Multilevel RS/convolutional concatenated coded QAM for hybrid IBOC-AM broadcasting

Chung, Sae-Young; Lou, Hui‐Ling

doi:10.1109/glocom.1999.831628

Cited by 6 publications

(8 citation statements)

References 10 publications

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“…We evaluate methods of applying outer CRC codes to PAC, an audio coder that has variable frame length. Similar experiments to these should also be repeated for other outer codes such as Reed-Solomon codes, which are preferred for digital audio broadcasting systems in the AM band with multilevel modulation [4], [26], [27]. We conclude that the variable length outer CRC code integrated with the PAC audio coder is a more effective method of applying the outer CRC code.…”

Section: B Variable Crc Resultsmentioning

confidence: 99%

Huffman code based error screening and channel code optimization for error concealment in perceptual audio coding (PAC) algorithms

Laneman

Sundberg²,

Faller³

2002

IEEE Trans. on Broadcast.

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Abstract-The class of Perceptual Audio Coding (PAC) algorithms yields efficient and high-quality stereo digital audio bitstreams at bit rates from 16 kb/sec to 128 kb/sec (and even higher bit rates). To avoid "pops and clicks" in the decoded audio signals due to erasure or undetected errors from transmission over unreliable channels, e.g., in the context of digital audio broadcasting (DAB), channel error detection combined with source error concealment, or source error mitigation, techniques are preferred to pure channel error correction. One simple and efficient way to perform channel error detection is to employ a high-rate block code; for example, the preferred solution for hybrid in-band on-channel (HIBOC) DAB in the FM band employs a cyclic redundancy check (CRC) code. Several joint source-channel coding issues arise in this framework because PAC contains a fixed-to-variable source coding component in the form of Huffman codes, so that the output audio packets are of varying length. We explore two such issues in this paper.First, we develop methods for screening for undetected channel errors in the audio decoder by looking for inconsistencies between the number of bits decoded by the Huffman decoder and the number of bits in the packet as specified by control information within the bitstream. We evaluate this scheme by means of simulations of Bernouli sources and real audio data encoded by PAC, both exposed to random bit errors as well as errors that pass undetected through a CRC decoder. Considerable reduction in undetected errors is obtained with little extra processing in the receiver and with little or no increase in the transmitted bit rate.Second, we consider several configurations for the channel error detection codes, in particular CRC codes, by means of representative simulations and informal listening tests, for several audio coder bit rates of interest in DAB. One configuration employs a fixed-rate, fixed-blocklength code of optimized length outside the PAC algorithm. Another preferable set of formats employs variable-blocklength, variable-rate outer codes matched to the individual audio packets, with one or more codewords used per audio packet. In this case, better performance is obtained; however, to maintain a constant bit rate into the channel, PAC and CRC encoding must be performed jointly, e.g., by incorporating the CRC into the bit allocation loop in the audio coder.

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Section: B Variable Crc Resultsmentioning

confidence: 99%

Huffman code based error screening and channel code optimization for error concealment in perceptual audio coding (PAC) algorithms

Laneman

Sundberg²,

Faller³

2002

IEEE Trans. on Broadcast.

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“…The paper showed that, by applying concatenated codes to only the lowest level of the multilevel scheme, an additional 0.8 dB of coding gain can be obtained, compared to the multilevel RS coded QAM scheme [103].…”

Section: Fec and Modulation Schemesmentioning

confidence: 99%

“…24 are concatenated outer RS codes and inner trellis-coded modulation (TCM) based on 16-, 32-, or even 64-QAM constellations [72], [96]. Due to the limited bandwidth available for hybrid IBOC-AM systems, alternate FEC schemes have also been explored [97], and the results are summarized in Section VI-C.…”

Section: A 30-khz Hybrid Iboc-am Systemmentioning

confidence: 99%

“…To further improve the performance, [103] also proposed using a concatenated coding scheme using an RS code as an outer code and a convolutional code (CC) as an inner code to the lowest levels of the multilevel RS coded QAM scheme, where errors are most likely to occur. The paper showed that, by applying concatenated codes to only the lowest level of the multilevel scheme, an additional 0.8 dB of coding gain can be obtained, compared to the multilevel RS coded QAM scheme [103].…”

Section: Fec and Modulation Schemesmentioning

confidence: 99%

“…Thus, RS codes were first proposed to be used in these systems, and several modulation schemes based on RS codes are constructed in [103] to optimize the performance. The paper showed that, for a code rate of 4/5 and using 32-QAM constellations, an additional coding gain of about 2.5 dB can be achieved at a BER of 10 ( 4 dB at BER ) by using a multilevel RS coded QAM scheme instead of using the straightforward RS to QAM mapping scheme [103].…”

Section: Fec and Modulation Schemesmentioning

confidence: 99%

See 2 more Smart Citations

Technical advances in digital audio radio broadcasting

Faller¹,

Juang

Kroon³

et al. 2002

Proc. IEEE

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Reed-Solomon decoding algorithms for digital audio broadcasting in the AM band

Laneman

Sundberg

2001

IEEE Trans. on Broadcast.

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Abstract-Digital audio broadcasting (DAB) systems for the AM band are being developed to provide higher-quality radio broadcasts, broader coverage, and data services. Transmission is typically done by means of multistreaming with QAM/OFDM in the high bits/sec/Hz regime, in which Reed-Solomon codes, either alone or in concatenation with inner trellis coded modulation (TCM), are natural choices for error control. For the AM DAB application, Reed-Solomon codes with suboptimal decoders of the bounded-distance type offer error correction important for bringing down the error probability, but also offers error detection important for generating block detected-error flags for use in the error concealment, or error mitigation, algorithm in the audio decoder. For multistream systems, the block detected-error flags can also be used to select the component streams retained by the audio decoder. In this paper, we evaluate the performance of Reed-Solomon codes in terms of both detected (flag) and undetected error rates for DAB applications. We provide simulation results for a variety of decoding algorithms, including hard-decision decoding (HDD), successive-erasure decoding (SED), and fixed-erasure decoding (FED), and discuss the channel environments in which each of these algorithms may be appropriate. Among other results, for example, we address the issue of matching the blocklength of the Reed-Solomon code to the audio decoder with its variable frame structure. From our simulation results for HDD, we conclude that the increased error correction capability of longer Reed-Solomon codes more than compensates for the mismatch in terms of error mitigation in the audio decoder. We also observe that SED provides only small improvements for uniform interference channels, while FED offers considerable improvements for some partial-band interference channels. We describe an appealing two-mode adaptive configuration using HDD and FED for mitigating partial-band interference caused by some second-adjacent AM broadcasts.

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Multilevel RS/convolutional concatenated coded QAM for hybrid IBOC-AM broadcasting

Cited by 6 publications

References 10 publications

Huffman code based error screening and channel code optimization for error concealment in perceptual audio coding (PAC) algorithms

Huffman code based error screening and channel code optimization for error concealment in perceptual audio coding (PAC) algorithms

Technical advances in digital audio radio broadcasting

Reed-Solomon decoding algorithms for digital audio broadcasting in the AM band

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