Operating Manual Vol 1 - ES Documentation

Digital Standard 3GPP W-CDMA (FDD)SMIQScrambling UnitIn the scrambling unit, the output of the scrambling code generator and the spread symbols are combined.If the input signal and the scrambling code signal are interpreted as complex numbers (C i , C q, SC i , SC q '∈ { -1, +1 }), the output signal is a complex multiplication of the two signals:This gives:S i + j S q = (C i + j C q ) * (SC i + j SC q ')S i = C i SC i – C q SC q 'S q = C i SC q ' + C q SC iThe signal obtained in this way has a constellation diagram like a QPSK signal:Sq21Si-2-112-1-2Fig. 2-100Note:Constellation diagram of a channel with 0 dB powerThere are auxiliary conditions for some types of channels that may result in differentconstellation diagrams.If, for instance, symbols of SCH or preamble part of PRACH are coded, a BPSKconstellation is obtained without the scrambling unit. For an explanation of the differentconstellation diagrams see section 2.14.3.Channelization code generatorThe channelization code generator cyclically outputs a channel-specific bit pattern. The length of thecycle corresponds to the duration of the source symbol to be spread, i.e. the number of bits correspondsto the spread factor. The spreading sequence for the I and Q branches is identical (real). Spreadingitself is a simple EXOR operation.Two different channelization code generators are used depending on the type of channel:Channelization code generator for all channels except SCHDue to this channelization code the channel separation takes place in the sum signal. Thechannelization code number is the row in an orthogonal spreading matrix which is generated by aniterative process (OVSF).Channelization code generator SCHThis generator replaces the one described above if the synchronization code symbol of the SCHchannels is spread.The spreading matrix is replaced by a method that forms the spreading sequence from a Hadamardsequence and a statistical sequence. For details see [2], section 5.2.3.1.Data sourceThe data source used in the SMIQ is implemented at the physical layer. There is neither mapping oflogical channels to physical channels nor is inner coding/outer coding performed. If the data source is tobe implemented at a higher layer, this can be done with the aid of a file interface (see section 5.6 in theoperating manual).1125.5555.03 2.174E-9