Mapping Optimization for Space–Time Bit-Interleaved Coded Modulation With Iterative Decoding

For space-time bit-interleaved coded modulation (ST-BICM) systems with iterative decoding, the overall performance is affected by the chosen mapping. In bit-error rate (BER) curves, one mapping reaches an error floor (EF) at a low signal-to-noise ratio (SNR), while other mappings result in a lower EF at a higher SNR. The constellation mappings are divided into groups where each group exhibits a distinctive BER curve. We show that the convergence abscissa of the system depends on the average total bit errors and the harmonic mean of the minimum squared Euclidean distance. In this letter, we characterize all mapping groups for ST-BICM with 8-phase-shift keying and present the optimal selection for each mapping group over independent fading channels     

Golden Space–Time Trellis Coded Modulation

In this paper, we present a multidimensional trellis coded modulation scheme for a high rate 2times2 multiple-input multiple-output (MIMO) system over slow fading channels. Set partitioning of the Golden code is designed specifically to increase the minimum determinant. The branches of the outer trellis code are labeled with these partitions and Viterbi algorithm is applied for trellis decoding. In order to compute the branch metrics, a sphere decoder is used. The general framework for code design and optimization is given. Performance of the proposed scheme is evaluated by simulation and it is shown that it achieves significant performance gains over the uncoded Golden code     

Constellation Design for Trellis-Coded Unitary Space–Time Modulation Systems

We consider the problem of creating signal constellations for trellis-coded unitary space-time communication links, where neither the transmitter nor the receiver knows the fading gains of the channel. Our study includes constellation-design techniques for trellis-coded schemes with and without parallel paths, which allows us to find a tradeoff between low complexity and high performance. We present a new formulation of the constellation design problem for trellis-coded unitary space-time modulation (TCUSTM) schemes. The two key differences in our approach against those of other authors are that we not only combine the constellation design and mapping by set partitioning into one step, but we also use directly the Chernoff bound of the pairwise error probability as a design metric. By novelly employing a theorem for the Clarke subdifferential of the sum of the k largest singular values of the unitary matrix, we also present a numerical optimization procedure for finding signal constellations resulting in high-performance communications systems. To demonstrate the advantages of our new design method, we report the best constellations found for TCUSTM systems. Simulation results show that these constellations achieve a 1-dB coding gain at a bit-error rate of 10^-4 against usually used constellations     

Performance Analysis of Bit-Interleaved Polar Coded Modulation

Wireless Personal Communications - Polar codes have been applied to the construction of bit-interleaved polar coded modulation schemes in recent years. Bit-interleaved polar coded modulation...     

RELAY ASSISTED TRANSMISSSION WITH BIT-INTERLEAVED CODED MODULATION

We investigate an adaptive cooperative protocol in a Two-Hop-Relay （THR） wireless system that combines the following： （1） adaptive relaying based on repetition coding; （2） single or two transmit antennas and one receive antenna configurations for all nodes, each using high order constellation; （3） Bit-Interleaved Coded Modulation （BICM）. We focus on a simple decoded relaying （i.e. no error correcting at a relay node） and simple signal quality thresholds for relaying. Then the impact of the two simple thresholds on the system performance is studied. Our results suggest that compared with the traditional scheme for direct transmission, the proposed scheme can increase average throughput in high spectral efficiency region with low implementation-cost at the relay.     

Bit-Interleaved Coded Modulation in the Wideband Regime

The wideband regime of bit-interleaved coded modulation (BICM) in Gaussian channels is studied. The Taylor expansion of the coded modulation capacity for generic signal constellations at low signal-to-noise ratio (SNR) is derived and used to determine the corresponding expansion for the BICM capacity. Simple formulas for the minimum energy per bit and the wideband slope are given. BICM is found to be suboptimal in the sense that its minimum energy per bit can be larger than the corresponding value for coded modulation schemes. The minimum energy per bit using standard Gray mapping on $M$-PAM or $M^2$ -QAM is given by a simple formula and shown to approach ${-}$ 0.34 dB as $M$ increases. Using the low SNR expansion, a general tradeoff between power and bandwidth in the wideband regime is used to show how a power loss can be traded off against a bandwidth gain.      

A Novel Constellation Shaping Technique for Bit-Interleaved Coded Modulation

We present a new and simple method which consists to apply constellation shaping to bit-interleaved turbo-coded modulation (BICTM) over additive white Gaussian noise channels. By assuming the example of a 3-bit/dim 16-PAM BITCM, it is shown that this technique can provide shaping gain of 0.79 dB.     

带递归检测的比特交织编码调制系统设计

文章介绍了带递归检测的比特交织编码调制方式,该方式通过去映射器或多输入多输出检测器与软输入软输出解码器之间的递归检测来减小系统的误码率.通过基于二进制交换算法,文章给出了16相正交幅度调制的两个比较合适的序列映射关系.     

Quasi-Cyclic Low-Density Parity-Check Codes for Space-Time Bit-Interleaved Coded Modulation

In this letter, it is shown that the diversity order of space-time bit-interleaved coded modulation (ST-BICM) system is determined by the number of submatrices having linearly independent column vectors in a parity-check matrix of quasicyclic low-density parity-check (QC-LDPC) code. It is also proved that this diversity order can be derived from the base matrix of QC-LDPC code, which can make it easy to design QC-LDPC codes suitable for ST-BICM systems. Finally, the simulation results are provided to confirm the analytical results.     

Coded Unitary Space–Time Modulation With Iterative Decoding: Error Performance and Mapping Design

This paper studies the bit error probability of coded unitary space-time modulation with iterative decoding where neither the transmitter nor the receiver knows the channel fading coefficients. The tight error bound with respect to the asymptotic performance is first analytically derived for any given unitary constellation and mapping rule. Design criteria regarding the choice of unitary constellation and mapping are then established. Furthermore, using the unitary constellation obtained from orthogonal design with quadrature phase-shift keying (QPSK or 4-PSK) and 8-PSK, two different mapping rules are proposed. The first mapping rule gives the most suitable mapping for systems that do not implement iterative processing, which is similar to a Gray mapping in coherent channels. The second mapping rule yields the best mapping for systems with iterative decoding. In particular, analytical and simulation results show that with the proposed mappings of the unitary constellations obtained from orthogonal designs, the asymptotic error performance of the iterative systems can closely approach a lower bound which is applicable to any unitary constellation and mapping     

Adaptive Transmission with Variable-Rate Turbo Bit-Interleaved Coded Modulation

We study an adaptive transmission scheme based on variable-rate turbo bit-interleaved coded modulation (VR- Turbo-BICM). The proposed coding scheme employs punctured turbo codes. A continuously varying transmission rate can be obtained by changing the code rate through both puncturing of the coded bits and adapting of the modulation constellation size. The main results are elaborated in two parts. First, we derive a closed-form expression for a set of achievable rate bounds (called rate thresholds) for VR-Turbo-BICM by employing recent results on the parallel channel performance of turbo code ensembles and the BICM parallel channel analysis model. The derived rate threshold is expressed as a fraction of the capacity of BICM with Gray mapping, where this fraction is a turbo code weight spectrum parameter. Simulation results illustrate that introduced rate thresholds predict well the rate versus SNR performance of VR-Turbo-BICM for a wide range of codeword error probabilities and codeword lengths. Next, based on a simplified rate threshold, we derive a power, puncturing rate, and modulation constellation size assignment policy for a slow fading channel.     

EXIT-chart aided near-capacity Irregular Bit-Interleaved Coded Modulation design

A near-capacity irregular Bit-Interleaved Coded Modulation based Iterative Decoding (Ir-BICM-ID) aided scheme is proposed. The irregular design of the scheme pervades the three basic components of BICM-ID, namely the encoder, the unity-rate precoder and the bit-to-symbol mapper. As a result, irregular BICM-ID schemes constituted by irregular components are created, which are capable of approaching the capacity of coded modulation. This is achieved by creating a marginally open EXtrinsic Information Transfer (EXIT) chart tunnel, and exploiting the theorem that the open tunnel's area is characteristic of how closely the scheme operates to the channel's capacity. The proposed Ir-BICM-ID scheme employs Irregular Convolutional Codes (IrCC), Irregular Unity-Rate Codes (IrURC) and Irregular Mappers (IrMapper).     

Reduced-Complexity Turbo Equalization for Turbo Coded MIMO/OFDM Systems

1IntroductionTowards wireless systems Beyondthe3G(B3G),it isa great challenge for the physical layer to support high-speed transmissioninthe mobile environment to providecomfortable Internet access.Multiple Input MultipleOutput(MI MO)technique is effectiv…     

Bit-Interleaved Coded Modulation With Iterative Decoding Using Constellation Shaping

We investigate the association between constellation shaping and bit-interleaved coded modulation with iterative decoding (BICM-ID). To this end, we consider a technique which consists of inserting shaping block codes between mapping and channel coding functions in order to achieve constellation shaping. By assuming the example of a 2-b/s/Hz 16-quadrature amplitude modulation BICM-ID, it is demonstrated using computer simulations that this technique can improve the performance of BICM-ID schemes by a few tenths of a decibel.     

比特交织迭代译码系统的迭代控制

利用迭代译码时的外部信息交换图特点,提出了一种非常简单有效的迭代控制策略。首先通过外部信息交换图分析得到一个有关信噪比的迭代次数矢量,其次系统根据估计信噪比选择对应值,从而实现迭代控制。该方案实现简单,同时也减少了系统延迟,便于分析系统性能。     

Fano Multiple-Symbol Differential Detectors for Differential Unitary Space–Time Modulation

We present a class of suboptimal multiple-symbol differential detectors (MSDDs) for differential unitary space-time (ST) codes in a time-selective Rayleigh flat-fading channel. These noncoherent detectors, termed Fano ST-MSDDs, employ the well-known Fano algorithm as their decoding engines. Their bit-error rate (BER) performance is excellent, as there is no irreducible error floor, even at very high fade rates. Compared with the sphere decoder, which is optimal, our best detector, termed an on-demand bi-Fano ST-MSDD, suffers only a 0.3 dB degradation in power efficiency. However, its computational complexity, as a function of the signal-to-noise ratio (SNR), is consistently lower than that of the sphere decoder and does not experience the exponential growth in complexity in the latter when the SNR decreases. It can thus be concluded that the Fano algorithm is a powerful detection strategy for differential ST codes in fading channels. Our main contribution is in making the modifications and improvements to the Fano algorithm that enables this realization. The innovations include the bi-Fano, edge-bi-Fano, and on-demand bi-Fano search strategies, as well as a new dynamic threshold adjustment scheme for avoiding unnecessary back-and-forth node evaluations during backtracking     

基于重复累积码的BICM系统译码算法

重复累积码(RA)由于其编译码复杂度低、性能接近香农限的优点,目前得到学术界的广泛关注。文中研究了RA码及其译码算法,并将其应用于比特交织编码调制(BICM)系统。针对低信噪比下基于RA码的编码调制系统误码率较高的问题,提出了一种改进算法,该算法通过在解调器和译码器之间引入迭代处理,利用译码器输出的外信息改善解映射结果,从而降低了系统误码率。仿真结果表明,在加性高斯白噪声(AWGN)信道、瑞利(Rayleigh)衰落信道下,BICM系统使用迭代的译码算法与原算法相比,误码性能有较明显提高。     

A New Modified Gaussian Approximation Detector for Space-Time Bit-Interleaved Coded Modulation Schemes

To reduce the receiver complexity of the space-time bit-interleaved coded modulation (ST-BICM) scheme, this letter describes a turbo-type iterative structure consisting of a modified Gaussian approximation (MGA) detector and an a posteriori probability (APP) decoder. Utilizing the characteristics of the interleaving and the central limited theoretic, the MGA detector first assumes the superposition of the transmitted signals as a Gaussian random variable. Then, P most significant signal combinations are identified to calculate the log-likelihood ratio of each bit. Without any pre-process on the received signals, the proposed method is free of matrix inverse operation and can be applied in systems with more transmit antennas than receive antennas. Furthermore, the performance of the MGA approaches that of the optimal detection     

A new labeling search algorithm for Bit-Interleaved Coded Modulation with Iterative Decoding

Bit-Interleaved Coded Modulation with Iterative Decoding （BICM-ID） is a bandwidth efficient transmission, where the bit error rate is reduced through the iterative information exchange between the inner demapper and the outer decoder. The choice of the symbol mapping is the crucial design parameter. This paper indicates that the Harmonic Mean of the Minimum Squared Euclidean （HMMSE） distance is the best criterion for the mapping design. Based on the design criterion of the HMMSE distance, a new search algorithm to find the optimized labeling maps for BICM-ID system is proposed. Numerical results and performance comparison show that the new labeling search method has a low complexity and outperforms other labeling schemes using other design criterion in BICM-ID system, therefore it is an optimized labeling method.     

Space–Time Coding Techniques With Bit-Interleaved Coded Modulations for MIMO Block-Fading Channels

The space-time bit-interleaved coded modulation (ST-BICM) is an efficient technique to obtain high diversity and coding gain on a block-fading multiple-input multiple-output (MIMO) channel. Its maximum-likelihood (ML) performance is computed under ideal interleaving conditions, which enables a global optimization taking into account channel coding. Thanks to a diversity upper bound derived from the Singleton bound, an appropriate choice of the time dimension of the space-time coding is possible, which maximizes diversity while minimizing complexity. Based on the analysis, an optimized interleaver and a set of linear precoders, called dispersive nucleo algebraic (DNA) precoders are proposed. The proposed precoders have good performance with respect to the state of the art and exist for any number of transmit antennas and any time dimension. With turbo codes, they exhibit a frame error rate which does not increase with frame length.