implementation of turbo decoder using max-log-map ... - ijater

International Journal of Advanced Technology & Engineering Research (IJATER)
The log-MAP algorithm is the most complex of the
four algorithms when implemented in software, but as will
be shown later, generally offers the best bit error rate
(BER) performance. The max-log-MAP algorithm is the
least complex of the four algorithms (it has twice the
complexity of the Viterbi algorithm for each half-iteration)
but offers the worst BER performance [9]. The max-log-
MAP algorithm has the additional benefit of being tolerant
of imperfect noise variance estimates when operating on
an AWGN channel.
F. SIMULATION RESULTS
pipelining architecture introducing for performing LLR
value computations, has been shown that decoder
achieved a slight reduction in power consumption and a
slight increase in area usage, it has achieved 58% speedup
compared to non-pipelined conventional decoder.
Therefore, by adopting this kind of techniques, the turbo
decoder can be applied to wireless communication systems
requiring high data rates and low power consumption.
Further implementation of improved technologies
like “sliding window” can improve the performance with
slight increase in resources.
V. Acknowledgment
The authors would like to thank Dr. A. T. Kalghatgi,
Chief Scientist, Mr. Manoj Jain, Member (Senior Research
Staff), Mrs. A.Thirija Sharmila, Member (Senior
Research Staff) and Mr. Chaitanya Umbare Member (Research
Staff), Central Research Laboratory, Bangalore, for
their constant encouragement and support to carry out this
work.
VI. References
Fig. 7 Branch metric result using MODELSIM
The ML-MAP turbo SISO decoder presented in this
paper was initially simulated at high level to verify its
functionality. In our simulation a 1024 size block type interleaver
has been used.
Fig. 8 State metric result using MODELSIM
The figure 7 above represents the branch metric {γ}
and fig 8 represents the state metric {α} for the value of k
= 1024 and system and parity bits of length 1024.
IV. Conclusion
Normalize operation was applied to branch metric
values instead of to state metric values. In addition, with
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