Bit-interleaved coded modulation (BICM) has established itself as the prevalent coded modulation scheme for wireless communication systems. There are a number of semi-analytical approaches for BICM performance analysis, all of which have limitations in terms of applicability and/or complexity. In this paper, we present a novel analytical approach to approximate the bit error rate (BER) of BICM. Our approach is unified in the sense that a (i) large class of fading channels, (ii) arbitrary labeling rules, and (iii) all common signal constellations are encompassed, and it is preferable over previous work in that we provide closed-form expressions. We also derive expressions for the asymptotic BER, which reveals the diversity order and coding gain of BICM transmission over fading channels. The accuracy of proposed analytical approximations is validated through comparison with selective simulation results.

Bit-interleaved coded modulation (BICM) has established itself as a quasi-standard for bandwidth- and power-efficient wireless communication. In this paper, we present an analytical approach to evaluate the performance of BICM transmission over frequency-flat fading additive white Gaussian noise channels. The statistic of the fading envelope is modeled as Nakagami-m distributed, which spans a wide range of practical multipath fading scenarios through adjustment of the m-parameter. For this setup, we derive approximations for the bit-error rate (BER) and cutoff rate of BICM. Different from previously proposed methods, our analysis is valid for general quadrature amplitude modulation and phase shift keying signal constellations and arbitrary bit-to-symbol mapping rules, and it results in simple closed-form expressions. The key idea is to use well-chosen subsets of signal points to approximate the probability density function of reliability metrics used for decoding. This approximation is accurate for signal-to-noise ratio regions of interest for BICM systems with moderate coding complexity such as, e.g., convolutional coded BICM systems. Based on this approximation we also derive an asymptotic BER expression, which reveals the diversity order and coding gain of BICM. The usefulness of the proposed analytical approach is validated through numerical and simulation results for a number of BICM transmission examples.

Bit-interleaved coded modulation (BICM) is often the method of choice for multilevel transmission over fading channels. If relatively simple forward error-correction (FEC) codes such as convolutional codes are employed, iterative decoding between demapper and FEC decoder can provide significant performance improvements over non-iterative decoding. To keep the complexity of iterative decoding low, the use of hard-decision feedback from FEC decoder to demapper is appealing. However, the price to be paid is a performance degradation due to feedback errors. In this letter, two new demapper designs are developed which are able to strongly mitigate the effect of erroneous feedback. The key ideas are (a) the use of an estimate of the average error rate for the hard-decision feedback and (b) the interpretation of feedback errors as additive impulsive noise. Simulation results show that the proposed designs achieve error rates close to those for iterative decoding with soft feedback, while they maintain the complexity advantage of using hard decision feedback.

Bit-interleaved coded modulation (BICM) has been adopted in many systems and standards for spectrally efficient coded transmission. The analytical evaluation of BICM performance parameters, in particular bit-error rate (BER), has received considerable attention in the recent past. In this paper, we derive BER approximations for BICM transmission over general fading channels impaired by Gaussian mixture noise (GMN). To this end, we build upon the saddlepoint approximation of the pairwise error probability (PEP) and a recently established approximation for the probability density function (PDF) of bit-wise reliability metrics for nonfading additive white Gaussian noise (AWGN) channels. We extend this PDF approximation to the case of GMN, and obtain closed-form expressions for its Laplace transform for fading GMN channels. The latter allows us to express the PEP and thus BER via the saddlepoint approximation. For the special case of fading AWGN channels the presented approximations are closed form, since the saddlepoint is well approximated by 1/2 for BICM decoding. Furthermore, we derive closed-form PEP expressions also for GMN channels in the high signal-to-noise ratio regime and establish the diversity and coding gain for BICM transmission over fading GMN channels. Selected numerical results for the BER of convolutional coded BICM highlight the usefulness of the proposed approximations and the differences between AWGN and GMN channels.

We present an analytical approach to determine the performance of bit-interleaved coded modulation (BICM) transmission over unfaded Gaussian channels. In particular, we derive expressions for bit-error rate and cutoff rate assuming general quadrature amplitude modulation (QAM) constellations. Different from previously proposed methods, our analysis is valid for arbitrary labeling rules and results in simple closed-form expressions. The key idea is to utilize a simplification to estimate the probability density function of reliability metrics, which is tight for signal-to-noise ratio regions of interest for BICM systems with moderate coding complexity such as, e.g., convolutional coded BICM systems. The usefulness of the proposed analytical approach is validated through numerical and simulation results for a number of BICM transmission examples.