Lehrstuhl für Rechnernetze und InternetWilhelm-Schickard-Institut für InformatikUniversität Tübingen
UMTS Networks
Leo Petrak, Dr. Christian Hoene und Prof. Georg Carle
UMTS Networks and Internet Telephony – Sommersemester 2006 2
Course Overview
MotivationStandardization issuesUMTS architecture basicsUMTS radio link
Physical layerSignaling
UE, UTRAN, PS Domain, CS Domain Basic functionalities:
Accessing the networkTransferring dataDetaching from the networkInformation storage
MobilityQoSSecurity
ChargingUMTS Evolution: from R99 to Rel7Beyond UMTS
UMTS Networks and Internet Telephony – Sommersemester 2006 3
Radio Communication FundamentalsDividing Radio ResourcesFrequency Licensing
UMTS Radio Link – Physical Layer
UMTS Networks and Internet Telephony – Sommersemester 2006 4
Modulation QPSK Modulation used in UMTS
Fourier AnalysisWave PropagationScarcity of Radio Resources
Radio Communication Fundamentals
UMTS Networks and Internet Telephony – Sommersemester 2006 5
Radio communication uses electromagnetic waves as thetransmission medium
UEs / Base Stations emit and receive waves of the carrierfrequency f
Signal strength of a waveP(t) = P0 cos (2πft - ϕ)
Radio Communication Fundamentals I
ϕ
0
P0
-P0
P(t)
2πft
UMTS Networks and Internet Telephony – Sommersemester 2006 6
Information is encoded by modulating (change midway) a wave of the carrier frequency f
P(t) = P0 cos (2πft + ϕ)Phase ϕ - Phase Shift Keying
Frequency f - Frequency Shift Keying
modulate Amplitude P0 - Amplitude Shift Keying
Radio Communication Fundamentals II - Modulation
UMTS Networks and Internet Telephony – Sommersemester 2006 7
Modulation in UMTS: QPSK
UMTS uses Quaternary Phase Shift Keying (aus 4-er bestehende…)
Four possible sequences of two bits are coded:• 0 0 - phase shift of 1/4 π• 1 0 - phase shift of 3/4 π• 1 1 - phase shift of 5/4 π• 0 1 - phase shift of 7/4 π
0
P(t)
t
1/4 πphase shift: 3/4 π 5/4 π 7/4 π
Bit sequence: 0 0 1 0 1 1 0 1
UMTS Networks and Internet Telephony – Sommersemester 2006 8
Fourier Analysis: Each signal can be described as an integral (sum) of sine waves
⇒ The modulated wave is a superposition of manywaves of different frequencies of a frequencyband ∆ f It can be shown that∆ f ≥ r (bandwidth ≥ data rate)
Radio Communication Fundamentals III - Fourier Analysis
1 2 3 4 5 6 7 8 9 10110
1
1 2 3 4 5 6 7 8 9 1011
1 2 3 4 5 6 7 8 9 10110
1
1 2 3 4 5 6 7 8 9 10110
1
0 1 1 0 0 0 1 0
0
1
T 1 2 3 4 5 6 7 8 9 1011
Signal Harmonics n
0
1 1. Harm.
2. Harm.
4. Harm.
8. Harm.
∑∞
=
=1
n 2sin(P)(n
tP π nf t+ ϕn)
f
Density D(f)
f0Carrier Frequency
Bandwidth ∆ f
(f0 +1/2r)
2/r
UMTS Networks and Internet Telephony – Sommersemester 2006 9
Radio Communication Fundamentals IV - Wave Propagation
The intensity of electromagnetic waves emitted by a „point source“(e.g. antenna) decreases with distanceElectromagnetic waves add linearly
Interference of waves emitted by different sources• When waves of same frequency interfere, extraction of information difficult
– Because a modulated wave occupies a frequency band of bandwidth ∆ f , interferencemay be a problem in mobile communications
UMTS Networks and Internet Telephony – Sommersemester 2006 10
Radio Communication Fundamentals V - Scarcity of radio resources
Radio spectrum is a scarce resourceShared by many systems
⇒ It is necessary to clearly separate radio resources used by different entities, e.g.- Technologies- Users of the same technology "Multiple Access"- "user -> network" (uplink) from
"network -> user" (downlink): "Duplex"⇒ it is necessary to efficiently use radio resources
Possibilities for separating radio resources- Frequency division- Time division- Space division- Code division- Combinations thereof
UMTS Networks and Internet Telephony – Sommersemester 2006 11
Radio Communication FundamentalsDividing Radio ResourcesFrequency Licensing
UMTS Radio Link – Physical Layer
UMTS Networks and Internet Telephony – Sommersemester 2006 12
Frequency divisionTime divisionSpace division
Cellular networksCode divisionExamples: GSM and UMTS
Dividing Radio Resources
UMTS Networks and Internet Telephony – Sommersemester 2006 13
Frequency Division
Radio Spectrum is divided into frequencybands
Power emitted outside these bands must bestrictly below a certain level
To be on the safe side, unused guard bandslimit interference between frequency bands
Receivers use filtering to receive carrierfrequency of interest
Already introduced in 1900 to organizeusage of radio transmitters, e.g. on ships
Usually used in combination with otherdivision techniques
time
frequency
Frequency band 3
Frequency band 2
Frequency band 1
Guard band
Guard band
UMTS Networks and Internet Telephony – Sommersemester 2006 14
Time Division
Radio Spectrum usage is divided into time slotsEach sender is assigned a time slot
To avoid collisions, all participating entities needto be synchronized
network needs to periodically synchronizeterminalsneed to consider finite traveling time of synchronization signal, depending on distance between terminal and synchronizing entity!
Guard times between slots prevent collisionsdue to imperfect synchronization
Usually used in combination with other divisiontechniques
Guard
time
time
frequency
Guard
time
Time slot1
Time slot2
Time slot3
UMTS Networks and Internet Telephony – Sommersemester 2006 15
Space Division
Usage of radio resources restricted to certain geographic areas (cells)
Transmission power is limiteddue to decrease of power with distance to sender, interference is limited
Re-use of same radio resource only at appropriate distance
In combination with e.g FrequencyDivision, very large areas can be covered
reuse frequency band only in distant cells
New antenna techniques (adaptive antenna arrays / MIMO) allow forming"beam" towards specific mobile
UMTS Networks and Internet Telephony – Sommersemester 2006 16
Space Division - The Cellular Concept
Space Division is today the technique of choice
patented in 1972 by Bell Labs
Instead of each antenna illuminating an area as big as possible(1G Systems), each antenna covers onlysmall area
lower transmission powermore efficient use of the spectrum => bettercoveragehigher infrastructure costsneed technique for switching moving usersfrom cell to cell: "Handover"
UMTS Networks and Internet Telephony – Sommersemester 2006 17
Code Division I
time
frequency
□ Several signals are sent in the same(wide) frequency band and the same time slot
□ Each signal is created by spreading a narrowband signal through the use of a unique user code to a multiple of theoriginal bandwidth (spreading) [Spreizung]
□ The receiver correlates the sum of thereceived signal with the (time-shifted) usercode, and thereby re-obtains the original narrowband signal (de-spreading)
□ power level of different signal needs to bealigned
□ codes need to be uncorrelated, otherwise interference
□ replanning cells becomes easier with thistechnique
code
Code 1
Code 2
Code 3
UMTS Networks and Internet Telephony – Sommersemester 2006 18
Code Division II - What are these codes?
Sequences S of 1 and -1 (chips)S = {S1, S2 , ... , Sn}, Si {-1,1}
Correlation: C(j) = Σi Si Ti+j• measures how "different" two codes S and T are• uncorrelated codes result in little interference• e.g. S = {-1, 1, 1, 1, -1, -1, 1, -1}T = {-1, -1, 1, -1, 1, -1, -1, -1}C(0) = 0, C(1) = 2, C(3) = 0,...but Autocorrelation A(j) e.g. of S:A(0) = 8, A(1) = 0, A(2) = 4,...
– Autocorrelation only high if synchronized!∋
UMTS Networks and Internet Telephony – Sommersemester 2006 19
Code Division III - Coding and Decoding
Data D(t)
-1 1 1 1 1 -1 -1 -1
Code S(t)
D(t) ·S(t)
Coding at sender
Decoding at receiverwith correct code
D(t) ·S(t) ·S(t - τ) = D(t)
Decoding at receiverwith wrong code
D(t) ·S(t) ·T(t - τ) = no data signal
Code T(t - τ)
-1 -1 1 -1 -1 -1 -11
UMTS Networks and Internet Telephony – Sommersemester 2006 20
Code Division III - Spreading
Chip rate greater bit rate • therefore bandwidth becomes higher after spreading [Spreizung]
f
D(f)
f0
Bandwidth ∆ f
f0+TD
1/TD
Data D(t)
D(t) ·S(t)
TD
TDS
f
D(f)
f0
Bandwidth ∆ f
f0+TDS
1/TDS
UMTS Networks and Internet Telephony – Sommersemester 2006 21
Code Division IV- near-far effect
De-spreading at receiver works best whenpower levels of different signals are aligned. However:When senders A and B emit with same power, the signal of B at the Antenna is stronger
⇒ power control is applied constantlyAntenna Controller tells sender with what power to send
A
B
UMTS Networks and Internet Telephony – Sommersemester 2006 22
Dividing Radio Resources: Summary
Uplink / downlink (D – Duplex)
Different users (MA – Multiple Access)
Frequency Division (FD) FDD FDMA
Time Division (TD) TDD TDMA Code Division (CD) - CDMA
Space Division (SD) - SDMA
The different techniques for dividing radio resources can be combined, e.g.
• pick one technique for separating uplink / downlink• pick one technique for separating different users
e.g. FDD - CDMA
UMTS Networks and Internet Telephony – Sommersemester 2006 23
GSM: FDD + TDMA + FDMA
GSM uses a both Frequency Division and Time DivisionUplink and Downlink use different frequencies: FDDUplink and Downlink frequency band is subdivided into frequency channels, each of thesechannels is divided into time slots:
each user sends on a particular frequency band, on a particular time slotIn GSM 900 have
25 MHz per direction124 frequency channels à 200 kHz per directioneach frequency band has 8 time slots
time
frequency
UMTS Networks and Internet Telephony – Sommersemester 2006 24
Flash OFDM: FDD + TDMA + FDMA + Frequency Hopping
Uses both Frequency Division and Time Division as GSM plus frequency hopping
Allows flexible assignement of bandwidthSimplifies frequency planningResults in spread spectrum, just as CDMA
time
frequency
UMTS Networks and Internet Telephony – Sommersemester 2006 25
UMTS: WCDMA I
UMTS uses two different methods for separating radio resourcesFDD + CDMA (UTRA FDD) (most popular method)TDD + TDMA + CDMA (UTRA TDD)
FDD + CDMA for UMTS is called WCDMA(Wideband CDMA), because compared to cdmaOne it uses a higher chip rate
chip rate is 3,84 Mega chips / s• chip rate is fixed• in cdma2000, chip rate can vary
Qualcomm owns key patents in UTRA FDD and cdma2000They managed to standardize them
UMTS Networks and Internet Telephony – Sommersemester 2006 26
UMTS: WCDMA II - why CDMA?
Very resource efficientpossibly more efficient than FDMA and TDMA
Resistance against interference and noise:any undesired signal will be spread when decodingInterception by adversary more difficult
signal strength can be lower than thermal noise => hide signal• Because total power in signal spread out over more frequencies
needs to know code
Can reuse frequencies in neighboring cellssimplifies network planningsimplifies introduction of more antennas
Allows flexible bandwidth assignementby varying spreading factor (chips per bit)
UMTS Networks and Internet Telephony – Sommersemester 2006 27
UMTS: WCDMA III - Orthogonal Codes
Constructed from a "tree", called OVSF Code TreeSequences on same hierarchical level or originating from different branches areorthogonalHigher bandwidth (larger bitrate) sessions are assigned shorter code Cshort
such that the overall chiprate does not exceed maximum chip ratethis blocks usage of all codes branching off code Cshort
• they would not be orthogonali.e. (quite logically) a high bandwidth session occupies more resources (codes) and thus reducesbandwidth available to other sessionsUse between 1 to 256 chips per bit
SF = 1 SF = 2 SF = 4
Cch,1,0 = (1)
Cch,2,0 = (1,1)
Cch,2,1 = (1,-1)
Cch,4,0 =(1,1,1,1)
Cch,4,1 = (1,1,-1,-1)
Cch,4,2 = (1,-1,1,-1)
Cch,4,3 = (1,-1,-1,1)
SF - Spreading Factor
UMTS Networks and Internet Telephony – Sommersemester 2006 28
UMTS: WCDMA IV – Orthogonal Codes cont’
Two types of codesOrthogonal codes
• Generated from code tree• Orthogonal correlation
– High autocorrelation if synchronized» Autocorrelation mediocre if unsynchronized
– Zero correlation between different codes if synchronized» Non-zero correlation if unsynchronized
Pseudo Noise codes• “Randomly generated” with particularly properties• “Quasi orthogonal” correlation
– High autocorrelation if synchronized– Almost zero correlation between different codes even if unsynchronized
UMTS Networks and Internet Telephony – Sommersemester 2006 29
UMTS: WCDMA V - Code Distribution
Uplink Direction Downlink DirectionScrambling Codes (Pseudo Noise Code)
User separation Cell separation
Channelization Codes(Orthogonal Code)
Data and control channels from same UE
Users within a cell
Spreading Code Channelization code x scrambling code
Problem: Synchronization between cells and between UEs hard to achieveEach signal is spread with the spreading code, i.e.channelization code x scrambling codeChannelization codes spread all user data to same bandwidth
Have different lengthDownlink (Network -> UE):
Neighboring cells use different scrambling codes ("cell ID")Each UE is assigned a different channelization code
=> UE receives data with unique spreading codeUplink (UE -> Network):
Each UE is assigned a different scrambling codeEach UE may use any channelization codeThis allows UE to manage bandwidth of its sessions independently
UMTS Networks and Internet Telephony – Sommersemester 2006 30
UMTS: WCDMA VI - Macrodiversity
SF - Spreading Factor
WCDMA support multipath propagationSignals can take different path from sender to receiver
• Due to reflection, diffraction,...• Signal may be picked up by more than one antenna
Signals are collected and aggregated at receiverImproves reception qualityThis is called Diversity
Utilizing multipath propagation via more than one antenna is calledMacrodiversity […Mehrfachverbindungen]
Usually the further away from the antenna, the stronger the signal a UE has to emit (near-far effect)This leads to interference with neighboring cellsMacrodiversity allows reducing emission power
UMTS Networks and Internet Telephony – Sommersemester 2006 31
Radio Communication FundamentalsDividing Radio ResourcesFrequency Licensing
UMTS Radio Link – Physical Layer
UMTS Networks and Internet Telephony – Sommersemester 2006 32
IMT 2000 Worldwide Frequency Plans
1850 1900 1950 2000 2050 2100 2150 2200 2250 MHz
1850 1900 1950 2000 … 2100 2150 2200 2250
1850 1900 1950 2000 … 2100 2150 2200 2250
2010 MHzITU allocations
IMT 2000 IMT 2000
JapanKorea (w/o PHS) IMT 2000 MSSMSSIMT 2000PHS
1885 MHz 1980 MHz
1885 MHz 2025 MHz 2110 MHz 2170 MHz
Europe UMTS MSSDECT UMTS MSSGSM 1800
1880 MHz 1980 MHz
UMTS MSSChina UMTS MSSGSM 1800
North America
2160 MHz
Reserved MSS1895 1918 MHz
MSSA D B E F C A D B E F CPCS
DECTGSM 1800
UMTS FDDUMTS TDD
20 20 60 30 15 60 3060
MSSMobile Satellite System
UMTS Networks and Internet Telephony – Sommersemester 2006 33
IMT-2000 Licences in Germany
FDD Frequencies
TDD Frequencies
Source: www.regtp.deLicences oblige operator to cover 25% of the population by end of 2003, and 50% by end of 2005Licences expire end of 2020Mannesmann became Vodafone, VIAG became O2, Group 3G became QuamMobilCom returned licence
UMTS Networks and Internet Telephony – Sommersemester 2006 34
Summary
UMTS uses QPSK (Quaternary Phase Shift Keying) as modulation technique
UMTS employs WCDMASignal is spread using orthogonal codes
The higher the bit rate of a signal, the less it is spread
Because of near-far effect, power control is important
Multiple propagation paths of signal can be combined to improve receptionquality
• Reception with different antennas: Macrodiversity
Lehrstuhl für Rechnernetze und InternetWilhelm-Schickard-Institut für InformatikUniversität Tübingen
Warum ist das Handy-Telefonierenso teuer?
Warum ist UMTS so teuer?
UMTS Networks and Internet Telephony – Sommersemester 2006 36
UMTS Auktion – Kosten für jedermann!
Gesamterlöß war 100 Milliarden DM = 50,5 Milliarden €(August 2000)Jährlich Zinsen für diesen Betrag50.000.000.000 * 4% = 2 Milliarden € pro Jahr
Monatliche Tilgung über 15 Jahre sind 395,40 Mio € pro Monat
“Vodafone D2 übertrifft Marke von einer Million UMTS-KundenJahresziel bereits jetzt erreicht”, 21. November 2005
Ungefähr 2,5 Mio (UMTS) oder 45 Mio (Handy) Kunden zur Zeit
394,40/2,5 = 157,76 € pro UMTS-Kunde pro Monat
Oder 394,40/45 = 8,76 € pro Handy pro Monat
UMTS Networks and Internet Telephony – Sommersemester 2006 37
Wirtschaftspolitische Einschätzung
Kommentar des finnische Kommunikationsministers Kimmo Sasi18.09.2002, Tageszeitung "Kauppalehti"
"Ich rate Deutschland zu überdenken, ob man zum Rückkauf derLizenzen von den Unternehmen bereit ist, die sie wieder abgeben
wollen. Und man sollte sie für denselben Preis zurückkaufen, der von den Unternehmen bezahlt wurde." Der finnische Minister begründete
seinen Vorschlag damit, dass "die gesamte Telekommunikations-branche nur auf diese Weise wieder auf die Füße kommen kann".
"Deutschland und Großbritannien könnten damit die führende Position Europas gegenüber den USA in der Telebranche zerstören“
“größter industriepolitischen Fehler seit dem Zweiten Weltkrieg“
UMTS Networks and Internet Telephony – Sommersemester 2006 38
Kosten bezahlen nicht nur die UMTS-Kunden:DTAG und DAXDAX Kurse seit dem 1.1.2000:
DAX
UMTS Networks and Internet Telephony – Sommersemester 2006 39
Layer Model for the Radio Link (Uu Interface)Protocols on Uu Interface Channels
Logical ChannelsTransport ChannelsPhysical Channels
Usage Example
Radio Link Signaling
UMTS Networks and Internet Telephony – Sommersemester 2006 40
Layer Model for the Radio Link
L3
Logical Channels
Control-plane signalling User-plane data
PHY L1
L2
MAC
BMC
controlRRC
RLC
PDCP
Transport Channels
Legend see next slidesPhysical Channels
UMTS Networks and Internet Telephony – Sommersemester 2006 41
Layer Model for the Radio Link (Uu Interface)Protocols on Uu Interface Channels
Logical ChannelsTransport ChannelsPhysical Channels
Usage Example
Radio Link Signaling
UMTS Networks and Internet Telephony – Sommersemester 2006 42
Protocols on Uu Interface I
PHYTasks that are directly related to the air interface
ModulationError protection of type FEC (Forward Error Correction)
• Data transmitted somewhat redundantly by means of Channel Coding– „Channel Coding“ is not the same as „Channelization Codes“ (Slide Set IV)!
Messaging on synchronization, macrodiversity, fast power controlMeasurements of conditionson radio interface (handover necessary?)(de)Multiplexing of transport channels to physical channelsProviding transport channels to the layer above…
Control plane signaling
UMTS Networks and Internet Telephony – Sommersemester 2006 43
Protocols on Uu Interface II
MACMultiplexing of channels
Multiplex different flows of the same user onto the same dedicated transportchannelMultiplex flows of several users onto a shared transport channelpacket scheduling / priority controlpossibly encryption (unless done on RLC)
RLC - Radio Link Control LayerTasks related to protected transmission of data
error protection and error free data transmissionsegmentation / reassemblyflow controldirectly used by CS domain L3 functions
UMTS Networks and Internet Telephony – Sommersemester 2006 44
Protocols on Uu Interface III
PDCP - Packet Data Control ProtocolEnables independence of L3 and lower layers
• adaptations to facilitate IP on L3 (for PS domain) • Makes possible independent development of lower layers and L3
(and above)– E.g. transition from IPv4 to IPv6
header compression
BMC - Broadcast and Multicast Controlscheduling and delivery of cell broadcast and multicast messages
UMTS Networks and Internet Telephony – Sommersemester 2006 45
Protocols on Uu Interface IV
RRC - Radio Resource ControlControl and configuration of protocol stack on Uu Interface
one RRC connection for each UE, which controls the radio link for all sessions of this UE
• convenient in case of handoverhas control interfaces to all other radio link protocolsFDD frequency managementmobility managementouter loop power controlcollection of measurement from lower layersbroadcast of system informationtunneling of core network control information
• Session management, mobility management,…
UMTS Networks and Internet Telephony – Sommersemester 2006 46
Layer Model for the Radio Link (Uu Interface)Protocols on Uu Interface Channels
Logical ChannelsTransport ChannelsPhysical Channels
Usage Example
Radio Link Signaling
UMTS Networks and Internet Telephony – Sommersemester 2006 47
Channels
(sub)layers use Channels to transmit dataEach channel has specific properties
allows decoupling of functionality -> greater flexibilitye.g. one transport channel can carry several types of logical channels
Transport Channel 1
Logical Channel 1
Logical Channel 2
Transport Channel 2Logical Channel 3
Transport Channel 3
Logical Channel 4
Logical Channel 5
Logical Channel 6
CCTrCH
Physical Channel 1
Physical Channel 2
CCTrCH:Coded Composite Transport Channel(Connection between Transport Channeland Physical Channel)
PHY
MA
C
RL
C
UMTS Networks and Internet Telephony – Sommersemester 2006 48
Channels
Logical channels between RLC and MACspecific to type of information
• logical control channels for control plane signaling• logical transport channels for user plane data
Transport channels between MAC and PHYspecific to how information is transferred (quality level)
Physical channels used by PHYactual transmission on physical layer
UMTS Networks and Internet Telephony – Sommersemester 2006 49
Logical Channels ILogical Control Channels for control plane signaling
BCCH Broadcast Control Channel• distributes information that allows UEs to attach to network
– information about radio environment: power levels, network identity..
CCCH Common Control Channel• for exchange of first messages with attaching UE
– no specific (dedicated) control channel has been assigned yet
DCCH Dedicated Control Channel• for exchange of control information with attached UE
– e.g. power control
PCCH Paging Control Channel• for paging UEs
– when a UE receives a call it needs to be located
UMTS Networks and Internet Telephony – Sommersemester 2006 50
Logical Channels II
Logical Transport Channels for user plane dataCTCH Common Transport Channel
• unidirectional downlink channel• for broadcasting information to all, or a group of UEs
DTCH Dedicated Transport Channel• exchange of user data
UMTS Networks and Internet Telephony – Sommersemester 2006 51
Transport Channels ITransport Channels
Specific to how information is transferredProvide specific service quality, e.g.
• bit rate, error protection• power level, access method, etc
Data packets that are transmitted over Transport Channels are called„Transport Blocks“
• Several are transmitted simultaneously in „Transport Block Sets“Each Transport Channel is described by a set of „Transport Formats“, i.e.
• Transport Block size• Transport Block Set size• Transmission time interval
– How long does it take to transmit a Transport Block Set• Type of error protection (Channel Coding and Cyclic Reduncancy Check)
– Channel Coding: redundant transmission of information• Efficiency of Channel Coding
For each Transport Block Set transmission, a suitable Transport Format ischosen from the Transport Format Set
UMTS Networks and Internet Telephony – Sommersemester 2006 52
Transport Channels II
e.g.BCH Broadcast Channel
• downlink, fixed bit rate, high power level (needs to be audible to all)• used for BCCH
RACH Random Access Channel• uplink, random access• mostly used by CCCH and DCCH (also DTCH)
DCH Dedicated Channel• uplink and downlink, dedicated to a particular UE• one DCH may carry several DCCH and DTCH
DSCH Downlink Shared Channel• dedicated user traffic but shared by several users• very important for data traffic (no dedicated bandwidth for one user)• optional to implement
Note there is no Uplink Shared Channel• At the time of standardization no use was anticipated
UMTS Networks and Internet Telephony – Sommersemester 2006 53
Physical Channels
Transmission on physical layere.g.
P-SCH Primary Synchronization Channel (for FDD)• P-SCH sends known, invariant signaling sequence of 256 chips• allows UE to synchronize
CPICH Common Pilot Channel• a signaling sequence known to network and UE is spread with the code used in
the P-CCPCH, in which further information is available• allows UE to "backengineer" the code
P- CCPCH Primary Common Control Physical Channel• used by BCCH / BCH• uses code diseminated by CPICH so UE can always listen in
DPDCH Dedicated Physical Data Channel• physical channel dedicated to a user
UMTS Networks and Internet Telephony – Sommersemester 2006 54
Mapping of Channels onto each other
BCCH PCCH DCCH CCCH CTCH DTCH
BCH PCH RACH FACH DSCH DCH
P-CCPCH S-CCPCH PRACH PDSCH DPDCH
Control Plane User Plane
Logical Channels
Transport Channels
PhysicalChannels
UMTS Networks and Internet Telephony – Sommersemester 2006 55
Layer Model for the Radio Link (Uu Interface)Protocols on Uu Interface Channels
Logical ChannelsTransport ChannelsPhysical Channels
Usage Example
Radio Link Signaling
UMTS Networks and Internet Telephony – Sommersemester 2006 56
Usage Example: voice transmission I*
In the Core Network / UE, a voice call is (trans)codedto 4 – 12 kb/s
Bit rate depends on current transmission quality on radio link• High bit rate when transmission quality is good• Lower bitrate when transmission quality bad
-> need more bits for error protectionTranscoded voice bits come in 3 classes A, B and C
Class A most sensitive to transmission errors• Needs more error protection than classes B and C
Hence Class A bits are transmitted in different Transport Channel Transmission attributes described in Transport Format
All Transport Channels for this voice call are multiplexed onto same Physical Channel
* Example taken from “UMTS” by Pierre Lescuyer
UMTS Networks and Internet Telephony – Sommersemester 2006 57
Usage Example: voice transmission II*
* Example taken from “UMTS” by Pierre Lescuyer
DTCH Logical Channel
DCH ATransport Block
DCH B DCH C
Transport Channels
Physical ChannelTFCI A B C
Radio Link Frame
Channel CodingIndicates Transport Formats used to allow decoding
DPDCH
UMTS Networks and Internet Telephony – Sommersemester 2006 58
Summary
Protocols used on UuMAC and RLC on L2 for both control and user plane
PDCP and BMC on L2 additionally for user plane to PS Domain
RRC on L3 for control plane
Each Layer uses Channel to transport dataLogical Channels, Transport Channels, Physical Channels
UMTS Networks and Internet Telephony – Sommersemester 2006 59
Course Overview
MotivationStandardization issuesUMTS architecture basicsUMTS radio link
Physical layerSignaling
UE, UTRAN, PS Domain, CS Domain Basic functionalities:
Accessing the networkTransferring dataDetaching from the networkInformation storage
MobilityQoSSecurity
ChargingUMTS Evolution: from R99 to Rel7Beyond UMTS
UMTS Networks and Internet Telephony – Sommersemester 2006 60
ArchitectureUSIMUE Tasks
User Equipment (UE)
UMTS Networks and Internet Telephony – Sommersemester 2006 61
UE Architecture
UICC (Universal Integrated Circuit Card)User subscription dependent part of the UEContains one or both of
• USIM (Universal Subscriber Identity Module)• ISIM (IMS Subscriber Identity Module)
MT (Mobile´Termination)Terminates radio transmissionAdapts TE capabilities to those of radio transmissionCouples TE and UICC
TE (Terminal Equipment)Provides end-user application functionsTerminates upper layersCommunicates with peer TE on the other end of the communication sessionMay be „non-UMTS entity“ coupled via TAF (Terminal Adaptation Function)
• E.g. Laptop, printer,…
towardsUTRAN
UE Mobile Termination (MT)
RTAF
Uu
Terminal Equipment(TE)
USIM ISIMUICC
Cu
UMTS Networks and Internet Telephony – Sommersemester 2006 62
UICC
Same concept as SIM card in GSMLittle „plastic card“Identifies User
Identifies how to bill this userUser subscription-dependent part of the UE
Separated from rest of UE • allows separate selling and management of physical equipment and user
subscriptionUnaccessible to user⇒ Creates trusted environment⇒ Key to many commercial applications
Without UICC only emergency calls are possibleTerminal may hold slots for several UICCs
Allows several subscribers to use same terminal• Separate private / business use of one UE• In the future may allow (ad-hoc) networks to access UMTS network
UMTS Networks and Internet Telephony – Sommersemester 2006 63
USIM
USIM contains all user-specific data to enter PS / CS domainIdentities
• USIM identity (IMSI - International Mobile Subscriber Identity)– Unique USIM number
• temporary USIM identities(TMSI for CS Domain, P-TMSI for PS Domain)
– assigned after initial registration– used to protect user identity against eavesdroppers
• users phone number(MSISDN - Mobile Station International ISDN number)
– There can be more than one MSISDN per IMSI
preferred language• used for displaying information
security keyscurrent locationlist of unaccessable networks
UMTS Networks and Internet Telephony – Sommersemester 2006 64
UE Tasks: technology relatedWith Node B
Rate matchingSpreading and modulationPower controlError Correction
With RNCSignaling for connection set-up and releaseSignaling for handoverEncryption / DecryptionMeasurements to detect necessity for handover
• S/N ratio, error rate, signal strength,... Power control
With Core Networkmobility managementsession management
• Connection set-up maintainance and tear-down• Port negotiation• QoS negotiation• …
location managementidentity management
Sending data…
UMTS Networks and Internet Telephony – Sommersemester 2006 65
UE features: user-related
Large displaycamera with MPEG codeclong battery lifetimegaming-capable
fast processor, substantial memory
other user software (web browser,…)small and lightUser API
UMTS Networks and Internet Telephony – Sommersemester 2006 66
Summary
UE is composed of UICC with USIM/ISIM, TE, MT
UICC contains all subscriber-related information
Uu interface towards the UTRAN
UE has to perform a high number of complex tasks
communicating with Node B, RNC and Core Network
UMTS Networks and Internet Telephony – Sommersemester 2006 67
ArchitectureNode BRNC
cf. TS 25.401 "UTRAN overall description",TS 25.301 "Radio Interface Protocol Architecture"
UMTS Radio Access Network (UTRAN)
UMTS Networks and Internet Telephony – Sommersemester 2006 68
UTRAN ArchitectureNode B
responsible for radio transmission / reception in one or more cellsRNC - Radio Network Controller
controls use and integrity of radio resourcescontrols one or more Node Bs
RNS - Radio Network Subsystemcontains one RNC and a set of cells
RNS
RNC
RNS
RNC
Core Network (PS Domain and CS Domain)
Node B Node B Node B Node B
Iups / Iucs
Iur
Iub IubIub Iub
UTRAN
UEUu
Iups / Iucs
cell
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UMTS Radio Access Network (UTRAN)
ArchitectureNode BRNC
cf. TS 25.401 "UTRAN overall description"
UMTS Networks and Internet Telephony – Sommersemester 2006 70
Node B Functionality
Spreading and Modulationcode generationsupports FDD, TDD or both, and CDMA
Terminates Physical Channelsand Transport Channels
Logical Channels terminate at RNCTransport / Physical Channels include error correction
Fast power control ("Inner Loop")Node B measures strengths of received signals and informs UE if it needsto adjustTarget value set by RNC
measures connection quality and strength• handover necessary?
Forwards user traffic
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UMTS Radio Access Network (UTRAN)
ArchitectureNode BRNC
cf. TS 25.401 "UTRAN overall description"
UMTS Networks and Internet Telephony – Sommersemester 2006 72
RNC Functionality I
Radio Resource Managementguarantees stability and „Quality of Service“ (QoS) of radio connection(radio bearer)
Power control ("outer loop")Handover control
• should there be a handover?• decide based on measurements by UE and Node B• signals with UE about handover realization
Admission control and packet scheduling• can a new session be established on the UTRA
without compromising the quality of existing sessions?• Plan channel use, calculate interference and utilisation levels• Configure radio resources accordingly
Code managementMacrodiversity management
UMTS Networks and Internet Telephony – Sommersemester 2006 73
RNC Functionality II
UTRA Controlset-up, maintainance and release ofradio connection (radio bearer)
System information broadcasting• e.g. radio measurement criteria, ...
Initial Access and Signaling Connection set-up and management• synchronization, broadcast of initial scrambling code,...
UTRAN security functions• protects user and control data by encryption and integrity protection
UTRAN level mobility management• informing new cell (Node B) and UE about handover, new channel, etc• Serving RNS relocation
Database handling• stores cell information, and sends it to corresponding Node Bs and UEs
– cell identity, power levels, connection qualities, neighboring cell information (needed for handover)
UE positioning• selects and controls UE positioning method
– using cell ID, round-trip times, "angle-of-arrival", GPS,...
Forwards user traffic
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RNC Functionality III - Relocation
For each UE, one RNC is responsible - Serving RNC (SRNC) typically this is the RNC controlling the cell in which the UE is located
If the UE moves to a cell controlled by a different RNC, this becomes the Drift RNC (DRNC)
control stays with SRNCAlso Macrodiversity may introduce DRNCsSRNC may relocate control to DRNC via Iur
now former DRNC becomes SRNCuseful for optimizing routing (data always travels via SRNC)
SRNC
Core Network
Iu
DRNC Iur
UE
Cells
UMTS Networks and Internet Telephony – Sommersemester 2006 75
Illustration
Node Bs RNC
UMTS Networks and Internet Telephony – Sommersemester 2006 76
Summary
UTRAN is home to Node B
• radio transmission / reception in one or more cells
• terminates physical and transport channels
RNC• controls use and integrity of radio resources
• controls one or more Node Bs
• terminates logical channels
• UE controlled by SRNC, however data may also travel via DRNC
Interfaces Uu, Iu, Iub, Iur
UMTS Networks and Internet Telephony – Sommersemester 2006 77
Course OverviewMotivationStandardization issuesUMTS architecture basicsUMTS radio link
Physical layerSignaling
UE, UTRAN, PS Domain, CS Domain Basic functionalities:
Accessing the networkTransferring dataDetaching from the networkInformation storage
MobilityQoSSecurity
ChargingUMTS Evolution: from R99 to Rel7Beyond UMTS
UMTS Networks and Internet Telephony – Sommersemester 2006 78
Packet-switched Domain
ArchitectureSGSN FunctionsGGSN FunctionsProtocols
cf. TS 23.002 "Network Architecture", TS 23.060 "General Packet Radio Service (GPRS)"
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PS Domain Architecture I
Logical architectureSGSN and GGSN perform
• Mobility management• Session management• Location management• Identity management• Service negotiation• User data transport
GfUu Gi
Gn
IuGc
Gp
Signalling and Data Transfer InterfaceSignalling Interface
UE UTRAN External networks
Gr
HLR
Other PLMN
SGSN
GGSN
GGSN
EIR
SGSN
GnGb
GSM Radio Access
PS Domain
HLR Home Location Register• Subscription information• Master security keys• Location information
EIR Equipment Identity Register• Equipment information
– list of stolen or lost equipment
IMS
Gi
UMTS Networks and Internet Telephony – Sommersemester 2006 80
Possible physical architectures
Duplicate nodes for reliabilitySGSN and GGSN may or may not be colocated, there doesn‘t need be a 1:1 relationship
SGSNs and GGSNs of one operatorare connected by an IP-based network
When CS-Domain IP-based can attach MGWs and MSC Servers to samephysical IP backbone as PS domain
PS Domain Architecture II
IP Network
SGSN
GGSN
GGSN
SGSNSGSN
IP Network
SGSN
GGSNGGSN
MGWSGSN
MSC Sv.
SGSN/GGSN
SGSN/GGSN
SGSN
GGSNGGSN
SGSN
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SGSN Functions
Authentication and Authorizationbased on data in HLR
Admission controldoes PS domain have enough resources for supporting a new session?Can negotiate lower QoS
Charging data collectionMobility Management
SGSN may change due to mobilitytemporary storage of data on subscribers attached
e.g. locationRouting
finding the appropriate GGSN through which session leaves for externalnetworks / the IMSestablishes a tunnel (PDP context) to GGSN
UMTS Networks and Internet Telephony – Sommersemester 2006 82
GGSN Functions
Gateway to other packet-based networksprotocol conversionmay act as Policy Enforcement Point (PEP) for the IMSblocking undesired data flows
Routingof data packets to corresponding SGSN / packet-based network
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Protocols - User Plane
L1
RLC
PDCP
MAC
E.g., IP,PPP
Application
L1
RLC
PDCP
MAC
L1
UDP/IP
GTP-U
L2
Relay
L1
UDP/IP
L2
GTP-U
E.g., IP,PPP
SGSNUTRANUEIu-PSUu Gn Gi
GGSN
L1
UDP/IP
GTP-U
L2
L1
UDP/IP
GTP-U
L2
Relay
End-to-end IP layer
IP layer terminating at GGSN
GTP-U: GPRS Tunneling Protocol - User Planetunnels data between SGSN and GGSNs
• hides mobility to upper IP layer• gives network owner control over where traffic leaves its network
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Protocols - Control Plane I
RLC
RRC
L1
GMM /SM / SMS
RRC
MAC
L1
RANAP
L2
Relay
L1
L2
SGSNUTRANUE Iu-PsUu
RLC
SCCP
SignallingBearer
MAC
L1
SignallingBearer
RANAP
SCCP
GMM /SM / SMS
Control Plane between UE and SGSNGMM / SM GPRS Mobility Management / Session Management
• attaching and detaching of UEs, security, location managementRANAP RAN Application Protocol (see CS Domain)SCCP / RANAP part of SS7 protocol stack (see CS Domain)„Signaling Bearer“ either is rest of SS7 protocol stack or an adaptation to run SCCP on top of ATM or IP
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Protocols - Control Plane II
Control Plane for SGSN - GGSN or SGSN-SGSN interfaceGTP-CGPRS Tunneling Protocol for the control plane
• tunnels signaling messages between SGSNs and GGSNs and between SGSNs
UDP
L2
L1
IP
L2
L1
IP
UDP
Gn or GpGSN GSN
GTP-C GTP-C
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Protocols - Control Plane III
Control Plane for SGSN - HLR interface (SS7 signaling)MAP (Mobile Application Part)TCAP for managing control connections between two nodes (from GSM)Runs over SCCP / signaling bearer just as RANAP
SCCP SCCP
GrSGSN HLR / EIR
TCAP
MAP
TCAP
MAP
SignallingBearer
SignallingBearer
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Summary
PS Domain is home to SGSN and GGSN• mobility management• session management• location management• identity management• service negotiation• GGSN is gateway to other packet-based networks• Important interfaces Gi, Gn and Iu
Protocols used on user planeone end-to-end IP layer, and a tunneled IP layer local to thePS domain
tunneling protocol is GTP-U
Protocols used on control planeGMM / SM, SMS, RANAP and SCCP
UMTS Networks and Internet Telephony – Sommersemester 2006 88
Course OverviewMotivationStandardization issuesUMTS architecture basicsUMTS radio link
Physical layerSignaling
UE, UTRAN, PS Domain, CS DomainBasic functionalities:
Accessing the networkTransferring dataDetaching from the networkInformation storage
MobilityQoSSecurity
ChargingUMTS Evolution: from R99 to Rel7Beyond UMTS
UMTS Networks and Internet Telephony – Sommersemester 2006 89
Architecture R99 Architecture Post - Rel4Protocols and SGW
cf. TS 23.002 "Network Architecture", TS 23.205 "Bearer-independent circuit-switched core network"
Circuit-switched Domain
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Logical architectureMSC and GMSC perform
• Mobility management• Session management• Location management• Identity management• Service negotiation• Transcoder control• User data transport
VLR stores• Subscription information• Currently used security keys• Location information
FUu
E
IuC
Signalling and Data Transfer InterfaceSignalling Interface
UE UTRAN External networks
C, D
HLR/ AuC
MSC / VLR GMSC
EIR
MSC / VLR
E, GA
GSM Radio Access
CS Domain
HLR Home Location Register / AuC• Subscription information• Master security keys• Location information
EIR Equipment Identity Register• Equipment information
– List of stolen or lost equipment
CS Domain Architecture R99
UMTS Networks and Internet Telephony – Sommersemester 2006 91
MSC split into control node and user traffic transport nodeMSC Server
• All MSC signaling functions– Mobility management– Session management– Location management– Identity management– Service negotiation– Transcoder control
• Control of MGW• VLR functionality
FUu
Nc
IuC
Signalling and Data Transfer InterfaceSignalling Interface
UE UTRAN
Externalnetworks
C, D
HLR/ AuC
MSC Server GMSC Sv.
EIR
MSC / VLRE, G
AGSM Radio Access
CS Domain
CS Domain Architecture Post-Rel4
NbMGW MGW
McMc IP or
ATM
Media Gateway (MGW)• All MSC transport functions
– User data transport
Signaling Gateway (SGW)• Translates SS7 protocol stack
into IP/ATM-based protocol stack– Location as need be
SGW
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Protocols – User Plane
MGW – MGW and MGW - RNCTwo possibilities depending on transport network technology
• IP – based– RTP Real Time Transport Protocol (accompanied by RTCP (RTP Control Protocol)
• ATM – based– AAL2 offers real-time transport to small packets
L2
NbMGW MGW / RNC
IP
UDP
L1
RTP
Payload
L2
IP
UDP
L1
RTP
Payload
ATM
NbMGW MGW / RNC
AAL2
Payload
L1
ATM
AAL2
Payload
L1
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Protocols – Control Plane, SS7 I
CS Domain to a large extent relies on SS7 protocolsSS7 – Signaling System No. 7
Standard signaling system in telecommunication networksSeparates control signaling network and user network
• E.g. ISDN B-Channels (user) / D- Channel (control)Performs e.g. call set-up / mgmt / tear-down, resource reservation, mobile subscriber authentication, toll-free numbers, call forwarding, conference calls,…
UMTS Networks and Internet Telephony – Sommersemester 2006 94
Protocols – Control Plane, SS7 II
Architectural ElementsSSP – Service Switching Point
• Originate, terminate or tandem calls• Communicates with other SSPs via STPs
STP – Service Transfer Point• Routes signaling messages, e.g. based on “addresses” contained in the message
– Dialed number, mobile subscriber number,…
SCP – Service Control Point• Database
SSPSSP
SSP
STP STP
STP
SCP SCPSCP
UMTS Networks and Internet Telephony – Sommersemester 2006 95
Protocols – Control Plane, SS7 III
SS7 protocol stack in fixed networksMTP Message Transfer Part (Layers 1 – 3)
• reliable message routing between all SS7 nodes – Rerouting around failed links, congestion control, error checking,…
• Offers service to User Parts and Application PartsSCCP Signaling Connection Control Part
• Translates from “user addresses” (telephone numbers etc) into destination point addressTCAP – Transaction Capabilities Application Part
• Non-circuit related signaling, e.g. SCP queriesTUP - Telephone User Part
• Analog call handlingISUP – ISDN User Part
• Set-up, manage and release calls
For mobile networks additional Application Parts are defined
MAP, RANAP, BICC, ALCAP
MTP 1
MTP 2
MTP 3
TUP
SCCP
TCAP ISUP
L1
L2
L3
L4
L5-7
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Protocols - Control Plane IV
Control Plane for MSC (Server) – HLR/EIR/AuC interfaceMAP (Mobile Application Part)
SCCP SCCP
B,C,D,E,F,GMSC (Server) HLR / EIR / AuC
TCAP
MAP
TCAP
MAP
MTP 1-3 MTP 1-3
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Protocols – Control Plane VRNC – MSC / MSC Server
Three possibilities depending on transport network technology• „Full SS7“ / MTP- based (see previous slides)• IP – based
– SCTP / M3UA enable running „SS7“ over IP– RANAP – RAN Application Part
» establishes separate logical connection to each UE for control traffic• ATM – based
– AAL5 offers transport to variable-sized packets– „Signaling Bearer“is an adaptation to run SCCP on top of ATM– ALCAP controls AAL2 of user plane
IucsRNC MSC Sv. IucsRNC MSC Sv.
L2IP
SCTP
L1
M3UASCCP
L2IP
SCTP
L1
M3UA
SCCP
ATMAAL5
Sign. Bearer
L1
ATMAAL5
Sign. Bearer
L1
RANAP RANAP
SCCP
RANAP
SCCP
RANAP
ALCAP ALCAP
UMTS Networks and Internet Telephony – Sommersemester 2006 98
Protocols - Control Plane VI
MSC- MSC and MSC Server – MSC ServerMSC – MSC protocol stack as in ISDNMSC Server – MSC Server protocol stack migrates to „SS7 over IP or ATM“ (ATM not shown)
• BICC - Bearer Independent Call Control
MTP2 MTP2
EMSC MSC
MTP3
ISUP
MTP3
ISUP
MTP1 MTP1
L2 L2
NcMSC Server MSC Server
IP
SCTP
L3
SCTP
L1 L1
M3UA
BICC
M3UA
BICC
UMTS Networks and Internet Telephony – Sommersemester 2006 99
Summary
CS Domain is home to MSC and GMSC in R99„SS7 Network“
With Rel4 split (G)MSC into MSC Server and MGWSeparation control / user plane Introduce IP or ATM based transport networkControl signaling with „SS7 top“ and IP/ATM baseSGWs translate between pure SS7 signaling and SS7 over IP/ATM