Operating Manual Vol 1 - ES Documentation

SMIQDigital Standard 3GPP W-CDMA (FDD)Resolve all ConflictsIf you select the RESOLVE ALL button in the domain conflict info window, the SMIQ tries to arrange theactive code channels so that no overlapping occurs in the code domain. The channelization codenumber of the channels is varied to do this. The effect of a conflict resolution is shown by the codedomain display.Fig. 2-130WCDMA/3GPP – BS CONFIGURATION / CODE DOMAIN menu (after conflict resolution)If the assigned domain of all active channels is greater than the physically available domain (e.g. 5channels with 960 ksps at a chip rate of 3.84 Mcps), conflicts can no longer be resolved. The message "noresolution of domain conflicts possible" is displayed.2.14.2.10 Effect of CLIPPING LEVEL Parameter on SignalW-CDMA signals may have very high crest factors - especially if the number of channels is high and the dataoffset is unfavourable (see sections 2.14.3.3 and 2.14.3.4). High crest factors entail two basic problems:1. The nonlinearity of the power amplifier (compression) causes intermodulation which expands thespectrum (spectral regrowth).2. Since the level in the D/A converter is relative to the maximum value, the average value is convertedwith a relatively low resolution. This results in a high quantization noise.Both effects increase the adjacent-channel power.From all the possibilities listed in section 2.14.3.4 for influencing the crest factor, changing theCLIPPING LEVEL is the simplest and most effective. In this case a limit value is defined which is apercentage of the highest peak value. All current values exceeding this limit will be clipped to this value.Since clipping is done prior to filtering, the procedure does not influence the spectrum. The EVMhowever increases. Since clipping the signal not only changes the peak value but also the averagevalue, the effect on the crest factor is unpredictable. The following table shows the effect of theCLIPPING LEVEL on the crest factor for typical scenarios.1125.5555.03 2.213E-9