Ce diaporama a bien été signalé.
Nous utilisons votre profil LinkedIn et vos données d’activité pour vous proposer des publicités personnalisées et pertinentes. Vous pouvez changer vos préférences de publicités à tout moment.
Part 2:
UMTS Planning
TRAFFIC
MODELLING
AIR INTERFACE
DIMENSIONING
NOMINAL
CELL PLAN
RADIO
NETWORK
DESIGN
• Site type
• Site Count
• Site to Sit...
Overall Planning Process
 The overall Planning Process can be described with the following figure:
• 3G neighbour lists
•...
Dimensioning Objective
 To dimension radio capacity with reasonable accuracy
before using planning tools
 To establish t...
Input Data
 Environment and Coverage
– Area to cover and coverage degree
– Channel Model for EbNos
– Propagation Model (O...
Input Data
 Subscriber Density and Subscriber Behaviour
– Number of Subs per area
– Traffic per Sub at Busy Hour
– Activi...
Traffic Profile
 Average user in BH
– Voice/Video in mE
– PS in kB/BH
 UL/DL Asymmetry = 15-20%
 BH Traffic = 10-15% Da...
Air Interface Dimensioning
Assume an
uplink loading
Calculate uplink
coverage/Lmax
Calculate uplink
capacity
Estimate site...
Link Budget Method - Overview
- PHSDPA
- HSDPA cell average throughput
- HSDPA cell border throughputDone!
Lsa or PDCH
too...
What decides HSDPA cell border throughput and cell average throughput is basically Lsa and
power left for HSDPA.
The dimen...
System Reference Point
Eb/No vs BLER
Eb/No = 1 dBA
Eb/No = 6 dBB
A BER > B BER
 Propagation models predict only mean values of signal strength
 Mean signal strength value fluctuates, the deviation of...
Uplink Dimensioning
Cell range and cell area can be calculated
The number of sites required for meeting
coverage requireme...
Uplink Service
Service Speech CS Data PS Data
Service Rate 12.2 64 64 kbps
Transmitter - Handset
Max Tx Power 21 21 21 dBm...
HSDPA’s Effect on Uplink Coverage
Service PS Data PS Data PS Data PS Data
Service Rate 16 64 128 384 kbps
Transmitter - Ha...
BIUL - Noise Rise is referred as the increase in receiver noise floor
when a system is more loaded.
0
2
4
6
8
10
12
0 0,1 ...
 Maximum Pathloss (Okumura-Hata)
Lpath = A - 13.82log(ha) + (44.9 - 6.55log(ha))logR - a(hm)
[dB]
Where the following A v...
2
3
2
3
RArea= 2
3
8
9
RArea=
RSite to Site 3=
2
3
2
3
RArea=
R RR
R3=Site to SiteR
2
3
=Site to Site
Calculating Site Dis...
 Transmitter (RBS) is in a single point, Receivers (Terminals) are
distributed in the cell
 DL coverage and capacity are...
Downlink Service
Service Speech CS Data PS Data PS Data PS Data
Service Rate 12.2 64 64 128 384 kbps
Transmitter - Node B
...
Uplink v/s Downlink
HSDPA Dimensioning
 Average cell throughput
– What is the expected average HSDPA capacity?
 Cell border throughput
– Wha...
HS-DSCH power calculation
 Treated as true best effort in dimensioning
– Will take whatever power that is left in RBS aft...
HS-DSCH power calculation (2)
 PHS-DSCH calculated as:
DCHASCCHHSDCHCCHreftotDSCHHS PPPPPP  = ,
Power needed by
DC...
Traffic estimation
• The traffic estimation requires information related to the network topology, subscribers &
traffic:
•...
Load Calculation: Uplink Load
  jjb
j
j
NE
RW
L

1
/
/
1
1
0

=
=
=
N
j
jUL L
0

νj: Activity factor; for Speech so...
Inter-Cell Interference: Little i
– In the real environment we will never have separated cell. Therefore, in the load fact...
Uplink Load calculation
• Simplified UL load equation  UL DCH capacity
– for 1 service type j only
– W/Rj >> (Eb/No)j
• N...
Downlink Load calculation
Cell Type α
Macro Cell 0.4 – 0.9
Micro Cell > 0.9
Load Calculation Examples
– Load factor for different services has to be calculated separately, total load is then the sum...
Planning Tasks
– Scrambling Code Planning
– Neighbour List Planning
– Location, Routing and UTRAN Registration Area
Planni...
34
• ALLOCATION CRITERIA
– Additional conditions on Ec/Io
– Reuse distance
– SC domain assigned to the cell
– Number of sc...
35
• EXAMPLES OF ALLOCATION STRATEGIES
AUTOMATIC ALLOCATION
CLUSTERED
DISTRIBUTED
PER CELL
ONE
CLUSTER
PER SITE
Planning Tasks
– Scrambling Code Planning
– Neighbour List Planning
– Location, Routing and UTRAN Registration Area
Planni...
Introduction
• There are the following types of neighbor lists
• Intra-frequency (3G to 3G)
• Inter-frequency (3G to 3G)
•...
CPICH Ec/Io SC100
SC200
Drop
Cell
Selection
Time
Missing neighbours can be identified
from UE log files:
1) Decrease of CP...
• When a UE is in SHO the neighbor lists belonging to each of the active set AS cells
are combined
• Neighbor lists are co...
Inter-Frequency IF Neighbors (3G to 3G) (1/2)
• Used for IF cell re-selection & inter-frequency HHO
• Following procedures...
Inter-frequency
neighbour list
Inter-Frequency Neighbors (3G to 3G) (2/2)
• When a UE is in intra-RNC SHO the neighbor lis...
Inter-System Neighbors (3G to 2G) (1/2)
• Used for cell re-selection and (hard) handover towards 2G
• GSM neighbor list ca...
Inter-System Neighbors (3G to 2G) (2/2)
• When a UE is in intra-RNC SHO the neighbor lists belonging to each of the active...
Maximum Neighbor List Length (1/2)
• SIB11 is used to instruct the UE which cells to measure in RRC Idle, CELL_FACH &
CELL...
Maximum Neighbor List Length (2/2)
• Enables transmission of all defined neighbors
• 32 intra-frequency
• 32 inter-frequen...
Planning Tasks
– Scrambling Code Planning
– Neighbour List Planning
– Location, Routing and UTRAN Registration Area
Planni...
Node B
MSC
UE
RNC
Iu cs
SGSN
Single RRC
Connection
Iu ps
CS
state
PS
state
CS
state
PS
state
Two Iu Signalling
Connections...
• Identification of LA
• Globally using a Location Area Identification (LAI)
• LAI: concatenation of Mobile Country Code (...
• Identification of LA
• Globally using a Routing Area Identification (RAI)
• A LAI is a concatenation of Location Area Id...
Paging Capacity
• NSN RAN provides either a 8 kbps or 24 kbps PCH transport channel on the S-CCPCH
• One page message has ...
Design of LA/RA Borders
• 2G LA/RA borders often good starting point of 3G LAs/RAs, as usually already
optimized
• To avoi...
• A LA/RA can have both 2G and 3G cells
• Requires unique 2G and 3G Cell Identities (CI) and Cell Global Identities (CGI)
...
UE States
 Idle mode
– No connection to radio network (No RRC connection established)
– This minimizes resource utilizati...
System Information
 System parameters are broadcast on BCCH. It has information
regarding Idle Mode Behaviour.
 The Syst...
Idle mode Functions
 PLMN Selection
 Cell Selection and
Reselection
 Location Area (LA) and
Routing Area (RA)
updating
...
PLMN Selection
 PLMN selection performed upon power on or upon recovery from lack of coverage
 If there is no last regis...
Start
Stored Information
Cell selection
Initial
Cell Selection
Cell selection
when leaving
connected mode
Connected
mode
I...
Cell Selection
 UE looks for a suitable cell in the selected PLMN and camps on to it
 Cell search procedure
– UE acquire...
Cell Selection Parameters
 For cell selection criteria the UE calculates
Squal = Qqualmeas - qQualMin (for WCDMA cells)
S...
Cell Reselection
 Allows UE’s to move between cells in idle and cell_FACH
connected mode
 Always camp on the best cell t...
Cell Reselection Parameters
 UE ranks available cells using R criteria
R(Serving) = Qmeas(s) + qHyst(s)
R(Neighbour) = Qm...
Cell Reselection Measurements
Serving cell
Neighbour 1
Neighbour 2
QHyst1
Qoffset1sn
3
2
1
tReselection
Measurement
Quanti...
Location and Routing Area updating
 Location Area = The area to which the Core Network sends a paging
message for circuit...
Paging
 Two types of paging
– Core Network informs a UE of a terminating service request
– RAN informs all UE’s that the ...
Part 2  planning of 3G
Prochain SlideShare
Chargement dans…5
×

Part 2 planning of 3G

5 936 vues

Publié le

3g Optimization

Publié dans : Ingénierie

Part 2 planning of 3G

  1. 1. Part 2: UMTS Planning
  2. 2. TRAFFIC MODELLING AIR INTERFACE DIMENSIONING NOMINAL CELL PLAN RADIO NETWORK DESIGN • Site type • Site Count • Site to Site Distance • Carrier Required Hardware dimensioning • Channel Elements • Input Analysis • Mapping of Radio Access Bearer Use TEMS Cellplanner and digitized map Radio Planning Process
  3. 3. Overall Planning Process  The overall Planning Process can be described with the following figure: • 3G neighbour lists • 2G neighbour lists • Antenna tilts • Local area parameter tuning • Site selection • Site design • 3G neighbour lists • 2G neighbour lists • Scrambling codes • Location areas • Routing areas • RNC areas Link budget analsysis • RF carriers • Sectorisation • ROC to CEC • Node B power • Baseband proc. • Transmission Capacity Evolution Performance Monitoring System Dimensioning Radio Network Planning Pre-launch Optimisation Post-launch Optimisation • 3G neighbour lists • 2G neighbour lists • Antenna tilts • Local area parameter tuning • Site selection • Site design • 3G neighbour lists • 2G neighbour lists • Scrambling codes • Location areas • Routing areas • URA areas Link budget analysis • Node B count & configuration • Adapter count & configuration • Transmission capacity & configuration • RF carriers • Sectorisation • System modules • Node B power • Baseband proc. • Transmission Performance Monitoring Wide area parameter tuning • 3G neighbour lists • 2G neighbour lists • Antenna tilts • Local area parameter tuning • Additional sites • User experience optimisationoptimisation • HSDPA • Microcells • •
  4. 4. Dimensioning Objective  To dimension radio capacity with reasonable accuracy before using planning tools  To establish the parameters and assumptions to be used throughout the project
  5. 5. Input Data  Environment and Coverage – Area to cover and coverage degree – Channel Model for EbNos – Propagation Model (Ok-Hata > 1km, Walfish < 1km)  Service Characteristics – Services and RABs – Grade of Service – UE Type
  6. 6. Input Data  Subscriber Density and Subscriber Behaviour – Number of Subs per area – Traffic per Sub at Busy Hour – Activity Factor for services – Body Loss  System Design Data – Retransmissions – Handover parameters – Site Configuration – Bandwidth (# carriers) – Load
  7. 7. Traffic Profile  Average user in BH – Voice/Video in mE – PS in kB/BH  UL/DL Asymmetry = 15-20%  BH Traffic = 10-15% Daily Traffic Traffic model in average Short term Medium term Long term per user during BH after 1 year after 2-3 years after 4 to 6 years Voice (mE) 8 to 30 10 to 30 10 to 30 Typical voice (mE) 15 to 20 15 to 20 15 to 20 Typical CS64 data (mE) 0,1 to 0,5 around 1 2 to 3 PS data (KByte/BH) 20 to 100 60 to 250 up to 500 to 600 Typical PS data(KB/BH) 40 to 60 100 to 150 200 to 300
  8. 8. Air Interface Dimensioning Assume an uplink loading Calculate uplink coverage/Lmax Calculate uplink capacity Estimate sitecount for coverage Estimate sitecount for capacity Balanced? Yes No Calculate PCPICH, ref based on UL Lmax Calculate DL Capacity Calculate PDCH Calculate PCCH, ref DL Capacity fulfill req. No Finished Yes Input Data
  9. 9. Link Budget Method - Overview - PHSDPA - HSDPA cell average throughput - HSDPA cell border throughputDone! Lsa or PDCH too large Lsa or PCCH too large Average DL network load (Q) - Link budget margins - HW configuration - Cell border parameters Uplink PS & CS traffic Start UL link budget Step 1 Lsa CPICH link budget Step 2 PCCH, Lsa DL link budget Step 3 PCCH, PDCH, Lsa, HSDPA dimensioning Step 4
  10. 10. What decides HSDPA cell border throughput and cell average throughput is basically Lsa and power left for HSDPA. The dimensioning is done in 4 steps: Step 1 Lsa is given from link budget calculations, starting with R99 UL link budget that decides Lsa. Step 2 Lsa is used in the CPICH link budget to calculate needed CPICH and CCH power. If the needed power turns out to be too large, Lsa needs to be reduced (redoing the UL link budget, i.e step 1) Step 3 Lsa is used to calculate needed power for R99 RABs, both per link (as a normal link budget when the user is standing on the cell border) and as average needed RBS power (when loading the system with many users that are distributed within the cell). If the needed power turns out to be too large, Lsa needs to be reduced (redoing the UL link budget, i.e step 1) Step 4 Lsa and needed power for CCH and R99 RABs are used to calculate HSDPA throughput. Inputs The ”reddish” color shows different inputs that affects the end result. -The amount UL CS and PS traffic decides the UL link budget (noise rise). -Link budget margins (antenna gain, building penetration loss, body loss, etc), HW configurations (RBS power) and DL network load decides Lsa. Note that the network load is assumed to 100% for HSDPA dimensioning.
  11. 11. System Reference Point
  12. 12. Eb/No vs BLER Eb/No = 1 dBA Eb/No = 6 dBB A BER > B BER
  13. 13.  Propagation models predict only mean values of signal strength  Mean signal strength value fluctuates, the deviation of the local has a nearly normal distribution in dB, compared to the predicted mean  Probability that the real signal strength will exceed the predicted one on the cell border is around 50%  For higher coverage probability than 50% an additional margin has to be added to the predicted required signal strength  The LNF margin depends on:  Radio channel properties (channel model)  Area type (Clutter type)  Required coverage confidence  soft handover gain Log Normal Fade Margin 75 85 90 95 98 Rural, Suburban –4.1 –1.7 0 2.3 4.6 Urban –3.9 –0.9 1.1 4.1 7.2 Urban Indoor –3.8 0.6 3.4 7.5 12.1 Dense Urban Indoor –3.8 1.1 4.3 9 14.3 Environment Area coverage %
  14. 14. Uplink Dimensioning Cell range and cell area can be calculated The number of sites required for meeting coverage requirement can be found Max path loss due to propagation
  15. 15. Uplink Service Service Speech CS Data PS Data Service Rate 12.2 64 64 kbps Transmitter - Handset Max Tx Power 21 21 21 dBm Tx Antenna Gain 0 2 2 dBi Body Loss 3 0 0 dB EIRP 18 23 23 dBm Receiver - Node B Node B Noise Figure 3 dB Thermal Noise -108 dBm Uplink Load 50 % Interference Margin 3.0 dB Interference Floor -102.0 Service Eb/No 4.4 2 2 dB Service PG 25.0 17.8 17.8 dB Receiver Sensitivity -122.6 -117.8 -117.8 dB Rx Antenna Gain 18.5 18.5 18.5 dBi Cable Loss 2 2 2 dB Benefit of using MHA 2 2 2 dB UL Fast Fade Margin 1.8 1.8 1.8 dB UL Soft Handover Gain 2 2 2 dB Building Penetration Loss 12 12 12 dB Indoor Location Prob. 90 90 90 % Indoor Standard Dev. 10 10 10 dB Slow Fade Margin 7.8 7.8 7.8 dB Isotropic Power Required -121.5 -116.7 -116.7 dB Allowed Prop. Loss 139.5 139.7 139.7 dB
  16. 16. HSDPA’s Effect on Uplink Coverage Service PS Data PS Data PS Data PS Data Service Rate 16 64 128 384 kbps Transmitter - Handset Max Tx Power 24 24 24 24 dBm HS-DPCCH Overhead 4.6 2.8 1.6 1.1 dB Tx Antenna Gain 2 2 2 2 dBi Body Loss 0 0 0 0 dB EIRP 21.4 23.2 24.4 24.9 dBm Receiver - Node B Node B Noise Figure 3.0 dB Thermal Noise -108.0 dBm Uplink Load 50.0 % Interference Margin 3.0 dB Interference Floor -102.0 dBm Service Eb/No 2.5 2 1.4 1.7 dB Service PG 23.8 17.8 14.8 10.0 dB Receiver Sensitivity -123.3 -117.8 -115.4 -110.3 dB Rx Antenna Gain 18.5 18.5 18.5 18.5 dBi Cable Loss 2 2 2 2 dB Benefit of using MHA 2 2 2 2 dB UL Fast Fade Margin 1.8 1.8 1.8 1.8 dB UL Soft Handover Gain 2 2 2 2 dB Building Penetration Loss 12 12 12 12 dB Indoor Location Prob. 90 90 90 90 % Indoor Standard Dev. 10 10 10 10 dB Slow Fade Margin 7.8 7.8 7.8 7.8 dB Isotropic Power Required -122.2 -116.7 -114.3 -109.2 dB Allowed Prop. Loss 143.6 139.9 138.6 134.1 dB
  17. 17. BIUL - Noise Rise is referred as the increase in receiver noise floor when a system is more loaded. 0 2 4 6 8 10 12 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 Load InterferenceincreaseDI[dB] E.g. 20%=0,97dB, 50%=3dB where Q is the uplink system loading UL Noise Rise
  18. 18.  Maximum Pathloss (Okumura-Hata) Lpath = A - 13.82log(ha) + (44.9 - 6.55log(ha))logR - a(hm) [dB] Where the following A values are valid for 2050 MHz: A = 155.1 in urban areas ha base station antenna height [m = 147.9 in suburban and semi–open areas hm UE antenna height [m] = 135.8 in rural areas R distance from transmitter [km] = 125.4 in open areas a(1.5) = 0  Range R = 10, where:  = [Lpath - A + 13.82logHb]/[44.9 - 6.55logHb]  Use Walfish Ikegami if cell range <1km Calculating Cell Range
  19. 19. 2 3 2 3 RArea= 2 3 8 9 RArea= RSite to Site 3= 2 3 2 3 RArea= R RR R3=Site to SiteR 2 3 =Site to Site Calculating Site Distances
  20. 20.  Transmitter (RBS) is in a single point, Receivers (Terminals) are distributed in the cell  DL coverage and capacity are not only dependent on the number of terminals, but also on their distribution in a cell and their relative position towards other cells Downlink Dimensioning
  21. 21. Downlink Service Service Speech CS Data PS Data PS Data PS Data Service Rate 12.2 64 64 128 384 kbps Transmitter - Node B Max Tx Power (Total) 43 dBm Max Tx Power (per Radiolink) 34.2 37.2 37.2 40.0 40.0 dBm Cable Loss 2 2 2 2 2 dB MHA Insertion Loss 0.5 0.5 0.5 0.5 0.5 dB Tx Antenna Gain 18.5 18.5 18.5 18.5 18.5 dBi EIRP 50.2 53.2 53.2 56.0 56.0 dBm Receiver - Handset Handset Noise Figure 8 dB Thermal Noise -108 dBm Downlink Load 80 % Interference Margin 7.0 dB Interference Floor -93.0 Service Eb/No 7.9 5 5 4.7 4.8 dB Service PG 25.0 17.8 17.8 14.8 10.0 dB Receiver Sensitivity -110.1 -105.8 -105.8 -103.1 -98.2 dBm Rx Antenna Gain 0 2 2 2 2 dBi Body Loss 3 0 0 0 0 dB DL Fast Fade Margin 0 0 0 0 0 dB DL Soft Handover Gain 2 2 2 2 2 dB MDC Gain 1.2 1.2 1.2 1.2 1.2 dB Building Penetration Loss 12 12 12 12 12 dB Indoor Location Prob. 90 90 90 90 90 % Indoor Standard Dev. 10 10 10 10 10 dB Slow Fade Margin 7.8 7.8 7.8 7.8 7.8 dB Isotropic Power Required -90.5 -91.2 -91.2 -88.5 -83.6 dB Allowed Prop. Loss 140.6 144.4 144.4 144.5 139.6 dB
  22. 22. Uplink v/s Downlink
  23. 23. HSDPA Dimensioning  Average cell throughput – What is the expected average HSDPA capacity?  Cell border throughput – What is the expected HSDPA cell border throughput?  Decided by: – Signal Attenuation, Lsa – Power left for HSDPA
  24. 24. HS-DSCH power calculation  Treated as true best effort in dimensioning – Will take whatever power that is left in RBS after common channels and dedicated channels has taken their part – No ”headroom” is needed time Power Max cell power CCH power HS-SCCH power Admission control threshold HS-DSCH power DCH power
  25. 25. HS-DSCH power calculation (2)  PHS-DSCH calculated as: DCHASCCHHSDCHCCHreftotDSCHHS PPPPPP  = , Power needed by DCH RABs (PS & CS) RBS power at Tx reference point Common Channel Power (CPICH, BCH, etc.) High-Speed Shared Control Channel power Power needed for A-DCH on DL
  26. 26. Traffic estimation • The traffic estimation requires information related to the network topology, subscribers & traffic: • Cell Area from Coverage Dimensioning • Subscriber density from Marketing • Subscriber traffic profile from Marketing Basic Traffic Model Air Interface Dimensioning Channel Card Dimensioning Iub Dimensioning + Topology Subscribers Subs densityCell area Traffic / subscriber Traffic / cell Traffic / site
  27. 27. Load Calculation: Uplink Load   jjb j j NE RW L  1 / / 1 1 0  = = = N j jUL L 0  νj: Activity factor; for Speech some 67% due to VAD/DTX; for Data: 1 Load Lj of subscriber with Service j ηUL total Cell Load Activity Factor Processing Gain 0 2 4 6 8 10 12 14 16 18 10 20 30 40 50 60 70 80 90 95 98 loading/% loss/dB InterferenceMargin[dB] UL = 30 – 50 % Cell Load [%] Load Calculation Formulas in analogy to H. Holma “WCDMA for UMTS”
  28. 28. Inter-Cell Interference: Little i – In the real environment we will never have separated cell. Therefore, in the load factor calculation the other cell interferences should be taken into account. – This can be introduced by means of the Little i value, which describes how much two cells overlap (bigger overlapping  more inter-cell interferences) Iother ceinterferencellown ceinterferencellother =i Inter-Cell Interference Ratio “Little i”     == j jjb jj jUL NE RW iLi   1 / / 1 1 )1()1( 0
  29. 29. Uplink Load calculation • Simplified UL load equation  UL DCH capacity – for 1 service type j only – W/Rj >> (Eb/No)j • Nj: No. of Trunks • Nj x Rj = Cell Throughput = Capacity [kbps] j jb jjUL RW NoE Ni / )/( )1(  =
  30. 30. Downlink Load calculation Cell Type α Macro Cell 0.4 – 0.9 Micro Cell > 0.9
  31. 31. Load Calculation Examples – Load factor for different services has to be calculated separately, total load is then the sum of different services in the cell area – UL/DL single connection load examples are shown in the table below – For example 50 % UL load means on average 50 speech users or about 9 64 kbits/s users/cell in a 3-sector (1+1+1) configuration Services UL Fractional Load DL Fractional Load 12.2 kbit/s 0,97% 1,00% 64 kbits/s 4,80% 6,21% 128 kbits/s 8,56% 11,07% 384 kbits/s 22,89% 29,59% Total Load 37,22% 47,87%
  32. 32. Planning Tasks – Scrambling Code Planning – Neighbour List Planning – Location, Routing and UTRAN Registration Area Planning
  33. 33. 34 • ALLOCATION CRITERIA – Additional conditions on Ec/Io – Reuse distance – SC domain assigned to the cell – Number of scrambling codes per cluster • ALLOCATION STRATEGIES – Clustered • Use a minimum number of clusters – Distributed per Cell • Use as many clusters as possible – One Cluster per site AUTOMATIC ALLOCATION 7.SCRAMBLINGCODEPLANNING Cluster = Scrambling Code Group
  34. 34. 35 • EXAMPLES OF ALLOCATION STRATEGIES AUTOMATIC ALLOCATION CLUSTERED DISTRIBUTED PER CELL ONE CLUSTER PER SITE
  35. 35. Planning Tasks – Scrambling Code Planning – Neighbour List Planning – Location, Routing and UTRAN Registration Area Planning
  36. 36. Introduction • There are the following types of neighbor lists • Intra-frequency (3G to 3G) • Inter-frequency (3G to 3G) • Inter-system • 3G to 2G • 3G to LTE • Neighbor lists are usually refined during pre-launch or post- launch optimization • Neighbor list planning should be as accurate as possible • Impact upon pre-launch optimization has to be recognized • Pre-launch optimization often limited to specific drive route which may not identify all neighbors • Neighbor list tuning usually achieves the greatest gains during pre-launch optimization • High quality neighbor lists are essential for a good performance of the network Intra- frequency Inter- frequency Inter- system 3G to 2G Inter- system 3G to LTE
  37. 37. CPICH Ec/Io SC100 SC200 Drop Cell Selection Time Missing neighbours can be identified from UE log files: 1) Decrease of CPICH Ec/Io until connection drops 2) Then sudden improvement after cell selection Example: SC200 missing from neighbour list associated with SC100 UE movement Intra-Frequency Neighbors (3G to 3G) (1/2) • Used for cell re-selection, SHO, softer handover & intra-frequency HHO • Missing neighbors • Poor signal to noise ratio (EC/I0) • UEs transmitting with high power close to neighboring site, but not served by it • Excessive number of neighbors • Increase of UE measurement time • May lead to deletion of important neighbors during soft handover • Intra-frequency neighbor lists are transmitted in SIB11 & dedicated measurement control messages
  38. 38. • When a UE is in SHO the neighbor lists belonging to each of the active set AS cells are combined • Neighbor lists are combined for both intra-RNC & inter-RNC SHO • The RNC generates a new intra-frequency neighbor list after every AS update procedure (events 1a, 1b & 1c) • The RNC transmits the new intra-frequency neighbor list to the UE if the new list differs from the existing one • 3GPP allows the network to specify max. of 32 intra-frequency cells for the UE to measure (1-3 AS cells + 29- 31 neighbors) Priorities for generating combined neighbor lists AS cells Neighbor cells common to 3 AS cells Neighbor cells common to 2 AS cells Neighbor cells defined for only 1 AS cell Active set update Intra-Frequency Neighbors (3G  3G) (2/2) AS: Active Set
  39. 39. Inter-Frequency IF Neighbors (3G to 3G) (1/2) • Used for IF cell re-selection & inter-frequency HHO • Following procedures are not supported: • IF handover from Cell_FACH • IF handover while anchoring at an RNC • Missing neighbors: • UE cannot escape bad actual carrier • Poor signal to noise ratio (EC/I0) and / or coverage (RSCP) • Excessive number of neighbors • Increase of UE measurement time • May lead to selection of non optimum target cell • IF neighbor lists are transmitted in SIB11 and dedicated measurement control messages • IF neighbors are usually introduced after network launch; refining them is a post launch optimization task IF: Inter-Frequency
  40. 40. Inter-frequency neighbour list Inter-Frequency Neighbors (3G to 3G) (2/2) • When a UE is in intra-RNC SHO the neighbor lists belonging to each of the active set cells are combined • Neighbor lists are not combined for Inter-RNC SHO (no support of inter-frequency neighbor signaling across Iur) • The RNC generates a new inter-frequency neighbor list after an active set update procedure, if compressed mode CM is not running • In CM the neighbor list valid at the time to trigger the hard handover is taken • NSN allows the network to specify a max. of 32 inter-frequency cells for the UE to measure per carrier, and a max. of 48 cells for all carriers Priorities for generating combined neighbor lists • Neighbor cells which are common to 3 AS cells • Neighbor cells which are common to 2 AS cells • Neighbor cells which are defined for only 1 AS set cell AS: Active Set
  41. 41. Inter-System Neighbors (3G to 2G) (1/2) • Used for cell re-selection and (hard) handover towards 2G • GSM neighbor list can be based upon existing BSC 2G neighbor list if 3G and 2G sites are co-sited • If an operator has both GSM900 and DCS1800 networks then inter-system neighbors can be defined only for GSM900 or only for DCS1800 • The following procedures are not supported • Inter-system handover from Cell_FACH • Inter-system handover while anchoring at an RNC • Missing neighbors • UE cannot escape bad actual carrier • Poor signal to noise ratio (EC/I0) and / or coverage (RSCP) • Excessive number of neighbors • Increase of UE measurement time • May lead to selection of non optimum target cell • Inter-system neighbor lists are transmitted in SIB11 and dedicated measurement control messages •The RNC instructs the UE to measure all GSM neighbors (RSSI), but to verify the BSIC for one specific neighbor only Just like Inter- frequency
  42. 42. Inter-System Neighbors (3G to 2G) (2/2) • When a UE is in intra-RNC SHO the neighbor lists belonging to each of the active set cells are combined • Neighbor lists are not combined for inter-RNC SHO (no support of inter-system neighbor signaling across Iur) • The RNC generates a new inter-system neighbor list after an active set update procedure, if compressed mode is not running • In compressed mode the neighbor list valid at the time to trigger the HHO is taken • 3GPP allows the network to specify a maximum of 32 inter-system cells for the UE to measure Priorities for generating combined neighbor lists • Neighbor cells which are common to three active set cells • Neighbor cells which are common to two active set cells • Neighbor cells which are defined for only one active set cell Inter-system neighbour list
  43. 43. Maximum Neighbor List Length (1/2) • SIB11 is used to instruct the UE which cells to measure in RRC Idle, CELL_FACH & CELL_PCH • According TS 25.331 contradiction about SIB11 • Should be able to accommodate information regarding 96 cells Intra- frequency Inter- frequency Inter- system 3G to 2G Inter- system 3G to LTE
  44. 44. Maximum Neighbor List Length (2/2) • Enables transmission of all defined neighbors • 32 intra-frequency • 32 inter-frequency • 32 inter-system (both to 2G and LTE together) Urban Suburban 3G intra-freq Rural 3G inter-freq inter-sys 3G to 2G 14 10 10 14 10 10 16 12 12 Typical Neighbor List Lengths • Neighbor list lengths are scenario dependant, e.g. • Simple layering (two or more carriers serving the same coverage area) • Hierarchical cell structure (macro umbrella cells and underlying micro cells) • Typical values
  45. 45. Planning Tasks – Scrambling Code Planning – Neighbour List Planning – Location, Routing and UTRAN Registration Area Planning
  46. 46. Node B MSC UE RNC Iu cs SGSN Single RRC Connection Iu ps CS state PS state CS state PS state Two Iu Signalling Connections Core Network Service States • To describe the presence of a UE within the core network, each service domain (CS or PS) uses independently the following state machine • Detached (UE not registered) • Idle (UE registered, but no Iu signaling connection exists • Connected (UE registered and Iu signaling connection exists) • In idle and connected mode the core network has to track the location of a UE • Location area LA used by CS domain • Routing area RA used by PS domain • Both LA and RA are handled by the non access stratum NAS layer within the core network and the UE • The position of the UE has to be updated • Idle mode  if UE moves to another LA or RA • Connected mode  if UE moves to another cell or UTRAN registration area
  47. 47. • Identification of LA • Globally using a Location Area Identification (LAI) • LAI: concatenation of Mobile Country Code (MCC), Mobile Network Code (MNC) & Location Area Code (LAC) • The cells of a LA can belong to • One or several RNC • Just to a single MSC/VLR • The size of a LA can range between • Single cell (minimum) • All cells connected to a single VLR (maximum) • The mapping between LA and its associated RNCs is handled by the MSC/VLR • The mapping between LA and its cells is handled by the RNC Location Area 2 Bytes for LAC 00 00 and FF FE values reserved Almost 65536 LAC values per PLMN VLR area LA3 LA2 LA1
  48. 48. • Identification of LA • Globally using a Routing Area Identification (RAI) • A LAI is a concatenation of Location Area Identification (LAI) & Routing Area Code (RAC) • The cells of a RA can belong to • One or several RNC • Just to a single SGSN • Just to a single LA • The size of a RA can range between • Single cell (minimum) • All cells belonging to a single LA (maximum) • The mapping between RA and its associated RNCs is handled by the SGSN • The mapping between RA and its cells is handled by the RNC 1 Byte for RAC 256 RAC values per of LA Routing Area LA split into several RAs RA2 RA1 LA1 LA3 RA3 LA identical with RA
  49. 49. Paging Capacity • NSN RAN provides either a 8 kbps or 24 kbps PCH transport channel on the S-CCPCH • One page message has a size of 80 bits and is transmitted within 10 ms (1 radio frame) • With 8 kbps PCH thus 100, with 24 PCH 300 UEs can be paged per second • In practice in most cases the 8 kbps PCH clearly is sufficient Trade Off Between Paging and LA/RA Update • Number of cells per LA/RA: to be designed as compromise between signaling traffic  paging and  LA/RA update Small LA/RA • Less page traffic, as page messages transmitted to fewer cells • More LA/RA updates, as more cells at LA/RA borders • Optimum design if network dominated by slow moving UEs Large LA/RA • More page traffic, as page messages transmitted to more cells • Less LA/RA updates, as less cells at LA/RA borders • Optimum design if network dominated by fast moving UEs Splitting of LA into several RA • Usually LA and RA are planned to be identical • Splitting of LA into smaller RAs needed only in case of high PS page traffic
  50. 50. Design of LA/RA Borders • 2G LA/RA borders often good starting point of 3G LAs/RAs, as usually already optimized • To avoid large number of LA/RA updates, borders should not • Go parallel to major roads / railway lines • Traverse areas of high subscriber density • To verify success of LA/RA update procedure, LA/RA borders should cross clusters defined for drive test LA1 LA2 Road
  51. 51. • A LA/RA can have both 2G and 3G cells • Requires unique 2G and 3G Cell Identities (CI) and Cell Global Identities (CGI) • A CGI is a concatenation of Location Area Identification (LAI) and Cell Identity (CI) • CN not able to distinguish between 2G & 3G network for paging purpose  both 2G & 3G paging appears on both the 2G & 3G network • Less probable that UE misses paging message when it completes inter-system cell re-selection • But increased paging traffic on both systems and coordinated cell identities needed • In practice implementation of the same location areas for 2G & 3G may be difficult • 2G & 3G network often have different coverage area • Not all sites are co-sited LA/RA with both 2G and 3G Cells
  52. 52. UE States  Idle mode – No connection to radio network (No RRC connection established) – This minimizes resource utilization in UE and the network  CELL_FACH mode – User Equipment (UE) in Connected Mode (has an RRC Connection to radio network) – UE uses the common transport channels RACH or FACH – If the parameter interFreqFDDMeas Indicator = 1, the UE will evaluate cell reselection criteria on inter-frequency cells (0)  CELL_DCH mode – User Equipment (UE) in Connected Mode (has an RRC Connection to radio network) – UE uses dedicated channels for transmitting data and signalling
  53. 53. System Information  System parameters are broadcast on BCCH. It has information regarding Idle Mode Behaviour.  The System Information elements are broadcast in System Information Blocks (SIB’s). Each SIB contains a specific collection of information.
  54. 54. Idle mode Functions  PLMN Selection  Cell Selection and Reselection  Location Area (LA) and Routing Area (RA) updating  Paging  System Information Broadcast
  55. 55. PLMN Selection  PLMN selection performed upon power on or upon recovery from lack of coverage  If there is no last registered PLMN, or if it is unavailable, the UE will try to select another PLMN “AUTOMATICALLY” or “MANUALLY” depending on its operating mode  Manual mode – UE displays all PLMNs (allowed and not allowed) by scanning all frequency carriers – The user makes a manual selection and the UE attempts registration on the PLMN  Automatic mode – Each PLMN in the user-controlled PLMN list in the USIM, in order of priority – Each PLMN in the operator-controlled PLMN list in the USIM – Other PLMNs according to the high-quality criterion  Roaming – Roaming is a service through which a UE is able to obtain services from another PLMN – The UE in Automatic mode, having selected and registered a Visited PLMN (VPLMN) periodically attempts to return to its Home PLMN (HPLMN) according to a timer. Default = 30mins
  56. 56. Start Stored Information Cell selection Initial Cell Selection Cell selection when leaving connected mode Connected mode In Automatic mode, new PLMN selection Camped on an Acceptable cell (Limited Service) Camped Normally Cell Reselection Process No suitable cell found Suitable cell found Location registration failed Measurements evaluation Suitable cell selected No suitable cell found No suitable cell found Suitable cell found Cell selection and reselection procedure
  57. 57. Cell Selection  UE looks for a suitable cell in the selected PLMN and camps on to it  Cell search procedure – UE acquires slot synchronization using P-SCH – It acquires frame synchronization using S-SCH – Primary scrambling code is obtained from CPICH  UE then monitors the paging and system information, performs periodical radio measurements and evaluates cell reselection criteria  Strategies used for the cell selection process: – Initial Cell Selection: UE has no knowledge of the WCDMA radio channels  UE scans all WCDMA radio frequency channels to find a suitable cell with the highest signal level and read BCCH  The PLMN is determined from the mcc and mnc in the MIB in BCCH – Stored Information Cell Selection: UE knows the carrier frequencies that have previously been used
  58. 58. Cell Selection Parameters  For cell selection criteria the UE calculates Squal = Qqualmeas - qQualMin (for WCDMA cells) Srxlev = Qrxlevmeas - qRxLevMin – Pcompensation (for all cells) Where Pcompensation = max(maxTxPowerUL – P,0) P is output power of UE according to class  Cell selection criteria (S criteria) is fulfilled when Squal>0 ( for WCDMA cells only) and Srxlev>0  Recommended values qQualMin= -19dB qRxLevMin= -115dBm maxTxPowerUL = 24
  59. 59. Cell Reselection  Allows UE’s to move between cells in idle and cell_FACH connected mode  Always camp on the best cell the UE performs the cell reselection procedure in the following cases: – When the cell on which it is camping is no longer suitable – When the UE, in “camped normally” state, has found a better neighbouring cell than the cell on which it is camping – When the UE is in limited service state on an acceptable cell
  60. 60. Cell Reselection Parameters  UE ranks available cells using R criteria R(Serving) = Qmeas(s) + qHyst(s) R(Neighbour) = Qmeas(n) – qOffset(s,n) Qmeas is the quality value of the received signal – Derived from the averaged received signal level for GSM cells – Derived from CPICH Ec/Io or CPICH RSCP for WCDMA cells depending on the value of qualMeasQuantity (2, Ec/Io) qHyst(s) = qHyst1 when ranking based on CPICH RSCP (4) qHyst(s) = qHyst2 when ranking based on CPICH Ec/Io (4) qOffset(s,n) = qOffset1sn when ranking based on CPICH RSCP qOffset(s,n) = qOffset2sn when ranking based on CPICH Ec/Io The above two values are 0 for WCDMA cells and 7 for GSM cells
  61. 61. Cell Reselection Measurements Serving cell Neighbour 1 Neighbour 2 QHyst1 Qoffset1sn 3 2 1 tReselection Measurement Quantity ranking ranking ranking 2 1 2 1 3 3 Neighbour 1 is the new serving cell
  62. 62. Location and Routing Area updating  Location Area = The area to which the Core Network sends a paging message for circuit switched.  Routing Area = The area to which the Core Network sends a paging message for packet switched.  If the Location Area Identity (LAI) or Routing Area Identity (RAI) read on system information is different to the one stored on the USIM, the UE performs a LA or RA registration update  Three types of registration update – Normal – Periodic – according to T3212, T3312 – IMSI attach/detach - used if att = 1 (1)  UE sends “attach” or “detach” messages when the UE is powered on or off
  63. 63. Paging  Two types of paging – Core Network informs a UE of a terminating service request – RAN informs all UE’s that the system information has been modified  Paging messages sent to all UE’s in LA or RA – Discontinuous Reception: UE listens to PICH at predefined times only – Discontinuous Reception (DRX) cycle = (2^k) * 10 (ms) where k = cnDrxCycleLengthCs (7) for CS and cnDrxCycleLengthPs (7) for PS

×