An adaptive modulation algorithm applied to MC-CDMA underwater acoustic communication system

自适应调制技术能有效地利用系统有限的功率和频谱资源,改善系统的误码率性能.针对资源受限的水声MC-CdMA系统提出一种自适应的调制算法.采用该方案的自适应水声MC-CdMA系统在获得有效频谱效率和分集增益的同时,还能获得很好的误码率性能.分析了提出的自适应调制算法的性能,并通过MATlAb系统仿真,表明自适应调制算法较非自适应调制可以使系统性能有明显的提高,说明了自适应调制技术在水声MC-CdMA中的有效性.Adaptive modulation techndogy can improve the system performance with finite power and high spectral efficiency.In this paper,a combining scheme of UWAC MC-CDMA and adaptive modulation is proposed in order to achieve the spectral efficiency and the frequency diversity without loss of much BER performance.The performance of the adaptive modulation algorithm is analyzed.MATLAB simulation results also indicate that the adaptive modulation algorithm can obviously improve the system performance compared with non-adaptive one.The affectivity of adaptive modulation has been verified in UWA MC-CDMA

Simulation of Uplink Channel Estimation for MC-CDMA Underwater Acoustic Communication System

研究水声信道优化估计问题,在资源受限的水声环境下,多载波码分多址(MC-CdMA)上行系统信道,由于受到各种干扰,怎样获取多用户的信道准确信息是一个难题。为此提出了一种采用dfT的上行信道估计算法,可以很好的解决了上述问题。算法是在频域上构造不同的导频信号,在时域上估计用户的冲激响应从而得到其信道传输函数。采用改进方案的水声MC-CdMA系统在获得有效频谱效率和分集增益的同时,还能获得很好的误码率性能。首先利用dfT信道估计算法的性能,进行仿真。结果表明,dfT及改进算法较传统的lS信道估计算法,可以使水声系统性能有明显的提高,降低多用户干扰的影响,为水声多用户信道优化估计提供了依据。A large amount of uplink channel information is difficult to estimate for MC-CDMA underwater acoustic communication(UWAC) uplink system.In this paper,an uplink channel estimation algorithm was proposed to solve this problem with spectral efficiency,as well as the frequency diversity without loss of much BER performance for MC-CDMA UWAC system.The basic idea is constructing different pilots in frequency domain and estimating channel impulse response in time domain.The performance of the algorithm was analyzed.Matlab simulation results also indicate that the uplink channel estimation algorithm can obviously improve the system performance compared with the one based on LS norm,with the reduction of the multiuser interference

物联网技术在微控制器实验教学中的应用

微控制器（Microcontroller,俗称单片机）技术广泛应用在物联网（Internet of Things,loT）终端中,负责收集节点传感器状态、执行节点功能控制、网络接入等.传统的微控制器课程通常侧重单机应用的教学,较少涉及微控制器的联网功能.将物联网技术融入到微控制器课程的实验教学中,学生在微控制器实验的过程中可同时掌握物联网的接入技术,丰富并拓展微控制器课程的教学内容,提高该课程的实用性.厦门大学第二批示范性网络课程《单片机原理与实验》,（2015）厦大教40号

基于串行总线的红外保健屋的设计

以AT89C2051作为核心控制器,采用串行总线的设计思路实现一种新型保健产品——红外保健屋的设计

Comparison of LMS Algorithm and RLS Algorithm Using

摘要:为了减小水声通信系统中存在的由于多径传播效应引起的符号间干扰,可在系统中使用线性均衡器。首先介绍了LMS 算法和RLS 算法基本原理,利用Matlab 仿真软件,给出了两种算法在水声信道通信系统中的自适应均衡的仿真系统,并对这两种算法对于均衡器的影响进行了比较,最后对比较的结果进行了分析。Abstract : To induce inter symbol interference which is due to multipath transmit effect in the water acoustic communication sys2 tem ,linear equalization can be adopted in the system. This article introduces the basic principle of LMS algorithm and RLS algorithm , and makes use of Matlab simulation software to provide the adaptive equalization system in the water acoustic system based on these two algorithms ,compares the performance of these two algorithms ,and analyzes the result of comparison at last .基金项目:国家自然科学基金(60572106

Convolutional decoder design and DSP implementation of underwater acoustic ofDM system

纠错编码是水声OfdM通信系统必须采用的关键技术。本文从译码性能和工程实现角度出发,采用卷积交织、卷积编码和VITErbI软译码相结合的差错控制方案,通过仿真和水池实验确定其参数,并在TMS320dM642上实现。在dSP实现时,卷积交织采用查表法,VITErbI译码采用蝶形运算宏定义等处理方法,极大地提升了运算速度,保证了卷积码的实时性。最后通过海洋实验验证了其译码性能。Error correction coding is a key technology in underwater acoustic ofDM communication system.Convolutional interleaving,convolutional coding and Viterbi soft decoding are implemented on TMS320DM642 in underwater acoustic ofDM system.Look-up table method used in convolutional interleaving and definition of butterfly macro in Viterbi decoding improve DSP computing speed and ensure real-time communication.Finally,the performance of the decoder in sea test is given.国家自然科学基金资助(No.60772141

Diversity of bacterial community structure and its driving factors in three bays of Bohai Sea

[Background] Sustainable development of coastal ecosystem has become one of the most important concerns for people nowadays. Riverine output and anthropogenic interrupt have important impacts on the coastal environment. [Objective] In this study, we collected 12 samples from three transects including Bohai Bay, Liaodong Bay and Laizhou Bay to explore the microbial community and diversity in summer of 2015. [Methods] DNA was extracted from water samples by using DNA extraction kit. Samples were analyzed by Illumina HiSeq sequencing technology. We compared the differences among these three transects according to the analysis results. [Results] The diversity index and rarefaction curves showed significant differences among these three transects. The order of diversity value was Laizhou Bay>Bohai Bay>Liaodong Bay. The distribution of the dominant community was as follows: the proportion of Proteobacteria, Bacteroidetes, Cyanobacteria, Actinobacteria and Planctomycetes in the Bohai Bay was 39.8%, 25.7%, 22.4%, 5.85% and 4.38%, respectively. The dominant community proportion in Liaodong bay was Proteobacteria (37.8%), Bacteroidetes (25.7%), Cyanobacteria (17.8%), Actinobacteria (10.4%) and Planctomycetes (5.64%). While in Laizhou Bay there were only four dominant communities as follows: Proteobacteria (59.0%), Bacteroidetes (17.5%), Cyanobacteria (8.2%), Actinobacteria (7.88%). By using the principal component analysis (PCA) and Heatmap correlation analysis, we found that environmental factors were key roles in controlling the microbial diversity in the Bohai Sea. Among them, the concentration of nitrate was particularly significant according to the Mantel test analysis. [Conclusion] The microbial diversity in the three bays of Bohai Sea was very rich and multifarious. The population structure and species in the Laizhou Bay is the most complex and abundant among these three bays, and then it is Bohai Bay and Liaodong Bay. There was a significant correlation among microbial diversity, environmental factors and the spatial distribution. Above all, this study will provide a theoretical basis for further protection and ecological development of Bohai Sea

Implement of Timing Synchronization for ofDM Underwater Communication System on FPGA

结合水声信道和线性调频(lfM)信号的特点,采用lfM信号作为OfdM水声通信系统的定时同步信号。介绍lfM信号的产生和检测原理,并在fPgA上实现了lfM定时同步信号的产生和同步信号的检测。通过实验室水池实验,验证了该方案的可行性。Based on characteristics of underwater acoustic channel and Linear Frequency Modulation(LFM) signal,LFM signal is adopted for timing synchronization signal of ofDM underwater communication system.The generation and detection principle of LFM signal are summed up.Then the scheme based on the theory above is implemented on Field Programmable Gate Array(FPGA).Finally,the result of pool test shows the feasibility of the scheme.国家自然科学基金资助项目(60772141

Comparison of LMS Algorithm and RLS Algorithm Using in the Underwater Acoustic Communication System

为了减小水声通信系统中存在的由于多径传播效应引起的符号间干扰,可在系统中使用线性均衡器。首先介绍了LMS算法和RLS算法基本原理,利用Matlab仿真软件,给出了两种算法在水声信道通信系统中的自适应均衡的仿真系统,并对这两种算法对于均衡器的影响进行了比较,最后对比较的结果进行了分析。To induce inter symbol interference which is due to multipath transmit effect in the water acoustic communication system,linear equalization can be adopted in the system.This article introduces the basic principle of LMS algorithm and RLS algorithm,and makes use of Matlab simulation software to provide the adaptive equalization system in the water acoustic system based on these two algorithms,compares the performance of these two algorithms,and analyzes the result of comparison at last.国家自然科学基金(60572106

Research and implementation of underwater acoustic real-time voice communication prototype based on MELP

根据水声通信的复杂信道特性,对混合激励线性预测语音编码MElP算法和低密度奇偶校验码ldPC的结合进行了研究,设计了基于ArM+dSP的多载波水声实时语音通信样机。经水池实验测试,系统表现出良好的实时性和语音可懂度性能,可分辨出不同说话人的声音。Taking the complexity of the underwater acoustic communication channel characteristics into account,the combination of mixed excited linear prediction(MELP) and low density parity check(LDPC) were studied and a multi-carrier underwater acoustic real-time voice communication prototype based on ARM+DSP was designed.By the expreimental test in pool,the proposed system showed a good real-time and voice intelligibility performance,and could distinguish the voice of different speakers.中央高校基本科研业务费专项资金资助(2010121062