基于低码重分布的一类随机交织器设计

提出一种新的Turbo码的随机交织器的设计方法.该方法不仅考虑了重2自结尾序列对低码重分布的影响,还考虑了2重重2自结尾序列对低码重分布的影响.如果重2和2重重2自结尾序列是Turbo码低码重分布的主要分量,用这种交织器就可以获得更大的最小码重.计算机仿真显示,无论是高斯白噪声信道还是衰落信道,与S交织器和仅消除重2自结尾序列的交织器相比,该方法设计的交织器可以获得更大的编码增益.     

Combined turbo codes and interleaver design

The impact of the distance spectrum and interleaver structure on the bit error probability of turbo codes is considered. A new turbo code design method for Gaussian channels is presented. The proposed method combines a search for good component codes with interleaver design. The optimal distance spectrum is used as the design criterion to construct good turbo component codes at low signal-to-noise ratios (SNRs). In addition, an interleaver design method is proposed. This design improves the code performance at high SNR. Search for good component codes at low SNR is combined with a code matched interleaver design. This results in new turbo codes with a superior error performance relative to the best known codes at both low and high SNR. The performance is verified by both analysis and simulation     

A simple figure of merit for evaluating interleaver depth for theland-mobile satellite channel

The selection of interleaver depth for the land-mobile satellite channel is investigated by analyzing the performance of convolutionally encoded BPSK and DPSK over a frequency-nonselective correlated Ricean fading channel. By extending previous analyses of partially interleaved convolutional codes over such channels, a new figure of merit-which is a function of the channel correlation function-is identified. Simulation results for the first-order Butterworth, Jakes (1974), and Divsalar (1991) fading spectra are presented which demonstrate the applicability of the figure of merit as an aid in interleaver design. The figure of merit also tracks the nonmonotonic, or quasi-oscillatory, behavior of the decoded bit error rate with increasing interleaver depths in those situations where this occurs     

确定性交织器的研究

本文分析了交织器在turbo码中的重要作用，以及随机交织器存在的缺陷，并提出了一种确定性交织器的设计方法。该交纪念品器具有简明的解析表达式，易于实现。计算机仿真结果表明，该确定交织器可以获得的性能优于随机交织器的平均性能。     

A code-matched interleaver design for turbo codes

A code-matched interleaver design for turbo codes in which a particular interleaver is constructed to match the code weight distribution is proposed. The design method is based on the code distance spectrum. The low weight paths in the code trellis which give large contributions to the error probability in the signal-to-noise ratio region of interest for practical communication systems are eliminated so that they do not appear in the overall code trellis after interleaving. The proposed interleaver improves the code error performance at moderate to high signal-to-noise ratio and considerably increases the asymptotic slope of the error probability curves     

衰落信道中结合短帧交织的Turbo码的研究

Turbo码作为信道编码方案,可以获得较高的误比特性能,而交织器的设计是影响Turbo码性能的关键环节。在码的重量分析的基础上,借用稀疏矩阵概念,对S型随机交织器进行改进,提出了一种短帧交织器的设计原则,它可以减少低重量码的数量,从而提高Turbo码的性能。     

Collision free row column S-random interleaver

Parallel decodable turbo codes (PDTCs) are suitable for concurrent decoding and hence have low latency. Memory collision issue is an important problem met during parallel processing. In this article, we propose a collision free interleaver for parallel processing operations. The performance of PDTCs is analyzed with the proposed random interleaver preventing the memory collision problem. Distance spectra of PDTCs with the proposed interleaver are computed and compared to those with S-random interleaver.     

Differential turbo-coded modulation with APP channel estimation

A serially concatenated coding system which can operate without channel state information (CSI) with use of a simple channel-estimation technique is presented. This channel-estimation technique uses the inner decoder's a posteriori probability (APP) information about the transmitted symbols to form a channel estimate for each symbol interval, and is termed "APP channel estimation." The serially concatenated code is comprised of an outer rate-2/3 binary error-control code, separated by a bit interleaver from an inner code consisting of an 8-phase-shift keying (PSK) bit mapping and differential 8-PSK modulation. Coherent decoding provides bit-error rate performance 0.6 dB from 8-PSK capacity for large interleaver sizes. APP channel-estimation decoding without initial CSI over constant and random walk phase models shows near-coherent results, with fractions of a decibel performance loss for random walk and linear phase models.     

随机交织器的设计与实现

本文首先分析了随机交织器在Ｔｕｒｂｏ码中的重要作用。然后讨论了交织器长度的选择原则,并且对ＡＷＧＮ信道和Ｒａｙｌｅｉｇｎ衰落信道条件下交织深度对Ｔｕｒｂｏ码性能的影响进行了计算机模拟。在此基础上,给出了随机交织器的两种硬件电路实现方案,其中方案二便于ＡＳＩＣ实现。     

A novel all-fiber optical interleaver with flat-top passband

An all-fiber optical interleaver with almost rectangular wavelength response is developed by using a new configuration. The device consists of a 2/spl times/2 and a 3/spl times/3 directional fiber coupler. Based on the digital approximation method of Fourier series, the relationships among the splitting ratios of the couplers, the length difference of interference arms, and the intensity transmission spectrum are analyzed. The results indicate that a uniform flattop spectral response can be obtained by the configuration when the length difference of interference arms and the coupling coefficient of the couplers, with some certain values, are given. The passband and stopband of optical interleaver are improved remarkably. The coupling ratio of couplers and the proportion of the length differences can be controlled accurately in the course of fabricating the interleaver. A novel structure of an interleaver is fabricated by using the fused biconical taper technics in experiment. The experimental results are in good agreement with the analytical ones.     

Adaptive interleaver based on rate-compatible punctured convolutional codes

This letter focuses on the design of an adaptive Bit- Interleaved Coded Modulation (BICM) scheme for frequency selective slow fading channels where the transmitter has certain knowledge of the channel response. In particular, we consider the design of the interleaver stage for a specific convolutional code operating with OFDM modulation. The adaptive interleaver uses the puncturing tables of the Rate-Compatible Punctured Convolutional Codes (RCPC codes) to rearrange the bits as a function of the fading values and the specific constellation. The performance of different interleavers are compared, revealing that the adaptive RCPC-based interleaver produces larger Euclidean distances between the received codewords and reduces the packet error rate (PER), specially when the number of deep-faded subcarriers increases. Numerical results also evidence the importance of the interleaver choice when comparing the performance of different power allocation strategies.     

具有良好S距离特性QPP交织器的设计

交织器的设计对提高Turbo码的性能有着重要的影响。首先研究了QPP交织器的设计原则,给出了具有良好S距离特性的QPP交织的设计方法。仿真结果表明:设计得到的QPP交织器的性能并不比通过随机搜索得到的一般S-随机交织器性能差。     

基于3GPP交织器的可变码长Turbo码并行交织器设计

高速Turbo译码器实现中交织器的设计是一个非常重要的问题。在没有任何性能损失的情况下设计无内存访问冲突、高并行度的交织器已有多种方法，但是它们不能够根据码长参数的变化实时产生，这限制了译码器设计的灵活性。现提出了一种基于3GPP中可变码长交织器的并行交织器，其最大的优点就是可以实时产生。并且通过计算机仿真给出了这种交织器的性能，并与3GPP标准中的交织器做了性能比较。     

Analysis and design of optimum interleaver for iterative receivers in IDMA scheme

In this paper, we propose a new tree based interleaver (TBI) to generate different chip‐level interleaving sequences for different users in an interleave division multiple access (IDMA) system, which reduces computational complexity. This method of generation also solves the memory cost problem and reduces the amount of information exchange between mobile stations (MSs) and base stations (BSs) required to specify the interleaver. Simulation results are presented to show that the proposed interleavers perform well as compared to random interleavers in an IDMA system. Copyright © 2008 John Wiley & Sons, Ltd.     

紫外光通信QPP交织器研究

交织器是Turbo码的重要组成部分,它可以有效地提高Turbo码在整个通信系统中的性能.依据S随机交织器的设计思想,运用计算机搜索的方法,提出了一种具有最大S距离的二次转换多项式(SQPP)的搜索算法,并在紫外光通信多次散射信道中对SQPP交织器的性能进行了仿真和分析,最后得出了适合紫外光通信的SQPP交织器的参数.     

Turbo码的优选扩散交织器设计

该文提出了Turbo码交织器的一种新的设计方法,适用于任意长度的交织设计,称为优选扩散交织,文中阐述了它的设计原则与步骤,以及对16状态Turbo码交织器的设计分析,并对其性能进行了仿真。     

全光纤马赫-曾德尔干涉仪型不等带宽梳状滤波器

提出了由2个3×3和1个3×3单模光纤耦合器级联组成的全光纤Mach-Zehnder干涉仪(MZI)型不等带宽交错(梳状)滤波器。分析结果表明:两对光纤干涉臂长度差相等时,各耦合器的耦合系数选取适当值,器件实现了奇偶信道上不等带宽输出,分别用于10和40Gb/s传输,信道间隔为0.8nm,信道隔离度大于25dB。与其它不等带宽梳状滤波器相比,该器件基于MZI型梳状滤波器,且在实际制作时可以对每个耦合器的分光比进行准确监测和控制,大大降低了制作困难。实验所得结果与理论分析相吻合。     

Multistage recursive interleaver for turbo codes in DS-CDMA mobileradio

A multistage recursive block interleaver (MIL) is proposed for the turbo code internal interleaver. Unlike conventional block interleavers, the MIL repeats permutations of rows and columns in a recursive manner until reaching the final interleaving length. The bit error rate (BER) and frame error rate (FER) performance with turbo coding and MIL under frequency-selective Rayleigh fading are evaluated by computer simulation for direct-sequence code-division multiple-access mobile radio. The performance of rate-1/3 turbo codes with MIL is compared with pseudorandom and S-random interleavers assuming a spreading chip rate of 4.096 Mcps and an information bit rate of 32 kbps. When the interleaving length is 3068 bits, turbo coding with MIL outperforms the pseudorandom interleaver by 0.4 dB at an average BER of 10^-6 on a fading channel using the ITU-R defined Vehicular-B power-delay profile with the maximum Doppler frequency of f_D = 80 Hz. The results also show that turbo coding with MIL provides superior performance to convolutional and Reed-Solomon concatenated coding; the gain over concatenated coding is as much as 0.6 dB     

MB-OFDM UWB系统中交织器盲识别方法

借助峰值平均功率比(PAR)与反转误码率(RSER)信息,实现MB-OFDM UWB系统在发送端选择最佳交织器后,在不传送交织辅助信息情况下,在接收端恢复发送端使用的交织器编号,实现交织过程盲识别。将反转误码率的检测应用到对交织器的盲识别中,改进MB-OFDM UWB系统中的交织器与解交织器部分,通过对反转误码率的比较识别出发送端所选择的交织器规格,进而达到对交织序列的盲识别。对常规与改进后的系统进行误比特率仿真比较后,发现改进后的MB-OFDM UWB系统具有较好的可靠性,可以通过反转误码率的比较信息得出交织器编号,进而得到交织序列,释放信道,达到真正意义上的交织盲识别,从而实现智能通信。     

Photosensitisation of silica planar lightwave interleaver for phaseerror correction

Photosensitivity locking with a 248 nm KrF laser was applied to a hydrogen-soaked silica planar waveguide to improve the refractive index response for post-laser phase trimming of an interleaver. A more than tenfold photosensitivity enhancement was stabilised by annealing the interleaver circuit at 150°C for 24 h. The interleaver channel isolation was improved from 6 to 18 dB by balancing the interferometer phase errors with a modest KrF laser dose