Post on 02-Jun-2018
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PT Nexwave Indonesia
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CHAPTER 1: WCDMA Overview and Network Architecture
CHAPTER 2: WCDMA Wireless Overview
CHAPTER 3: Physical Layer and WCDMA Channel
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Overview
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What is 3G?
3rdGeneration of mobile communication based on IMT-2000 global standardization
3G characteristic:
Designed for multimedia communicationfrom the beginning
Provides more efficientmeans for image and video transfer
Variable bit rates up to 2 Mbps (Rel99)
Multiple access using Wideband CDMA (WCDMA) All cells are using same frequency band, no need Frequency planning
Using codes for separate user and channel
Effective Signal Bandwidth 3.84MHz (wider bandwidth compared to GSM)
Short time delay (compared to GSM), 10ms frame length with 15 time slots
Multiple carriers can be used to increase capacity
Inter frequency functionality to support mobility between frequencies carrier Compatibilitywith GSM technology
Inter System functionality to support mobility between GSM and UMTS
Soft Handover, add margin which improved performance
Overview
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Overview
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Architecture
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User Equipment (UE)
Mobile equipment (ME): Radio communication over Uu interface
UMTS Subscriber Identity Module (USIM): Subscriber identity information, authentication
algorithms, encryption keys, etc
UMTS Terrestrial Radio Access Network (UTRAN)
Node B (Base Station): Handles/manages the traffic between Uu and Iub interfaces. Basic
tasks like coding, interleaving, rate adaptation, modulation, spreading, closed loop power
control
Radio Network Controller (RNC): Control radio resources in its operation area. Provideservices for Core Network (CN). Load and congestion control, admissions control, code
allocation, radio resource management tasks.
Mobile Services Switching Centre (MSC) / Visitor Location Centre (VLR)
Handles switching in Circuit Switched (CS) connectionsand hold visitingusers service
profiles.
Serving GPRS Support Node (SGSN)
Similar functionality as in MSC/VLR but used for Packet Switched (PS) services
Other CN elements
Gateway MSC (GMSC): Handles incoming and outgoing CS connections
Gateway GPRS Support Node (GGSN): Like GMSC but in PS domain
Home Location Register (HLR): Master copy of users service profiles
Authentication Center (AuC): Handles authentication based on SIM data
Equipment Identity Register (EIR): Handles blacklist of Mobile Phone based on IMEI
Architecture
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CHAPTER 1: WCDMA Overview and Network Architecture
CHAPTER 2: WCDMA Wireless Overview
CHAPTER 3: Physical Layer and WCDMA Channel
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A method which allowed two ways communication between two points simultaneously.
Air Interface Overview
Ai I t f O i
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5 3
3 1
4 52
3
5
4
3
Power
Frequency
1 2 3 4 5
1
2
3
4
5
1
2
2
1
TDM
-Time Division
Multiple Access-
2G e.g. GSM PDC
FDM
-Frequency Division
Multiple Access-
1G e.g. AMPS,
NMT, TACS
CDM
-Code Division
Multiple Access-
3G e.g. UMTS, CDMA2000
1 2 3UE 1 UE 2 UE 3 4 UE 4 UE 55
4 2
OFDM
-Orthogonal
Frequency
Division
Multiple Access-
e.g. LTE
multiple access method allows several users connected
to the same multi-point transmission medium to
transmit over it and to share its capacity
Each User has a unique
frequency
Each User has a unique
time slot
Each Transmitter has a uniquespreading code
Each Data Channel has a unique
orthogonal code
No dedicated physical
channel any more
Air Interface Overview
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Spreading Code
Spread Signal
Data
Bits (In this drawing, 1 bit = 8 Chips SF=8)
Baseband Data
-1
+1
+1
-1
+1
-1
+1-1
+1
-1
ChipChip
Air Interface
Chips & Bits & Symbols
Air Interface Overview
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Consist of two steps:
1. Channelization Operation; which transform data into chips
2. Scrambling Operation; which applied to the spreading signal
Spreading means increasing the bandwidth of the signal beyond the bandwidth normally required
to accommodate the information.
Channelization Operation, which transforms every data symbol into a number of chips, thus
increasing the bandwidth of the signal. The number of chips per data symbol is called theSpreading Factor (SF). Channelization codes are orthogonal codes, meaning that in ideal
environment they do not interfere each other.
Scrambling is used on top of spreading, so it does not change the signal bandwidth but only
makes the signals from different sources separable from each other. As the chip rate is already
achieved in channelization by the channelization codes, the chip rate is not affected by the
scrambling.
Air Interface Overview
Air Interface O er ie
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Air Interface Overview
Air Interface Overview
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SF = chip rate / symbol rate
High data rate Low SF code
Low data rate High SF code
Air Interface Overview
Air Interface Overview
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Scrambling code: GOLD sequence
Not orthogonal
Does not change signal bandwidth and only make makes the signals from different
sources separable from each other
There are 224 long uplink scrambling codes which are used for scrambling of the
uplink signals. Uplink scrambling codes are assigned automatically by RNC.
For downlink, 512 primary scrambling codes are used. Downlink scrambling codes
must be planned carefully in network.
The scrambling code is always applied to one 10ms frame
Air Interface Overview
Air Interface Overview
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WCDMA Codes:
In WCDMA two separate codes are used in the spreading operation: Channelization code
Channelization code is used to distinguish different physical channels of one transmitter
DL: separates different physical channels of one cell
UL: separates different physical channels of one user/UE
Scrambling code
Scrambling code is used to distinguish different transmitters
DL: separates cells in same carrier frequency
UL: separates users in same carrier frequency
Data
Bit Rate
ChannelizationCode
Scrambling Code
To be Transmit
Block Diagram:
Air Interface Overview
Air Interface Overview
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Air Interface Overview
Air Interface Overview
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Air Interface Overview
Air Interface Overview
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Air Interface Overview
Air Interface Overview
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Air Interface Overview
Air Interface Overview
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Diversity technique is used to obtain uncorrelated signals for combining
Reduce the effects of fading
Fast fading caused by multi-path
Slow fading caused by shadowing
Improve the reliability of communication
Increase the coverage and capacity
Diversity techniques:
Time diversity
Frequency diversity
Space diversity
Polarization diversity
Air Interface Overview
Air Interface Overview
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Air Interface Overview
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CHAPTER 1: WCDMA Overview and Network Architecture
CHAPTER 2: WCDMA Wireless Overview
CHAPTER 3: Physical Layer and WCDMA Channel
Physical Layer
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y y
Physical Layer
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RAB (Radio Access Bearer) : The service that the access stratum provides to the non-access stratum for transfer of user data between User Equipment and CN.
RB (Radio Bearer) : The service provided by the layer 2 for transfer of user data
between User Equipment and Serving RNC.
RL(Radio Link) : A "radio link" is a logical association between single UserEquipment and a single UTRAN access point. Its physical realization comprises one ormore radio bearer transmissions.
y y
Physical Layer
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Radio Access Bearers are mapped onto these classes.
Traffic class Conversational class
conversational RT
Streaming class
streaming RT
Interactive class
Interactive best effort
Background
Background besteffort
Fundamental
characteristics
Preserve timerelation (variation)between informationentities of thestream
Conversationalpattern (stringentand low delay )
Preserve timerelation(variation)betweeninformation
entities of thestream
Requestresponse pattern
Preservepayload content
Destination isnot expectingthe data withina certain time
Preservepayload content
Example of the
application
- voice - streaming video - Web browsing - background down-load of emails
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Physical Layer
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Physical Layer
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WCDMA Channels
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Physical Channels
Transmission media.
Two types of physical channels defined in L1: FDD and TDD.
FDD is characterized by frequency, code, I/Q phase
Follow a layered structure of radio frames and time slots
Transport Channels describes the way information is transferred over the radio interface
Logical Channels the type of information transferred characterizes a logical channel
WCDMA Channels
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WCDMA Channels
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WCDMA Channels
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WCDMA Channels
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WCDMA Channels
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WCDMA Channels
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WCDMA Channels
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Synchronization Channel (SCH) Used for cell search
SCH is transmitted at the first 256 chips of every time slot
Common Pilot Channel(CPICH)
Carries pre-defined sequence
Fixed rate 30KbpsSF=256 The P-CPICH is a phase reference for SCH, Primary CCPCH, AICH, PICH.
Only one CPICH per cell
Broadcast over the entire cell
Primary Common Control Physical Channel (PCCPCH)
Carry BCH transport channel
Fixed rate30kbpsSF=256
WCDMA Channels
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Secondary Common Control Physical Channel (SCCPCH) Used to carry the FACH and PCH.
SF =256 - 4.
Paging Indicator Channel (PICH)
PICH is a fixed-rate (SF=256) physical channel used to carry the Paging Indicators (PI).
WCDMA Channels
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Physical Random Access Channel (PRACH) The Physical Random Access Channel (PRACH) is used by the UE to access the network and
to carry small data packets.
Acquisition Indicator Channel (AICH)
The Acquisition Indicator Channel (AICH) is a common downlink channel used to control the
uplink random accesses. When the NodeB receives the random access from a mobile, it sends back the signature of
the mobile to grant its access.
WCDMA Channels
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Uplink Dedicated Physical Channel DPDCH carries data generated at Layer 2 and higher layer
DPCCH carries control information generated at Layer 1
DPDCH is used to bear data at physical layer. DPCCH provide control data for DPDCH, such
as demodulation, power control etc.
Downlink Dedicated Physical Channel DCH consists of dedicated data and control information.
The functions of downlink DPDCH/DPCCH are similar with uplink DPDCH/DPCCH..
WCDMA Channels
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High-Speed Physical Downlink Shared Channel (HS-PDSCH) HS-PDSCH is a downlink physical channel that carries user data and layer 2 overhead bits
mapped from the transport channel: HS-DSCH.
SF=16, can be configured several channels to increase data service
High-Speed Shared Control Channel (HS-SCCH)
HS-SCCH is a fixed rate (60 kbps, SF=128) downlink physical channel used to carry downlinksignaling related to HS-DSCH transmission
Carries physical layer signaling to a single UE ,such as:
Modulation scheme (1 bit),
channelization code set (7 bit),
transport block size (6bit),
HARQ process number (3bit), redundancy version (3bit),
new data indicator (1bit),
UE identity (16bit).
WCDMA Channels
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