SMIQ
Digital Standard 3GPP W-CDMA (FDD)
1125.5555.03
E-9
2.177
Summation
After application of the channel power, the components of the individual channels are summed up.
The constellation diagram of the sum signal is obtained by superposition of the diagrams of the
individual channels. If the signal consists of two channels with a power of -6 dB and -12 dB and each
channel contains independent source data (DPCH), the following constellation diagram is obtained:
1
1
-1
-1
Fig. 2-102
Constellation diagram of a 3GPP W-CDMA signal with two DPCH channels
Filtering
An unfiltered spread signal is obtained after summation. Due to filtering the number of samples is
increased by the oversampling factor and band-limiting is performed.
Multi code
3GPP W-CDMA supports multi-code transmission for downlink-dedicated physical channels (DPCH) .
This form of transmission is used for channels intended for the same receiver, i.e. those receivers that
belong to a radio link. The first channel of this group is used as a master channel.
Shared parts (pilot, TPC and TCFI) are spread for all channels using the spreading code of the master
channel.
Note:
Instead of changing the spreading code within a slot several times, the master code rather
than the shared parts can be sent at higher power. The other channels then have to be
blanked out correspondingly.
2.14.2
Generation of 3GPP W-CDMA Signals
The DIGITAL STD - WCDMA/3GPP menu is used to configure W-CDMA signals to the 3GPP standard
(FDD). Up to 512 channels (distributed amongst up to four base or mobile stations) can be simulated in
the downlink. The operation in the uplink was changed due to the extension to 3GPP version 3.1.1. In
contrast to the 3GPP versions 2.0.0 and 2.1.0, there is no longer a large channel table with 128 DPDCHs.
A mobile station has now 6 DPDCHs at maximum, the parameters of which are prescribed to a large
extent by the standard. In order to obtain clear and simple operation, distinction is now made between
3 modes in the uplink (PRACH only, PCPCH only and DPCCH + DPDCH). In each mode, only the
relevant parameters are displayed. But it is still possible to simulate a signal scenario of up to 4 mobile
stations.
The menu is hierarchical with several levels. This organizes the large number of parameters in a clear
way.
There are also other menus with parameters that modify the W-CDMA signal.