BER
(IJCSIS) International Journal of Computer Science and Information Security, Vol. 9, No. 1, January 2011
1.e-1 1.e-2 1.e-3 1.e-4 1.e-5 1.e-6 1.e-7 1.e-8 1.e-9 1.e-10 1.e-11 1.e-12 1.e-13 1.e-14 1.e-15 1.e-16 1.e-17 1.e-18 1.e-19 1.e-20 1.e-21 1.e-22 1.e-23 1.e-24 1.e-25 1.e-26 1.e-27
VII . CONCLUSIONS
N = 1000
A construction of concatenated codes CC's have presented and constructed in this paper with three main basic schemes: PCCC, SCCC, and HCCC, over AWGN and Rayleigh fading channels. The effects of various parameters on the performance of CC's, using an upper bound to the softinput, soft-output (SISO) maximum a posteriori (MAP) decoding algorithm are investigated. These parameters are : the interleaver length, and the number of iterations. The analytical results showed that coding gain was improved by increasing the interleaver length, and the number of iterations.
No iteration iteration = 2 iteration = 3 iteration = 4 iteration = 5
1
2
3
4
5
Eb / No
6
7
8
dB
Fig. 12. Analysis of Iterative decoding algorithm for 1/4 HCCC with different No of
REFERENCES
iterations [1] N. Sven, " Coding and Modulation for Spectral Efficient Transmission ", PhD dissertation .. Institute of Telecommunications of the University of Stuttgart, 2010. [2] Z. Chance, and D. Love, " Concatenated Coding for the AWGN Channel with Noise Feedback ", School of Electrical and Computer Engineering, Purdue University, West Lafayette, USA, 2010. [3] E. Lo, and K. Lataief, " Cooperative Concatenated Coding for Wireless Systems", Proceeding of IEEE Communication Society, 2007. [4] B. Cristea, " Viterbi Algorithm for Iterative Decoding of Parallel Concatenated Convolutional Codes ", 18th European Signal Processing (EUSIPCO), Aalborg, Denmark, August 2010. [5] R. Maunder, and L. Hanzo, " Iterative Decoding Convergence and Termination of Serially Concatenated Codes ", IEEE Transactions on Vehicular Technology, VOL. 59, NO. 1, January 2010.
A. The effect of interleaver length It is well known that a good interleaving affects the CC's error performance considerably. Figures 4, 5, and 6 represent the BER of PCCC, SCCC, and HCCC, respectively, versus the interleaving length, N. From these figures, it is shown that BER improve with increasing the length of interleaver.
B. The effect of number of decoder iterations The choice of decoding algorithm and number of decoder iterations also influences performance. A functional diagrams of the iterative decoding algorithm for CC's were presented in figures 7, 8, and 9 for PCCC, SCCC, and HCCC, respectively. It could be observed, from figures 10, 11, and 12, that the slope of curves and coding gain are improved by increasing the number of iterations.
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