umts radio path and transmissionnew

1. 1 © NOKIA
UMTS Radio Path and TransmissionUMTS Radio Path and Transmission

2. 2 © NOKIA
Topics
• Quick review of air interface technologies (optional topic)
• The WCDMA (Air/Uu) interface and its properties
• Radio resource management introduction
• Appendix: Overview of UMTS-TDD solution (optional topic)
• Appendix: Low Chip rate TDD mode (TD-SCDMA, optional
topic)
• Appendix: Briefly about issues related to network planning
(optional topic)

3. 3 © NOKIA
Module objectives
After completing this module, the participant should be able to:
• Explain the terms carrier, spreading, power, FDD, cell
characteristics, channelisation code, and scrambling code.
• List and identify the structure of the UMTS air interface. The
student should be capable of following a model and explaining
what is happening to data at every phase in the Uu interface for
the UMTS-FDD implementation.
• List and clearly explain the key functions and tasks in radio
resource management. These are admission, code, power,
handover, and diversity control.
without using any references if not otherwise stated).

4. 4 © NOKIA
Power (P)
Frequency (f)
Time
Now, image if all the users
shared the same frequency, at
the same time.
Radio path basics (review)
Frequency 2 - Channel 2
Frequency 1 - Channel 1
Frequency 3 - Channel 3
Frequency 4 - Channel 4
FDMA - Frequencies are allocated
one per user.
f1 - Ch 1 f1 - Ch 2 f1 - Ch 3 f1 - Ch 4
f2 - Ch 1 f2 - Ch 2 f2 - Ch 3 f2 - Ch 4
f3 - Ch 1 f3 - Ch 2 f3 - Ch 3 f3 - Ch 4
f4 - Ch 1 f4 - Ch 2 f4 - Ch 3 f4 - Ch 4
TDMA - Several users share the
same frequency, only divided by
time.
f
t
How do you determine the
different users?
(spreading
) codes
By allocating each channel a
unique code, known as the
spreading code.
What is the W in WCDMA?
There is no limit - Its origin is from that the European & Japanese
interfaces have a higher bandwidth than their US CDMA counterpart!

5. 5 © NOKIA
Basic WCDMA theory (review)
Frequency
Band
duration
(Spreading
Factor)
Power
WCDMAOriginating Bit Received Bit

6. 6 © NOKIA
Variable slices are allocated (review)
Frequency
5MHz
Power
Time
Users Separated by
Codes
High bit rate user
Low bit rate user

7. 7 © NOKIA
IMT-2000 frequency allocations
2200 MHz20001900 1950 2050 2100 21501850
JapanIMT-2000
PHS
IMT-2000
ITU
Mobile
Satellite
IMT-2000 IMT-2000
Europe
UMTS
(FDD)
DECT
UMTS(TDD)
GSM
1800
UMTS(TDD)
UMTS
(FDD)
USA
PCS
unlicensed
PCSPCS
UMTS(TDD)IMT-2000(TDD)
Mobile
Satellite
Mobile
Satellite
Mobile
Satellite
Mobile
Satellite
Mobile
Satellite
Mobile
Satellite
Mobile
Satellite

8. 8 © NOKIA
UMTS-FDD and -TDD modes
Guard
Period
f
t
Uplink
Downlink
Bandwidth 5MHz
Uplink Downlink
Bandwidth 5MHz
Separation 190MHz
f
t Bandwidth 5MHz

9. 9 © NOKIA
Air interface structure
Channel Coding
TxRAKE
Signalling Data
Channels
Radio Framing
Spreading &
Channelisation
Scrambling
Modulation
Air interface
SMSSMS
define the UE actions
The user data is coded,
depending on the
applicationThe specifications
1 Different channels carry
different information
2
Data is coded, framed,
spread and channelised
The signal is now
scrambled
3
The signal is modulated
on a frequency to
represent binary values4
The UE uses a special
receiver to RAKE through
the air interface
5

10. 11 © NOKIA
Modulation
Bit combinations in Radio Path:
'10'
135°
'00'
45°
'11'
225°
'01'
315°
Rx
Tx
QPSK
OQPSK
Node B
UE
DataData

11. 12 © NOKIA
Basic WCDMA terminology
5 M H z
3 .8 4 M H z
f
WCDMA Carrier (in one direction)
Frequency
Time
DS = Direct Sequence
CDMA Sequencing Principles

12. 13 © NOKIA
WCDMA frame structure
f
t
Middlepoint of
WCDMA Carrier
WCDMA Frame 10 ms
15 slots, each of them 2/3 ms

13. 14 © NOKIA
Channelisation and scrambling codesDOCUMENTTYPE 1 (1)
eUnitOrDepartmentHere
eYourNameHere TypeDateHere
Channelisation code Scrambling code
Usage Uplink: Separation of physical data and
control channels from the same terminal
Downlink: Separation of downlink
dedicated user channels
Uplink: Separation of terminals
Downlink: Separation of sectors (cell)
Length Variable (depends on the user allocation) Fixed
Number
of codes
Depends on the spreading factor (SF) Uplink: Several millions
Downlink: 512

14. 15 © NOKIA
Where are codes used?
In the Uplink (UE →
Node B), the user's data
and signalling
information is separated
by Channelisation
Codes
data
signalling
In the Downlink (Node
B→UE), cells are seperated
by Scrambling Codes
In the Uplink (UE → Node
B), terminals are separated
by Scrambling Codes
In the Downlink (Node B →
UE), user connections are
separated by Channelisation
Codes
Dedicated User Channel
Channel Coding
TxRAKE
Air interface
Signalling Data
Call set-up,
SMS etc.
messages
Voice, video
and other
user data
Channels
Radio Framing
Spreading &
Channelisation
Scrambling
Modulation

15. 16 © NOKIA
Code
-1
Data x
Code
Code
Data
+1
+1
+1
+1
+1
-1
-1
-1
-1
ChipChip
DespreadingDespreading
Uu
WCDMA terminology - Chips & Symbols
Bits (In this drawing, 1 bit = 8 Chips)
Rate
matched
baseband
Data
Scrambling

16. 17 © NOKIA
Spreading
SF = 1 SF = 2 SF = 4
ch,1,0= (1)
ch,2,0 = (1,1)
ch,2,1 = (1,-1)
ch,4,0=(1,1, 1, 1)
ch,4,1 = (1,1,-1,-1)
ch,4,2 = (1,-1,1,-1)
ch,4,3 = (1,-1,-1,1)
Data (Baseband, Channel Coded & Rate-Matched)
Spread and Combined with Channelisation Code
Data is Spread...
…by a certain factor. The channelisation code
is selected based upon how much the data is
spread

17. 18 © NOKIA
Channelisation and scrambling
SF = 1 SF = 2 SF = 4
ch,1,0= (1)
ch,2,0 = (1,1)
ch,2,1 = (1,-1)
ch,4,0=(1,1, 1, 1)
ch,4,1 = (1,1,-1,-1)
ch,4,2 = (1,-1,1,-1)
ch,4,3 = (1,-1,-1,1)
Data (Baseband, Channel Coded & Rate-Matched)
Spread and Combined with Channelisation Code
Data is Spread...
…by a certain factor. The channelisation code
is selected based upon how much the data is
spread
Data
Channelisation Code Scrambling Code
Downlink Example
Bit rate Chip rate Chip rate

18. 19 © NOKIA
Spreading Factor = Processing Gain
B
B
G
Bearer
Uu
p
=
FactorSpreading
RateSymbolBearer
RateChipSystem
==

19. 20 © NOKIA
Code sets
P r im a r y S c r a m b lin g C o d e
S e c o n d a r y S c r a m b lin g C o d e # 1
S e c o n d a r y S c r a m b lin g C o d e # 2
S e c o n d a r y S c r a m b lin g C o d e # 1 5
C h a n n e lis a tio n C o d e S e t ( 2 5 6 C o d e s )
C h a n n e lis a tio n C o d e S e t ( 2 5 6 C o d e s )
C h a n n e lis a tio n C o d e S e t ( 2 5 6 C o d e s )
C h a n n e lis a tio n C o d e S e t ( 2 5 6 C o d e s )
P r im a r y S c r a m b lin g C o d e
S e c o n d a r y S c r a m b lin g C o d e # 1
S e c o n d a r y S c r a m b lin g C o d e # 2
S e c o n d a r y S c r a m b lin g C o d e # 1 5
C h a n n e lis a tio n C o d e S e t ( 2 5 6 C o d e s )
C h a n n e lis a tio n C o d e S e t ( 2 5 6 C o d e s )
C h a n n e lis a tio n C o d e S e t ( 2 5 6 C o d e s )
C h a n n e lis a tio n C o d e S e t ( 2 5 6 C o d e s )
- 5 1 2 C o d e S e t s x 1 6 S c r a m b lin g C o d e s = 8 1 9 2 C o d e s n u m b e r e d f r o m 0 .. . 8 1 9 1 a v a ila b le

20. 21 © NOKIA
Channelisation code tree
SF = 1 SF = 2 SF = 4
ch,1,0 = (1)
ch,2,0 = (1,1)
ch,2,1 = (1,-1)
ch,4,0 = (1,1,1,1)
ch,4,1 = (1,1,-1,-1)
ch,4,2 = (1,-1,1,-1)
ch,4,3 = (1,-1,-1,1)

21. 22 © NOKIA
Receiving signals at the UE
UE listening to
several Node Bs
Attached Node B
Path of user

22. 23 © NOKIA
Simplified diagram of the RAKE Receiver
Delay
Code used
for the
connection
Rx
Output
Finger
t
Cell-x
Cell-x
Cell-x
Cell-y
Rx
Rx
Rx
Finger
Finger
Finger
Delay
Delay

23. 24 © NOKIA
Channel coding, rate matching
• 1/2 and 1/3 rate convolutional channel coding and
turbo coding will be implemented.
• Rate matching is used to "fit" the data bit rate so that it
corresponds to the pre-defined fixed bit rates of the
air interface. Also puncturing can be used.
Rate
Matching
- Convolutional coding
- Interleaving
Baseband data (n kb/s)
- 30 kb/s
- 60 kb/s
- 120 kb/s
- 240 kb/s
- 480 kb/s
- 960 kb/s

24. 25 © NOKIA
Channel Organisation in UMTS
UE
Node B
RNC
Logical channels
content is organised in separate channels, e.g.
user data, paging information, radio link control information
Transport channels
logical channel information has to be organised (e.g. in time)
before it is physically transmitted
Physical channels
(frequency band &
spreading code)
Frames
transmission organised
based via the Iub
interface

25. 26 © NOKIA
The dedicated user traffic for one user service in the downlink direction is sent through the
Dedicated Traffic Channel.
DS-WCDMA-FDD = Direct Sequencing, WCDMA Frequency Division Duplex. Suitable for
outdoor use, and will be the first implementation in 3G. In the Case of DS, data is spread over the
band as a function of time.
In the DS-WCDMA-FDD model, there are 3 layers. The first and top-most layer are the logical
channels, which carry specific information per channel.
DS-WCDMA-FDD Channels
The network must inform the UE about the radio environment, the information consists of codes,
power levels, neighboring information and etc.. The information for the UE is carried in the
Broadcast Control Channel.
When there is need to reach the mobile station, the network pages the UE on the Paging Control
Channel.
All common actions that the network must perform for all UE's in a cell are managed in the
Common Control Channel. Common Traffic Channel is for traffic for all (or a specified group of)
UEs in the cell
When there is a dedicated, active connection, the network sends control information through the
Dedicated Control Channel.
In the Uplink direction, there are the Common Control Channel, Dedicated Traffic Channel and
the Dedicated Control Channel.
The second level is known as the Transport Channels. In some cases, a transport channel may
contain one or more logical channels.
The BCCH and PCH Transport Channels carry their respective logical channels (Broadcast and
Paging Channels).
The FACH (Forward Access Channel) carries information (when specified by RNC) from the
common and dedicated control channels.
The DCH (Dedicated Channel) is the only dedicated transport channel, the rest are common.
One DCH channel, may carry one or more DTCH.
In the Uplink, and as in GSM, the RACH (Random Access Channel) carries initial access
information when required.
The Common Packet Channel is used to carry packet(s), providing the common resources of the
system are used for this purpose.
The final layer use in the channels, is known as the physical channels. These are the channels
that are present on the air-interface of a cell.
The Network Synchronisation information is carried in the Synchronisation Physical Channel.
This channel is created in Node B, so it does not need any logical or transport channels.
There are 2 Common Control Physical CHannels, primary and secondary. The primary carries
the cell information, whereas the secondary carries other common control information.
The DPCH (Dedicated Physical Channel) is a multiplexed combination of the DPDCH (dedicated
user traffic) and the DPCCH (dedicated signaling channel)..
The Physical Random Access CHannel carries the RACH data.
The user's traffic and signaling information is divided in the uplink direction between the DPDCH
and DPCCH physical channels.
Downlink Uplink
Logical
Channels
BCCH PCCH DCCH DTCH CCCH DTCH DCCH
Transport
Channels
BCH PCH DCH DCH
RAC
H
CPCH
Physical
Channels
SCH1/2
(created
in Node
B)
CCPCH-1 CCPCH-2 PRACHDPDCHDPCCH
CCCH CTCH
FACH DSCH
PDSCH PCPCH
DPCH
(DPDCH+DPC
CH)
When sending short packets, and a dedicated channel is not needed, then they are sent on the
PCPCH (Physical Common Packet Channel).
DTCH is a point to point channel dedicated
to one UE for transfer of the user information
PDSCH is a downlink shared channel for user data.
t carries the DSCH transport channel which is controlled
On a frame by frame basis thus allowing for variation in bitrates

26. 27 © NOKIA
FDD-mode: Logical and Transport Channel
DL
BCCH
Broadcast Control Channel,
(system information)
PCCH
Paging Control Channel
(paging & notification)
CCCH
Common Control Channel
(control information without
RRC connection)
DCCH
Dedicated Control Channel
(power control, TFI, etc.)
DTCH
Dedicated Traffic Channel
(user data)
Logical Channels (content)
BCH
Broadcast Channel,
PCH
Paging Channel
FACH
Forward Access Channel
DSCH
Downlink Shared Channel
DCH
Dedicated Channel
Transport Channels
dedicated
transport
channels
common
transport
channels

27. 28 © NOKIA
FDD-mode: Logical and Transport Channel
UL
CCCH
Common Control Channel
(control information without
RRC connection)
DCCH
Dedicated Control Channel
(power control, TFI, etc.)
DTCH
Dedicated Traffic Channel
(user data)
Logical Channels (content)
RACH
Random AccessChannel
CPCH
Common Packet Channel
DCH
Dedicated Channel
Transport Channels
dedicated
transport
channels
common
transport
channels

28. 29 © NOKIA
Downlink transport to the physical channel
mapping
SCH-1/SCH-2
(created in
NodeB)
BCCH
BCH
PCCH
PCH
CCPCH-1
CCCH
FACH
CCPCH-2
DCCH
(DPDCH+DPCCH)
DTCH Logical Channels
Transport Channels
Physical ChannelsDPCH
CTCH
DCH DSCH
PDSCHSCH-1/SCH-2
(created in
NodeB)
BCCH
BCH
PCCH
PCH
CCPCH-1
CCCH
FACH
CCPCH-2
DCCH
(DPDCH+DPCCH)
DTCH Logical Channels
Transport Channels
Physical ChannelsDPCHDPCH
CTCH
DCH DSCH
PDSCH

29. 34 © NOKIA
FDD-mode: Physical Channel
UE Node B
Downlink DPDCH
& DPCCH
Uplink DPDCH
Uplink DPCCH
Slot Slot Slot DPDCH
Dedicated Physical Data Channel
DPCCH
Dedicated Physical Control Channel

30. 35 © NOKIA
Physical uplink mapping
C C C H
P R A C H
R A C H
D T C H
D P D C H
D C H
D C C H
D P C C H P C P C H
C P C H
L o g ic a l C h a n n e ls
T r a n s p o r t C h a n n e ls
P h y s ic a l C h a n n e ls

31. 38 © NOKIA
Radio Resource Management
Iub Iu
Iur
I
n
t
e
r
f
a
c
e
U
n
i
t
s
I
n
t
e
r
f
a
c
e
U
n
i
t
s
(Wideband)
Switching
Control
Units
Radio
Resource
Management
O&M
Interface
to/from Network
Management
to/from
other
RNCs
to/from
Core
Network
to/from
the BSs
• Radio Resource Control (RRC)
• Admission Control
• Code Allocation
• Power Control
• Handover Control and Macro Diversity

32. 39 © NOKIA
Radio Resource Management functions
PC
HC connection
based
functions
LC
AC network
based
functions
PS
RM
• Packet Scheduler - PS
• Resource Manager - RM
• Admission Control - AC
• Load Control - LC
• Code Allocation
• Power Control - PC
• Handover Control, Macro
Diversity
- HC

33. 40 © NOKIA
RRC states
Idle
mode
Connected Mode
Cell DCH
URA PCH
Cell PCH
Cell FACH

34. 41 © NOKIA
Management of channels in RRC
RLC RLC RLC
RRC
signalling
CS RAB
(speech)
PS RAB
(data)
MAC
L1
Iub/IurMAC for
Common
Channels
• Segmentation
• Retransmission across the air
• Ciphering of NRT data
• Buffering
Iu
2. Transport channels
3. Physical Channel(s) (Radio)
1. Logical Channels
RLC: Radio Link Control
MAC: Medium Access Control
• Selection of the data to be inserted
in the Radio Frame
• Selection of common or dedicated channels
• Multiplexing of logical channels into
same transport channels
• Ciphering for RT

35. 42 © NOKIA
Admission Control
R a d io A c c e s s B e a r e r s
in U u I n t e r f a c e
U u In te rfa c e B a n d w id th
S I R - A llo w e d R a n g e
A d m is s io n C o n tr o l
Interference Margin (dB) and Load Factor
0
5
10
15
20
25
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Load Factor
InterferenceMargin(dB)






−
⋅=
FactorLoad
LogI
_1
1
10

36. 43 © NOKIA
TRHO_threshold
Prx_target
Prx_target_BS
UL interference power
Load
Planned load area
Marginal load area
planned uplink
interference power
Defines the limit (the first UL overload threshold) for
the UL interference power, after which the BTSBTS
starts its load control actions to prevent overload.
Prx_offset
Uplink Admission Control
Prx_target defines the optimal operating point of the cell interfernce power, up to which
the Admission Control of the RNC can operate.

37. 44 © NOKIA
Code allocation
CELL 1 CELL 3CELL 2
1. Scrambling codes
2. Channelisation codes
full code set / cell
SUBS2SUBS1

38. 45 © NOKIA
Scrambling code planning
• 512 DL scrambling codes are used, 8 in each of the 64 code groups.
• All cells that MS is able to measure should have different scrambling codes.
1. Use different scrambling code groups in the neighbouring base
stations.
2. Probably code group allocation will be done in network planning.
Functionality needed in the network planning tool, which reminds
of frequency planning in GSM planning tools.
3. The re-use factor could be 64 as there are 64 code groups. The
scrambling code group planning for different carriers can be done
independently. It is for further studies, whether or not more
optimisation would be needed.

39. 46 © NOKIA
Tree of orthogonal short codes in
downlink• Hierarchical selection of short codes from a "code tree" to maintain orthogonality.
• Several long scrambling codes can be used within one sector to avoid shortage of short codes.
C1(0) = [ 1 ]
C2(0) = [ 1 1 ]
C2(1) = [ 1 0 ]
C4(0) = [ 1 1 1 1 ]
C4(1) = [ 1 1 0 0 ]
C4(2) = [ 1 0 1 0 ]
C4(3) = [ 1 0 0 1 ]
C8(0) = [ 1 1 1 1 1 1 1 1 ]
C8(1) = [ 1 1 1 1 0 0 0 0 ]
. . .
. . .
Spreading factor:
SF = 1 SF = 2 SF = 4 SF = 8
C8(2) = [ 1 1 0 0 1 1 0 0 ]
C8(3) = [ 1 1 0 0 0 0 1 1]
. . .
. . .
C8(4) = [ 1 0 1 0 1 0 1 0 ]
C8(5) = [ 1 0 1 0 0 1 0 1 ]
. . .
. . .
C8(6) = [ 1 0 0 1 1 0 0 1 ]
C8(7) = [ 1 0 0 1 0 1 1 0 ]
. . .
. . .
Example of
code allocation

40. 47 © NOKIA
Power control
Node B
P1 P2
Open Loop Power Control (Initial Access)
Closed Loop Power Control
Outer Loop Power Control
Node B RNC

41. 48 © NOKIA
Packet Scheduler
• A non-real time call constitutes of a bursty sequence of packets.
• In the downlink, the Packet Scheduler decides which channel to use, DCH or FACH.
• The load target can be reached by scheduling the transmission of NRT packets .
time
packet service session
packet call
reading time
packet size packet arrival interval

42. 49 © NOKIA
Handover types
CN
RNC
MSC
BSC
GSM900/1800GSM900/1800
WCDMA FDDWCDMA FDD
Inter-SystemInter-System
Intra-SystemIntra-System
WCDMA TDDWCDMA TDD
Inter-SystemInter-System

43. 50 © NOKIA
Active cells and soft handovers
CN
RNC
fram
e reliability info
frame reliability info
frame
selection /
duplication
BS1 BS2
Soft handover window
P
2) Add BS2
1) Connection to BS1
3) Drop BS1
4) Connection to BS2

44. 51 © NOKIA
Handover types
Soft
Handover
4
Hard/Inter-Frequency Handover
Softer Handover
Inter-System Handover
Node B
Frequency
f1
Frequency
f1
Frequency
f1
Frequency
f2
UMTS GSM900/1800
Sector 1
f1
Sector 2
f1
Sector 3
f1
Multipath Signal
through Sector 1
Multipath Signal
through Sector 3
Frequency
f1
Frequency
f1
RNC RNC
Iur
Iub Iub
Node B
Node B Node B
Node B
Node B
Node B
Node B BTS

45. 52 © NOKIA
GSM BCCH or
SACHH
System information
GSM SACHH Measurement
Report
Resource
Reservation
Resource Reservation
acknowledge and Handover
command
GSM DCCH Inter-system Handover
command
DCCH/DCH Handover to UTRAN
complete
Node B
UMTS GSM900/1800UMTS GSM900/1800
Intersystem handover from GSM
UE GSM BSS MSC UTRAN
Release resources

46. 53 © NOKIA
Node B
BCCH system information
or
DCCH measurement
control
DCCH/DCH measurement
report
Resource
Reservation
Resource Reservation
acknowledge and Handover
command
DCCH Inter-system Handover command
GSM DCCH Handover Access
UMTS GSM900/1800UMTS GSM900/1800
Intersystem handover from UTRAN
UE GSM BSSMSCUTRAN
Release resources
RNC

47. 54 © NOKIA
Micro Diversity control
Node B
Receiver
(RAKE)
Same signal propagating different
ways in the Radio Path
Summed signal
Uplink Direction (Micro) Diversity Point

48. 55 © NOKIA
Macro Diversity in the RNC
Node B
Node B
Node B
RNC
RNC
Macro Diversity Point
Core
Network
Active
Set

49. 56 © NOKIA
Handover control
Measurement
Reports
Handover
Algorithm:
Criteria fulfilled?
- Activate new BTS
- Update Active Set
Measurement Phase
Decision Phase
Execution Phase
- Signal Strength
- Quality
- Interference
YES
NO
Created & collected
by the UE and the BTS
Investigated by the RNC
Commanded by the RNC,
performed by the UE
Procedure: Functional Split:

50. 57 © NOKIA
Logical description of Load Control
• The purpose of load control is to optimise the capacity of a
cell and prevent overload situation.
• Load control consists of Admission Control (AC) and Packet
Scheduler (PS) algorithms, and Load Control (LC), which
updates the load status of the cell based on resource
measurements and estimations provided by AC and PS.
LC
AC
PS
NRT load
Load change
info
Load status

51. 58 © NOKIA
Load Control
• Load Control's (LC) task is to make sure that the system is not
overloaded and remains stable.
• LC can be divided into two functions:
• 1. Preventive control = Guards the system from overload.
• 2. Overload control = Returns the system from a overload state
to normal
state in a fast and controlled way.
• Since interference is the main resource criteria for CDMA, the
load control measures:
• UL total received wideband interference power
• DL total transmission power
• Periodically under one RNC on cell basis.
• Radio Resource Manager (RRM) acts according to these
measurements and parameters set by Radio Network
Planning.

52. 59 © NOKIA
The restriction of CDMA system is
interference
The more transmission power
is required to achieve certain
quality
The further away
users are connected
The more users
that are connected
Finally the capacity is filled

53. 60 © NOKIA
• The traffic can be divided into two groups:
Real Time (RT) and Non-Real Time (NRT).
• Thus some slide of capacity must be reserved for the RT traffic
for mobility purposes all the time. The proportion between RT
and NRT traffic varies all the time.
Capacity
Time
Overload
Load Target
Overload Margin
Power
Estimated capacity for
NRT traffic.
Measured load caused
by non-controllable load

54. 61 © NOKIA
A d m is s io n
C o n t r o l
L o a d
C o n t r o l
P a c k e t
S c h e d u le r
P r x T a r g e t o r
P t x T a r g e t
P r x T a r g e t + P r x O f f s e t o r
P t x T a r g e t + P t x O f f s e t
P r x T h r e s h o ld o r
P t x T h r e s h o ld
P _ C e llM a x
N o a c t io n s
P S in c r e a s e s t h e
a m o u n t o f N R T
b e a r e r s
A C a d m it s R T
b e a r e r s n o r m a lly
N o a c t io n s
L o a d p r e v e n t iv e L C
a c t io n s
O v e r lo a d a c t io n s
A C d o e s n o t a d m it
n e w b e a r e r s
A C d o e s n o t a d m it
n e w b e a r e r s
P S d e c r e a s e s t h e
b it r a t e s a n d d r o p s
N R T b e a r e r s
P S d e c r e a s e s t h e
b it r a t e s o f N R T
b e a r e r s
P S d o e s n o t
in c r e a s e N R T lo a d ,
b u t c a n c h a n g e
N R T b it r a t e s
P o w e r
L o a d
Summary

55. 62 © NOKIA
3G-UMTS Radio Path & Transmission Key
Points 1
• UMTS FDD & TDD
• WCDMA Carrier 5 MHz (3,84 MHz)
• Direct Sequencing
• Codes: Channelisation Code:
— Spreading
— Separation of user connections
Scrambling Code:
— Separation of users (UL)
— Separation of cells (DL)
• SF= Spreading Factor
• If SF=low => Bit Rate=high + Power=high
• If SF=high => Bit Rate=low + Power=low
• 3 layers of channels: Logical, Transport & Physical

56. 63 © NOKIA
3G-UMTS Radio Path & Transmission Key
Points 2
• Receiver in UE and BS: Antimultipath RAKE receiver
• Radio Resource Management in RNC:
• Radio Resource Control => States: Idle & Connected
• Admission Control => SIR
• Code Allocation
• Power Control => Open Loop, Closed Loop & Outer
Loop
• Handover Control and Macro Diversity
=> Soft, Softer, Hard & Inter System
• Cell Breathing:
• Cell capacity and coverage are related.

57. 64 © NOKIA
3G/UMTS Radio Path & Transmission
Review Questions

58. 65 © NOKIA
1. In UMTS, there are two methods used for transport through the
air interface. The first is UMTS-FDD. What is the second one?
a. TDD, Time Doubled Division
b. CDD, Code Division Duplex
c. TDD, Time Division Duplex
d. CDD, Code Divided Data
2. Which of the following sentences best describes the phenomenon
called cell breathing?
a. When more capacity is used, the cell spreads in size.
b. When more capacity is used, the cell shrinks in size.
c. The cell will adjust its size in line with the furthest users. For example, if the
user is
5 km away, the cell is 5 km. If the user is 2 km away, the cell is 2 km.
d. Cell breathing is the height of the cell: from 2 - 3 km towards the atmosphere.
Review (1/8)

59. 66 © NOKIA
3. There are two types of codes used in WCDMA. These are the
channelisation and scrambling codes. Why are the scrambling
codes used?
a. To separate downlink physical channels in a cell.
b. To separate user data and signalling in the network.
c. As security to check if the User Equipment (UE) is not stolen.
d. To separate different cells in the downlink direction.
4. In UMTS, there are three layers of channels (logical, transport
and physical). Which of the following is not a physical channel?
a. BCCH
b. CCPCH
c. DPCH
d. DPDCH
Review (2/8)

60. 67 © NOKIA
5. Which of the following statements about channelisation is true?
a. The lower the bit rate, the more data can be spread.
b. Before spreading, an error-protection code needs to be added to the
baseband data to ensure a safe path through the air interface.
c. The channelisation code is added as part of the spreading function.
d. The channelisation code depends on the spreading factor used.
e. All of the above.
6. What type of modulation is used in UMTS?
a. GMSK
b. QPSK
c. 8PSK
d. BPSK
Review (3/8)

61. 69 © NOKIA
7. For which of following tasks is the RAKE receiver not responsible?
a. Multipath Propagation Delay
b. Listening to surrounding BTSs
c. Channel coding
d. Speech coding
8. Which of the following is a true statement about Admission Control?
a. The UEs handle resource allocation.
b. The RNC makes the decision of resource allocation, based upon
interference.
c. The RNC will not limit the number of the users on a cell.
d. As more users are allocated a code, the load on a cell remains the same.
Review (4/8)

62. 70 © NOKIA
9. The RNC is responsible for the allocation of codes. Which of the following
sentences (only one) is true?
a. Each cell has a scrambling code that acts like a cell ID.
b. Channelisation codes are dependent upon the subscribers' identity.
c. Scrambling codes are generated randomly.
d. Scrambling codes are used in channelisation.
10. When a mobile is in idle mode, which of the following power controls is
used?
a. Closed loop power control
b. Outer loop power control
c. Internal loop power control
d. Open loop power control
Review (5/8)

63. 72 © NOKIA
11. Select the right handover type.
1. Soft 2. Softer 3. Hard
4. Inter-system 5. Not possible
a. Sector 1 to Sector 2 (same BTS)
b. BTS x to BTS y
c. RNC to RNC with Iur interface
d. RNC to RNC with no Iur interface
e. UMTS-FDD to UMTS-TDD
f. WCDMA to GSM
g. WCDMA to IS-95
Review (6/8)

64. 73 © NOKIA
12. What is the difference between micro and macro diversity?
a. There is no difference.
b. Micro diversity is the combination of signals between the BTS and the UE,
whereas macro diversity is the combination of signals from many BTSs in the
RNC.
c. Macro diversity is the combination of signals between the BTS and the UE,
whereas micro diversity is the combination of signals from many BTSs in the
RNC.
d. Macro and micro diversity are UE-specific functions.
13. In WCDMA, what is meant by the active set?
a. A group of UEs.
b. A group of Active RNCs.
c. A group of cells communicating with a UE.
d. It is the same as a location area.
Review (7/8)

65. 75 © NOKIA
14. Which of the following sentences is true about WCDMA radio
network
planning?
a. Capacity is linked to the number of time slots.
b. Power should be as high as possible to ensure good quality.
c. Coverage and capacity are linked.
d. The size of a cell remains constant.
15. When planning the Iub Interface in UMTS, which of the
following sentences true?
a. Cellular transmission is based upon ATM.
b. GSM and UMTS sites cannot be co-located.
c. Radio links cannot be used to connect BTS together.
d. It is easy to plan the capacity requirements.
Review (8/8)

66. 80 © NOKIA
UMTS & GSM network planning
G S M 9 0 0 /1 8 0 0 : 3 G ( W C D M A ) :

67. 81 © NOKIA
Characteristic of a cell
Dedicated Channels
Common Channels
Coverage and capacity are
related. The more capacity used,
the cell shrinks. This is known as
cell breathing.

68. 82 © NOKIA
Differences between WCDMA and GSM
High bit rates
Spectral
efficiency
Different quality
requirements
Efficient
packet data
Downlink
capacity

69. 83 © NOKIA
Different UMTS cells and BTS
F1
F2
F2
F3
F3
F3
Micro BTS
Macro BTS
Pico BTSs
1 - 10 km
50 - 100 m
200 - 500 m

70. 85 © NOKIA
Power control in network planning
(Near-Far example)
S
BS
MS1
MS2
If the power of MS1 is not properly controlled
it will jam the weaker signal of MS2.

71. 86 © NOKIA
Coverage & Capacity
f1
128 kbps
64 kbps
8 kbps
f1
144 kbps
64 kbps
64 kbps
144 kbps
'Cell breathing'
The size of cell varies
according the traffic load
High load 800 kbps
→ smaller coverage
Low load 200 kbps
-> large coverage
144 kbps
64 kbps
64 kbps
• Load factor directly corresponds to the supported traffic per cell.
• More traffic means more interference → cell breathing
NOTE!
WCDMA capacity is a function of radio environment, user
mobility/location and propagation conditions. Examples above
are just examples of WCDMA cell capacities of a 3 sector
macro cell BS configuration.

72. 87 © NOKIA
Cell load
0
5
10
15
20
25
0 0,2 0,4 0,6 0,8 1
Load factor
Loss(dB)
• Max. recommended load: 70%, typically 30-50%
• 50% load means 3 dB loss in link budget

73. 88 © NOKIA
Physical layer bit rates (Downlink)
• The number of orthogonal channelisation codes = Spreading factor
• The maximum throughput with 1 scrambling code ~2.5 Mbps or ~100 full rate
speech users
Half rate speech
Full rate speech
128 kbps
384 kbps
2 Mbps

74. 89 © NOKIA
Uplink coverage of different bit rates
0
0.5
1
1.5
2
2.5
3
3.5
32 kbps 64 kbps 144 kbps 384 kbps 1024 kbps 2048 kbps
Range[km]
Suburban area with 95 % outdoor location probability
Continuous high bit rate coverage
in uplink is challenging
→Coverage solutions are important

75. 90 © NOKIA
Node BNode B
UE
UE
Cell edge
2Mbps downlink coverage
2Mbps Uplink coverage
Possible Macro cell coverage example
Approximately
2.2 Km
Approximately
1.1 Km
144Kbps Uplink coverage
Downlink 2Mbps
can be 50-100%
of cell area

76. 91 © NOKIA
Node BNode B
UE
UE
2Mbps downlink coverage
2Mbps Uplink coverage
Approximate
ly
2.2 Km
Approximate
ly
1.1 Km
144Kbps Uplink coverage
NOTE:Several assumptions combining the benefits of WCDMA
have been made to create this simplified cell example
•Cell coverage is purposely limited
•Six sectors under one Node B
•All users are evenly distrubuted over the cell area
• 3dB interference margin assumed;but other values could be tolerated
•Max Up Link output power 21dBm(125mW)
•Several types of gains assumed:
• Variable processing gains for various bitrates
• Multipath gains
• User speed less than 3Km/h
Cell performance example; approximate capacities.
Note that these numbers are alternative uses; not simultaneous
• 98 Full Rate speech users/sector supported
• 588 Full Rate speech user on the cell area
• 96 144 Kbps users supported on the full cell area
• DL 6 2Mbps users supported on 50-100 % of cell area
• UL 6 2Mbps supported on 50 % of cell area.
• UL main limitation is UE UL power
Possible Macro cell coverage example

77. 92 © NOKIA
Processing gain
Frequency (Hz)
Voice user (12,2 kbit/s)
Packet data user (384 kbit/s)
Powerdensity(W/Hz)
W
R
Frequency (Hz)
Unspread narrowband signal
Spread wideband signal
Processing Gain
G=W/R=25 dB
Powerdensity(W/Hz)
W
R
Unspread
"narrowband"
signal
Spread wideband signal
Processing Gain
G=W/R=10 dB
• Spreading sequences of
different length
• Processing gain is
dependent
on the user data rate
(User data rate) x
(spreading ratio)=
const.=W=3,84
Mcps

78. 93 © NOKIA
Distribution of load
Voice traffic Data Traffic
Soft Capacity
Capacitypercellpercarrier
More DataMore Voice
800kbps Air Interface (L1) rate50 Erlang
Not Real Time (NRT) Packet switched
• greater efficiency
• greater total capacity
Real Time (RT) circuit switched
• low predictable delay
• lower total capacity

79. 94 © NOKIA
Cellular transmission planning
RNC
BS
BS
BS

80. 95 © NOKIA
RNC capacity planning
B S S p e e c h T r a ff i c :
K b it /s / C e ll & C o d e C h a n n e l A m o u n t
B S D a t a T r a f f ic :
K b it /s /C e ll & C o d e C h a n n e l A m o u n t
P a c k e t S w it c h e d T r a f f ic :
K b it /s
C ir c u it S w it c h e d T r a f f ic :
E r la n g s [ K b it /s ]
C o n c e n t r a t io n
R N C