Turbo Decoder for Low-Power Ultrawideband Communication Systems
A new method to reduce the computational complexity of the turbo decoding in ultrawideband (UWB) orthogonal frequency division multiplexing (OFDM) system is proposed. Existing stopping techniques for turbo decoding process using constrained decoding assume fixed signal-to-noise ratio (SNR) for all t...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Wiley
2008-01-01
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| Series: | International Journal of Digital Multimedia Broadcasting |
| Online Access: | http://dx.doi.org/10.1155/2008/897069 |
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| Summary: | A new method to reduce the computational complexity
of the turbo decoding in ultrawideband (UWB) orthogonal
frequency division multiplexing (OFDM) system is proposed.
Existing stopping techniques for turbo decoding process using
constrained decoding assume fixed signal-to-noise ratio (SNR)
for all the OFDM symbol bits so they fail to yield an acceptable
bit-error rate (BER) performance in multicarrier systems. In
this paper, we propose a bit-level stopping technique for turbo
decoding process based on the constrained decoding method. In
this technique, we combine the cyclic redundancy check (CRC)
with an adaptive threshold on the log likelihood ratio (LLR)
on each subcarrier to detect for convergence. The threshold is
adaptive in the sense that the threshold on the LLR of a bit is
determined by the average SNR of the OFDM symbol and the
channel gain of the transmission subcarrier. Results show that
when the channel state information (CSI) is used to determine
the threshold on LLR, the stopping technique can reduce the
computational complexity by about 0.5–2.5 equivalent iterations
compared to GENIE turbo without degradation in the BER
performance. |
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| ISSN: | 1687-7578 1687-7586 |