Operating Manual Vol 1 - ES Documentation

Digital Standard IS-95 CDMASMIQ2.12.2 PRBS Data Source in Forward LinkA PN generator is used as PRBS data source for forward link modes. This PN generator provides apseudo random bit sequence with a period of 2 17 -1. The PRBS data sequence is a so-called sequenceof maximum length that is generated by means of a feedback shift register. The following schematicshows the PN generator with feedback to registers 3 and 0 (output). The data of the start value areentered into the register.EXOR1 1 1 0 0 1 116 15 143 2 1 0DATAThe start value of the PN generator is 1100 0100 1110 0011 1The bit sequence after the start thus is:1100 0100 1110 0011 1111 0001 1111 1110...... 0011 1111 0000 0111 1110 0011 1001 1100...... 0111 1111 1011 1111 1100 0001 0010 0000...... 1110 0100 0001 0011 1110 0010 0100 0110..........The generated bits are assigned to the modulation data of the different forward link modes as follows:Mode FWD_LINK_18The PN bits are assigned to the different code channels as follows:Modulation data bit 0:1100 0100 1110 0011 1111 0001 1111 1110 ...↑↑c31, ch30, .........................ch0 ...Modulation data bit 1:0011 1111 0000 0111 1110 0011 1001 1100 ...↑↑ch31, ch30, ........................ch0 ...etc.The data bits of the unused code channels c18 to c31 and those of the deactivated code channelsare discarded, ie not used.Modus FWD_LINK_64The PN bits are assigned to the different code channels as follows:Modulation data bit 0:11000100111000111111000111111110 00111111000001111110001110011100 ...↑ ↑ ↑ ↑c31, ch30, ..................ch0,ch63, ch62, ................ch32 ...Modulation data bit 1:01111111101111111100000100100000.11100100000100111110001001000110 ...↑ ↑ ↑ ↑c31, ch30, ..................ch0,ch63, ch62, ................ch32 ...etc.The data bits of the deactivated code channels are discarded, ie not used.1125.5555.03 2.134E-9