一种甚低速率语音编码的抗误码算法

为满足在高误码率的窄带信道上进行语音通信的需求，本文研究了一种适用于甚低速率语音通信的抗误码参数估值算法。在一定的解码状态下，声码器通过计算最小均方误差（MMSE）估计的方法估计最优参数，充分降低信道误码对重建语音质量的影响。对于解码状态参数，通过计算最大后验转移概率的方法作最佳估计，并给出了一种简化的计算方法。这种抗误码算法复杂度低。计算机仿真结果表明，在不同误码率下该算法恢复出的语音的平均谱失真（ASD）低于帧删除方法的谱失真最大可达0.4dB。     

基于FM0记忆辅助特性的RFID标签碰撞检测

为实现两个射频识别(RFID)碰撞标签信息的检测和分离，提出一种利用Gen2标准中FM0标签编码固有记忆特性的检测方法。通过对FM0比特编码特点和碰撞标签信息的无记忆检测分析，得到基于单个比特持续时间的无记忆检测方法的条件错误概率和单个标签信息检测的误码率；然后利用单个FM0比特编码需要前一比特的“记忆”特性，得到对应于前一比特的一对测量值和对应于下一比特的一对测量值，进而得到碰撞标签信息的1比特记忆辅助检测时的条件错误概率和误码率性能；并对在帧Aloha媒质接入方案中采用提出的检测方法时的N个标签群的总延迟减少性能进行了分析。仿真实验结果表明，提出的1比特记忆辅助检测方法，相比于无记忆检测具有更好的误码率性能，且能减少标签群接入时的总延迟。     

基于抖动的Serdes接口误码率量产测试评价方法

高速串行接口应用的普及给集成电路性能测试带来了新的挑战。误码率(BER)是衡量通信系统性能的关键指标,衡量高速Serdes接口的误码率是十分必要的。通常测试误码率时需要发送大量数据通过长时间稳定的运行,统计接收到的错误比特数来计算误码率,测试时不仅需要大量测试时间,还需在测试路径等硬件中对信号完整性进行优化,避免出现由于测试本身对结果产生影响。从误码率产生的机理出发,探寻一种高效、可靠的误码率评价方法,提出一种基于抖动(jitter)的误码率量产测试方案。     

基于正交空时分组码的空间脉冲位置调制

针对在湍流信道下空间脉冲位置调制(SPPM)系统误码性能较差的问题,文章将空时分组码与空间调制技术结合,提出了基于比特补码正交空时分组码的空间脉冲位置调制(BCOSTBC-SPPM),利用空时编码增加信息冗余度以改善系统误码性能。同时基于最大似然(ML)检测推导了系统的理论误比特率上界,并通过蒙特卡洛仿真对理论上界进行了验证。仿真结果表明,BCOSTBC-SPPM的误码性能相比SPPM有较大提升。在弱湍流信道下,当系统误比特率为10-4时,(4,2,4)-BCOSTBC-SPPM相比(4,1,4)-SPPM信噪比改善约10 dB。该方式相较于传统正交空时编码方案在频谱效率方面有一定提升,实现了系统有效性和可靠性的合理权衡。     

TDCS大规模分区多址通信方法

针对传统的变换域通信系统多址干扰严重,抑制用户数和误码率性能的问题,提出了一种分区方法降低多址干扰,适用于大规模变换域多址通信。提出多用户的区域划分方法,将用户分为区内用户和干扰较小的区外用户,并推导出误码率计算公式;提出分区向量计算方法,引入CAN算法,提高分区向量的自相关性;从频谱效率和高斯信道下的误码率等角度,分析该方法的总体性能,并给出分区向量最优长度的计算方法。仿真结果表明,该方法能较大程度地扩充用户数,保证误码率在一定范围以内,并且频谱效率较高。      

HVD: horizontal-vertical-diagonal error detecting and correcting code to protect against with soft errors

This paper presents a high level error detection and correction method called HVD code to tolerate multiple bit upsets (MBUs) occurred in memory cells. The proposed method uses parity codes in four directions in a data part to assure the reliability of memories. The proposed method is very powerful in error detection while its error correction coverage is also acceptable considering its low computing latency. HVD code is useful for applications whose high error detection coverage is very important such as memory systems. Of course, this code can be used in combination with other protection codes which have high correction coverage and low detection coverage. The proposed method is evaluated using more than one billion multiple fault injection experiments. Multiple bit flips were randomly injected in different segments of a memory system and the fault detection and correction coverages are calculated. Results show that 100% of the injected faults can be detected. We proved that, this method can correct up to three bit upsets. Some hardware implementation issues are investigated to show tradeoffs between different implementation parameters of HVD method.     

Equalization for discrete multitone transceivers to maximize bitrate

In a discrete multitone receiver, a time-domain equalizer (TEQ) reduces the intersymbol interference (ISI) by shortening the effective duration of the channel impulse response. Current TEQ design methods such as the minimum mean-squared error (MMSE), maximum shortening SNR (MSSNR), and maximum geometric SNR (MGSNR) do not directly maximize bit rate. We develop two TEQ design methods to maximize the bit rate. First, we partition an equalized multicarrier channel into its equivalent signal, noise, and ISI paths to develop a new subchannel SNR definition. Then, we derive a nonlinear function of TEQ taps that measures the bit rate, which the proposed maximum bit rate (MBR) method optimizes. We also propose a minimum-ISI method that generalizes the MSSNR method by weighting the ISI in the frequency domain to obtain higher performance. The minimum-ISI method is amenable to real-time implementation on a fixed-point digital signal processor. Based on simulations using eight different carrier-serving-area loop channels, (1) the proposed methods yield higher bit rates than MMSE, MGSNR, and MSSNR methods; (2) the proposed methods give three-tap TEQs with higher bit rates than 17-tap MMSE, MGSNR, and MSSNR TEQs; (3) the proposed MBR method achieves the channel capacity (as computed by the matched filter bound using the proposed subchannel SNR model) with a five-tap TEQ; and (4) the proposed minimum-ISI method achieves the bit rate of the optimal MBR method     

基于矢量天线的新型三维调制解调方法

借助于矢量天线,提出了一种将信号相位、极化幅度与极化俯仰角参数进行三维调制的方法。给出了极化与相位联合三维调制解调的实现策略,讨论了三维联合调制的星座图和星座点分布方案。推导出了三维联合调制信号误码率的解析表达式并进行了仿真。分析与仿真结果均表明:提出的调制方法具有传输速率高和误码率低的特点。     

An efficient antenna shuffling scheme for a DSTTD system

A new antenna shuffling scheme for DSTTD (double space time transmit diversity) is proposed. The proposed method obtains the shuffling pattern directly from the estimated channel by maximizing minimum post-processing SNR (signal to noise ratio), while the conventional method minimizes channel correlation. Since the minimum post-processing SNR is directly related with error performance, the proposed method shows better bit error rate performance than the conventional method.     

Model-based channel estimation for OFDM signals in Rayleigh fading

This paper proposes a robust pilot-assisted channel estimation method for orthogonal frequency division multiplexing (OFDM) signals in Rayleigh fading. Our estimation method is based on nonlinear regression channel models. Unlike the linear minimum mean-squared error (LMMSE) channel estimate, the method proposed does not have to know or estimate channel statistics like the channel correlation matrix and the average signal-to-noise ratio (SNR) per bit. Numerical results indicate that the performance of the proposed channel estimator is very close to the theoretical bit error propagation lower bound that is obtained by a receiver with perfect channel response information     

JPEG2000无线标准JPWL性能分析及应用研究

对JPEG2000标准第11部分印JPEG2000无线传输(JPWL)进行了系统描述和性能分析,结合实例提出了具体的应用方法:根据错误敏感度描述符提供的码流错误敏感度,利用错误保护块对码流执行头保护的基础上进行不等错误保护;在解码时利用残余错误描述符提供的码流残余错误信息进行错误隐藏.仿真结果表明,和常用方法相比,该方法能够保持码流中的重要信息,有效地纠正传输误码,显著地提高了解码能力和恢复图像的质量.     

Reducing Host Interference from Spread Spectrum Watermarking

Spread spectrum watermarking (SSW) is one of the most promising watermarking techniques. While SSW is very robust against additive noise, it suffers from an inherent noise. The noise results from host interference on detection of the embedded hidden information. The host interference is one of the main reasons for the relatively low embedding rate in SSW and its reduction is important. In this paper, a new method for use in an SSW detector is proposed to reduce the host interference. The proposed method is based on the law of large numbers and symbol detection of embedded information, instead of bit detection. Since the method is based on the detection of symbols longer than one bit, the detector can employ PN sequences with a larger length, resulting in decrease of the interference. The symbol error rate using this algorithm is calculated employing the maximum a posteriori criterion. Comparison of bit error rates between the modified SSW algorithm and conventional bit detection shows that the modified algorithm is much more robust against the host interference.     

最小误码率准则盲源分离算法

针对通信混合信号的盲分离问题,结合通信系统中的误码率性能指标,本文提出一种基于最小误码率准则的盲源分离算法。本算法基本原理是,将推导的最小误码率准则结合最大似然原则建立盲源分离代价函数,形成一种最小误码率约束的代价函数,接着借助于自然梯度下降搜索,最小化代价函数实现盲源分离。仿真实验分析表明提出的最小误码率约束代价函数得到的盲源分离算法,比原有的最大似然原则代价函数得到的盲源分离算法,具有更好的收敛性能和分离精度。      

大气弱湍流信道下松弛极化码译码方法

针对自由空间光通信中存在的大气湍流降低通信系统误码性能的问题,提出了基于松弛极化码的分段式极化码-循环冗余校验-串行抵消列表(PC-CRC-SCL)译码方法,并将其用于自由空间光通信系统中,在大气弱湍流强度下进行了仿真分析.仿真结果表明:与完全极化码的分段式CRC-SCL译码方法相比,在误码率为10-4时,基于松弛极化...     

A wavelet-based two-stage near-lossless coder.

In this paper, we present a two-stage near-lossless compression scheme. It belongs to the class of "lossy plus residual coding" and consists of a wavelet-based lossy layer followed by arithmetic coding of the quantized residual to guarantee a given L(infinity) error bound in the pixel domain. We focus on the selection of the optimum bit rate for the lossy layer to achieve the minimum total bit rate. Unlike other similar lossy plus lossless approaches using a wavelet-based lossy layer, the proposed method does not require iteration of decoding and inverse discrete wavelet transform in succession to locate the optimum bit rate. We propose a simple method to estimate the optimal bit rate, with a theoretical justification based on the critical rate argument from the rate-distortion theory and the independence of the residual error.     

基于置信度的S模式信号随机多位纠错技术

针对现有纠错技术只能对少量随机错误或突发错误进行纠错的不足,提出了一种基于置信度的随机多位纠错方法。该方法在准确进行置信度判断的基础上,通过缩短循环冗余校验（CRC）处理时间或增加并行运算能力以增加纠错位数。同时给出了可运用于工程实际的保守技术和强力技术的联合纠错处理流程。通过解码纠错实验,统计结果表明该置信度判定法则的准确性为98.24%,通过图形处理器（GPU）强力纠错可实现高达83.37%的解码率,通过现场可编程门阵列（FPGA）强力纠错可实现73.66%的解码率,较现有强力纠错技术的纠错能力有较大提高,可增强对航空器监视的连续性。     

一种新的数字脉冲间隔调制解调方法

针对数字脉冲间隔调制(DPIM)包序列发生差错时会出现符号增减从而导致差错性能下降的问题,提出了一种新的解调方法。给出了解调方法的解调过程,推导了其差错解概率,并与门限解调法进行了比较分析。数值仿真表明,当误包率为10-6以及包信息为24bit时,相较于门限法,可节省约1.5dBm的平均接收功率,且调制阶数对其影响不大;但当包信息量增大时,性能改善的程度将减弱。在不增加冗余信息的情况下,提出的DPIM解调方法能够有效地改善系统的差错性能,可为无线光通信链路的设计提供参考。     

Estimation of Bit and Frame Error Rates of Finite-Length Low-Density Parity-Check Codes on Binary Symmetric Channels

A method for estimating the performance of low-density parity-check (LDPC) codes decoded by hard-decision iterative decoding algorithms on binary symmetric channels (BSCs) is proposed. Based on the enumeration of the smallest weight error patterns that cannot be all corrected by the decoder, this method estimates both the frame error rate (FER) and the bit error rate (BER) of a given LDPC code with very good precision for all crossover probabilities of practical interest. Through a number of examples, we show that the proposed method can be effectively applied to both regular and irregular LDPC codes and to a variety of hard-decision iterative decoding algorithms. Compared with the conventional Monte Carlo simulation, the proposed method has a much smaller computational complexity, particularly for lower error rates.     

Enhanced Low Complex Double Error Correction Coding with Crosstalk Avoidance for Reliable On-Chip Interconnection Link

As the technology scales down, shrinking geometry and layout dimension, on- chip interconnects are exposed to different noise sources such as crosstalk coupling, supply voltage fluctuation and temperature variation that cause random and burst errors. These errors affect the reliability of the on-chip interconnects. Hence, error correction codes integrated with noise reduction techniques are incorporated to make the on-chip interconnects robust against errors. The proposed error correction code uses triplication error correction scheme as crosstalk avoidance code (CAC) and a parity bit is added to it to enhance the error correction capability. The proposed error correction code corrects all the error patterns of one bit error, two bit errors. The proposed code also corrects 7 out of 10 possible three bit error patterns and detects burst errors of three. Hybrid Automatic Repeat Request (HARQ) system is employed when burst errors of three occurs. The performance of the proposed codec is evaluated for residual flit error rate, codec area, power, delay, average flit latency and link energy consumption. The proposed codec achieves four magnitude order of low residual flit error rate and link energy minimization of over 53 % compared to other existing error correction schemes. Besides the low residual flit error rate, and link energy minimization, the proposed codec also achieves up to 4.2 % less area and up to 6 % less codec power consumption compared to other error correction codes. The less codec area, codec power consumption, low link energy and low residual flit error rate make the proposed code appropriate for on chip interconnection link.     

一种基于增强奇偶校验码级联极化码的新型编译码方法

极化码作为一种纠错码,具有较好的编译码性能,已成为5G短码控制信道的标准编码方案。但在码长较短时,其性能不够优异。提出一种基于增强奇偶校验码级联极化码的新型编译码方法,在原有的奇偶校验位后设立增强校验位,对校验方程中信道可靠度较低的信息位进行双重校验,辅助奇偶校验码在译码过程中对路径进行修剪,以此提高路径选择的可靠性。仿真结果表明,在相同信道、相同码率码长下,本文提出的新型编译码方法比循环冗余校验(cyclic redundancy check,CRC)码级联极化码、奇偶校验(parity check,PC)码级联极化码误码性能更优异。在高斯信道下,当码长为128、码率为1/2、误码率为10-3时,本文提出的基于增强PC码级联的极化码比PC码级联的极化码获得了约0.3 dB增益,与CRC辅助的极化码相比获得了约0.4 dB增益。