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WCDMA3G_TimeSwitch


Description: Time switch for primary CCPCH, PSCH and SSCH
Library: 3GPPFDD 10-99, Common Physical Channels
Class: SDFWCDMA3G_TimeSwitch

Parameters

Name

Description

Default

Type

ChipRate

chip rate of the system: Chip Rate 3.84M

Chip Rate 3.84M

enum

DL_TXDiversity

downlink transmit diversity method: No_Diversity, DL_STTD

No_Diversity

enum

Pin Inputs

Pin

Name

Description

Signal Type

1

PCCPCH

primary CCPCH data

complex

2

SCH

sum of PSCH data and SSCH data

complex

Pin Outputs

Pin

Name

Description

Signal Type

3

Ant1

output data on antenna1 with STTD or output data without STTD

complex

4

Ant2

output data on antenna2 with STTD or all zero without STTD

complex

Notes/Equations
  1. This model is used to switch between the primary common control physical channel (PCCPCH), the primary synchronization channel (PSCH), and the secondary synchronization channel (SSCH).
    Each firing, 2560 tokens of Ant1 and 2560 tokens of Ant2 are produced when 256 tokens of SCH and 2560 tokens of PCCPCH are consumed.
  2. In a downlink, open loop downlink transmit diversity uses a space time block coding based transmit diversity (STTD). Higher layers signal if STTD encoding is used for the PCCPCH by modulating the SCH. Primary and secondary synchronization codes are modulated by the symbol given in the following table.
    Symbol a Modulating SCH

    STTD Encoding Status

    symbol a

    PCCPCH STTD encoded

    a = +1

    PCCPCH not STTD encoded

    a = -1

    The Primary CCPCH is a fixed rate (30 kbps, SF = 256) downlink physical channel used to carry the BCH. The Primary CCPCH is not transmitted during the first 256 chips of each slot; primary and secondary SCHs are transmitted during this period.
    When STTD is not used on PCCPCH, this model masks the first 256 chips of each slot of PCCPCH and outputs data on Ant1 as illustrated in the following figure. Output data on Ant2 is all zero.
    When STTD is used on PCCPCH, data symbols of PCCPCH are STTD encoded. The last odd data symbol in every frame (10ms) is not STTD encoded and the same symbol is transmitted with equal power from the two antennas. For more information regarding STTD encoding, refer to WCDMA3G_STTDEncoder.
    SCH is transmitted by the time switched transmit diversity (TSTD). In even numbered slots, PSCH and SSCH are transmitted on Ant1; in odd numbered slots, PSCH and SSCH are transmitted on Ant2.

    Primary CCPCH Frame Structure
    Output data on Ant1 and Ant2 is shown in the following figure.

    Structure of SCH Transmitted by TSTD; PCCPCH Transmitted by STTD

References
  1. 3GPP Technical Specification TS 25.211 V3.0.0, "Physical Channels and Mapping of Transport Channels onto Physical Channels (FDD)," October 1999.
  2. 3GPP Technical Specification TS 25.213 V3.0.0, "Spreading and Modulation (FDD)," October 1999.
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