL
0 MCB LCB1234 TCH 0 TCH 1 TCH 2 TCH 35 TCH 4 TCH 5 TCH 6 TCH 76 TCH 0 TCH 1 TCH 2 TCH 37 TCH 4 TCH 5 TCH 6 TCH 78 TCH 0 TCH 1 TCH 2 TCH 39 TCH 4 TCH 5 TCH 6 TCH 7
101112131415 EDAP EDAP EDAP EDAP16 EDAP EDAP EDAP EDAP17 EDAP EDAP EDAP EDAP18 EDAP EDAP EDAP EDAP19 EDAP EDAP EDAP EDAP20 EDAP EDAP EDAP EDAP21 EDAP EDAP EDAP EDAP22 EDAP EDAP EDAP EDAP232425 TRXsig1 TRXsig226 TRXsig327 BCFsig28293031 Q1-management
TRX1
TRX2
TRX3
EGPRS
pool
Nokia Dynamic Abis Dimensioning - with EGPRS Data Traffic
• Fixed master TSL in Abis for all EGPRS air TSL • Slave TSL’s (64 k) in EDAP pool for each air TSL• TRX and for OMU signaling fixed• TSL 0 and 31 typically used for signaling• EDAP pool dimensioning considerations
• Planned throughput in radio interface
RTSL territory size MS multiclass
• Number of TRXs/BTSs connected to DAP• Total number of PCU Abis Sub-TSLs • Gb link size• GPRS/EDGE traffic ratio
0 MCB LCB1 TCH 0 TCH 1 TCH 2 TCH 32 TCH 4 TCH 5 TCH 6 TCH 73 TCH 0 TCH 1 TCH 2 TCH 34 TCH 4 TCH 5 TCH 6 TCH 75 TCH 0 TCH 1 TCH 2 TCH 36 TCH 4 TCH 5 TCH 6 TCH 77 TCH 0 TCH 1 TCH 2 TCH 38 TCH 4 TCH 5 TCH 6 TCH 79 TCH 0 TCH 1 TCH 2 TCH 310 TCH 4 TCH 5 TCH 6 TCH 711 TCH 0 TCH 1 TCH 2 TCH 312 TCH 4 TCH 5 TCH 6 TCH 7
13 TRXsig 1 TRXsig 214 TRXsig 3 TRXsig 415 TRXsig 5 TRXsig 616 BCFsig171819 EDAP1 EDAP1 EDAP1 EDAP120 EDAP1 EDAP1 EDAP1 EDAP121 EDAP1 EDAP1 EDAP1 EDAP122 EDAP1 EDAP1 EDAP1 EDAP123 EDAP1 EDAP1 EDAP1 EDAP124 EDAP1 EDAP1 EDAP1 EDAP125 EDAP1 EDAP1 EDAP1 EDAP126 EDAP1 EDAP1 EDAP1 EDAP127 EDAP1 EDAP1 EDAP1 EDAP128 EDAP1 EDAP1 EDAP1 EDAP129 EDAP1 EDAP1 EDAP1 EDAP130 EDAP1 EDAP1 EDAP1 EDAP131 Q1-management
TRX 1
TRX 2
TRX 3
TRX 4
TRX 5
TRX 6
EGPRS DAP
Packet Control Unit (PCU) - Introduction
• BSC plug-in unit that controls the (E)GPRS radio resources, receives and transmits TRAU frames to the BTSs and Frame Relay packets to the SGSN
• Implements both the Gb interface and RLC/MAC protocols in the BSS
• Acts as the key unit in the following procedures:• (E)GPRS radio resource allocation and management
• (E)GPRS radio connection establishment and management
• Data transfer
• Coding scheme selection
• PCU statistics
• The first generation PCUs are optimized to meet GPRS requirements, i.e. non real time solutions (QoS classes "Background" and "Interactive“)
• The second generation PCUs (PCU2) supports the real time traffic requirements and enhanced functionality (GERAN) beyond (E)GPRS
Gb Interface - Introduction
• The Gb interface is the interface between the BSS and the Serving GPRS Support Node (SGSN)
• Allows the exchange of signaling information and user data
• The following units can be found in Gb• Packet Control Unit (PCU) at the BSS side
• Packet Processing Unit (PAPU) at the GPRS IP backbone side
• Each PCU has its own separate Gb interface to the SGSN
BSC
PCU
BSS
SGSN
PAPU
GPRS
Gb
Gb Interface
• Allow many users to be multiplexed over the same physical resource
• Resources are given to a user upon activity (sending/receiving)
• GPRS signaling and user data are sent in the same transmission plane and no dedicated physical resources are required to be allocated for signaling purposes
• Access rates per user may vary without restriction from zero data to the maximum possible line rate (e.g., 1 984 kbit/s for the available bit rate of an E1 trunk)
BSC
PCU
BSS
SGSN
PAPU
GPRS
Gb
RF PLANNING VS DATA PERFORMANCE
CONTENTS
• FREQ. PLANNING
• C/I VS THROUGHPUT GRAPHS
Frequency Planning
Combined interference and noise estimations needed for (E)GPRS link budget
Frequency allocation and C/I level• The existing frequency allocation has high impact on EGPRS performance• Loose re-use patterns will provide better performance for all MCSs
Data rate and network capacity• EGPRS highest data rates require high C/I, typ > 20dB for MCS-7, 8 & 9• Possibly no extra spectrum for EDGE so efficient use of the existing spectrum is very
important• EGPRS traffic suited to BCCH use - typically the layer with highest C/I. But limited no. of TSLs
available on BCCH; may need to use TCH layer too
Sensitivity in tighter reuse and higher load• EDGE can utilize tighter reuse schemes and this is beneficial when planning for high load with
limited frequency resources• For systems with stringent spectrum constraints, EGPRS can offer good performance even
with tight re-use patterns (1/3 or 3/9). Load dependent
Data rate vs. CIR in Time (Field Measurement)
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Data ThroughputApplication Throughput
TEMS-C/I-GMSKPoly. (TEMS-C/I-GMSK)
Good quality environment
Data rate vs. CIR in Time (Field Measurement)
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Data ThroughputApplication Throughput
TEMS-C/I-GMSKPoly. (TEMS-C/I-GMSK)
Average quality environment
Data rate vs. CIR in Time (Field Measurement)
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Data ThroughputApplication Throughput
TEMS-C/I-GMSKPoly. (TEMS-C/I-GMSK)
Worse quality environment
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