3g Optimization

1. Part 2:
UMTS Planning

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. 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. 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. 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. 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. 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. 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. 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. 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. System Reference Point

12. Eb/No vs BLER
Eb/No = 1 dBA
Eb/No = 6 dBB
A BER > B BER

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. 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

16. 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

17. 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

18. 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

19.  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

20. 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

21.  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

22. 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

23. Uplink v/s Downlink

24. 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

25. 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

26. 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

27. 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

28. 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”

29. 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

30. 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(  =

31. Downlink Load calculation
Cell Type α
Macro Cell 0.4 – 0.9
Micro Cell > 0.9

32. 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%

33. Planning Tasks
– Scrambling Code Planning
– Neighbour List Planning
– Location, Routing and UTRAN Registration Area
Planning

34. 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

35. 35
• EXAMPLES OF ALLOCATION STRATEGIES
AUTOMATIC ALLOCATION
CLUSTERED
DISTRIBUTED
PER CELL
ONE
CLUSTER
PER SITE

36. Planning Tasks
– Scrambling Code Planning
– Neighbour List Planning
– Location, Routing and UTRAN Registration Area
Planning

37. 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

38. 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

39. • 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

40. 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

41. 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

42. 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

43. 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

44. 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

45. 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

46. Planning Tasks
– Scrambling Code Planning
– Neighbour List Planning
– Location, Routing and UTRAN Registration Area
Planning

47. 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

48. • 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

49. • 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

50. 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

51. 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

52. • 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

53. 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

54. 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.

55. Idle mode Functions
 PLMN Selection
 Cell Selection and
Reselection
 Location Area (LA) and
Routing Area (RA)
updating
 Paging
 System Information
Broadcast

56. 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

57. 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

58. 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

59. 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

60. 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

61. 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

62. 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

63. 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

64. 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