Transcript
(E)GPRS Network Infrastructure MS MSC
BSC
BTS
PSTN SS7 Network
SMS-GMSC
SGSN
HLR/AuC Nokia Security GW
SGSN Nokia Security GW
EIR
CG
Router
Nokia IP650 sec GW
STM-1
Router
LAN SWITC H
Router
GPRS IP Backbone Network
Router
STM-1
MODEM POOL FOR DIALUP
SGSN Company Confidential
Nokia IP650 sec GW
Nokia Security GW
Internet Nokia Security GW
MODEM POOL FOR DIALUP
SGSN
LIG GGSN
GGSN Router
DNS
Nokia IP650 sec GW Corporate 1 Intranet
Corporate 2 Intranet
ELECTRICAL ET
Metro BSC
Hub GB LINK
GB LINK
SGSN
GGSN Company Confidential
NSEI PLANNING NSEI 1
NSEI 2
NSEI 3
NSEI 4
Company Confidential
Network Element and Configuration Audit - Summary HLR
BSS
BTS
• PCU variant & dimensioning
• GPRS territory • BTS HW considerations (TRX & BB-card)
TC
• PCU strategy in mixed configuration
• BTS SW (EPCR)
TCSM
MSC/VLR
• GPRS settings
SGSN • Unit capacity (PAPU etc.)
• BSS SW and features
• BSS Gb Flow control
MS/Client parameters
Gs
• GPRS/EDGE capability and release •Multislot support
• QoS profile
HLR/ AC/ EIR
IP/MPLS/IPoATMbackbone RF
BTS
BSC Abis
Gb
2G SGSN
GGSN
Gn Gi
Application Applicatio Servers n Servers (colocated
RF interface • Coverage •C/I • Capacity
Gb interface Abis interface
• Traffic volume
• EDAP size / dimensioning
• Mobility
• # of E1/T1s
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• GPRS/EDGE traffic
• Bearer size
Server
• IP v.s. FR
• load
• Dimensioning
• settings (Linux/Win)
INPUT GIVEN FOR THE GPRS PLANNING • No. of time slot required for the GPRS territory : CDED=1 and CDEF=1 • No. of BTS per EDAP i.e the No. of sectors prevalent : 3 • No. of time slot used for EDAP on Abis (64 Kbps) : 3 Time slot • % of upgrade is the Teritory upgrade for the future perspective : 10 % • No. Of sites planned per BSC : 100 • Access rate (CIR) is the speed required at the GB interface : 256 Kbps
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OUTPUT REQUIRED • No. of sites per NSEI required • No. of NSEI required in BSC • No. of PCU or No. Of BCSU required • No. Of Gb Link required • No. of E1 required from the BSC to Metro Hub
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How to calculate what • No. of EGPRS resources used in 1 sector * No. of sectors : 2 x 3 • No. of time slot/sector * no of time slot used for EDAP :- 2 * 3 = 6 • So total time slots per site 6 + 6 = 12 • 1 NSEI support 256 time slot with upgrade % as 10 so total no of time slots which can be equipped is 256 - 10% of 256 = 230.4 ~ 230 • So no. of sites per NSEI is 230/12 = 19.16 ~ 19 • So no NSEI required / BSC : 100 / 19 = 5.2 +1 (for future use) ~ 6 • 2 NSEI supports 1 BCSU so no. of PCU required : 6/2 = 3 • No. of NSEI required is equivalent to the no. of Gb link = 3 • On 1 E1 we can get 31x64 = 1984 , so access rate can be given by 1 E1 = 1984/ access rate (256) = 1984 / 256 ~ 7
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ransm ss on requ remen or EGPRS coding schemes in Abis interface Coding scheme MCS-1
8.8 kbit/s
MCS-2
11.2 kbit/s
MCS-3
14.8 kbit/s
MCS-4
17.6 kbit/s
MCS-5
22.4 kbit/s
MCS-6
29.6 kbit/s
MCS-7
44.8 kbit/s
MCS-8
54.4 kbit/s
MCS-9
59.2 kbit/s
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Data rate
Abis PCM allocation (fixed + pool)
EDGE modulations
Scheme
Modulatio n
Maximum rate [kb/s]
MCS-9
8PSK
59.2
MCS-8
54.4
MCS-7
44.8
MCS-6
29.6 / 27.2
MCS-5
22.4
MCS-4
GMSK
17.6
MCS-3
14.8 / 13.6
MCS-2
11.2
MCS-1
8.8
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GPRS & EGPRS coding schemes MCS-1
• GPRS has four coding schemes, CS-1...4. All use GMSK. • EDGE has nine modulation and coding schemes, MCS-1...9. • MCS-1...4 use GMSK, MCS-5...9 use 8-PSK modulation • Operator can set the MCS to start with •
E.g. always start with MCS-9
RLC/MAC block (radio block)
22 MCS-2 28 MCS-3
redundancy from channel coding
37
RLC data block, number of octets
MCS-4 44 MCS-5 56
CS-1
MCS-6
20
74 MCS-7
CS-2
56
30
56 MCS-8
CS-3 36
68 MCS-9
CS-4 50
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68
74
74
EDGE link performance
Ideal Link Adaptatio
In RLC layer (kbit/TSL) •
GPRS with re-transmission with same coding scheme
•
Retransmissions with EDGE can be sent with the new scheme
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MCS-1 MCS-2 MCS-3 MCS-4 MCS-5 MCS-6 MCS-7 MCS-8 MCS-9
•Bit Error Probability (BEP) is a new MS quality measurement introduced •
In general, a higher coding scheme has higher coding rate, and consequently higher peak throughput, but it also tolerates less noise or interference.
•
New parameters
50
• Max BLER for Ack and Non-Ack modes • Can be used to tune to use more higher MCS’s • Mean BEP offset for GMSK and 8-PSK • Set threshold for MCS change •
40
The figure shows throughput vs. C/I of EGPRS coding schemes in TU50iFH, without incremental redundancy.
30
20
10
0 0 Company Confidential
5
10
15
20
25
30
C/I
GPRS: territory (S9-10) TRX 1
CCCH
TS
TS
TS
TS
TS
TS
TS
TRX 2
TS
TS
TS
TS
TS
TS
TS
TS
Additional GPRS Capacity
The main principle is that GPRS (PS) uses the capacity that remains from the CS traffic.
Default GPRS Capacity
Circuit Switched Territory Packet Switched Territory
Dedicated GPRS Capacity
C i rc u i t S w i tc he b y i n n ot a ff ec d c a p t ro d ac i ty u c i t ed ng G P R S
Territory border moves Dyn a m ica lly based on Circuit Switched traffic load
Given as % over dual TCH tsls of
The f ollowing are the operator configurable parameters for territory management:
GPRSenabled(BTS-level) GENA
GPRSenabledTRX (TRX-level)
DedicatedGPRScapacity (BTS-level)
DefaultGPRScapacity (BTS-level)
PreferBCCHfreqGPRS (BTS-level)
TerritoryUpdateGuardTimeGPRS (BSC-level)
GPRS enabled TRXs.
•
Circuit Switched traffic has priority
Includes dedicated time slots.
•
In each cell Circuit Switched & Packet Switched territories are defined
Rounded do wnwards.
•
Territories consist of consecutive timeslots
GTRX CDED CDEF BFG
CDEF CDED Used capacity for speech
Used capacity for GPRS PEAK GPRS CHANNELS /c2063(S9) peak_gprs_channels AVG. AVAILABLE DEDICATED GPRS CHANNELS ava_17 (S9) ave_GPRS_channels_sum/ave_GPRS_channels_den PEAK DEDICATED GPRS CHANNELS /c2066(S9) peak_permanent_gprs_ch
UNAVAILABLE TCH c2040
AVG. AVAILABLE TCH in CS territory ava_15 (S9) ave_avail_TCH_sum/ ave_avail_TCH _den
AVG. AVAILABLE GPRS CHANNELS in PS territory ava_16 (S9) ave_GPRS_channels_sum/ave_GPRS_channels_den
ADDIT.GPRS CH USED ach_1
AVG. BUSY TCH = CS traffic trf_12b ave_busy_tch/ res_av_denom14
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Free capacity
Allocated resources Availability ava_1d
AVG. TSL used for UL GPRS trf_78b AVG. TSL used for DL GPRS trf_79b
Used resources
GTUGT
DL Data Scheduling Example – “No need to share case” • There are enough EDAP resources to handle adequately all the TBFs and MCS requests. (e.g PS Active EGPRS ch < EDAP resources) TRX 1 RTSL
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0
CS-2 1
MCS-1 MCS-9 MCS-7 MCS-1 MCS-7
2
3
4
5
6
Requests
7
PCM subTSL 8 L S 9 T 10 M C 11 P
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CS-2
1
2
3
4
5
5
5
-
4
4
4
4
7
7
7
-
2
-
-
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MCS-1 MCS-9 MCS-7 MCS-1 MCS-7
Grants
DL Data Scheduling Example (sharing case) • Because EDAP is a shared resource between a higher number of EGPRS TSL it is possible to encounter the situation where there are not enough EDAP resources to handle “adequately” all the TBFs (e.g PS Active EGPRS ch > EDAP resources) TRX 1 RTSL
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0
CS-2 MCS-5 MCS-9 MCS-8 MCS-1 MCS-7 1
2
3
4
5
6
Requests
7
PCM subTSL L S T 10 M C 11 P 12
PCU-TRX 0
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1
2
3
4
5
5
5
3
4
4
4
-
2
7
7
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CS-2 MCS-5 MCS-7 MCS-7 MCS-1 MCS-6
Grants
EDAP utilization •6 EGPRS RTSLs (Dedicated + Default territory) • 50 % utilization assumed (3 Data Erlangs traffic) • On average 3 RTSLs used
TRX 1
TRX 2
TS TS BCCH PBCCH
TS
TS
TS
TS
TS
TS
TS
TS
TS
TS
TS
TS
TS
TS TS
TS
Dedicated EGPRS TSL Default territory EGPRS TSL
RTSLs use MCS7 (44.8 kbit/s) with average C/I=13dB and throughput 30kbit/s • Effective data rate factor excluding retransmissions over the air-interface is 30/44.8 ~ 0.7 •
•
Slave group utilization is 0.7*0.5= 0.35
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PLAN A Company Confidential
PLAN B
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SNO
PLAN A
PLAN B
1
Both Non BCCH and BCCH Trx can access the EDGE Facility
Only BCCH TRX can access the EDGE facility
2
If the BCCH TRX goes faulty then also the EDGE users can access the N/W since the 2nd TRX has been defined on the EDAP Pool
If BCCH TRX goes faulty then The EDGE Service can not be accessed since the 2nd TRX has not been defined on the EDAP POOL
3
Using this plan we can change the BFG priority depending on the Interference in the N/W
We can not change the BFG unstill and unless the EDAP pool need to be redesigned
4
In case of extending the time slot of EDGE in Non BCCH TRX also can be done if congestions is observed in the Site
We can not extend the Non BCCH TRX time slot during the congestion since that TRX is not mapped on the EDAP Pool
5
While expanding the N/W from the 222 to 332 configuration we need to Modify the EDAP pool
Need not to modify the EDAP pool since only BCCH TRX is being mapped
Conclusion • The No. of sites per NSEI depend on the EDAP pool size and no. of time slot used for the GPRS territory • Beside if we need to extend the resourced at ABIS end we need to defince the EDAP pool • If we require the Speed at GB we need to go to higher CIR
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