View
228
Download
1
Category
Preview:
Citation preview
3 generation
UMTS
2012, October, R. Bestak
History of WCDMA
• 1988: RACE I (Research of Advance Communication Techn. in Europe) Basic 3G research work (modulation, channel coding, access methods, etc.)
• 1992-1995: RACE II Development of testbeds to test in real time performance of CDMA and TDMA
• 1995: ACTS (Advanced Communication Technologies and Services) Within ACTS, a project FRAMES (Future Radio Wideband Multiple Access Sys.)
• Objective of FRAMES – defining a proposal for a UMTS radio access system
• Several partners (Nokia, Siemens, France Telecom + several European Universities)
• Results - Multiple access platform consisting of 2 modes
i) FMA1 (FRAMES Multiple Access) – based on a wideband TDMA
ii) FMA2 – based on a wideband CDMA
…submitted to ETSI as candidates for UMTS Terrestrial Radio Access
• 1997: according to the FRAMES proposals, five groups are formed in ETSI
• 1998: ETSI selects technologies for the UMTS air interface WCDMA for UMTS (FDD)
WTDMA/CDMA for (TDD)
2
2012, October, R. Bestak
3GPP (3rd Generation Partnership Project)
• Before 3GPP - several technologies discuss/standardized around the world Waste of resource for the participating companies
Global equipment compatibility would be difficult to reach
• Creation of a single forum for WCDMA standardization 3GPP (1998) Standardization of UTRA
UMTS Terrestrial Radio Access (ETSI) Universal Terrestrial Radio Access (3GPP)
3GPP
ETSI (Europe)
ARIB (Japan)
TTA (Korea)
TTC (Japan)
CCSA (Chine)
ATIS (USA)
Partners from:
GSM association
UMTS forum,
IPv6 forum, etc.
Companies are members of 3GPP via the standardization organization
ARIB (Association for Radio Industries and Businesses)
TTC (Telecommunication Technology Committee)
TTA (Telecommunication Technology Association)
ATIS (Aliance for Telecommunication Association)
CCSA Chine Communications Standard Association
3
3GPP (3rd Generation Partnership Project)
• Created 1998
• Association of standardization bodies & forums
ETSI (Europe), ARIB (Japan), ATIS (USA), CCSA (Chine), etc.
UMTS forum, IPv6 forum, etc.
• Specification of UMTS (…and EDGE)
• www.3gpp.org
RAN
TSG
Services and
System
Aspect TSG
CN and
Terminals
TSG
GERAN
TSG
3GPP
TSG - Technical Specification Groups
2012, October, R. Bestak 4
2012, October, R. Bestak
Releases
• Release 99 (1999) First release
• Release 4 (2001) Minor adjustment with respect to the Release 99
• Release 5 (2002) HSDPA (High Speed Downlink Packet Access) IMS (IP Multimedia Subsystem)
• Release 6 (2004/2005) MBMS (Multimedia Broadcast/Multicast Services) HSUPA (High Speed Uplink Packet Access)
• Release 7 (2005/2006/2007) HSPA +
• Release 8 (2008) LTE (Long Term Evolution) SON (Self Organizing Network) H(e)NB
• Release 9 (2008, 2009) LTE, SON,H(e)NB
• Release 10 (2010, 2011) LTE-A (LTE- Advanced)
5
2012, October, R. Bestak
Frequency bands (Europe)
Mode Uplink Downlink Band
UMTS-FDD 1920 - 1980 MHz 2110 - 2170 MHz 60 + 60 MHz
UMTS-TDD 1900 - 1920 MHz
2010 - 2025 MHz 20 + 15 MHz
Satellite 1980 - 2010 MHz 2170 - 2200 MHz 30 + 30 MHz
In 2000, new frequency bands 806 - 960 MHz, 1710 - 1885 MHz
2500 - 2690 MHz
The frequency bands were specified in 1992
GSMEurope
DE
CT
GSM
1800
1800 1900 2000 2100 2200 2500 2600 2700
UMTS
FDD
UM
TS
Sate
llite
UM
TS
TD
D
UM
TS
TD
D
UMTS
FDD
UM
TS
Sate
llite
UMTS
[MHz]
6
2012, October, R. Bestak
Features
• Several simultaneous radio connections per user
• High adaptability of radio connections Setting of connections according to supported services
• Wide range of services with different QoS Voice, web, email, video/Audio streaming, etc.
…UMTS allows good support for existing and for future services
144 kbit/s 384 kbit/s 2 Mbit/s 14 Mbit/s 5,8 Mbit/s
Rural outdoor
environments
Urban outdoor
environments
Indoor and low range
outdoor environments HSDPA* HSUPA**
*HSDPA (High Speed Downlink Packet Access) **HSUPA (High Speed Uplink Packet Access)
7
2012, October, R. Bestak
Services in 3G
• Every 3G (UMTS) service has specific requirements on Wireless delay
Bit error rate
Data rate
• Tendency Delay critical services via packet switched bearers instead of
circuit switch ones
• 4 QoS classes or traffic classes The main factor: how sensitive services are to delay
8
2012, October, R. Bestak
QoS classes
Traffic class Conversational Streaming Interactive Background
Delay
Preserve time
relation between
information
Preserve time
relation between
information
Request response
pattern
Destination is not
expecting the data
within a certain time
<< 1 s ~ 1s < 10 s > 10 s
Tolerant to
errors Yes Yes No No
Mode Circuit switch Circuit switch
Packet switch Packet switch Packet switch
Example Voice,
Video-telephony
Streaming
multimedia
Web browsing
Database retrieval Email, SMS, MMS
9
2012, October, R. Bestak
UMTS architecture (1/3)
• Air interface WCDMA (Wideband Code Division Multiple Access)
Radio channel 5 MHz
• New protocol on the radio interface
• Core network based on the GSM/GPRS core network
10
2012, October, R. Bestak
UMTS architecture (2/3)
UE: User Equipment
UTRAN: UMTS Terrestrial Radio Access Network, (or RAN)
CN: Core Network
UE UTRAN CN External
Network
11
2012, October, R. Bestak
UMTS architecture (3/3) …networks elements
UE Node B
RNC
MSC/
VLR
SGSN
Node B
HLR
GMSC
Internet
PLMN,
ISDN
UTRAN CN External Network
GGSN
UE: User Equipment MSC: Mobile Switching Centre SGSN: Serving GPRS Support Node
RNC: Radio Network Controller VLR: Visitor Location Register GMSC: Gateway MSC
HLR: Home Location Register GGSN: Gateway GPRS Support Node
UE
12
2012, October, R. Bestak
User Equipment
• ME Radio terminal used for communication over the radio interface
• USIM ~SIM in GSM
Subscriber identity, authentication algorithm, encryption keys, etc.
USIM
ME
UE
Mobile Equipment
UMTS Subscriber
Identity Module
13
2012, October, R. Bestak
UTRAN entities
• Node B Performs physical layer processing
(e.g., channel coding and interleaving, spreading/dispreading, rate adaptation, modulation/demodulation, or physical measurements)
Performs some basic Radio Resources Management operations (e.g., softer handover or power control)
• RNC Controls functions related to the UMTS
radio interface in its domain (e.g., admission control, radio resource control, or power control)
Manages protocol exchanges on the radio interfaces (UE-RNC, RNC-RNC or RNC-MSC/SGSN)
14
2012, October, R. Bestak
CN entities
• HLR Stores user’s profiles (e.g., allowed services, forbidden
roaming areas or supplementary services information) + UE’s locations on the level MSC/VLR or SGSN
• MSC/VLR Circuit switched oriented services
VLR stores user’s profiles + UE’s locations
• GMSC Interface between UMTS PLMN - external CS networks
• SGSN Packet switched oriented services
• GGSN Interface between UMTS PLMN - external PS networks
15
2012, October, R. Bestak
UMTS interfaces
UE Node B
RNC
MSC/
VLR
SGSN
Node B
HLR
GMSC
Internet
PLMN,
ISDN
GGSN
Uu Iub Iu
Iur
D
C
Gr Gc
PSTN
Gn
Gs
Iu-CS
Iu-PS
MSC/
VLR
E
16
2012, October, R. Bestak
UTRAN evolutions
• IP transport in UTRAN (…instead of ATM)
Iur/Iub, Iu-CS
Node B RNC
UE MSC/
VLR
RNC
• Iu flex (flexible) RNC have more than one Iu-CS/Iu-PS interfaces with CN
MSC/
VLR
• HSPA HSDPA, HSUPA
17
2012, October, R. Bestak
CN evolutions
MGM: Media Gateway MRF: Media Resource Function
HSS: Home Subscriber Server CSCF: Call Session Control Function
IMS: IP Multimedia Subsystem MGCF: Media Gateway Control Function
MGW
SGSN
MGW
GGSN
UTRAN
MSC
server
GMSC
server
Iu-CS
Iu-CS
Iu-PS
HSS
PSTN
Internet
MRF CSCF MGCF
IMS
Data & control
Control
Elements for provision
of IP multimedia services
(audio, video, chat, etc.)
delivered over the PS.
18
2012, October, R. Bestak
Synchronous vs. asynchronous CDMA
• Synchronous Features
• Node Bs synchronized with a central clock
• GPS (cdmaOne, cdma2000) or cable
Usage • cdmaOne, cdma2000, UMTS (TDD)
Disadvantage • System deployment is more difficult
Advantage • Synchronization temporal – procedure of synchronization is simplified
• Asynchronous Features
• Node Bs transmit independently
Usage • UMTS (FDD)
19
Physical layer in (w)cdma
2012, October, R. Bestak
Spread Spectrum Techniques
• Frequency Hopping (FH)
• Direct Sequence (DS)
• Time Hoping (TH)
• Multi Carrier CDMA (MC CDMA)
21
2012, October, R. Bestak
Frequency Hopping (1/3)
• The carrier frequency changes at regular time intervals
• Frequencies
Are selected from a pre-determined group within available spectrum
Change in order defined by pseudo-random sequence (with characteristics
similar to thermal noise … PN, Pseudo-Noise sequence)
Frequency
Time
f1
f2
f3
f4
f5
22
2012, October, R. Bestak
Frequency Hopping (2/3)
Information
bits
Baseband
modulation
PN sequence
generator
Frequency
synthetizer PN sequence
generator
Frequency
synthetizer
Information
bits
Base band
demodulation
Bandbase
filter
f1 f2 f3 f4 fn
seq2 seq1 seqn seq4
f2 f1 fn f4
1
2
3
4
1
2
3 4
seq2 seq1 seqn seq4
f2 f1 fn f4
9
8
6
7
9
8
6 7
5
5
23
2012, October, R. Bestak
Frequency Hopping (3/3)
• Tx&Rx PN sequences have to be identical + synchronized
• Depending on the hoping rate
Fast Frequency Hopping (FFH)
• hopping rate ≥ bit rate of the base band signal
Slow Frequency Hopping (SFH)
• hopping rate ≤ bit rate of the base band signal
• The higher the hopping rate & number of frequencies,
the greater privacy and interference protection
24
2012, October, R. Bestak
Direct Sequence
• Easy implementation → mostly used … is not required a high speed frequency synthesizer
• Occupies whole available frequency band continuously
• cdma2000, WCDMA
25
2012, October, R. Bestak
Spreading of signal
• Spreading - an information bit is processed by n consecutive bits of spreading sequence bits of Spreading sequence = chips
# of chips/per one information bit = Spreading Factor (e.g., SF= 4, 8, 16, …512)
A B AB
0 0 0
0 1 1
1 0 1
1 1 0
XOR
100 kbps (or kcps)
10 kbps 100 kbps Information
bits
Spreading
sequence
Spread
information
logical fun..XOR and analogue product
A B AB
+1 +1 +1
+1 -1 -1
-1 +1 -1
-1 -1 +1
26
2012, October, R. Bestak
Spreading/despreading
Information bits (R)
Spreading sequence (Sp)
(SF = 8)
Spread information (RSp)
(= R * Sp)
Spreading
Spreading sequence (Sp) Despreading
Data (R)
Information bit
Chip
1
-1
1
-1
1
-1
1
-1
1
-1
• RSp has the same random (pseudo-noise-like) appearance as Sp
• R * Sp widening of the occupied spectrum of the spread signal
Tx and Rx Sp
have to be identical
and synchronized
27
2012, October, R. Bestak
Direct Sequence system
Information
bits
Baseband
modulation
PN sequence
generator
PN sequence
generator
Information
bits
Baseband
demodulation
1
2
3
4
1
3
2
5
9
8
6
7
9
8
4 6
5
7
28
2012, October, R. Bestak
Processing gain (1/3)
• Despreading - strengthens the desired signal in relation to
other signals ….Processing gain (PG)
PG
SNRin SNRout(dB) = SNRin(dB) + PG(dB)
SNR - Signal to Noise Ratio
Despreading
29
2012, October, R. Bestak
Processing gain (2/3) …in Direct Sequence systems
RPN – chip rate (PN sequence rate) RInfo – information bit rate
• Example RPN = 3,84 Mcps RInfo = 12,2 kbps
PG = 10*log10(3,84*106/12,2*103) = 25 dB
• After despreading, the signal power needs to be a few dB above the interference and noise power
][log10 10 dBR
RP
R
RP
Info
PNG
Info
PNG
30
2012, October, R. Bestak
Processing gain (3/3) …in Frequency Hopping
systems
• In simple way, PG is defined as # of frequencies available for hopping
… PG increases with the number of frequencies
][log10 10 dBNPNP freqGfreqG
31
2012, October, R. Bestak
Despreading of the DS-CDMA signal
• Channels that remain spread are considered as interferes to the user and determined the SNR at the output
• Example
RPN = 3,84 Mcps RPN = 3,84 Mcps RInfo = 12,2 kbps RInfo = 2 Mbps PG = 25 dB PG = 2,8 dB
… let’s consider (for good communication) SNRout = 7 dB SNRout = SNRin + PG SNRIN = SNROUT - PG = -18 dB SNRIN = SNROUT - PG = 4,2 dB
The desired signal level can be 18 dB (4,2 dB) below (above) the interference caused by other users and noise
32
2012, October, R. Bestak
Spreading codes
• Features Influence interference among users
Have to have random behavior
• Choice according to Auto-correlation features
Cross-correlation features
• Types of codes PN sequence (Pseudo random Noise sequence)
• MLS (Maximal Length Sequence)
Gold code
Walsh code
33
2012, October, R. Bestak
Auto-Correlation Function (1/2)
Similarity between a function F(t) and
itself at different time (phase offset) dttFtFACF
)()(
• ACF of bit sequence
→ bit-by-bit comparison of a sequence
(length L) with the shift version of itself
(offset from 1 to L)
NCCCCACF
# Coinciding bits between sequences
# Non-Coinciding bits between sequences
34
2012, October, R. Bestak
Auto-Correlation Function (2/2)
-2
0
2
4
6
8
Phase offset
(bits) Sequence phase CC NCC ACF
0 1011100 7 0 7
1 0111001 3 4 -1
2 1110010 3 4 -1
3 1100101 3 4 -1
4 1001011 3 4 -1
5 0010111 3 4 -1
6 0101110 3 4 -1
7 1011100 7 0 7
• The max. of ACF is every
time, when both compared
sequences have the same
phase offset.
Corr
ela
tion
PN offset
04 05 06 00 01 02 03 04 05 06 00 01 02 03
35
2012, October, R. Bestak
Auto-Correlation features of codes
• Important role in the synchronization process
• 2 steps in synchronization:
Acquisition
• Tries to achieve code alignment of locally generated and received
sequences by shifting the locally generated sequence
Tracking
• Maintains the correct alignment
36
2012, October, R. Bestak
Cross-Correlation Function
similarity between functions F(t) and G(t) taken with a time difference between them
dttGtFCCF
)()(
• CCF of bit sequence
→ bit-by-bit comparison of sequences F(t)
and G(t), with the same length L
NCCCCCCF
# Coinciding bits between sequences
# Non-Coinciding bits between sequences
• Orthogonal codes: CCF = 0
37
2012, October, R. Bestak
Codes in UMTS (1/5) …downlink
User data
Si
Channelization code
(Walsh)
Symbol rate
(variable)
Chip rate
(fix)
• Spreading codes = Walsh codes
Each code represents one channel channelisation codes
Identify users in the cell
Code length is variable and depends on services
Ci
Ci+1
Si+1
Ck
Sk
38
2012, October, R. Bestak
Codes in UMTS (2/5) …downlink
• Scrambling: multiplication of spread sequence by a second sequence
Used on the top of spreading
No change of the signal bandwidth (… no change of the rate)
• Scrambling codes = Gold codes
Improves auto-correlation features of Channelization codes
Identifies Node Bs (… to each Node B is assigned different code)
Scrambling code
(Gold)
Chip rate
User data
Si
Channelization code
(Walsh)
Symbol rate
(variable)
Chip rate
(fix)
Ci
Ci+1
Si+1
Ck
Sk
39
2012, October, R. Bestak
Codes in UMTS (3/5) …downlink
• Node B
Transmitted signals from Node B are synchronized in time
• UE (…reception)
Due to multi-path propagation, the orthogonal feature of
transmitted signals get break
40
2012, October, R. Bestak
Codes in UMTS (4/5) …uplink
• Channelisation code Walsh
Separation of physical data and control channels
• Scrambling code Short (Gold) or Long (PN sequences)
Separation of users
• User’s signals are not orthogonal Transmitted signals from UEs are asynchronous
41
2012, October, R. Bestak
Codes in UMTS (5/5)
Channelisation code Scrambling code
Use
Downlink: separation of UE within one cell
Uplink: separation of physical/control ch.
from same UE
Downlink: separation of cells
Uplink: separation of UE
Chip length Downlink: 4-512 chips
Uplink: 4-256 chips
Downlink: 10 ms = 38400 chips
Uplink: 10 ms = 38400 chips or
66,7 µs = 256 chips
Number of
codes # of codes under one scrambling code = SF
Downlink: 512
Uplink: several millions
Bandwidth Increase transmission bandwidth Does not affect transmission bandwidth
42
Radio resource management
2012, October, R. Bestak
Radio Resource Management (RRM)
• RRM
Responsible for efficient utilization of the radio resources
• RRM is needed to
Guarantee QoS
Maintain the planned coverage area
Offer high capacity
• Type of RRM algorithms
Power control
Handover
Admission control, etc.
44
2012, October, R. Bestak
Power control (1/2)
• number of active UE = level of interference in the system
A UE generates interference
a) To all other UEs within the same cell
b) To all UEs in neighbor cells
• UE transmission power = interference (system capacity)
45
2012, October, R. Bestak
Power control (2/2) …near-far problem in cdma
UE2 UE1
Node B
• Tight & fast power control is one of the most important aspect in cdma system
• A single overpowered UE
could block a large part of
the cell
Near-far problem
Power control → minimize interference and thus increase the system capacity
46
2012, October, R. Bestak
Fast closed-loop power control
• Uplink Node B measures the received SIR (Signal to Interference Ratio)
IF SIRmeasured > SIRtarget then Node B command the UE to power IF SIRmeasured < SIRtarget then Node B command the UE to power
Rate 1 commands/slots, i.e. 1500/s (1500Hz) • In GSM - slow power control, 2 Hz
• Mechanism operates faster than any significant path loss change could occur
Basic step 1dB/slot • …eventually 2dB/slot (30dB correction within 10 ms frame)
• Smaller step sizes are emulated (0,5dB = 1dB/2 slots …)
… UE in a deep fade causes increased inference to other cell (high tx power)
• Downlink No near-far problem (…scenario one Node B to many UEs)
Node B increases the power of signal belonging to UEs at the cell edge
UE2 UE1
Node B Power command
tx power Power command
tx power
47
2012, October, R. Bestak
Open loop power control
• Rough initial power setting of the UE
Downlink beacon signal is used for the setting
Setting is very inaccurate
• Fast fading is uncorrelated between uplink & downlink
• Large frequency separation of uplink and downlink band
48
2012, October, R. Bestak
Outer loop power control
• SIRtarget is set according to required BER or BlER (e.g.,BlER = 1%)
• SIRtarget = f (speed of UE) … change of UE speed ≈ change of BER
SIRtarget has to be change according to the UE speed
• Outer loop power control SIRtarget (in Node B) is adjusted to keep a constant quality, i.e. BER
RNC
(Outer loop power control)
Node B
(Fast closed power control) UE
Frame reliability info
SIRtarget adjustment
commands
SIRtarget
Time
49
2012, October, R. Bestak
Handover
• Handover, or Hand-off (Handoff)
• Allow mobility of UEs between cells by changing the
communication radio channel
• Types
Hard handover
Soft handover
50
2012, October, R. Bestak
Hard handover
BTS 1
(F1,TS5)
BTS 2 BTS 1
(F2,TS3)
BTS 2
MSa MSa
• A MS communicates simultaneously with just one BTS
• A MS may experience a brief interruption in the connection when switching from the old channel to the new one
(e.g., GSM)
51
2012, October, R. Bestak
Soft handover … general
• CDMA systems
• UE communicates with two or more Node Bs simultaneously
A UE starts communication with a Node B2 while still connected to the Node B1
Seamless transmission between cells
• Several simultaneous connections to different Node Bs → Macro-diversity
Node B1 Node B2
1
UEa Node B1
Node B2
2
UEa
Node B1
Node B2
UEa
Node B3
52
2012, October, R. Bestak
Soft vs. softer handover
• Soft UE is located in a coverage are of 2
different Node Bs • Communication UE/Node B takes
place via 2 radio channels
• Combination of signals (uplink) is realized in the RNC
Two power control loops per connection are active
Sector 1
Sector 2
RNC
Node B
1
UEa
Node B2
Sector 1
Sector 2
RNC Node B
UEa
• Softer UE is located in a coverage are of 2
sectors of the same Node B • Communication UE/Node B takes place
via 2 radio channels
• Combination of signals (uplink) is realized in the Node B
One power control loop per connection is active
53
Transport and physical channels
2012, October, R. Bestak
Protocol architecture
PDCP: Packet Data Convergence Protocol BMC: Broadcast/Multicats Control Protocol
User plane
Medium Access Control (MAC)
Physical Layer (PHY)
BMC PDCP
Radio Resource
Control
Radio Link Control (RLC)
Control plane
contr
ol
Layer 3
Layer 2
Layer 1
Transport channels
Logical channels
Physical channels
55
2012, October, R. Bestak
Transport channels
• DCH: Dedicated Ch.
• E-DCH: Enhanced DCH
• BCH: Broadcast Ch.
Transport channels
Dedicated transport ch. Common transport channels
DCH (Up/Down)
E-DCH (Up)
BCH (Down)
FACH (Down)
PCH (Down)
RACH (Up)
HS-DSCH (Down)
DSCH (Down)
CPCH (Up)
• CPCH: Common Packet Ch.
• DSCH: Downlink Shared Ch.
• HS-DSCH: High Speed DSCH
• PCH: Paging Ch.
• FACH: Forward Access Ch.
• RACH: Random Access Ch.
56
2012, October, R. Bestak
Common transport channel
• Broadcast Ch. (BCH) Info specific to UTRA network or cell (random access codes, access slots, etc.)
• Paging Ch. (PCH) Info relevant to the paging procedure (call to the UE)
• Forward Access Ch. (FACH) Signaling (eventually + small amount of packet data)
1 or more FACH/cell (at least 1 channel with a low rate)
• Downlink Shared Ch. (DSCH) Packet data and/or signaling
Associated with DCH
… DCH gives power control info, info when to decode DSCH and which spreading code to use
• High Speed DSCH (HS-DSCH) Packet data and/or signaling
Associated with DCH
• Random Access Channel (RACH) Signaling eventually + small amount of packet data (1-2 frames)
(Signaling – registration of UEs to the network, location update when moving from one location area to another, initialization of a call)
• Uplink Common Packet Channel (CPCH) …Extension of RACH (…higher amount of packet data - several frames)
57
2012, October, R. Bestak
Transport channels …features
Type Channel Direction
Fast power
control / soft
handover
Coverage of
whole cell
TTI
(ms) Data Notes
Dedicated DCH
Downlink
Uplink Yes / Yes
Yes (or part of it) (beam-forming ant.)
10-80 Yes
E-DCH Uplink Yes /Yes Yes 10 Yes HSUPA (Rel 6)
Common
BCH Downlink No Yes 20 No Low bit
rate channel PCH Downlink No Yes 10 No
FACH Downlink No / No
(Slow power control
or no power control)
Yes Small amount 1 or x Chs/cell
DSCH Downlink Yes / No No 10 Yes Rel99
HS-DSCH Downlink No /No No 2 Yes HSDPA (Rel 5)
RACH Uplink No / No No 10,20 Small amount Slotted ALOHA
CPCH Uplink Yes / No Yes Small/medium
amount
Fast setup/release
channel
58
2012, October, R. Bestak
Physical channels …mapping
DCH (Down/Up)
E-DCH (Up)
BCH (Down)
FACH (Down)
PCH (Down)
RACH (Up)
HS-DSCH (Down)
DSCH (Down)
CPCH (Up)
SCH (Synchronization Ch.)
CPICH (Common Pilot Ch.)
AICH (Acquisition Indication Ch.)
PICH (Paging Indication Ch.)
CPCH (CPCH Status Indication Ch.)
CD/CA-ICH (Collision Detection/Channel Assignment Indicator Ch.)
DPDCH (Dedicated Physical Data Ch.)
DPCCH (Dedicated Physical Control Ch.)
PCCPCH (Primary Common Control Physical Ch.)
SCCPCH (Secondary Common Control Physical Ch.)
PDSCH (Physical Downlink Shared Ch.)
PRACH (Physical Random Access Ch.)
PCPCH (Physical Common Packet Ch.)
HS-PDSCH (High Speed PDSCH) HS-SCCH (HS Shared Control Ch.), HS-DPCCH (HS DPCCH)
E-DPDCH, E-DPCCH: Enhanced DPDCH, DPCCH E-AGCH (E-DCH Absolute Grant Ch.), E-RGCH (E-DCH Relative Grant Ch.),
E-HICH (E-DCH Hybrid ARQ Indicator Ch.)
Signaling
physical channels
59
2012, October, R. Bestak
Physical channels
• Defined by Frequency
Channelisation code
Time duration
• Structure of radio frame 38400 chips
Duration 10 ms
15 slots • 2560 chips/slot
• 666 μs/slot (…GSM - 577 μs/slot)
0 1 2 3 4 5 6 7 … 13 14
Radio frame = 10 ms (38400 chips)
slot
60
2012, October, R. Bestak
Uplink dedicated channel …DPDCH,DPCCH
• DPDataCH Data of DCH transport channels
0, 1 or several channels/radio link (…useful to use 1 ch. as long as possible multicode transm. = reduction of amplifier efficiency
Variable SF, data rate can vary from frame to frame
• DPControlCH Control physical layer info (Transmission Power Control TPC, TFCI, Ch. estimation, Feedback etc.)
1 channel on radio/radio link
Fix SF
0 1 2 3 4 5 6 7 … 13 14
Radio frame = 10 ms (38400 chips)
DPDataCH (SF = 4 256)
1slot (2560 hips)
DPControlCH (SF = 256)
SF Bits/Slot Bits/Frame Channel bit
rate (kbps)
256 10 150 15
:
8 320 4800 480
4 640 9600 960
61
2012, October, R. Bestak
Downlink dedicated channel …DPCH
• Dedicated Physical Channel (DPCH) DPDCH (…data)
DPCCH (…control)
• Time multiplexing of DPDCH and DPCCH
0 1 2 3 4 5 6 7 … 13 14
Radio frame = 10 ms (38400 chips)
1slot (2560 hips)
SF Bits/Slot Data1, Data2
(bits)
TPC, TFCI,
Ch. est (bits)
Channel bit
rate (kbps)
512 10 0, 4 2, 0, 4 15
:
8 320 56, 232 8, 8, 16 480
4 1280 248, 1000 8, 8, 16 1920
Data1 TPC TFCI Data2 Ch.estimation
DPDCH DPCCH DPCCH DPDCH DPCCH
62
2012, October, R. Bestak
Uplink random channel …PRACH
#1 #2 #3 #4 #5 #6 #7 #8 #0 #11 #12 #13 #14 #9 #10
5120 chips
Random Access Transmission
Random Access Transmission
Random Access Transmission
Random Access Transmission
Radio frame, 10 ms Radio frame, 10 ms
UE starts the random-access transmission at the beginning of well-defined time intervals - access slots (15 access slots / 2 frames)
Preamble Preamble Preamble …
4096 chips
Message part
10 ms (1 radio frame) or
20 ms(2 radio frame)
Preamble detected and Ack via AICH
SF = 256…32 (15…120 kbits)
63
2012, October, R. Bestak
Access procedure (RACH)
1. UE decodes BCH (to find out the available RACH sub-channels/access slots and their scrambling codes and signatures)
2. UE randomly select 1 RACH access slot and 1 available signature
3. UE sets the initial tx power according to the downlink measurements (loop power control …inaccurate)
4. UE transmits RACH preamble (with the selected signature)
5. UE decodes AICH to see if the Node B detected the preamble If yes UE transmits the RACH message part (10 or 20 ms)
else UE increases the tx power about one step (+1dB) and retransmits the preamble in the next available access slot
AICH (preamble)
RACH (preamble)
RACH (preamble)
RACH (message)
AICH
RACH
1 or 2 frames
64
2012, October, R. Bestak
Access procedure (CPCH)
• CPCH procedure is similar to RACH one, but CPCH uses detection of collision
• Phases 1. to 5. …same as RACH procedure
6. UE sends a CD preamble with the same power, but with another available signature,
7. Node B echoes the CD preamble back
8. After receiving the echoed CD preamble, UE starts the transmission
AP-AICH (preamble)
CPCH (preamble)
CPCH (preamble)
CPCH
transmission
AP-AICH
CPCH CPCH
(CD pream.)
CD-ICH (CD pream.) CD-ICH
• Status monitoring & channel assignment CSICH: status indication of CPCHs (this avoid unnecessary access attempts if all CPCHs are busy)
CD-ICH: information for UEs about a CPCH channel assignment (CA is sent in parallel with CD)
Several frames (max. # of frames is set by UTRAN
during services negotiation)
65
2012, October, R. Bestak
Paging procedure
• If a paging message appear for any UE of the paging group, PI periodically appears on PICH
• Once the UE detects PI, the UE decodes the next PCH frame (Secondary CCPCH) to see whether if there is a paging message intended for it
UEGP1
UEGP1
UEGP1
UEGP2
UEGP2 UEGP1
UEGP1
UEGP2 UEGP2
Every UE is
assigned to a
paging group
The less often the PIs appear, the less often the UE wakes up from the sleep mode
→ the longer the battery life becomes
Node B
66
Protocol architecture of UTRAN
2012, October, R. Bestak
Protocol architecture (1/2)
PDCP: Packet Data Convergence Protocol BMC: Broadcast/Multicats Control Protocol
User plane
Medium Access Control (MAC)
Physical Layer (PHY)
BMC PDCP
Radio Resource
Control
Radio Link Control (RLC)
Control plane
contr
ol
Layer 3
Layer 2
Layer 1
Transport channels
Logical channels
Physical channels
68
2012, October, R. Bestak
Protocol architecture (2/2)
Node B RNC
UE
MAC
RLC
RRC
Phy
MAC
RLC
RRC
Phy
PDCP PDCP BMC BMC
69
2012, October, R. Bestak
Data transmission in UMTS
MAC
Phy
MAC
PDCP
IP
PDCP
IP IP
Proxy Radio Access Network
Core
Networks +
Internet
Phy
RLC RLC
RNC NodeB UE
TCP TCP
Server
AI
RR
C
RR
C
70
MAC
• Medium Access Control
• Functions Mapping
• Logical channels Transport channels
Multiplexing/Demultiplexing • RLC blocks transport blocks
Priority handling (scheduling)
Traffic measurement
...
User plane
BMC PDCP
RRC
Control plane
MAC
RLC
PHY
2012, October, R. Bestak 71
2012, October, R. Bestak
MAC …entities
MAC entity Transport channel Release
MAC-b Broadcast ch. BCH (Broadcast channel) Rel’99
MAC-c/sh/m Common ch. PCH (Paging channel)
FACH (Forward Access channel)
RACH (Random Access channel)
DSCH (Downlink Shared channel)
USCH (Uplink Shared channel)
Rel’99
MAC-d Dedicated ch. DCH (Dedicated channel) Rel’99
MAC-hs HSDPA HS-DSCH (HS Downlink Shared channel) Rel’5
MAC-e/es HSUPA E-DCH (Enhanced Dedicated channel) Rel’6
MAC-m Common ch. FACH (Forward Access channel) …MBMS* Rel’6
*MBMS – Multimedia Broadcast Multicast Service
72
2012, October, R. Bestak
MAC …entities - UE
Associated
Downlink
Signalling
E-DCH
MAC-d
FACH
RACH
DCCH DTCH DTCH
DCH DCH
MAC Control
USCH ( TDD only )
CTCH BCCH CCCH SHCCH ( TDD only )
PCCH
PCH
MAC-hs
HS-DSCH
Associated
Uplink
Signalling
Associated
Downlink
Signalling
MAC-es /
MAC-e
Associated
Uplink
Signalling
MAC-m
MTCH MSCH MTCH MSCH
MCCH
FACH
MAC-c/sh/m
FACH USCH ( TDD only )
DSCH ( TDD only )
DSCH ( TDD only )
HSUPA
HSDPA
73
2012, October, R. Bestak
MAC …entities - UTRAN
FACH RACH
DCCH DTCH DTCH
DSCHTDD only
MAC Control
Iur or local
MAC Control
DCH DCH
MAC-d
USCH TDD only
MAC-c/sh/m
CCCH CTCH
BCCH
SHCCH TDD only
PCCH
FACH PCH USCH TDD only
DSCHTDD only
MAC Control
HS-DSCH HS-DSCH
Associated Uplink
Signalling Associated Downlink
Signalling
MAC-hs
Configuration
without MAC -c/sh Configuration
with MAC
Configuration
with MAC-c/sh
E-DCH
Associated Uplink
Signalling Associated Downlink
Signalling
MAC Control
MAC-es
MAC-e
MAC Control
Iub
c/sh
MSCH
MTCHMCCH
Node B RNC
HSUPA HSDPA
74
RLC
• Radio Link Control
• Functions
Segmentation/Reassembly
• Upper layer blocs RLC blocks
Error corrections (ARQ)
Flow control
In-sequence delivery to upper layer
Ciphering
…
User plane
BMC PDCP
RRC
Control plane
MAC
RLC
PHY
2012, October, R. Bestak 75
PDCP
• Packet Data Convergence Protocol
• Functions
Compression (decompression)
of headers
…
User plane
BMC PDCP
RRC
Control plane
MAC
RLC
PHY
2012, October, R. Bestak 76
BMC
• Broadcast/Multicast Control protocol
• Functions
Scheduling of BMC messages
Transmission of BMC messages to UEs
...
User plane
BMC PDCP
RRC
Control plane
MAC
RLC
PHY
2012, October, R. Bestak 77
RRC
• Radio Resource Control protocol
• Control plane
• RRC units Signaling of RRC
Signaling of upper layer
• Functions Establishment/maintenance/release RRC conn.
Power control
…
User plane
BMC PDCP
RRC
Control plane
MAC
RLC
PHY
2012, October, R. Bestak 78
Recommended