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

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Presentation on theme: "© 2002 The MathWorks, Inc. 1 WCDMA Design using Simulink Alex Rodriguez The MathWorks, Inc. May 30 th, 2002 You should here music."— Presentation transcript:

1 © 2002 The MathWorks, Inc. 1 WCDMA Design using Simulink Alex Rodriguez The MathWorks, Inc. May 30 th, 2002 You should here music now. If you do not, check that your PC speakers are on and you can play sounds on your computer.

2 © 2002 The MathWorks, Inc. 2 Agenda About WCDMA WCDMA Simulink Model –About the models –Physical Layer –Mask parameters –Coding and Multiplexing –Modulation and Spreading –RAKE Receiver –Channel Models –Visualizing the results Enhancements Radiolab 3G

3 © 2002 The MathWorks, Inc. 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 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).

4 © 2002 The MathWorks, Inc. 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

5 © 2002 The MathWorks, Inc. 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 © 2002 The MathWorks, Inc. 6 About the models WCDMA Library WCDMA Multiplexing and Coding WCDMA Spreading and Modulation WCDMA Physical Layer To open the models, type wcdmademos R12.1 !! For NT, Linux and Unix w/o accelerator

7 © 2002 The MathWorks, Inc. 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 © 2002 The MathWorks, Inc. 8 WCDMA Physical Layer Transmitter Channel Coding and Multiplexing Layer 2 MAC Transport Channels Layer 1 CCTrCh Physical Channel Mapping Spreading And Modulation Channel DPCH Pilot Bits TPC TFCI Control Channels Interference (OCNS) Orthogonal Codes Slot DPCH - 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

9 © 2002 The MathWorks, Inc. 9 WCDMA Physical Layer Model

10 © 2002 The MathWorks, Inc. 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 © 2002 The MathWorks, Inc. 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 © 2002 The MathWorks, Inc. 12 Coding and Multiplexing Overview CRC Concat/ Segment Channel Encoder Rate Matching 1 st Interleaver Radio Frame Segment CCTrCH CRC Concat/ Segment Channel Encoder Rate Matching 1 st Interleaver Radio Frame Segment Layer 1 Coding Schemes: - No coding - Convolutional Coding - Turbocoding Accommodates data rates to a fixed channel bit rate Interleaves bits within each Transport Channel Limits Max Size of Codewords Multiplexes bits from different Transport Channels every 10 ms. Attaches CRC Size={0,8,12,16,24} Transmission Time Interval {10,20,40 and 80ms} Radio Frame {10ms}

13 © 2002 The MathWorks, Inc. 13 Coding and Multiplexing Model Layer 1 Layer 2 Transmission Time Interval {10,20,40 and 80ms} Radio Frame {10ms} Transport Channels CCTrCh CRC Concatenation and Segmentation Channel Encoder Rate Matching First Interleaver

14 © 2002 The MathWorks, Inc. 14 Physical Channel Mapping Overview Physical Channel Segmentation 2nd Interleaver One CCTrCH can be mapped onto one or several PhCHs Slot Builder CCTrCh DPCH TFCI Power Control Bits Pilot Bits Interleaves bits within a Radio Frame coming from different Transport Channels Transport Format Combination Index contains information of how the different transport channel have been processed Data 1TPCTFCIData 2 Pilot Structure of slot is defined by the Higher Layers via Slot Format Data is sent to the Modulation and Spreading block

15 © 2002 The MathWorks, Inc. 15 Physical Channel Mapping Model Slot {10/15 ms} Radio Frame {10ms} Physical channel segmentation 2 nd Interleaver Slot Builder

16 © 2002 The MathWorks, Inc. 16 References 3GPP TS – “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 © 2002 The MathWorks, Inc. 17 Modulation and Spreading Specifications Modulation: –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 © 2002 The MathWorks, Inc. 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 © 2002 The MathWorks, Inc. 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 © 2002 The MathWorks, Inc. 20 Modulation and Spreading Overview DPCH Spreading I&Q Mapping Common Channels Scrambling Power Settings + To Channel Orthogonal Codes OVSF PN Sequence Gold Codes OCNS SCH QPSK Modulation Bit RateChip Rate {3.84Mcps} Channelization Common Channels are introduced Scrambling Power Weighting Physical Channels are added before being sent to Pulse Shaping

21 © 2002 The MathWorks, Inc. 21 Modulation and Spreading Model Spreading Scrambling Power Adjustment Pulse Shaping Introduce Common Channels Introduce Interference Modulation

22 © 2002 The MathWorks, Inc. 22 References 3GPP TS – “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 © 2002 The MathWorks, Inc. 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 © 2002 The MathWorks, Inc. 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 © 2002 The MathWorks, Inc. 25 RAKE Finger Overview From Channel ↓ Correlator Channel Estimation Phase Correction + From Other Fingers From Other Fingers To Decoder Pilot Sequence, Channelization and Scrambling Code are generated at the receiver Pilot Reference Orthogonal Codes Data / Pilot Tick Rate Bit Rate Chip Rate Derotates data using channel estimates Paths are aligned and added coherently Oversampled data

26 © 2002 The MathWorks, Inc. 26 RAKE Receiver Model Sequence Generators Pilot Reference Generator RAKE Combiner Pilot and Data Correlators Channel Estimator Phase Correction

27 © 2002 The MathWorks, Inc. 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 © 2002 The MathWorks, Inc. 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 © 2002 The MathWorks, Inc. 29 References 3GPP TS – “UE Radio Transmission and Reception”.

30 © 2002 The MathWorks, Inc. 30 Visualizing the results 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. Spreading and Modulation Demo Multiplexing and Coding Demo Physical Layer Demo BER (Bit Error Rate) Time Scopes Frequency Scopes BER BLER (Syndrome Detector) BER BLER Time Scopes Frequency Scopes

31 © 2002 The MathWorks, Inc. 31 Visualizing the results To open and close the scopes, double-click on the switch icon

32 © 2002 The MathWorks, Inc. 32 Enhancements

33 © 2002 The MathWorks, Inc. 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 © 2002 The MathWorks, Inc. 34 Radiolab 3G

35 © 2002 The MathWorks, Inc. 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”

36 © 2002 The MathWorks, Inc. 36 Remember to fill out the survey !!

37 © 2002 The MathWorks, Inc. 37 Thank you


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