Research on Key Techniques of Digital Iterative Receive for M-ary Differential Chaos Shift Keying Modulation System

以近似噪声的混沌信号为载波的混沌调制方式因其利用了混沌信号所具有的一些固有特性，如高自相关和低互相关的特性，以及宽带特性，使得混沌通信系统在对抗多径干扰、安全通信以及与现存窄带通信系统共存性方面具有优异的表现。因此，作为超宽带(Ultra-Wideband，UWB)技术的一种参选调制方案，混沌调制方式能够与UWB技术一起在以无线体域网(WirelessBodyAreaNetwork，WBAN)为代表的众多功率受限系统中得到应用，为这些系统提供高速、可靠的通信服务。本文以提高多元差分混沌移位键控(M-aryDifferentialChaosShiftKeying，M-aryDCSK)系统的通信可...Due to the inherent characteristics of chaos signal, such as wideband spectra, high auto-correlation and low correlations between different signals, chaotic communication systems which use noise-like chaotic signals as the carrier, have strong anti-inference ability for multi-path fading and high communication security. Moreover, they also can co-exist with other conventional narrowband communicat...学位：工学博士院系专业：信息科学与技术学院_电路与系统学号：2312011015408

Survey of Beyond-BP Decoding Algorithms: Theory and Applications

低密度奇偶校验码因其具有逼近香农限的优异性能,现已在多种标准和系统中得到广泛的应用。但为了使其能够满足不同应用场景下通信系统对纠错性能、计算复杂; 性、译码时延、硬件资源损耗以及功耗等方面的要求,需要对用于LDPC码译码的置信传播算法进行进一步的研究与改进。该文从译码算法的改进动机、方法论、; 计算复杂度以及性能表现等角度入手,对近些年出现的一些Beyond-BP译码算法进行了综述。并在最后对用于迭代接收系统的译码算法改进工作进行了讨论; ,为未来算法的改进工作提供一点思路。Low Density Parity Check (LDPC) codes are employed in several standards; and systems, due to their Shannon limit approaching ability. However, in; order to satisfy the communication systems' requirements at the aspects; of error correction ability, computing complexity, decoding latency,; hardware source consumption and power consumption under different; application circumstances, the Belief Propagation (BP) algorithm used; for decoding LDPC codes needs to be further investigated and improved.; In this survey, authors summarize several different Beyond-BP algorithms; from the aspects of motivation, methodology, complexity and performance.; Moreover, this survey also discusses the optimization of decoding; algorithms for iterative receive system, which can provide a reference; for further investigation on this topic.国家自然科学基

Construction of irregular protograph-based LDPC convolutional codes with windowed decoding

时延是现代通信系统的一个重要指标。滑动窗译码能够在保证性能的基础上降低时延。基于滑动窗译码提出了一种不规则原模图低密度奇偶校验(lOW dEnSITy PArITy CHECk,ldPC)卷积码的构造方法。通过对基于Ar4JA(ACCuMulATE-rEPEAT-by-4-JAggEd-ACCuMulATE)的ldPC卷积码在AWgn(AddITIVE WHITE gAuSSIAn nOISE)信道下的P-EXIT性能分析发现,利用这种构造方式能够设计出多码率并且在bP译码和滑动窗译码方式下都能逼近容量限的ldPC卷积码。计算机仿真证明了基于Ar4JA的ldPC卷积码性能优于规则的ldPC卷积码,而且在滑动窗译码方式下在降低至少56.7%时延的同时表现出了很好的性能。结合提出的不规则原模图ldPC卷积码的构造方法和滑动窗译码得到了一种能够实现译码时延与码字性能良好折中的码字构造有效方式。Latency is an important indicator for modern communication systems.The windowed decoding scheme exhibits good performance with reduced latency.In this paper,a construction scheme for irregular protograph-based low-density parity-check( LDPC) convolutional codes with windowed decoding is proposed.The protograph-EXIT( P-EXIT) analysis for the accumulate-repeat-by-4-jagged-accumulate( AR4JA)-based LDPC convolutional codes over the additive white Gaussian noise( AWGN) channel shows that this flexible construction technique can give rise to the LDPC convolutional codes with different code rates and thresholds close to capacity,for both BP decoding and windowed decoding.The computer simulations identify the AR4JA-based LDPC convolutional codes outperform the regular LDPC convolutional codes and the AR4JAbased LDPC convolutional codes exhibit good performance with at least 56.7% reduced latency.Combining the proposed construction scheme for irregular protograph-based LDPC convolutional codes and the windowed decoding scheme can provide an efficient way to trade-off the decoding latency and the code performance.TheNationalNaturalScienceFoundationofChina(61271241)~

Performance of different DCSK schemes over the UWB in- body channel

混沌调制(differential chaos shift keying,DCSK)技术应用于超宽带(ultra wideband,UWB)短距离传输系统具有潜在的优势。提出了分别基于多元DCSK(M-ary DCSK,M-DCSK)、调频DCSK(frequency modulation-DCSK,FM-DCSK)和QCS-DCSK(quadrature code shifted-DCSK)的超宽带无线体内传输系统,分析了提出的基于最新几种混沌调制的超宽带体内传输系统的BER(bit error ratio)性能,对影响基于混沌调制的超宽带体内传输系统性能的参数积分时间和保护间隔做了理论研究和仿真分析。通过设置不同的扩频因子,在体内信道下QCS-DCSK相比MDCSK及FM-DCSK能够确保更好的传输质量,且功率损耗更低。在给定扩频因子β和信号持续时间Tc时,存在能使QCS-DCSK系统性能达到最优的保护间隔。在设定扩频因子β、信号持续时间Tc和保护间隔Tg时,存在能够使FM-DCSK系统性能达到最优的积分间隔。Because of its characteristics,differential chaos shift keying( DCSK) system is well suited for wireless short-range communication system. Based on M-ary DCSK,FM-DCSK and QCS-DCSK respectively,the ultra wideband wireless in-body communication systems are proposed. By deeply analyzing main characteristics about these systems,studying and simulating factors such as guard interval and integration time which affect performance of ultra wideband wireless in-body communication systems based on M-ary DCSK,FM-DCSK and QCS-DCSK,some optimizations have been made for these factors. The BER performance of those three schemes demonstrates that QCS-DCSK can provide better communication quality and require lower power consumption compared to other two DCSK schemes. For given spreading factor β and duration time Tc,the simulation results of QCS-DCSK over in-body channel with different guard intervals show that the optimal guard interval can ensure the best performance of QCS-DCSK over the UWB in-body channel. With given spreading factor β,duration time Tcand guard interval Tg,the optimal integration interval can improve the performance of FM-DCSK over the UWB in-body channel.The National Natural Science Foundation of China(61271241;61001073)~

Protograph-based LDPC decoder applied to magnetic recording channel

针对传统原模图低密度奇偶校验(lOW dEnSITy PArITy CHECk,ldPC)码在译码硬件实现中,由于采用随机扩展方式,导致数据拥塞和布线困难,继而产生译码延时和资源消耗的提高及吞吐量的下降问题,通过2步准循环扩展得到了适于硬件实现的码字结构,设计了一种面向磁记录信道的原模图ldPC码译码器。该译码器信息更新采用基于TdMP(TurbO dECOdIng MESSAgE PASSIng)分层译码的归一化MIn-SuM算法使得译码器具有部分并行架构;同时为了降低译码时间及功耗,给出一种低资源消耗的提前终止迭代策略。硬件实现结果表明,该译码器的译码性能十分接近相应的浮点算法,在低资源消耗的前提下,工作频率可达183.9 MHz,吞吐量为63.3 MbIT/S,并可同时适用于多种原模图ldPC码。Using random expansion algorithm,the hardware implementation of conventional protograph-based LDPC(low density parity check) decoders has difficulty with wiring and data transmission,which results in the improvement of resource consumption and decrease in throughput.In this paper,an easy-hardware-implementation quasi cyclic protographbased LDPC code is obtained by the use of a two-step lifting procedure,and we also propose a protograph-based LDPC decoder for magnetic recording channels.Utilizing the normalized Min-Sum algorithm based on the TDMP(Turbo decoding message passing) layered decoding scheme,the proposed decoder has a partially parallel architecture.Moreover,an early termination strategy is also proposed to reduce the latency and power consumption of the decoder.The proposed LDPC decoder is evaluated on a Xilinx Spartan 6 FPGA(field programmable gate array) platform and the results indicate that the proposed decoder requires low resource and can be utilized for multiple protograph-based LDPC codes.国家自然科学基金(61271241)~

Implementation of FPGA-based PSK demodulator

自适应调制系统要求其解调器能够对多种调制方式进行解调。通过研究发现,采用合理电路结构与算法,可使基于fPgA(fIEld-PrOgrAMMAblE gATE ArrAy)的PSk(PHASE SHIfT kEyIng)数字解调器在仅改变部分电路结构的情况下,对多种PSk调制方式进行解调。对一些现有解调技术进行探讨,并利用这些算法,设计了一种基于fPgA的可实现解调多种PSk调制方式的数字解调器。并通过ISE与MOdElSIM软件,在XIlInX公司的XC4VlX60芯片上进行了实现。综合和仿真结果表明,解调器工作效果良好,可应用于自适应调制系统中。The adaptive modulation system requires its demodulator can demodulate various modulation modes.By researching digital demodulation techniques deeply,we find out that an FPGA-based digital PSK demodulator can be used to demodulate various PSK modulated mode,with partial circuit structure changed rather than the whole,when chosen reasonable circuit structure and algorithms.We designed an FPGA-based digital demodulator,which can be used to demodulate various PSK modulated mode,employing those algorithms we discussed in the paper.With the ISE and ModelSim software,we also implement this design on XC4VLX60 produced by Xilinx.Simulation results show that this demodulator has high performance,and that can be used in adaptive modulation system.国家自然科学基金(60972053)---

Measurement of integrated luminosity of data collected at 3.773 GeV by BESIII from 2021 to 2024

We present a measurement of the integrated luminosity e+e- of collision data collected by the BESIII detector at the BEPCII collider at a center-of-mass energy of Ecm = 3.773 GeV. The integrated luminosities of the datasets taken from December 2021 to June 2022, from November 2022 to June 2023, and from October 2023 to February 2024 were determined to be 4.995±0.019 fb-1, 8.157±0.031 fb-1, and 4.191±0.016 fb-1, respectively, by analyzing large angle Bhabha scattering events. The uncertainties are dominated by systematic effects, and the statistical uncertainties are negligible. Our results provide essential input for future analyses and precision measurements

Determination of the number of ψ(3686) events taken at BESIII

The number of ψ(3686) events collected by the BESIII detector during the 2021 run period is determined to be (2259.3±11.1)×106 by counting inclusive ψ(3686) hadronic events. The uncertainty is systematic and the statistical uncertainty is negligible. Meanwhile, the numbers of ψ(3686) events collected during the 2009 and 2012 run periods are updated to be (107.7±0.6)×106 and (345.4±2.6)×106, respectively. Both numbers are consistent with the previous measurements within one standard deviation. The total number of ψ(3686) events in the three data samples is (2712.4±14.3)×10^