Exploiting UEP in QAM-based BICM: interleaver and code design

Alvarado, Alex; Agrell, Erik; Szczeciński, Leszek; Svensson, Arne

doi:10.1109/tcomm.2010.02.080525

Cited by 28 publications

(83 citation statements)

References 46 publications

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“…The condition that the coded and interleaved sequence could be asymmetric can be obtained for example by using an encoder with nonuniform outputs, or by a particular puncturing scheme applied to the coded bits. This can be combined with the use of multiple interleavers and multiplexing [63], which would allow P C k (u) = 1/2. Examples of how to construct a BICM scheme where nonuniform input symbol distributions are obtained include the "shaping encoder" of [64], [65] and the nonuniform signaling scheme based on a Huffman code of [66].…”

Section: Bicm With Arbitrary Input Distributionsmentioning

confidence: 99%

Optimal Alphabets and Binary Labelings for BICM at Low SNR

Agrell

Alvarado

2011

IEEE Trans. Inform. Theory

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Abstract-Optimal binary labelings, input distributions, and input alphabets are analyzed for the so-called bit-interleaved coded modulation (BICM) capacity, paying special attention to the low signal-to-noise ratio (SNR) regime. For 8-ary pulse amplitude modulation (PAM) and for 0.75 bit/symbol, the folded binary code results in a higher capacity than the binary reflected Gray code (BRGC) and the natural binary code (NBC). The 1 dB gap between the additive white Gaussian noise (AWGN) capacity and the BICM capacity with the BRGC can be almost completely removed if the input symbol distribution is properly selected. First-order asymptotics of the BICM capacity for arbitrary input alphabets and distributions, dimensions, mean, variance, and binary labeling are developed. These asymptotics are used to define first-order optimal (FOO) constellations for BICM, i.e., constellations that make BICM achieve the Shannon limit −1.59 dB. It is shown that the E b /N0 required for reliable transmission at asymptotically low rates in BICM can be as high as infinity, that for uniform input distributions and 8-PAM there are only 72 classes of binary labelings with a different firstorder asymptotic behavior, and that this number is reduced to only 26 for 8-ary phase shift keying (PSK). A general answer to the question of FOO constellations for BICM is also given: using the Hadamard transform, it is found that for uniform input distributions, a constellation for BICM is FOO if and only if it is a linear projection of a hypercube. A constellation based on PAM or quadrature amplitude modulation input alphabets is FOO if and only if they are labeled by the NBC; if the constellation is based on PSK input alphabets instead, it can never be FOO if the input alphabet has more than four points, regardless of the labeling.

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Section: Bicm With Arbitrary Input Distributionsmentioning

confidence: 99%

Optimal Alphabets and Binary Labelings for BICM at Low SNR

Agrell

Alvarado

2011

IEEE Trans. Inform. Theory

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“…BICM appears as a simple out-of-the box coded modulation scheme, however, its full potential is achieved only if its design is optimized. For example, the unequal error protection (UEP) caused by the binary labeling of equally spaced (ES) constellations can be exploited to improve its performance [4]- [6]. More generally, if the equivalent channel seen by the encoder/decoder pair offers UEP, gains in terms of bit error rate (BER) can be obtained, cf.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, aiming at further gains compared to those in [4], [5], we propose to control the relative protection levels of different coded bits via non-equally spaced (NES) constellations. In particular, we use the so-called hierarchical constellations [7], which have received a great deal of attention in many applications, e.g., in simultaneous voice and multiclass data transmission [8], or in digital video broadcasting [9].…”

Section: Introductionmentioning

confidence: 99%

“…II]. Recently, the so-called multiple interleavers (M-interleavers) were shown to improve the performance of the system by exploiting the UEP in both BICM [4] and BICM with iterative decoding [6].…”

Section: Introductionmentioning

confidence: 99%

“…[14]. We show that such a deterministic multiplexing of the coded bits outperforms the R-MUX used in [4], [5].…”

Section: Introductionmentioning

confidence: 99%

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Constellation and Interleaver Design for BICM

Hossain

Alvarado

Szczeciński

2011

2011 IEEE Global Telecommunications Conference - GLOBECOM 2011

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In this paper, we propose a new BICM design which considers hierarchical (nonequally spaced) constellations, a bitlevel multiplexer, and multiple interleavers. It is shown that this new scheme outperforms previous BICM designs because it exploits the temporal structure of the coded sequence. An analytical bound on the bit error rate (BER) of the proposed BICM scheme in terms of the constellation parameters and the multiplexer is developed for Nakagami-m fading channels. This bound is used to design a BICM transceiver with improved BER performance. Numerical results show that the gains compared to conventional BICM designs depend on the fading parameter and reach 2 dB for a target BER of 10 −7 and m = 5.

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Interleaver Design

2014

Bit‐Interleaved Coded Modulation

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Exploiting UEP in QAM-based BICM: interleaver and code design

Cited by 28 publications

References 46 publications

Optimal Alphabets and Binary Labelings for BICM at Low SNR

Optimal Alphabets and Binary Labelings for BICM at Low SNR

Constellation and Interleaver Design for BICM

Interleaver Design

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