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IS2000 CDMA System, Reverse Link
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 after orthogonal spreading with the appropriate Walsh code. Eb/No level at this point is defined by variable EcsNo (Energy of Channel Symbols) in Global Definitions. The relationship between EbNo and EcsNo is given below:
EcsNo = EbNo - db_pow( CodeN/CodeB * 2 * WalshLen)
where CodeN/CodeB correction factor is due to the coding rate, the factor of 2 is due to the symbol repetition, and WalshLen is the length of the Walsh code used for orthogonal spreading.
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
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 can be set via the FCH_Wcode variable. The value defined in the specifications is 4.
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.
Levels of Eb/Nt for each channel are defined in Specification Document: TIA-EIA-98-E and are repeated below:
------ * FCH_Chip_Bit
FCH Eb Ior
------ = -------------------------
FCH_Chip_Bit = 1228800
-------- = -7 dB
-------- = -16 dB at 9600 bps
------ = 2 dB
System Diagram - IS2000_RL
Graph - SER
Graph - Power Levels
|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_RL||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_RL||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_RL||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_RL|