5. UTRAN Radio Interface Protocol
L3
control
control
control
control
Logical
Channels
Transport
Channels
C-plane signalling U-plane information
PHY
L2/MAC
L1
RLC
DCNtGC
L2/RLC
MAC
RLC
RLC
RLC
RLC
RLC
RLC
RLC
Duplication avoidance
UuS boundary
BMC
L2/BMC
control
PDCP
PDCP L2/PDCP
DCNtGC
Radio
Bearers
RRC
6. Channel Types
For the radio interfaces in WCDMA system, according to different
protocol layer, channels that carry user businesses are divided into:
Logical Channel：
Directly carry user business；according to the business that carried is of
control side or user side, it is divided into two categories, control channel
and business channel.
Transportation Channel：
Describes how data is transmitted at air interface; it is the interface
between radio interface 2 and physical layer, and the services that
physical layer provided to MAC layer; Transportation channel is divided
into private channel and public channel, which are respectively used to
transmit private information to single user and public information to all
users.
Physical Channel：
The ultimate forms when all kinds of information are transmitted at radio
interface, with each form using a specific carrier frequency, code
(spreading code and scrambling code) and relative carrier phase. All these
can be considered as a specific channel.
8. Business and Functions of L1
L1 is mainly to provide data transmission service to MAC and higher
layers；
Functions of L1：
Error detection for transportation channel
Interleaving and deinterleaving of transportation channel
Multiplexing and demultiplexing from transportation channel to
CCTrCH
Encoding transportation channel speed that adapts to physical
channel
CCTrCH reflection to physical channel
Weighing and combination of physical channel
Modulation/demodulation, spreading/despreading of physical
channel
Frequency and time synchronization
Radio features measurement（FER、SIR）
Close loop power control
RF processing
9. Business and Functions of MAC
MAC business is expressed by logical channel.
MAC Functions：
Reflection of logical channel and transportation channel
Selecting proper transportation format according to real-
time speed
Priority adjustment to the data flow of a same UE
Inter-UE priority adjustment
Multiplexing and demultiplexing of the last session data
being transported at public or private transportation
channels
Business flow monitoring
Switching Type and encryption of transportation channel
Business level selection while RACH launching
10. Business and Functions of RLC
Businesses that RLC provided to upper layer：
Establishment/Release of RLC connection, transparent data
transmission, no-answer data transmission, answered data
transmission, unrecoverable error notifications, etc.
RLC Functions：
Segmentation and Reassembly
Serial connection, and PADDING
Transmission of user data
Error detection
PDU sequential delivery
Repeat detection
Flow control
Serial number detection
Protocol error detection and recovery
Data information encryption
Hang up and recovery of data transmission
11. RLC Working Mode
Transparent Mode：
No protocol overhead is added to RLC before SDU. Incorrect PDU will be
discarded or marked as error.
Transparent mode is generally used for real-time or streaming business.
No-answer mode
No retransmission mechanism, the accuracy of data transmission cannot
be ensured. While receiving, the incorrect PDU will be discarded or
marked as error. At sending end, discarding will be performed based on
time, while sending, the timed out data will be discarded.
Typical no-answer mode applications are VOIP and cell broadcast.
Answered Mode
In answered mode, ARQ is used to ensure the accuracy of data
transmission. RLC is two-way in answered mode. Information need to be
exchanged on both the direction to judge the accurate receiving of the data,
thus data will be retransmitted while failure or notification will be given to
identify if data was successfully received.
Typical answered mode business is group business, such as WEB
browsing, mail downloading, etc.
12. PDCP Functions
Reflecting network PDU from network protocol to
RLC protocol；
Header compression/decompression, to reduce
the redundancy control message in upper layer
data, and improve the efficiency of air interface；
TCP/IP ——Non-real time IP
RTP/UDP/IP in Rel4——Real time IP（e.g. VOIP）
Cache, retransmission upper layer data
Note：PDCP exists only in PS
13. RRC Functions
Broadcast management of system information；
Paging/notification；
RRC connection management (establishment,
reestablishment, maintenance and release) ；
Radio carrier management (establishment,
reconfiguration and release) to provide service to
NAS；
Mobile management of RRC connection；
Initial cell selection；
Requested Qos control and reflection to different
resources in access layer
Management and control of radio resources；
UE measurement control and measurement report.
14. High Layer PDU
RLC SDU
High Layer PDU
RLC
Header
RLC
Header
MAC SDU MAC SDU
MAC
Header
MAC
Header
Transport Block Transport Block
CRC CRC
RLC SDU
……
……
……
……
……
High Layer
L2 RLC
（Non-transparent mode）
L2 MAC
(Non-transparent mode)
L1
Segmentation
and cascading
Reassembly
Data Flow at Uu Interface
15. Physical Channel
Dedicated Physical Channel (DPCH)
Physical Random Access Channel (PRACH)
Physical Common Packet Channel (PCPCH)
Uplink Physical Channels
Secondary Common Control Physical Channel (S-CCPCH)
Common Pilot Channel (CPICH)
Primary Common Control Physical Channel (P-CCPCH)
Synchronisation Channel (SCH)
Physical Downlink Shared Channel (PDSCH)
Downlink Physical Channels
Acquisition Indication Channel (AICH)
Page Indication Channel (PICH)
Dedicated Physical Channel (DPCH)
16. Transportation Channel
Random Access Channel (RACH)
Broadcast Channel (BCH)
Paging Channel (PCH)
Forward Access Channel (FACH)
Common Packet Channel (CPCH)
Common Transport Channels
Dedicated Transport Channels
Downlink Shared Channel (DSCH)
Dedicated Channel (DCH)
17. Logical Channel
Broadcast Control Channel (BCCH)
Paging Control Channel (PCCH)
Dedicated Control Channel (DCCH)
Common Control Channel (CCCH)
Control Channel (CCH)
Dedicated Traffic Channel (DTCH)Traffic Channel (TCH)
Common Traffic Channel (CTCH)
19. Course Contents
Type of System Channel
Function of the Channels
Physical Channel
Transportation Channel
20. Uplink Physical Channel
Two dedicated uplink physical channels (DPDCH and
DPCCH)
Two public physical channels (PRACH and PCPCH)
DPCCH
PRACH
PCPCH
DPCCH
uplink physical channels
public physical channels
21. Uplink Dedicated Physical Channel Structure
DPCCH contains 4 domains：
Pilot： used for channel estimation of base station receiver and frame
synchronization；
TFCI：Used to determine different TrCHS transmission format while multiplexing to
a same CCTrCH；
FBI： used for downlink closed loop emission classifications；
TPC：used for the power control instructions in downlink closed loop power control
Pilot
N pilot bits
TPC
N TPC bits
Data
N data bits
Slot #0 Slot #1 Slot #i Slot #14
T slot = 2560 chips, 10 bits
1 radio frame: T f = 10 ms
DPDCH
DPCCH
FBI
N FBI bits
TFCI
N TFCI bits
T slot = 2560 chips, N data = 10*2 k
bits (k=0..6)
22. Uplink Dedicated Physical Channel
Data side and control side of uplink dedicated physical channel uses
I/Q multiplexing, which means DPDCH and DPCCH are I/Q code
multiplexing in every radio frame.
For a connection, no matter how many the data channels are exists,
but only one control channel. In every wireless connection, there can
be 0, 1, or several uplink DPDCHs.
Uplink DPDCH is used to transmit DCH.
Uplink DPCCH is used to transmit the control information generated by
L1. Control information of L1 contains：
Known pilot bit that support channel estimation for related detection
TPC
FBI
An optional TFCI (TFCI transfers the real-time parameters of
different transmission channels that multiplexed on uplink DPDCH,
and meanwhile, correspondent with data that will be transmit in the
same frame。There is but only one uplink DPCCH in one
connection for each layer.)
23. PRACH
PRACH
Data channel and control channel of PRACH message are
also I/Q multiplexing, and the minimum spreading factor of its
data channel is 32, with 4 time slot formats. While control
channel has only one time slot format, with two domains:
Pilot domain and TFCI domain.
Pilot
N pilot
bits
Data
N data
bits
Slot #0 Slot #1 Slot #i Slot #14
T slot
= 2560 chips, 10*2 k
bits (k=0..3)
Message part radio frame T RACH
= 10 ms
Data
Control
TFCI
N TFCI
bits
Time slot structure of PRACH message
24. PRACH
PRACH
PRACH is made up of prefix part and message part.
Following is the structure of random access emission.
Random access emission contains one or more 4096-
chip-length prefixes and one message part of 10 or
20ms.
Message partPreamble
4096 chips 10 ms (one radio frame)
Preamble Preamble
Message partPreamble
4096 chips 20 ms (two radio frames)
Preamble Preamble
Structure of PRACH access emission
25. Downlink Physical Channel
Downlink physical channel contains dedicated
downlink physical channel, one shared physical
channel and 5 public control physical channels:
DPCH
SCH
CPICH
PICH
AICH
CCPCH
PDSCH
public control physical
channels
26. Dedicated Downlink Physical Channel
DL DPCH
DPCCH and DPDCH in downlink is time division
multiplexing, and DL DPCCH contains 3 domains：TPC
domain, TFCI domain and PLIOT domain, the SF of DL
DPDCH can be arranged from 4 to 512.
One radio frame, T f
= 10 ms
TPC
N TPC
bits
Slot #0 Slot #1 Slot #i Slot #14
T slot
= 2560 chips, 10*2 k
bits (k=0..7)
Data2
N data2
bits
DPDCH
TFCI
N TFCI
bits
Pilot
N pilot
bits
Data1
N data1
bits
DPDCH DPCCH DPCCH
Frame structure of DL DPCH
27. Public Downlink Physical Channel
CPICH
CPICH is a downlink physical channel with fixed speed
(30kbps，SF＝256), which is used to transmit
predefined bit/symbol sequence. The function of CPICH
is to assist UE to perform channel estimation for DCH.
Modulation format of CPICH：
slot #1
Frame#i+1Frame#i
slot #14
A A A A A A A A A A A A A A A A A A A A A A A A
-A -A A A -A -A A A -A A -A -A A A -A -A A A -A -A A A -A -AAntenna 2
Antenna 1
slot #0
Frame Boundary
28. CPICH
Divided into P-CPICH and S-CPICH ；
Non-encoded channel；
P-CPICH uses fixed spreading factor (Cch,256,0), has fixed bit rate
of 30kbit/s ；
Each cell has but only one P-CPICH which uses the primary
scrambling code ；
Used for the searching of cell primary scrambling code；
S-CPICH can use any of the SF=256 channel codes；
Used to assist UE to perform estimation for dedicated or public
channels；
P-CPICH provides phase and power benchmark for other channels；
P-CPICH is mainly used for measurement and estimation while
handover, cell selection and cell reselection；
Adjusts the transmission power of P-CPICH to balance the load of
different cells, determines cell coverage and cell respirations；
P-CPICH broadcast to the whole cell；
29. P-CCPCH
Public control physical channel is made up of P-CCPCH and S-
CCPCH.
P-CCPCH is a downlink physical channel with fixed speed (30kbps，
SF=256), which is to transmit BCH，and uses the primary scrambling
code of the cell.
In the first 256chips of every time slot, CCPCH performs not emission.
During this period, primary SCH and secondary SCH will be
transmitted, but with no Pilot/TPC/TFC domain.
Data
18 bits
Slot #0 Slot #1 Slot #i Slot #14
Tslot = 2560 chips , 20 bits
1 radio frame: Tf = 10 ms
(Tx OFF)
256 chips
Frame structure of P-CCPCH
30. S-CCPCH
S-CCPCH carries PCH and FACH, and has the following
characteristics：
Each cell has at least one S-CCPCH with low transmission speed ；
The difference between P-CCPCHS-CCPCH is that, P-CCPCH only has
fixed and pre-defined transmission format, but S-CCPCH can use TFCI to
support more transmission formats.
Slot #0 Slot #1 Slot #i Slot #14
Tslot = 2560 chips, 20*2k
bits (k=0..6)
Pilot
Npilot bits
Data
Ndata bits
1 radio frame: Tf = 10 ms
TFCI
NTFCI bits
Frame structure of S-CCPCH
31. SCH
SCH
Divided into P-SCH and S-SCH；
Non-spreading and non-scrambling channel；
Downlink signal used for cell searching, to provide chip synchronization,
time slot synchronization and frame synchronization for users；
The first 256 chips of each slot is used to transmit synchronization code.
Primary
SCH
Secondary
SCH
256 chips
2560 chips
One 10 ms SCH radio frame
acs
i,0
acp
acs
i,1
acp
acs
i,14
acp
Slot #0 Slot #1 Slot #14
32. SCH
P-SCH contains one 256chips-length modulation code and PSC
PSC is repeatedly transmitted in each slot to transfer the
completely known sequence；
PSC of every cell in the system is the same；
S-SCH repeatedly transmit a 15-sequence modulation code, with
length of each code is 256chips. SSC is transmitted spontaneously
with SCH；
SSC is identified with csi, k, and i=0，1，……，63,which is the
sequence number of scrambling code group; k=0，1，2……,
which is the time slot number.
Each SSC is selected from one of the 16 different codes with
length of 256；
SSC contains scrambling code group information, which can be
used to determine the scrambling code group that being used in
the cell..
33. PICH
PICH carries PI (Page Indication), whose SF=256, radio frame length is
10ms, contains 300bits, among which 288 bits carries PI, and the other12
bits are Tx Off.
PICH is always connected with one S-CCPCH, which is transmitting a
PCH.
In each PICH frame, Np PI were transmitted {P0, …, PNp-1}, and here
Np=18, 36, 72, or 144. If the Pli of one frame is set to 1, this means the UE
that correspondent with Pii should adjust the frame that related to S-
CCPCH.
b1b0
288 bits for paging indication
12 bits (transmission
off)
One radio frame (10 ms)
b287 b288 b299
Frame structure of PICH
34. Course Contents
Type of System Channel
Function of the Channels
Physical Channel
Transportation Channel
35. Dedicated Transportation Channel
DCH (UL/DL)
DCH is either an uplink or downlink channel. DCH does
not care what is carried whether actual user data or
high-layer control information, as its content is invisible
in physical layer.
DCH has the following characteristics：
Fast power control
Quick speed change frame by frame
Soft handover
36. Public Transportation Channel－BCH
BCH (DL)
BCH is a downlink transportation channel, which is used to
broadcast specific system or cell information, such as the
random accessing code, accessing slot, or the transmission
diversity method being used by other channels in the cell.
BCH is always transmitted in the whole cell with an
independent transmission format. Data rate of BCH is low
and fixed.
If UE cannot correctly decode BCH, it will not be able to
register in the cell. Therefore, the transmission power of BCH
is relatively higher, in order that all the UEs in the cell
coverage can receive it.
BCH is carried by P-CCPCH
37. Functions of FACH
FACH (DL)
FACH is a downlink public transportation channel,
which can carry either control information, or a small
portion of group data.
FACH has the following characteristics：
Open loop power control is used, but not closed loop.
At least one FACH is transmitting to the whole cell at low speed.
Physical channel that carries FACH is S-CCPCH
38. Functions of RACH
RACH (UL)
RACH is an uplink transportation channel, carries the
control information transmitted by UE, such as
connection request, registration, location update, and it
also send a small portion of group data. No matter
which position in the cell, base station should be able to
receive RACH that carries control information.
RACH has the following characteristics：
Uses open loop power control.
Physical channel that carries RACH is PRACH
39. Functions of PCH
PCH (DL)
PCH is a downlink transportation channel that carries
related paging data. Based on different system
configuration, same paging information can be sent to
one single cell or even several hundred cells. The
design of paging channel directly affects the power loss
of UE when it is idle.
Physical channel that carries PCH is S-CCPCH
