1. WCDMA Design using Simulink
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© 2002 The MathWorks, Inc.
Alex Rodriguez
The MathWorks, Inc.
May 30th, 2002

2. Agenda About WCDMA WCDMA Simulink Model Enhancements Radiolab 3G
About the models
Physical Layer
Mask parameters
Coding and Multiplexing
Modulation and Spreading
RAKE Receiver
Channel Models
Visualizing the results
Enhancements
Radiolab 3G

3. About WCDMA … WCDMA stands for Wideband Code Division Multiple Access.
WCDMA is one of the five air-interfaces adopted by the ITU under the name "IMT-2000 Direct Spread”.
WCDMA can support multiple and simultaneous communications such as voice, images, data, and video.
Very high and variable bit rates:
144 kbps: vehicle speed, rural environ.
384 kbps: walking speed, urban outdoor.
2048 kbps: fixed, indoor.
Different QoS for different connections.
High spectrum efficient.
Coexistence with current systems.
WCDMA is being specified by the 3GPP (Third Generation Partnership Project).
ITU-R (International Telecommunications Union Radio) Study Group 8

4. About WCDMA and the 3G Standardization Process
References:
ITU (International Telecommunication Union)
3GPP (3 Generation Partnership Project)
UWCC (Universal Wireless Communications Consortium)
UMTS Forum:
GSM World :
CDMA Development Group
ITU-R (International Telecommunications Union Radio) Study Group 8

5. About the models WCDMA has two basic modes of operation:
TDD (Time Division Duplex).
Low Chip Rate TDD (TD-SCDMA)
FDD (Frequency Division Duplex).
Duplex communications:
Downlink Channel
From Node B (Base Station) to UE (User Equipment).
Uplink Channel
From UE to Node B
Model simulates transmission of information data (DCH – Dedicated Channel) during a connection.

6. About the models R12.1 !! For NT, Linux and Unix w/o accelerator
WCDMA Library
WCDMA Multiplexing
and Coding
WCDMA Spreading
and Modulation
WCDMA Physical
Layer
To open the models,
type wcdmademos

7. Physical Layer Specifications
Physical layer provides data transport support to higher layers via Transport Channels.
Functions of the Physical Layer:
Error detection.
FEC encoding/decoding.
Rate Matching/Dematching.
Multiplexing/Demultiplexing different Transport Channels into/from a Coded Composite Transport Channel (CCTrCH).
Mapping/Demapping of CCTrCH into/from Physical Channels.
Modulation and Spreading/Demodulation and Despreading.
Power Weighting and combining of physical channels.
RF Processing. …

8. WCDMA Physical Layer Transmitter
DL Scrambling Code
- Channelization Code
- Transmit Diversity
Slot Format
- Power Settings
- Transport Block Set Size
- Transport Block Size
- Transmission Time Interval
- Size of CRC
- Type of Error Correction
- Coding Rate
- Rate Matching Attribute
Transport Format
Transport
Channels
Channel Coding and
Multiplexing
Slot
DPCH
Physical
Channel
Mapping
Spreading
And
Modulation
DPCH
CCTrCh
Pilot Bits
TPC
TFCI
Control Channels
Interference (OCNS)
Orthogonal
Codes
Layer 2
MAC
Layer 1
Channel

9. WCDMA Physical Layer Model

10. Initial Settings Mask – Layer 2
Multiplexing and Coding
Spreading and Modulation
Variables are stored in the workspace.
To view them, type who or whos

11. Coding and Multiplexing Specifications
Physical layer provides data transport support to higher layers via Transport Channels.
There is a Transport Format associated to each Transport Channel that describes the processing (CRC size, encoding scheme, coding rate, …) to be applied by the Physical Layer.
Every transport block is generated every 10, 20, 40 or 80 ms (Time Transmission Interval – TTI).

12. Coding and Multiplexing Overview
Layer 1
Radio
Frame
Segment
Concat/
Segment
Channel
Encoder
Rate
Matching
1st
Interleaver
CRC
CCTrCH
Accommodates data rates
to a fixed channel bit rate
Attaches CRC
Size={0,8,12,16,24}
Limits Max Size
of Codewords
Interleaves bits within each Transport Channel
Coding Schemes:
No coding
Convolutional Coding
Turbocoding
Multiplexes bits from different Transport Channels every 10 ms.
Radio
Frame
Segment
Channel
Encoder
Rate
Matching
1st
Interleaver
Concat/
Segment
CRC
Transmission Time Interval
{10,20,40 and 80ms}
Radio Frame
{10ms}

13. Coding and Multiplexing Model
Transport
Channels
Concatenation and
Segmentation
Channel
Encoder
Rate
Matching
First
Interleaver
CCTrCh
CRC
Transmission Time Interval
{10,20,40 and 80ms}
Radio Frame
{10ms}
Layer 2
Layer 1

14. Physical Channel Mapping Overview
Transport Format Combination Index contains information of how the different transport channel have been processed
Interleaves bits within a Radio Frame coming from different Transport Channels
Data is sent to the Modulation and Spreading block
Slot
Builder
TFCI
CCTrCh
DPCH
DPCH
2nd
Interleaver
DPCH
Physical
Channel
Segmentation
One CCTrCH can be mapped onto one or several PhCHs
Power Control Bits
Pilot Bits
Structure of slot is defined by the Higher Layers via Slot Format
Data 1
TPC
TFCI
Data 2
Pilot

15. Physical Channel Mapping Model
Slot Builder
Physical channel segmentation
2nd Interleaver
Radio Frame
{10ms}
Slot
{10/15 ms}

16. References 3GPP TS 25.302 – “Services provided by the Physical Layer”.
3GPP TS – “Physical channels and mapping of transport channels onto Physical Channels (FDD)”.
3GPP TS – “Multiplexing and channel coding”.
3GPP TS – “Channel coding and multiplexing examples”.

17. Modulation and Spreading Specifications
QPSK.
Same gain for I and Q components.
Spreading or Channelization Operation:
Transforms every bit into a given number of chips, hence increasing the bandwidth.
Chip Rate = 3.84 Mcps.
By using an orthogonal code for each physical channel, receiver can separate them.
Orthogonal codes are real-valued OVSF codes (Orthogonal Variable Spreading Factor) of different length.
Scrambling:
Separates different Base Stations.
Complex-valued Gold Code Sequences.

18. Modulation and Spreading Specifications
Power weighting:
Different power is applied to each physical channel before being added together.
Pulse shaping:
Root-raised cosine filter with ß=0.22.
Bandwidth is 5MHz.

19. Modulation and Spreading Specifications
Physical channels required during a connection:
Dedicated Channel:
DPCH  Dedicated Physical Channel
Common Channels:
P-CPICH  Primary Common Pilot Channel
Could be used at the receiver end for channel estimation, tracking
P-CCPCH  Primary Common Control Physical Channel
SCH  Synchronization Channel
Not multiplied by orthogonal code.
Used mainly for cell search: slot and frame timing acquisition.
PICH  Paging Indicator Channel
OCNS  Orthogonal Channel Noise Simulator
Simulates interference caused by other users or signals.

20. Modulation and Spreading Overview
Physical Channels are added before being sent to Pulse Shaping
PN Sequence
Gold Codes
Channelization
Orthogonal Codes
OVSF
Scrambling
Power
Settings
QPSK Modulation
Power Weighting
Spreading
Scrambling +
DPCH
I&Q
Mapping
To Channel
Common
Channels
OCNS
SCH
Common Channels are introduced
{3.84Mcps}
Bit Rate
Chip Rate

21. Modulation and Spreading Model
Pulse Shaping
Introduce Common Channels
Power Adjustment
Introduce Interference
Scrambling

22. References 3GPP TS 25.101 – “UE Radio Transmission and Reception”.
3GPP TS – “Physical channels and mapping of transport channels onto Physical Channels (FDD)”.
3GPP TS – “Spreading and Modulation (FDD)”.

23. RAKE Receiver Standard does not defined Receiver algorithms.
Although specifications has been defined in a such a way that a RAKE receiver will satisfy most of the cases.
RAKE receiver consists of several branches (RAKE Fingers) each of them assigned to a different receive paths, due to:
Diversity reception (“echoes”) : sum of attenuated and delayed versions of the transmitted signal.
Handoff.
The outputs of the different RAKE fingers are aligned in time and coherently combined.
Convert destructive interference into constructive interference.

24. RAKE Receiver Rake finger consists of:
Downsampler
Decorrelators for Data and Pilot
Receiver requires knowledge of channelization codes used by Data (Dedicated Physical Channel) and Pilot.
Channel Estimation
By comparing receiving pilot signal with reference signal.
Low Pass filter is introduced is smooth noise estimates.
Data Derotation or Phase Correction
Using channel estimates data is phase corrected.
Current RAKE receiver assumes perfect carrier and timing synchronization.

25. + ↓ RAKE Finger Overview Pilot Reference Channel Estimation Phase
Paths are aligned and added coherently
Pilot Sequence, Channelization and Scrambling Code are generated at the receiver
Channel
Estimation
From Other
Fingers
Pilot Reference +
Correlator
From Channel ↓
Phase
Correction To
Decoder
Orthogonal
Codes
Data / Pilot
Derotates data using channel estimates
Oversampled data
From Other
Fingers
Tick Rate
Chip Rate
Bit Rate

26. RAKE Receiver Model Pilot and Data Correlators
Pilot Reference Generator
Channel Estimator
RAKE Combiner
Sequence
Generators
Phase Correction

27. Channel Models
3GPP standard specifies minimum requirement tests under for different data rates under different propagation conditions:
Static Channel (AWGN)
Multipath Fading
6 different multipath profiles
Moving Propagation Conditions
Non fading channel with two taps (static – moving).
Birth-Death Propagation Conditions
Non fading channel with two taps that appear randomly.
Channel models are implemented using a Configurable Subsystem.

28. Channel Models
Use the mask of the demo, to select any predefined profile.
To define any multipath profile, use the option User Defined.

29. References
3GPP TS – “UE Radio Transmission and Reception”.

30. Visualizing the results
Spreading and Modulation Demo
Multiplexing and Coding Demo
Physical Layer Demo
BER
(Bit Error Rate)
Time Scopes
Frequency Scopes
BLER
(Syndrome Detector)
There is an intrinsic delay between transmission and reception of at least 2 TTI.
Simulink libraries contain several other types of displays such as eye diagrams, scatter plots or histograms.

31. Visualizing the results
To open and close the scopes, double-click on the switch icon

32. Enhancements

33. Enhancements
Current model and library can be used as a baseline to test different algorithms such as:
Turbo coding
Power Control
AFC
AGC
Tracking
Space Time Transmit Diversity
Two transmit antennae and one receiver antenna.
Open Loop
Close Loop Mode I and II
Cell Search
Multi-user detection. …

34. Radiolab 3G

35. Radiolab 3G: UMTS/W-CDMA Blockset
20 reference designs
Uplink and downlink
Transport channels and physical channels
Viterbi and Turbo decoding
Multi-user detection
Vary data rates during simulation (Bursty)
Fixed-point and floating-point
“RadioLab3G”

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37. Thank you