SCMA场景下的极化码编解码方案改进研究

极化码是目前唯一一种被证明可达到信道容量的编码方式,稀疏码分多址接入(Sparse Code Division Multiple Access,SCMA)可以提高频谱资源的利用率和接入系统的用户接入数量。为了提升SCMA与极化码的联合系统的误码率性能和译码时延,使联合系统的应用越来越广泛,提出了2种降低译码复杂度的方式:简化的左信息更新方式和剪枝译码算法。简化的左信息更新方式对于N=256,N=1024的极化码分别能降低37.6%和44.6%的存储资源占用数;剪枝译码算法在码率为0.5时能降低50%左右的计算复杂度。基于简化的SCAN算法改进了联合检测译码算法,在接收机采用外循环迭代的结构,引入了阻尼机制,选取最优的阻尼方式和最优阻尼值。仿真分析了所提联合检测译码算法与原有联合检测译码算法的误码率性能差异,外迭代接收机性能与内外双循环迭代的接收机性能相同,采用阻尼机制联合接收机的性能比无阻尼接收机的性能高0.8 dB左右,SJIDD的误帧率性能比保留宽度为32的SCLJDD的性能低0.7 dB左右,但能使接收机处理时延降至原来的1/4~1/8。     

一种基于DSP 的曼彻斯特Ⅱ码解析系统

为提高曼彻斯特Ⅱ码解析系统的灵活性和准确性,降低系统的硬件成本,设计一种基于DSP的曼彻斯特Ⅱ码解析系统。在深入分析曼彻斯特Ⅱ码信号特点的基础上,将经测井电缆传输后曼彻斯特Ⅱ码信号经过调理电路、限幅放大电路和整形及正负分离电路的处理后,送至DSP内部的脉冲捕获单元,最后由软件算法进行解析。实验结果表明：曼彻斯特Ⅱ码解析系统设计合理,满足生产测井过程中常规测井作业的需求。     

基于单片机的住宅智能安防系统设计

基于公共电话网的自动防灾报警系统,当系统检测到非法入侵者及火灾、煤气泄漏等报警信号时,报警主机发出报警声,同时通过电话线将警情报告给数个指定电话,保障财产及生命安全;设计是以单片机AT89C51,双音多频解码集成电路MT8888、ISD1420芯片、AT24C02串行EEPROM为核心;红外探测器、门磁探测器、感烟探测器、燃气泄漏探测器等探测灾情;当有非法入侵时,单片机执行中断程序,播放的语音,震慑盗贼,使其停止盗窃行为并自动拨打设定好的手机号码,起到防盗的作用;当有火灾及有害气体泄漏等灾情发生时,通过拨打设定号码,保护财产安全。     

Multisecret-sharing schemes and bounded distance decoding of linear codes

Error-correcting codes are used to correct errors when messages are transmitted through a noisy communication channel. Bounded distance decoding (i.e. decoding up to the error-correcting capacity) is a method of correcting errors that guarantees unique decoding. Secret sharing is a cryptographic protocol that allows a secret known from a person called the dealer to be distributed to n participants. No single participant knows the secret but some special subsets of participants called coalitions can. In this paper, we present a multisecret-sharing scheme based on an error-correcting code where secret reconstruction is made by using bounded distance decoding of the code. This scheme is ideal in the sense that the size of each secret equals the size of any share. Its security improves on that of multisecret-sharing schemes.     

Temporal segmentation and assignment of successive actions in a long-term video

Temporal segmentation of successive actions in a long-term video sequence has been a long-standing problem in computer vision. In this paper, we exploit a novel learning-based framework. Given a video sequence, only a few characteristic frames are selected by the proposed selection algorithm, and then the likelihood to trained models is calculated in a pair-wise way, and finally segmentation is obtained as the optimal model sequence to realize the maximum likelihood. The average accuracy on IXMAS dataset reached to 80.5% at frame level, using only 16.5% of all frames in computation time of 1.57 s per video which has 1160 frames on the average.     

Stochastic resonance in parallel concatenated turbo code decoding

In an array of threshold devices, we examine the effect of noise in improving performance of turbo code decoding. Such a phenomenon of noise-enhanced effect is termed stochastic resonance (SR). When signal is subthreshold, SR is observed by using Gaussian noise during iterative decoding. That is, the minimal bit error ratio (BER) is achieved at some non-zero noise intensity level. Besides, the larger the number of threshold devices is, the more remarkable the SR effect becomes. Especially when noise intensity is nearly optimal, BER approximates to zero after a few decoding iterations. Moreover, when Gaussian mixture noise is utilized, suprathreshold stochastic resonance (SSR) occurs in turbo decoding. These results show the beneficial effect of noise in channel coding and decoding.     

传真通信中MMR编码译码的实现

MMR编码技术是传真通信在发送端对图像进行分解、处理、调制，而在接收端进行解调、处理和传真图像合成而采用的一种编码方法，通过基本的软件语言来实现MMR编码与译码的基本功能。     

Accelerated computational implementation of reconciliation for continuous variable quantum key distribution on GPU

For the low computing speed of reconciliation for current continuous variable quantum key distribution， CPU&GPU-parallel reconciliation algorithms was designed based on LDPC of SEC protocol to speed up decoding computing.In order to raise decoding speed without sacrifice reconciliation efficiency,a static two-way cross linked list to efficiently store large scale sparse parity matrix was employed.The simulation experimental results show that the speed of the decoding rate reaches 16.4 kbit/s when the channel SNR is over 4.9 dB and the reliability of the 2×10⁵continuous variable quantum sequence,with reconciliation efficiency of 91.71%.The experimental based on the Geforce GT 650 MB GPU and the 2.5 GHz and 8 GB memory CPU hardware platform.Relative to the only CPU platform,computing speed increased by more than 15 times.     

A modified Min Sum decoding algorithm based on LMMSE for LDPC codes

A new modified Min Sum decoding algorithm based on parameter estimation theory for Low Density Parity Check (LDPC) codes is presented in this paper. First, Linear Minimum Mean Square Error (LMMSE) estimate criterion is used to model the magnitude of check-to-variable message and calculate estimated parameters, furthermore the golden section search algorithm is used to speed up getting the boundary, with which the parameters can be determined. Then, the parameters are modified further on the basis of the relationship between the iteration number and the estimated parameters. Finally, the same estimated parameters are used for different signal to noise ratio (SNR) to ensure the decoding performance and reduce the hardware complexity. The simulation results show that a gain of 0.3–0.5 dB can be achieved in comparison with other kinds of modified Min Sum algorithms, which is very close to that of BP algorithm. What's more, the algorithm has the following characteristics: low computation complexity, small decoding delay, easiness of calculation for estimated parameters, and simplicity in hardware implementation.     

一种符合EPCCIG2协议的RFID反向链路数据解码技术的实现

针对物联网协议EPcc1G2中反向链路数据的解码技术，以精简硬件资源和提高解码效率为目标，给出了基于MCU硬件平台，并利用其中TIMER模块和ADC模块实现反向链路数据解码技术的设计分析和实现思路，同时以实际运用中对FM0解码实现为实例，对解码效果、关键技术点进行了分析；还在结论中将此解码技术与常用技术方案进行了扼要比较，阐明了相关技术特点，得出了本技术的比较优势。