A mixed-signal integrated circuit for FM-DCSK modulation

This paper presents a mixed-signal application-specific integrated circuit (ASIC) for a frequency-modulated differential chaos shift keying (FM-DCSK) communication system. The chip is conceived to serve as an experimental platform for the evaluation of the FM-DCSK modulation scheme, and includes several programming features toward this goal. The operation of the ASIC is herein illustrated for a data rate of 500 kb/s and a transmission bandwidth in the range of 17 MHz. Using signals acquired from the test platform, bit error rate (BER) estimations of the overall FM-DCSK communication link have been obtained assuming wireless transmission at the 2.4-GHz ISM band. Under all tested propagation conditions, including multipath effects, the system obtains a BER = 10-3 for Eb/No lower than 28 dB.Ministerio de Ciencia y Tecnología TIC2003-0235

Performance of a Multiple-Access DCSK-CC System over Nakagami-mm Fading Channels

In this paper, we propose a novel cooperative scheme to enhance the performance of multiple-access (MA) differential-chaos-shift-keying (DCSK) systems. We provide the bit-error-rate (BER) performance and throughput analyses for the new system with a decode-and-forward (DF) protocol over Nakagami-$m$ fading channels. Our simulated results not only show that this system significantly improves the BER performance as compared to the existing DCSK non-cooperative (DCSK-NC) system and the multiple-input multiple-output DCSK (MIMO-DCSK) system, but also verify the theoretical analyses. Furthermore, we show that the throughput of this system approximately equals that of the DCSK-NC system, both of which have prominent improvements over the MIMO-DCSK system. We thus believe that the proposed system can be a good framework for chaos-modulation-based wireless communications.Comment: 4 pages, 5 figures, accepted, IEEE ISCAS, 201

Design and Performance Analysis of a Novel Trellis-Coded Differential Chaotic Modulation System

本文提出了一种新型的编码调制技术——网格编码差分混沌调制技术（TC-DCM:Trellis-CodedDifferentialChaoticModulation），其主要的思想是将网格编码调制技术（TCM:Trellis-CodedModulation）和以混沌信号为载波的多元差分混沌移位键控调制技术（M-DCSK:M-aryDifferentialChaoticShiftKeying）相结合。由于混沌信号具有类噪声的内在的扩频特性，在调制的同时直接对信号进行扩频，利用其良好的相关特性和连续带宽的功率谱特性，该系统具有较好的抗多径干扰的能力，弥补了传统的网格编码调制系统在这方面的不足。此外，由...In this paper, a novel coded modulation scheme named Trellis-Coded Differential Chaotic Modulation (TC-DCM) is proposed, which combines trellis codes with M-ary Differential Chaotic Shift Keying (M-DCSK). The new scheme not only reduces the multipath interference efficiently due to its inherent spreading property, but also avoids the use of Channel State Information (CSI), making the corresponding...学位：工学硕士院系专业：信息科学与技术学院_通信与信息系统学号：2332014115322

PERFORMANCE ANALYSIS OF QUADRATURE CHAOS SHIFT

One of the most famous techniques of non-coherent differential chaos shift keying (DCSK) is Quadrature chaos shift keying (QCSK) system, this system suffered from lowering the data rate and increasing the bit energy during the bit transmission even though its rate doubling the one of the DCSK. Short reference (SR) algorithm is proposed for the QCSK system to design the SR-QCSK communication system that enhances these drawbacks. The main idea of the short reference technique is minimizing the length of the reference chaotic signal (β) at a transmitter by a factor P comparing to produce R samples for the new reference signal while the length of the information-bearing signal remained unchanged, this occurs by duplicating the reference signal P times to get the same length as the conventional QCSK. Therefore, the symbol duration is reduced from 2βTc to (R+β)Tc. The data rate and energy saving improvement factor in a percent form is derived and compared with the QCSK and DCSK systems. Also, the BER analytical expression is derived for the SR-QCSK in additive white Gaussian noise and Rayleigh fading channel. The experimental simulation results proved that the theory derivation gives a good analysis tracking for the BER performance. The SR-QCSK system is compared with other DCSK techniques and the simulation results show that it has a superior performance in the multipath Rayleigh fading channel

Novel wireless modulation technique based on noise

In this paper, a new RF modulation technique is presented. Instead of using sinusoidal carriers as information bearer, pure noise is applied. This allows very simple radio architectures to be used. Spread-spectrum based technology is applied to modulate the noise bearer. Since the transmission bandwidth of the noise bearer can be made very wide, up to ultra-wideband regions, extremely large processing gains can be obtained. This will provide robustness in interference-prone environments. To avoid the local regeneration of the noise reference at the receiver, the Transmit-Reference (TR) concept is applied. In this concept, both the reference noise signal and the modulated noise signal are transmitted, together forming\ud the bearer. The reference and modulated signals are separated by applying a time offset. By applying different delay times for different channels (users) a new multiple access scheme results based on delay: Delay Division Multiple Access (DDMA). A theoretical analysis is given for the link performance of a single-user and a multi-user system. A testbed has been built to demonstrate the concept. The demonstrator operates in a 50 MHz bandwidth centered at 2.4 GHz. Processing gains ranging from 10¿30 dB have been tested. The testbed confirms the basic behavior as predicted by the theory

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)~

Chaotic communications with correlator receivers: theory and performance limits

This paper provides a review of the principles of chaotic digital communications using correlator receivers. Modulation schemes using one and two chaotic basis functions, as well as coherent and noncoherent correlation receivers, are discussed. The performance of differential chaos shift keying (DCSK) in multipath channels is characterized. Results are presented for DCSK with multiuser capability and multiple bits per symbol

The magnetic-resonance force microscope: a new tool for high-resolution, 3-D, subsurface scanned probe imaging

The magnetic-resonance force microscope (MRFM) is a novel scanned probe instrument which combines the three-dimensional (3-D) imaging capabilities of magnetic-resonance imaging with the high sensitivity and resolution of atomic-force microscopy. It will enable nondestructive, chemical-specific, high-resolution microscopic studies and imaging of subsurface properties of a broad range of materials. The MRFM has demonstrated its utility for study of microscopic ferromagnets, and it will enable microscopic understanding of the nonequilibrium spin polarization resulting from spin injection. Microscopic MRFM studies will provide unprecedented insight into the physics of magnetic and spin-based materials. We will describe the principles and the state-of-the-art in magnetic-resonance force microscopy, discuss existing cryogenic MRFM instruments incorporating high-Q, single-crystal microresonators with integral submicrometer probe magnets, and indicate future directions for enhancing MRFM instrument capabilities