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IS2000 CDMA System, Forward Link

Measurement Definition

The BER and FER measurements are performed at the uncoded bit level. Eb/No level at this point is defined by variable EbNo in Global Definitions.

The SER measurement is performed on the symbols before orthogonal spreading with the appropriate Walsh code. Eb/No level at this point is defined by variable EsNo (Symbol Energy) in Global Definitions. The relationship between EbNo and EsNo is given below:

EsNo = EbNo - db_pow( CodeN/CodeB )

where CodeN/CodeB correction factor is due to the coding rate.

The SNR at the channel level is defined by variable EcsNo in Global Definitions:

EcsNo = EsNo - db_pow( WalshLen)

where WalshLen is the length of the Walsh code used for orthogonal spreading.

Measurement Setup

Simulation can be configured via variables in the Global Definition window, which are denoted by the "=>" symbol.

Channel mode can be selected by setting ChannelMode variable. The options are:

      - 0: FCH RC3, 5 ms frame, 9.6kbps

      - 1: FCH RC3 or SCH RC3, 20 ms frame, 9.6kbps

      - 2: SCH RC3, 20 ms frame, 153.6kbps

Simulation can be configured to perform either BER/FER or SER measurements. This is done due to the fact that the regions of interest for BER/FER and SER measurements do not overlap; the "drop-off" regions of the "waterfall" curves for BER/FER and SER are offset by approximally 20dB. BER/FER or SER measurements can selected by setting the variable FER_SER_select to 0 for BER/FER measurements and 1 for SER measurement.

The Walsh code used for FCH, SCN and OCNS channels can be set via variables FCH_Wcode, SCH_Wcode and OCNS_Wcode variable. The default values are 1,2 and 3, respectively.

The output power level in dBm and carrier frequency in MHz can be set via OutPwrLvl_dBm and CtrFrq_MHz variables.

The SNR sweep is configured via three variables: SNR_start, SNR_span, SNR_step. For BER/FER measurements, these variable define the start, span and step of the sweeping of the EbNo variable. For SER measurements, these variables define the start, span and step of the EsbNo sweeping.

For BER/FER measurements, simulation is controlled via the FER_MIN_NUM_ERRS and FER_MAX_NUM_TRLS variables. For SER measurement, simulation is controlled by SER_MIN_NUM_ERRS and SER_MAX_NUM_TRLS variables. Simulation will continue at a point in the error rate curves until the minimum number of errors (FER_MIN_NUM_ERRS or SER_MIN_NUM_ERRS) is collected, or until the maximum number of trial blocks (FER_MAX_NUM_TRLS or SER_MIN_NUM_ERRS) is reached. If one of these two conditions is met, error rate computation is generated and the swept variable is advanced.

When BER/FER measurements are performed, the x-axis in the Error Rates graph denotes the Eb/No value. When SER measurements are performed, the x-axis denotes the Esb/No value. The actual Ecb/No value is shown by the EsNo annotation on the main system diagram.

Implemented channels

(Specification document: TIA-2000-2-D)

  * Pilot Channel

  * Fundamental Channel, Radio Configuration 3

      - 9600 bps, 5 and 20 ms frames

  * Supplemental Channel, Radio Configuration 3

      - 9600 bps and 153600 bps, 20 ms frame

  * OCNS

      - 5 ms and 20 ms frames

Channel levels for test measurements

(Specification document: TIA-EIA-98-E)

           FCH Ec

           ------  *  FCH_Chip_Bit

 FCH Eb     Ior

 ------ = -------------------------

   Nt               Ioc

                   -----

                    I^or

 FCH_Chip_Bit = 1228800 / 9600 = 128

 Pilot Ec

 -------- = -7 dB

    Ior

  FCH Ec

 -------- = -16 dB at 9600 bps

   Ior

  SCH Ec

 -------- = -16 dB at 9600 bps

   Ior

  I^or

 ------ = -1 dB

  Ioc

Nominal channel levels (for each Channel_Mode)

ChannelMode = 0:

   Pilot Ec/Ior = -7 dB

   FCH Ec/Ior = -16 dB

   SCH Ec/Ior = -16 dB

   OCNS Ec/Ior = -1.26126 dB

ChannelMode = 1:

   Pilot Ec/Ior = -7 dB

   FCH Ec/Ior = -16 dB

   SCH Ec/Ior = -16 dB

   OCNS Ec/Ior = -1.26126 dB

ChannelMode = 2:

   Pilot Ec/Ior = -7 dB

   FCH Ec/Ior = -7 dB

   SCH Ec/Ior = -3.7 dB

   OCNS Ec/Ior = -8.67779 dB

Measurements

1. FER/BER Measurement

- Frame Error Rate (FER) is defined in specification document TIA-EIA-98-E.  It is measured based on the CRC of the decoded signal at the receiver.

- Bit Error Rate (BER) is measured by comparing the transmitted source bits to the decoded source bits.  Number of bits transmitted on each frame is:

      Channel_Mode = 1:     24

      Channel_Mode = 2:    172

      Channel_Mode = 3:   3048

2. SER Measurement

- Symbol Error Rate (SER) is measured by comparing the QPSK symbols at the input of Orthogonal (Walsh) Spreading with the decoded QPSK symbols after Orthogonal (Walsh) De-spreading.  Number of QPSK symbols trasmitted on each frame is:

      Channel_Mode = 1:     96

      Channel_Mode = 2:    384

      Channel_Mode = 3:   6144

Time (ms) DB(PWR_vsT(TP.TX_out,1,0,1,0,0,1000,0,10,0,-1,0,-1,10,1,0,0.5,0,0,0,0,0)) (dBm) IS2000_FL DB(PWR_vsT(TP.TX_DUT_out,1,0,1,0,0,1000,0,10,0,-1,0,-1,10,1,0,0.5,0,0,0,0,0)) (dBm) IS2000_FL DB(PWR_vsT(TP.RX_DUT_in,1,0,1,0,0,1000,0,10,0,-1,0,-1,10,1,0,0.5,0,0,0,0,0)) (dBm) IS2000_FL DB(PWR_vsT(TP.RX_DUT_out,1,0,1,0,0,1000,0,10,0,-1,0,-1,10,1,0,0.5,0,0,0,0,0)) (dBm) IS2000_FL
510.521 48.5432 48.5432 59.4637 59.4637