 CPCH, DCH, DSCH, FACH + USCH (tdd) Turbo coding No coding 4.6.3.1 Convolutional Coding In UTRA we define convolutional codes with constraint length 9 and coding rates 1/3 and 1/2. Figure 4.50 illustrates the convolutional coder configuration. Output from the rate 1/3 convolutional coder follows the order output0, outputl, output2, output0, out- put1, output 2, output 0 .,output2; while output from the rate 1/2 convolutional coder follows the order output 0, output 1, output 0, output 1, output 0, output 1. We add 8 tail bits with binary value 0 at the end of the code block before encoding, and when starting to encode the initial value of the shift register of the coder = 'all 0'. Input Output 0 Go = 561 (octal) Output 1 G1 = 753 (octal) (a) Rate 1/2 convolutional coder Input Output 0 Go = 557 (octal) Output 1 G1 = 663 (octal) Output 2 G2 = 711 (octal) (b) Rate 1/3 convolutional coder Figure 4.50 Rate 1/2 and rate 1/3 convolutional coders. The UTRA Physical Layer Design 4.6.3.2 Turbo Coding From the two types of code concatenation, i.e. serial and parallel, the latter suits well for high quality of services in 3rd generation systems. This can provide very low-maximum bit error ratio, e.g. 10- has the lowest S/N. In parallel code concatenation we feed the informa- tion stream into a second encoder and encode data stream generating by multiplexing (and puncture) the encoded sequences resulting from both encoding processes [17]. Coder. In UTRA we apply the Parallel Concatenated Convolutional Code (PCCC) scheme of the turbo coder with two 8-state constituent encoders and one turbo code internal interleaver [10]. The turbo coder structure illustrated in Figure 4.51 has a cod- ing rate of 1/3. We express the transfer function of the 8-state constituent code for PCCC as: G(D) = 1810 (4.74) where go(D)=1+D2+D3,and 1(D) = + D³. The initial value of the shift registers in the 8-state constituent encoders = all zeros when starting to encode the input bits, and the output from the turbo coder is: (4.75) where X1,X2,...,XK ar