1. UTRA Physical Layer
November 18
Raul Bruzzone

2. Contents (I) Introduction FDD Mode Physical Channel Concept
Downlink Physical Channels
Uplink Physical Channels
Multiplexing, Coding, Spreading and Modulation
Radio Transmission and Reception
Procedures
Summary
November 18
V3.0

3. Contents (II) TDD Mode Frame Structures Physical Channels Burst Types
Transport Channels
Mapping of Transport Channels on Physical Channels
Summary
November 18
V3.0

4. Introduction
November 18
V3.0

5. UMTS Terrestrial Radio Access (UTRA) Access Modes
UTRA is able to operate on two access modes:
Frequency Division Duplex (FDD)
Time Division Duplex (TDD)
November 18
Raul Bruzzone

6. Frequency Division Duplex (FDD) Time Division Duplex (TDD)
Downlink
(fd)
Base
Station
Uplink
(fu)
In the FDD mode: fd = fu
In the TDD mode: fd = fu
User
Equipment
November 18
Raul Bruzzone

7. Implementation of FDD and TDD
Receiver
Transmitter RF
Switch
Filter
Receiver
Filter
Transmitter
Duplexer
Receiver and Transmitter operate simultaneously
When the Receiver operates, the Transmitter stops, and vice-versa
November 18
Raul Bruzzone

8. Frequency Division Duplex
(FDD)
Mode
November 18
V3.0

9. PHYSICAL CHANNEL CONCEPT
The basic Radio Resources are called “Physical Channels”.
These channels are characterized by:
Spreading Code
Carrier Frequency
Phase (with reference to the un-modulated carrier: 0 or p/2). This characteristic is only used in the Uplink.
November 18
Raul Bruzzone

10. PHYSICAL CHANNELS Classification
Physical Channels are classified in:
Downlink
Uplink
November 18
Raul Bruzzone

11. DOWNLINK PHYSICAL CHANNELS
November 18
V3.0

12. UMTS Downlink Physical Channels (FDD)
November 18
Raul Bruzzone

13. Downlink Dedicated Physical Channel
November 18
Raul Bruzzone

14. Frame Structure November 18 Raul Bruzzone DPCCH DPDCH TFCI Data 1 TPC
Pilot
NTFCI bits
Ndata1 bits
NTPC bits
Ndata2 bits N
bits
pilot
0.625 ms, 20*2 k
bits (k=0..6)
Slot #1
Slot #2
Slot #i
Slot #16 T
= 10 ms f
Frame #1
Frame #2
Frame #i
Frame #72 T
super
= 720 ms
November 18
Raul Bruzzone

15. Data Field Specifications
Reference Parameter: k
k = 0, 1, 2, 3, 4, 5, 6, 7
Total Quantity of Bits = 20 * 2k
k is related to the spreading factor (SF) of the physical channel by means of the expression:
Based on the above formula, each time slot may transport a minimum of 20 bits, and a maximum of 1280 bits.
Taking into account that the time slot length is ms, the data rate of one downlink DPDCH
November 18
Raul Bruzzone

16. Data and Control Fields
DPCCH
DPDCH
TFCI
Data 1
TPC
Data 2
Pilot
NTFCI bits
Ndata1 bits
NTPC bits
Ndata2 bits
Npilot bits
Note that there are duplicate lines for 16, 32 and 64 kbps, corresponding to the possibilities of including a TFCI field or not.
* If no TFCI, then the TFCI field is blank.
November 18
3GPP

17. Data Communication Efficiency
100 80 60
Efficiency (%) 40 20
Data Rate
(Kbps) 16 16 32 32 64 64
128
256
512
1024
2048
FDD mode efficiency is low for low data rates.
It varies from 20 to 97.5 % as the data rate increases.
Efficiency ranges from 20 to 97.5 % as the data rate increases.
November 18
Raul Bruzzone

18. Pilot Patterns Yellow Bits may be used for Frame Synchronization.
DPCCH
DPDCH
TFCI
Data 1
TPC
Data 2
Pilot
NTFCI bits
Ndata1 bits
NTPC bits
Ndata2 bits
Npilot bits
Yellow Bits may be used for Frame Synchronization.
Transmission order is from left to right.
Each two-bits pair represents an I/Q pair of QPSK modulation.
November 18
3GPP

19. Transmit Power Control Field Patterns
DPCCH
DPDCH
TFCI
Data 1
TPC
Data 2
Pilot
NTFCI bits
Ndata1 bits
NTPC bits
Ndata2 bits
Npilot bits
November 18
3GPP

20. Common Control Physical Channels
November 18
Raul Bruzzone

21. Primary Common Control Physical Channel (PCCPCH)
Used to carry the Broadcast Control Channel (BCH)
Fixed rate: 32 Kbps
Fixed Spreading Factor: 256
It is not transmitted during the first 256 chips of each Time Slot. This period is left to the Primary and Secondary Synchronization Channels.
The BCCH of UMTS is based on the same design principles of the BCCH used in GSM.
The high Spreading Factor implies a high Processing Gain and, therefore, high probability of good quality reception in bad propagation conditions.
November 18
Raul Bruzzone

22. Frame Structure November 18 3GPP
256 chips
(Tx OFF)
Data
10 bits
DATA (Ndata bits)
Pilot
8 bits
0.625 ms, 20 bits
Slot #1
Slot #2
Slot #i
Slot #16 T
= 10 ms f
Observe that the PCCCH has no TPC nor RI fields.
Frame #1
Frame #2
Frame #i
Frame #72 T
= 720 ms
super
November 18
3GPP

23. Secondary Common Control Physical Channels (SCCPCH)
Applications:
To transport the Paging Channel (PCH).
To transport the Forward Access Channel (FACH).
Number of SCCPCHs depend of Cell traffic
November 18
3GPP

24. Use of Transport-Format Channel Indicator (TFCI)
There are two types of SCCPCH:
With TFCI
Without TFCI
It is the UTRAN that determines if the TFCI should be transmitted.
It is mandatory for the User Equipment to be able to support the TFCI.
Spreading factor: SF = 256 / 2k (k = 0…6)
Data rates between 32 and 2048 kbps.
November 18
3GPP

25. Frame Structure November 18 3GPP TFCI DATA (Ndata bits) Pilot
Npilot bits N
bits
TFCI
0.625 ms, 20*2 k
bits (k = 0…6)
Slot #1
Slot #2
Slot #i
Slot #16 T
= 10 ms f
Frame #1
Frame #2
Frame #i
Frame #72 T
= 720 ms
super
November 18
3GPP

26. Secondary Common Control Channel Fields
TFCI
DATA (Ndata bits)
Pilot
Npilot bits N
bits
TFCI
November 18
3GPP

27. Differences between Primary and Secondary Common Control Physical Channels
PCCCH has a fixed rate (32 Kbps).
SCCCHs can support variable rate, based on the value of the associated Transport-Format Channel Indicator (TFCI) .
SCCCHs are only transmitted when there is data to send.
PCCCH is transmitted over the whole cell.
SCCCHs may be transmitted on narrow lobes pointed to the target UE channel (only valid for a Secondary CCPCH carrying the FACH).
November 18
3GPP

28. Synchronization Channel (SCH)
November 18
Raul Bruzzone

29. Synchronization Channel (SCH)
It is used for Cell Search.
It consists of two sub-channels:
Primary Synchronization Channel
Secondary Synchronization Channel
The PSCH uses a fixed, pre-defined Gold code.
November 18
3GPP

30. Characteristics of the Primary Synchronization Channel
Transmitted once per Time Slot.
Contents is the same in each Time Slot.
Aligned in time with the BCCH.
Un-modulated.
Spreading Factor = 256
November 18
3GPP

31. Characteristics of the Secondary Synchronization Channel (SSCH)
It consists of repeatedly transmitting a length = 16 sequence of un-modulated codes of length 256 chips.
Each Secondary Synchronization code is chosen from a set of 17 different codes of length 256.
The Secondary SCH sequence indicates which of the 32 different code the cell's downlink scrambling code belongs.
32 sequences are used to encode the 32 different code groups each containing 16 scrambling codes.
November 18
3GPP

32. Synchronization Channel Time Structure
1 Time Frame = 16 Time Slots
Primary
Synchronization
Channel (PSCH)
Secondary
Synchronization
Channel (SSCH)
1 Time Slot = 2560 Chips
256 Chips
The same code is used for all bursts of the PSCH
SSCH is a sequence of 16 different codes.
The SSCH sequence identifies the Cell Group
November 18
Raul Bruzzone

33. Interleaving of Synchronization Channel and Primary Common Control Channel
Physical Channel
(PSCH)
Data
Pilot
Data
Pilot
Primary
Synchronization
Channel (PSCH)
256 chips
256 chips
256 chips
Secondary
Synchronization
Channel (SSCH)
2560 chips
2560 chips
November 18
3GPP

34. Multiplexing of Synchronization Channels
Lower position during
256 chips per slot 1 S
SCH c p d i c s S S
To IQ modulator
DPDCH/DPCCH c
ch,1
& CCPCH c
scramb c
ch,N
November 18
ETSI

35. Physical Downlink Shared Channel (PDSCH)
November 18
Raul Bruzzone

36. Physical Downlink Shared Channel (PDSCH)
It is the physical channel that supports the Downlink Shared Channel.
It is shared by several UE by means of Code Multiplexing.
It is always associated with another physical channel.
November 18
3GPP

37. Physical Shared Channel Control Channel (PSCCCH)
November 18
Raul Bruzzone

38. Physical Shared Channel Control Channel (PSCCCH)
Contains information shared by several UE.
Its Control Information field includes TPC to be applied by the UE pool.
Detailed structure is still under development.
November 18
3GPP

39. Physical Shared Channel Control Channel (PSCCCH) Frame Structure
Slot #1
Slot #2
Slot #i
Slot #16
Frame #1
Frame #2
Frame #i
Frame #72
0.625 ms, 20*2 k
bits
Pilot N
pilot T f
= 10 ms
super
= 720 ms
CONTROL INFORMATION
November 18
3GPP

40. Acquisition Indication Channel (AICH) Page Indication Channel (PICH)
November 18
Raul Bruzzone

41. Acquisition Indication Channel (AICH)
It is a physical channel used to carry Acquisition Indicators (AI) corresponding to the signature of the Random Access Channel Preamble.
16 symbols (1 ms)
4 symbols (0.25 ms) AI
empty
AS #1
AS #2
AS #i
AS #8
One frame (10 ms)
AS: Access slot
November 18
3GPP

42. Page Indication Channel (PICH)
PICH provides Page Indicators (PI) to the User Equipment.
One PICH frame has 10 ms length.
Each frame comprises 8 access slots.
5, 10 or 20 Page Indicators may be included in an Access Slot.
20 symbols (1.25 ms)
AS #1
AS #2
AS #i
AS #8
One frame (10 ms)
November 18
AS: Access slot
3GPP

43. UPLINK PHYSICAL CHANNELS
November 18
V3.0

44. UMTS Uplink Physical Channels
Common
Dedicated
Physical Random Access Channel
Uplink Dedicated Physical Data Channels
(PRACH)
(DPDCH)
Fast Uplink Signalling Channel
(FAUSCH)
This chart shows the classification of UTRA uplink physical channels.
Physical Common Packet Channel
(PCPCH)
November 18
Raul Bruzzone

45. Uplink Dedicated Physical Data Channels
Uplink Physical Channels
Common
Dedicated
Physical Random Access Channel
Uplink Dedicated Physical Data Channels
(PRACH)
(DPDCH)
Fast Uplink Signalling Channel
(FAUSCH)
Physical Common Packet Channel
(PCPCH)
November 18
3GPP

46. Frame Structure November 18 3GPP DPDCH DPCCH 0.625 ms, 10*2
DATA
Ndata bits
DPDCH
Pilot
Npilot bits
TFCI
NTFCI bits
FBI
NFBI bits
TPC
NTPC bits
DPCCH
0.625 ms, 10*2 k
bits (k= 0..6)
Slot #1
Slot #2
Slot #i
Slot #16 T
= 10 ms f
There are two types of uplink dedicated physical channels, the uplink Dedicated Physical Data Channel (uplink DPDCH) and the uplink Dedicated Physical Control Channel (uplink DPCCH).
The uplink DPDCH is used to carry dedicated data generated at Layer 2 and above, i.e. the dedicated transport channel (DCH). There may be zero, one, or several uplink DPDCHs on each Layer 1 connection.
The uplink DPCCH is used to carry control information generated at Layer 1. The Layer 1 control information consists of:
Known pilot bits to support channel estimation for coherent detection
Transmit power-control (TPC) commands.
An optional transport-format combination indicator (TFI). The transport-format combination indicator informs the receiver about the instantaneous parameters of the different transport channels multiplexed on the uplink DPDCH.
Feedback mode transmit diversity and site selection diversity.
There is one and only one uplink DPCCH on each Layer 1 connection.
Frame #1
Frame #2
Frame #i
Frame #72 T
= 720 ms
super
November 18
3GPP

47. Data Field
DATA
Ndata bits
DPDCH
November 18
3GPP

48. Distribution of Bits in the Control Fields
Pilot
Npilot bits
TFCI
NTFCI bits
FBI
NFBI bits
TPC
NTPC bits
DPCCH
November 18
3GPP

49. Pilot Patterns
Pilot
Npilot bits
TFCI
NTFCI bits
FBI
NFBI bits
TPC
NTPC bits
DPCCH
Patterns for 5 Bits per Time Slot
Patterns are defined for 5, 6, 7 and 8 Pilot Bits per Time Slot.
Shadowed bits may be used for Frame Synchronization.
November 18
3GPP

50. Transport-Combination Format Indicator (TFCI) Field Pattern
Pilot
Npilot bits
TFCI
NTFCI bits
FBI
NFBI bits
TPC
NTPC bits
DPCCH
This field is optional: UTRAN may request its presence to the User Equipment.
If it is present, it is represented by a 32-bits word transmitted in each Frame.
The TFCI value may be negotiated between UTRAN and UE on a frame-to-frame basis.
Actual values of TFCI are not yet defined.
November 18
3GPP

51. Feedback Information Pattern
Pilot
Npilot bits
TFCI
NTFCI bits
FBI
NFBI bits
TPC
NTPC bits
DPCCH
The contents of this field is still under development.
November 18
3GPP

52. Transmit Power Control Field Patterns
Pilot
Npilot bits
TFCI
NTFCI bits
FBI
NFBI bits
TPC
NTPC bits
DPCCH
November 18
3GPP

53. Physical Random Access Channel
Uplink Physical Channels
Common
Dedicated
Physical Random Access Channel
Uplink Dedicated Physical Data Channels
(PRACH)
(DPDCH)
Fast Uplink Signalling Channel
(FAUSCH)
Physical Common Packet Channel
(PCPCH)
November 18

54. General Characteristics
Provides the UE the capability to access the Fixed Network.
Access Method is based on the Slotted Aloha principle.
Access Time Slots have 1.25 ms offset.
Access Time Slots boundaries are referred to the Broadcast Common Control Channel (BCCH) time reference.
November 18
Raul Bruzzone

55. Access Slots Timing
November 18
3GPP

56. Random Access Burst Structure
As the length:
Preamble + Idle
is equal to 1.25 ms (exactly the offset explained in the previous slide) there is no superposition of preambles coming from different UE.
This improves the capacity of the BS to differentiate messages coming from different UE.
Several Preambles are may precede the Message part.
November 18
3GPP

57. Preamble Structure Based on 16 Complex Symbols (Signature)
Each Symbol is spread by means of a 256 chips real orthogonal Gold code
There are a total of 16 possible Signatures
Complex Symbols means that each symbol has a specific I and Q component values.
November 18
Raul Bruzzone

58. Message Structure Data Data N bits Pilot TFCI Control N bits N bits T
= ms, 10*2 k
bits (k=0..3)
slot
According to the fixed set of spreading factors for the data part, the possible data rates are:
SF= 256 Rate= 16 Kbps
SF= 128 Rate= 32 Kbps
SF= 64 Rate= 64 Kbps
SF=32 Rate= 128 Kbps
Slot #1
Slot #2
Slot #i
Slot #16
Random-access messageT
= 10 ms
RACH
November 18
3GPP

59. Data and Control Fields Contents
bits
data
Pilot
TFCI
Control N
bits N
bits
pilot
TFCI
Data Field
Control Fields
November 18
3GPP

60. Fast Uplink Signalling Channel (FAUSCH) Physical Common Packet Channel (PCPCH)
Uplink Physical Channels
Common
Dedicated
Physical Random Access Channel
Uplink Dedicated Physical Data Channels
(PRACH)
(DPDCH)
Fast Uplink Signalling Channel
(FAUSCH)
Physical Common Packet Channel
(PCPCH)
FAUSCH and PCPCH will be included in the Release 2000
November 18
3GPP

61. Multiplexing, Coding, Spreading and Modulation
November 18
V3.0

62. Multiplexing of Physical ChannelsTC TC TC TC
Channel coding +
Coding +
Coding +
optional TC multiplex
interleaving
interleaving
Static rate matching
Rate
Rate
matching
matching
Inner interleaving
Interleaving
Interleaving
(inter-frame)
(optional)
(optional)
Transport-channel
multiplexing
Multiplex
Dynamic rate matching
Rate
(uplink only)
matching
Inner interleaving
(intra-frame)
Interleaving
November 18
3GPP

63. UTRA/FDD Transport Channels Coding
Convolutional
coding
Turbo
coding
Service-specific
coding
Different channel coding options are available:
* Convolutional Coding is suggested for BER=10-3 services.
* Reed Solomon + Outer Interleaving + Convolutional Coding is suggested for BER=10-6 services.
* Turbo Coding is an alternative under investigation for the previous case.
* Service specific coding is suggested to optimize the data throughput in (for example) voice and video applications.
November 18
3GPP

64. Downlink Spreading and Modulation (I)
cos( w t) I
p(t)
DPDCH/DPCCH S P c c
sin( ch
scramb w t) Q
p(t) c
: channelization code ch c
This scheme shows the signal processing performed on a downlink dedicated channel. It comprises the following stages:
Serial to parallel conversion
Double spreading (channelization and scrambling)
Pulse shaping (by means of root raised cosine filters)
I/Q modulation (Armstrong method)
: scrambling code
scramb
p(t): pulse-shaping filter (root raised cosine, roll-off 0.22)
November 18
3GPP

65. Downlink Spreading and Modulation (II)
Data and Control streams are de-interleaved by a serial-to-parallel conversion. Each output stream is applied to the I and Q paths.
I and Q paths are spreaded by a channel-specific code (Channelization Code).
I and Q paths are subsequently spreaded by a Cell-specific code (Scrambling Code).
Pulse Shaping is applied to reduce spectrum occupancy and Inter-Symbol Interference (ISI)
Pulse shaping is performed by Root Raised Cosine filters with 0.22 roll-off factor. The same type of filters are also used in the receiver side.
November 18
3GPP

66. Uplink Spreading and Modulation (I)
Channelization
codes (OVSF) c
cos( D w t) c ”
scramb I
DPDCH c’
(optional)
Real
p(t)
scramb
I+jQ c
sin( w t) C Q
Imag
DPCCH * j
p(t) c ,c
: channelization codes D C c’
: primary scrambling code
scramb
c’’
: secondary scrambling code (optional)
scramb
p(t): pulse-shaping filter (root raised cosine, roll-off 0.22)
November 18
3GPP

67. Uplink Spreading and Modulation (II)
Data information (DPDCH) uses the I-path.
Control information (DPCCH) uses the Q-path.
Independent spreading codes (Channelization Codes) are used for the I and Q paths.
A UE-specific spreading code (Scrambling Code) is subsequently applied.
November 18
V2.0Raul Bruzzone

68. Radio Transmission and Reception Characteristics
November 18
V3.0

69. Basic Characteristics Valid for Region 1 (Europe) and 3 (Asia) *
Frequency Bands:
1920 to 1980 MHz (Uplink)
2110 to 2170 MHz (Downlink)
RF Carrier Spacing:
5 MHz
RF Channel Raster:
200 KHz
Power Control Rate:
1600 Cycles per Second
* Region 2 (Americas) is not yet defined.
November 18
3GPP

70. User Equipment Transmitter Characteristics
This slide presents specifications of the User Equipment. Similar specifications apply to the Base Station (see corresponding standard ).
Frequency Stability
The UE modulated carrier frequency shall be accurate to within ±0.1 PPM compared to carrier frequency received from the BS. These signals will have an apparent error due to BS frequency error and Doppler shift. In the later case, signals from the BS must be averaged over sufficient time that errors due to noise or interference are allowed for within the above ±0.1 PPM figure.
Note: The slide presents only the most relevant specifications. For a more detailed description, refer to the corresponding standard.
November 18
3GPP

71. User Equipment Receiver Characteristics
A Bit Error Rate (BER) equal or less than must be achieved
under the following situations:
PCCPCH: Primary Common Control Physical Channel
DPCH: Dedicated Physical Channel
PN: Pseudo Noise
November 18
3GPP

72. Procedures
November 18
V3.0

73. Power Control Procedures
November 18
Raul Bruzzone

74. Uplink Power Control Open Loop Procedure
This Power Control mechanism is used to select the transmission power to be used by the UE in the Random Access Channel (RACH).
In order to avoid Rayleigh fading, the ME measures the received power at the Primary CCPCH and makes an average estimate.
Path Loss is calculated as the difference between the BS emitted power (whose value is broadcasted in the BCCH) and the measured received power.
The level of uplink interference at the BS is also known by the UE because it is broadcasted by the BS in the BCCH.
November 18
Raul Bruzzone

75. Uplink Power Control Outer Loop Procedure
This procedure is implemented by the UE in order to define the reference for the closed loop mechanism (see next chart).
Suitable procedures for estimating the connection quality and consequent target S/I are still under development.
November 18
Raul Bruzzone

76. Uplink Power Control Closed Loop Procedure
BASE STATION
PROCEDURE
MOBILE STATION
PROCEDURE
ESTIMATE
RECEIVED
DPCCH
DECREASE
POWER
DTPC dB
DOWN
TPC ?
ESTIMATE
TOTAL
UPLINK
RECEIVED
INTERFERENCE UP
INCREASE
POWER
DTPC dB No
Yes
TPC
DOWN
TPC UP
SIREST>SIRTARGET
November 18
Raul Bruzzone

77. Downlink Power Control Outer Loop Procedure
This procedure is implemented by the BS in order to set the target S/I for the closed loop procedure (see next slide).
Suitable procedures for estimating the connection quality and consequent target S/I are still under development.
November 18
Raul Bruzzone

78. Downlink Power Control Closed Loop Procedure
MOBILE STATION
PROCEDURE
BASE STATION
PROCEDURE
DECREASE
POWER
DTPC dB
ESTIMATE
RECEIVED
DPCCH
DOWN
TPC ? UP
ESTIMATE
TOTAL
UPLINK
RECEIVED
INTERFERENCE
INCREASE
POWER
DTPC dB No
Yes
TPC
DOWN
TPC UP
SIREST>SIRTARGET
November 18
Raul Bruzzone

79. Cell Search Procedures (I) Initial Cell Search (Attachment)
ACQUIRE
Frame Synchronization
Timing
RECEIVE
Primary
Synchronization
Channel
ACQUIRE
Base Station
Scrambling Code
SELECT
Strongest
Base Station
DETECT
Primary Common
Control Channel
RECEIVE
Secondary
Synchronization
Channel
This procedure is implemented in the UE in order to select the most appropriate cell to camp on.
ACQUIRE
Super Frame
Synchronization
IDENTIFY
Base Station
Code Group
READ
Broadcast Control
Channel
November 18
Raul Bruzzone

80. Cell Search Procedures (I) Idle and Active Modes Cell Search
READ
Base Stations
Priority List
SEARCH
Base Station
See details in next slide
These procedures are implemented in the UE during the Idle and Active modes.
Reasons for activating this procedure are the following: Due to the movement of the UE or increasing interference in its neighbourhood, it may require to select a new cell with which an acceptable quality communication might be set up. No
Base Station
Acquired ?
Yes
END
Search
November 18
Raul Bruzzone

81. Cell Search Procedures (II) Idle and Active Modes Cell Search
Base Station
ACQUIRE
Frame Synchronization
Timing
READ
Broadcast Control
Channel
RETURN
DETECT
Primary Common
Control Channel
ACQUIRE
Super Frame
Synchronization
November 18
Raul Bruzzone

82. Random Access Procedure
SELECT
Spreading Factor for Message Part
WAIT
ESTIMATE
Downlink Path Loss
ACQUIRE
Base Station
Synchronization
Yes
Time-out ?
CALCULATE
Uplink Transmit Power
READ
Broadcast Common Control Channel Information No No
Received BS
ACK ?
SELECT
(randomly) an Access Slot
Time Out is a waiting period for the reception of the Base Station ACK.
SELECT
Preamble Spreading Code
Yes
END
TRANSMIT
Random Access Burst
SELECT
Message
Spreading Code
November 18
V2.0Raul Bruzzone

83. Handover Procedures
November 18
Raul Bruzzone

84. Soft Handover (I)
During Soft Handover, two or more Base Stations are used to simultaneously communicate with the same Mobile Station.
These Base Stations form the Active Set.
All Active Set Base Stations use the same RF Carrier Frequency.
Each Active Set Base Station maintains its own Scrambling Code.
November 18
Raul Bruzzone

85. Soft Handover (II): Active Set Update
PROCEDURE
MONITOR
other Base Stations in current Carrier
REPORT
to Network those BS above threshold
UPDATE
Active Set
MEASURE
corresponding Signal Strengths
RECEIVE
Update Messages from the Network
This is a periodic procedure performed at the Mobile Station during Active Mode (the mode during on-going communication).
November 18
Raul Bruzzone

86. Softer Handover
It is the special case of Soft Handover in which Active Set Base Stations are part of the same physical site.
Softer Handover allows more efficient combining implementations than Soft Handover (e.g. to use Maximal Ratio Combining instead of Selection Combining).
November 18
V2.0Raul Bruzzone

87. Inter-frequency Handover (I)
In Inter-frequency Handover, the RF carrier frequency changes.
It is used in the following situations:
Handover between cells using different RF carrier frequencies.
Handover between overlapping cells.
Handover between different Operators and/or Systems (e.g. UMTS/GSM).
November 18
Raul Bruzzone

88. Inter-frequency Handover (II) Hierarchical Cell Structures
Hierarchical Cell Structures (HCS) are set of cells geographically co-located, but using different RF carriers.
Inter-frequency Handover is required in HCS.
November 18
European Commission

89. Inter-frequency Handover (III) Mobile Implementation
Slotted Mode
Two strategies are suggested:
Slotted Mode (see right)
Dual Receivers.
November 18
ETSI

90. Physical Layer Description (FDD) Summary (I)
UMTS-FDD is a Code Division Multiple Access (CDMA) system.
The Spreading Factor associated to each channel may be independently selected.
Cells are characterized by a specific spreading code (Scrambling Code).
Communication Sessions are also characterized by a specific spreading code (Channelization Code).
Pilot Symbols are used to allow coherent detection of QPSK signals and spreading codes.
November 18
Raul Bruzzone

91. Physical Layer Description (FDD) Summary (II)
In the downlink, two synchronization channels (primary and secondary) are regularly transmitted to allow attachment of the mobile stations.
Moreover, a broadcast channel (BCCCH) is regularly transmitted in order to provide to the mobile stations, information about specific parameters from the Cell.
In order to avoid the Near-Far Effect, UMTS incorporates 3 Power Control mechanisms: Open, Outer and Closed Loops.
Soft Handover is used when a mobile station migrates between Cells operating at the same carrier frequency.
November 18
Raul Bruzzone

92. Time Division Duplex (TDD) Mode
November 18
V3.0

93. TDD Frame Structure 16 Time Slots (TS) 1 Time Slot = 2560 chips
frequency
10 ms
4.096
Mchip/s
625 µs
time
16 Time Slots (TS)
1 Time Slot = 2560 chips
Each TS may be used in Uplink or Downlink
At least one TS must be used in Uplink
At least one TS must be used in Downlink
November 18
Raul Bruzzone

94. Single Switching Point Frames
10 ms
Symmetric DL/UL Allocation
10 ms
Asymmetric DL/UL Allocation
November 18
3GPP

95. Multiple Switching Point Frames
10 ms
Symmetric DL/UL Allocation
10 ms
Asymmetric DL/UL Allocation
November 18
3GPP

96. Use of CDMA in the TDD Mode (TD-CDMA Concept)
1 Time Frame = 10 ms
code 8 . . . .
code 1
1 TS = 625 µs
TDD mode traffic capacity is increased by means of superimposing several signals in the same Time Slot.
Each Signal differs from the other in the use of a separate Spreading Code.
In general, up to 8 signals may be code-multiplexed.
November 18
3GPP

97. Transport Channels and Physical Channels
Concepts of
Transport Channels and Physical Channels
Layer 2
Layer 2
Transport
Channel
Transport
Channel
Layer 1
Processing
Layer 1
Processing
Layer 1
This slide illustrates the concepts of Transport and Physical channels, for the case of an uplink communication.
Physical
Channel
User
Equipment
UTRAN
November 18
Raul Bruzzone

98. TDD Transport Channels
Common
Dedicated
Broadcast Channel
Dedicated Channel
(DCH)
(BCH)
Paging Channel
ODMA Dedicated Channel
(ODCH)
(PCH)
Forward Access Channel
(FACH)
Synchronization Channel
(SCH)
This chart shows the classification of UTRA uplink physical channels.
Downlink Only
Random Access Channel
Uplink Only
(RACH)
Uplink / Downlink
ODMA Random Access Channel
(ORACH)
November 18
Raul Bruzzone

99. TDD Physical Channels Physical Channels Common Dedicated
Common Control Physical Channel
Dedicated Physical Channels
(DPCH)
(CCPCH)
Physical Synchronization Channel
(PSCH)
Physical Random Access Channel
(PRACH)
This chart shows the classification of UTRA uplink physical channels.
Downlink Only
Uplink Only
Uplink / Downlink
November 18
Raul Bruzzone

100. TDD Burst Types Burst Type 1 Burst Type 2 November 18 Raul Bruzzone
This mode has two possible type of bursts.
Each burst is specially optimized for different applications.
November 18
Raul Bruzzone

101. Dedicated Physical Channels Burst Types Application
Burst Type 1 has a longer Midamble. Therefore it allows a more accurate multi-user detection, as is required in the Uplink.
Burst Type 2 has a shorter Midamble, and therefore, higher User Data throughput. It is more suitable for the Downlink, which will require more capacity in, e.g. Wireless Internet applications.
November 18
Raul Bruzzone

102. Common Control Physical Channels
Used to transport the BCH, PCH and FACH.
Burst type is the same as for the Dedicated Physical Channels (DPCHs)
November 18
Raul Bruzzone

103. Physical Random Access Channels
These channels support the bursts send by UEs in order to signal their presence to the Base Station of the cell where they intend to camp on.
As bursts are randomly sent, a certain risk of collision in the same Time Slot exists.
As each access burst has its own Spreading Code (8 different options), the risk of collision is significantly reduced.
November 18
Raul Bruzzone

104. Physical Random Access Channels Access Bursts
Two types of Random Access Bursts are specified.
Each Burst uses only 1/2 Time Slot.
The UE may send both bursts in a single Time Slot, thereby increasing the probability of reaching the Base Station without collision.
Extended GP
Data
Midamble GP
625 µs
312.5 µs
Access Burst 1
Access Burst 2
November 18
3GPP

105. Physical Synchronization Channel (PSCH)
It has a similar structure as in the FDD mode. Two code sequences are periodically broadcasted:
Primary Synchronization Code (Cp)
Secondary Synchronization Code (Cs)
In each Frame, two Time Slots are allocated for the Primary Synchronization Channel: TS0 and TS7.
November 18
3GPP

106. Physical Synchronization Channel (PSCH) Internal Burst Structure
November 18
3GPP

107. Mapping of Transport Channels on Physical Channels
November 18

108. Mapping of BCH, PCH and FACH on CCPCHs
Layer 2
Layer 2
FACH
PCH
BCH
BCH
PCH
FACH
Radio
Interface
Layer 1 Processing
CCPCH
Layer 1 Processing
In this slide, each BCH, PCH and FACH are mapped on independent CCPCHs.
This may be only required if the PCH or FACH traffics in the particular cell are very high. In other cases, a single CCPCH may support several Transport Channels.
Layer 1 Processing
CCPCH
Layer 1 Processing
Layer 1 Processing
CCPCH
Layer 1 Processing
User Equipment
UTRAN
November 18
Raul Bruzzone

109. Mapping of DCHs and ODCHs on DPCHs
Layer 2
Layer 2
DCH
DCH
Radio
Interface
DCH
DCH
ODCH
PCH
ODCH
ODCH
Layer 1 Processing
DPCH
Layer 1 Processing
DPCH
In this slide, each BCH, PCH and FACH are mapped on independent CCPCHs.
This may be only required if the PCH or FACH traffics in the particular cell are very high. In other cases, a single CCPCH may support several Transport Channels.
Layer 1 Processing
DPCH
Layer 1 Processing
DPCH
User Equipment
UTRAN
November 18
Raul Bruzzone

110. Mapping of RACH on PRACH
Layer 2
Layer 2
RACH
RACH
Radio
Interface
Layer 1 Processing
PRACH
Layer 1 Processing
In this slide, each BCH, PCH and FACH are mapped on independent CCPCHs.
This may be only required if the PCH or FACH traffics in the particular cell are very high. In other cases, a single CCPCH may support several Transport Channels.
User Equipment
UTRAN
November 18
Raul Bruzzone

111. Mapping of ORACH on PRACH
Layer 2
Layer 2
ORACH
ORACH
Radio
Interface
Layer 1 Processing
PRACH
Layer 1 Processing
In this slide, each BCH, PCH and FACH are mapped on independent CCPCHs.
This may be only required if the PCH or FACH traffics in the particular cell are very high. In other cases, a single CCPCH may support several Transport Channels.
User Equipment
Relay Station
November 18
Raul Bruzzone

112. Mapping of SCH on PSCH User Equipment UTRAN Layer 2 Layer 2 SCH SCH
Radio
Interface
Layer 1 Processing
PSCH
Layer 1 Processing
In this slide, each BCH, PCH and FACH are mapped on independent CCPCHs.
This may be only required if the PCH or FACH traffics in the particular cell are very high. In other cases, a single CCPCH may support several Transport Channels.
User Equipment
UTRAN
November 18
Raul Bruzzone

113. Physical Layer Description (TDD) Summary
In the TDD mode, the same carrier frequency is used in the uplink and downlink.
This mode allows asymmetric communication by allocating different number of Time Slots in the uplink and downlink.
Each Time Frame contains 16 Time Slots.
Each Time Slot may allocate 8 users, that may be distinguished by different Spreading Codes.
November 18
Raul Bruzzone

114. Data Communication Protocols
coming next ...
UTRA
Data Communication Protocols
Description
November 18
Raul Bruzzone