一种咬尾双二进制Turbo码并行译码方案

针对双二进制Turbo译码使用并行、滑动窗联合译码技术时,其咬尾的编码构造和窗分割导致边界状态值难以获取的问题,提出了一种新咬尾Turbo码并行、滑动窗译码方案——扩展交叠方案.该方案采用了边界状态盲估计和滑动窗状态回溯两种新译码技术.相比于传统的边界状态度量传播方法(又称迭代法),新方法一方面提高了边界状态度量的准确性,从而加快了译码收敛速度,一定程度上减小了高信噪比下的性能损失;另一方面避免了存储前一次译码的迭代度量值,更有利于硬件设计.仿真表明,新方案在64左右的中等窗长下即可消除并行和滑动窗影响,逼近原始无并行无滑动窗译码的性能,且窗长越小,其相较传统迭代法带来的译码性能增益就越明显.该方案具有较好的实用性和应用价值,可以满足5G的高速率、低时延和低存储的数据传输要求.     

一种X线探测器信号采集电路的设计

该文利用a-Si PIN结构X线平板探测器设计对应的信号采集电路,读出经由探测器阵列感测到的模拟信号并转化为数字信号供后续处理。用德州仪器成熟的商用芯片,经过电路设计、PCB制作实现硬件部分。控制代码使用VerilogHDL硬件描述语言编写,通过Modelsim软件仿真,最后利用Quartus II软件综合、布局布线,使用AlteraCycloneIV系列现场可编程门阵列(FPGA)实现信号输出从而控制信号采集电路的运行。最终实验与测试验证了电路的功能,成功获取X光的模拟和数字信号。验证了电路的功能,并为低剂量X光探测器信号的采集提供了一种设计参考。     

基于源码模式挖掘的软件辅助开发技术研究

由于软件代码的复杂性,对于不了解框架的新手,很难利用开源社区中的代码来开发软件。因此,利用数据挖掘技术挖掘现有代码中的编程模式成为研究热点。文中介绍了频繁项挖掘Apriori算法,并提出了基于源码模式的软件辅助开发方法。它能够根据用户输入的关键字来智能匹配类库中的特定父类,挖掘基于此父类的编程模式,给出优先要重写的方法以及关联规则。实验结果表明,新手可以利用这些编码建议,快速学习一个新的框架,提高开发效率。     

Gaussian integers and interleaved rank codes for space–time block codes

This paper presents the design of space–time block codes (STBCs) over maximum rank distance (MRD) codes, energy‐efficient STBCs, STBCs using interleaved‐MRD codes, the use of Gaussian integers for STBCs modulation, and Gabidulin's decoding algorithm for decoding STBCs. The design fundamentals of STBCs using MRD codes are firstly put forward for different number of transmit antennas. Extension finite fields (Galois fields) are used to design these linear block codes. Afterward, a comparative study of MRD‐based STBCs with corresponding orthogonal and quasi‐orthogonal codes is also included in the paper. The simulation results show that rank codes, for any number of transmit antennas, exhibit diversity gain at full rate contrary to orthogonal codes, which give diversity gain at full rate only for two transmit antennas case. Secondly, an energy‐efficient MRD‐STBC is proposed, which outperforms orthogonal STBC at least for 2 × 1 antenna system. Thirdly, interleaved‐MRD codes are used to construct higher‐order transmit antenna systems. Using interleaved‐MRD codes further reduces the complexity (compared with normal MRD codes) of the decoding algorithm. Fourthly, the use of Gaussian integers is utilized in mapping MRD‐based STBCs to complex constellations. Furthermore, it is described how an efficient and computationally less complex Gabidulin's decoding algorithm can be exploited for decoding complex MRD‐STBCs. The decoding results have been compared against hard‐decision maximum likelihood decoding. Under this decoding scheme, MRD‐STBCs have been shown to be potential candidate for higher transmit antenna systems as the decoding complexity of Gabidulin's algorithm is far less, and its performance for decoding MRD‐STBCs is somewhat reasonable. Copyright © 2015 John Wiley & Sons, Ltd.     

An algorithm for the selection of effective error correction coding in wireless networks based on a lookup table structure

In this paper, we propose an adaptive Forward Error Correction (FEC) coding algorithm at the Medium Access Control (MAC) layer used in wireless networks. Our algorithm is based on the lookup table architecture, including a distance lookup table and a bit error rate lookup table. These tables will store the best value of the FEC codes based on different distances and bit error rates. Because radio channels change over time, the bit error rate is always changing, or in the case of mobile nodes, when the transmission distance changes, the bit error rate also changes, so previously proposed algorithms take longer to find the optimal value of the FEC code for data transmission. Our proposed algorithm, however, is based on 2 lookup tables, and thus, it can always quickly select an optimal FEC code during early data transmissions and achieve high performance. We compare our algorithm with other methods based on performance metrics such as the recovery overhead of FEC codes, energy efficiency, and peak‐signal‐to‐noise ratio values in the case of image transmission. Our simulation indicates that the proposed algorithm achieves better performances and proves the correctness of the proposed lookup table architecture.     

The poset structures admitting the extended binary Golay code to be a perfect code

Brualdi et al. [Codes with a poset metric, Discrete Math. 147 (1995) 57-72] introduced the concept of poset codes, and gave an example of poset structure which admits the extended binary Golay code to be a 4-error-correcting perfect P-code. In this paper we classify all of the poset structures which admit the extended binary Golay code to be a 4-error-correcting perfect P-code, and show that there are no posets which admit the extended binary Golay code to be a 5-error-correcting perfect P-code.     

Path bundles on n-cubes

A path bundle is a set of 2^a paths in an n-cube, denoted Q_n, such that every path has the same length, the paths partition the vertices of Q_n, the endpoints of the paths induce two subcubes of Q_n, and the endpoints of each path are complements. This paper shows that a path bundle exists if and only if n>0 is odd and 0?a?n-⌈log₂(n+1)⌉.     

Intersections of q-ary perfect codes

The intersections of q-ary perfect codes are under study. We prove that there exist two q-ary perfect codes C ₁ and C ₂ of length N = qn + 1 such that |C ₁ ? C ₂| = k · |P _i |/p for each k ∈ {0,..., p · K ? 2, p · K}, where q = p ^r , p is prime, r ≥ 1, $n = \tfrac{{q^{m - 1} - 1}}{{q - 1}}$ , m ≥ 2, |P _i | = p ^nr(q?2)+n , and K = p ^{n(2r?1)?r(m?1)}. We show also that there exist two q-ary perfect codes of length N which are intersected by p ^nr(q?3)+n codewords.     

Distance regularity of Kerdock codes

A code is called distance regular, if for every two codewords x, y and integers i, j the number of codewords z such that d(x, z) = i and d(y, z) = j, with d the Hamming distance, does not depend on the choice of x, y and depends only on d(x, y) and i, j. Using some properties of the discrete Fourier transform we give a new combinatorial proof of the distance regularity of an arbitrary Kerdock code. We also calculate the parameters of the distance regularity of a Kerdock code.     

Few-cosine spherical codes and Barnes-Wall lattices

Using Barnes-Wall lattices and 1-cocycles on finite groups of monomial matrices, we give a procedure to construct tricosine spherical codes. This was inspired by a 14-dimensional code which Ballinger, Cohn, Giansiracusa and Morris discovered in studies of the universally optimal property. Their code has 64 vectors and cosines . We construct the Optimism Code, a 4-cosine spherical code with 256 unit vectors in 16-dimensions. The cosines are . Its automorphism group has shape ²1+8⋅GL(4,2). The Optimism Code contains a subcode related to the BCGM code. The Optimism Code implies existence of a nonlinear binary code with parameters (16,256,6), a Nordstrom-Robinson code, and gives a context for determining its automorphism group, which has form .