3rd GPP Spreading and modulation (FDD)
<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0><script> (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){ (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o), m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m) })(window,document,'script','//www.google-analytics.com/analytics.js','ga'); ga('create', 'UA-47423994-1', 'fortunecity.ws'); ga('send', 'pageview'); </script> <center> <br> <div> <script language="javascript" type="text/javascript" src="http://ad.broadcaststation.net/ads/show_ad.php?width=728&height=90"></script> </div> </center> <table cellpadding=0 cellspacing=0 border=0 height="100%"><tr> <td valign="top" width=190 BGCOLOR="#FFFFFF" TEXT="#080000"> <div> 3rd GPP Spreading and modulation (FDD)</div> <div> <A HREF="id24.htm" TARGET="_top" TITLE="Wideband CDMA "><U><B>back to Wideband CDMA</B></U></A></div> <bR> </td> <td valign="top" BGCOLOR="#FFFFFF" TEXT="#080000"> <bR> <div> <FONT SIZE="5" COLOR="#003333" FACE="Arial" ><IMG SRC="13b6d2b0.gif" border=0 width="365" height="43" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></FONT><FONT SIZE="3" COLOR="#3366FF" FACE="Arial" > | </FONT> <A HREF="index.htm" TARGET="_top" TITLE="Lemonrain_First_Page"><U>home</U></A></div> <div> <A HREF="id55.htm" TARGET="_top" TITLE="3rd GPP Physical layer General descript"><U>3rd GPP Physical layer - 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The first is the channelisation operation, transforming every data symbol into a number of chips, increasing the bandwidth of the signal. The number of chips per data symbol is called the Spreading Factor (SF). The second operation is the scrambling operation, where a scrambling code is applied to the spread signal. </div> <bR> <div> The channelisation process is when data symbol on so-called I- and Q-branches are independently multiplied with an OVSF (Orthogonal Variable Spreading Factor) code. With the scrambling operation, the resultant signals on the I- and Q-branches are further multiplied by complex-valued scrambling code, where I and Q denote real and imaginary parts, respectively.</div> <div> <A NAME="spreading"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></div> <div> <TABLE BORDER="0" CELLPADDING="0" CELLSPACING="1" WIDTH="791" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="ALL" ALIGN="BOTTOM" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=TOP BGCOLOR=#330099 HEIGHT= 16 WIDTH="789"><div> <B> </B><B>Spreading</B> </div> </tD> </tR> </TABLE></div> <div> <U> <A NAME="uplink_dedicated_physical_channels"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></U><U>Uplink Dedicated Physical Channels (uplink DPDCH/DPCCH)</U></div> <div> The binary DPCCH and DPDCHs to be spread are represented by real-valued sequences, i.e. the binary value "0" is mapped to the real value +1, the binary value "1" is mapped to the real value -1. One DPCCH and up to six parallel DPDCHs can be transmitted simultaneously.</div> <bR> <div> After the process of channelisation, the real-valued spread signals are weighted by gain factors. After weighting, the stream of real-valued chips on the I- and Q-branches are then summed and treated as a complex-valued stream of chips. The complex-valued signal is scrambled by the complex-valued scrambling code whereby QPSK modulation is then performed.</div> <bR> <div> <U> <A NAME="physical_random_access_channel__prach_"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></U><U>Physical Random Access Channel (PRACH)</U></div> <div> After pulse-shaping is transmitted using QPSK, the PRACH preamble part consist of a complex-valued code. The spreading and modulation of the PRACH (message part) is the same as for the uplink dedicated physical channels. The binary control and data parts to be spread are represented by real-valued sequences; the control part is spread to the chip rate by the channelisation code while the data part is spread to the chip rate by the channlisation code. The real-valued spread signals are then weighted by gain factors after channelisation. After weighting, the stream of real-valued chips on the I- and Q-branches are then summed and treated as a complex-valued stream of chips. The complex-valued signal is scrambled by the complex-valued scrambling code whereby QPSK modulation is then performed.</div> <div> <A NAME="code_generation_and_allocation"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></div> <div> <TABLE BORDER="0" CELLPADDING="0" CELLSPACING="1" WIDTH="791" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="ALL" ALIGN="BOTTOM" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=TOP BGCOLOR=#330099 HEIGHT= 16 WIDTH="789"><div> <B> </B><B>Code generation and allocation</B></div> </tD> </tR> </TABLE></div> <div> <U> <A NAME="channelisation_codes"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></U><U>Channelisation codes</U></div> <div> The channelisation codes used are Orthogonal Variable Spreading Factor (OVSF) codes that preserve the orthogonality between a user's different physical channels.</div> <bR> <div> <U> <A NAME="scrambling_codes"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></U><U>Scrambling codes</U></div> <div> There are 224 uplink scrambling codes. All uplink channels shall use either short or long scrambling codes, except for the PRACH, where the long scrambling code is used. Both short and long scrambling codes are represented with complex-value.</div> <bR> <div> <U> <A NAME="long_scrambling_code"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></U><U>Long scrambling code</U></div> <div> The long scrambling codes are formed where two codes, c1 and c2 are constructed as the position wise modulo 2 sum of 38400 chip segments of two binary m-sequences generated by means of two generator polynomials of degree 25. Two sequences; one using the primitive (over GF(2)) polynomial; X25+ X3+ 1and the other other; polynomial X25+ X3+ X2 +X +1. The resulting sequences thus constitute segments of a set of Gold sequences. The code, c2, used in generating the quadrature component of the complex spreading code is a 16,777,232 chip shifted version of the code, c1, used in generating the in phase component.</div> <bR> <div> The uplink scrambling code word has a period of one radio frame.</div> <bR> <div> <U> <A NAME="short_scrambling_code"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></U><U>Short scrambling code</U></div> <div> The short scrambling code is formed using c1 and c2 which are real and imaginary components of a complex sequence from the family of periodically extended S(2) codes.</div> <bR> <div> The generation and allocation of other codes are as follows;</div> <div> <IMG BORDER="0" SRC="Symb075c00b700c800000000.gif" HEIGHT="13" WIDTH="28" ALIGN="bottom" HSPACE="0" VSPACE="0">Random access codes - preamble codes </div> <div> <IMG BORDER="0" SRC="Symb075c00b700c800000000.gif" HEIGHT="13" WIDTH="28" ALIGN="bottom" HSPACE="0" VSPACE="0">Common packet channel codes - Access preamble; CPCH preamble signatures; Channelisation codes for the CPCH message part; and scrambling code for the CPCH message part.</div> <div> <A NAME="modulation"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></div> <div> <TABLE BORDER="0" CELLPADDING="0" CELLSPACING="1" WIDTH="791" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="ALL" ALIGN="BOTTOM" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=TOP BGCOLOR=#330099 HEIGHT= 16 WIDTH="789"><div> <B> Modulation</B> <A HREF="#top" TITLE="3rd GPP Spreading and modulation (FDD)"><U><IMG SRC="0621a0c0.gif" border=0 width="26" height="12" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></A></div> </tD> </tR> </TABLE></div> <div> The modulation chip rate is 3.84 Mcps. In the uplink, the modulation of both DPCCH and DPDCH is BPSK.</div> </td> </tr></table></body>