Chaotic communication scheme with multiplication

Spectrum sensing is performed by secondary users (SUs) to detect primary users (PUs) in cognitive radio networks. The limited time duration allocated for spectrum sensing may result in high false alarm probability, which always leads to low spectrum utilization and degrades the SU throughput. To overcome this problem, we propose a novel joint sensingtime adaption and data transmission (JSTA-DT) scheme. In our proposed JSTA-DT scheme, two adjacent sensing periods are bundled to form a sensing block. In each sensing block, the SU performs partial time spectrum sensing in the first sensing period. If the sensing result indicates that the PU is absent, the SU transmits its data; otherwise, the SU performs full time spectrum sensing adaptively. Both theoretical analyses and simulation results show that compared to the conventional partial time spectrum sensing and data transmission scheme, the spectrum utilization and achievable SU throughput are improved significantly by using our proposed JSTA-DT scheme.

본 논문에서는 카오스 신호를 이용하여 음성신호의 보안전송을 위한 아날로그 비화통신 시스템을 제안하고 통신성능을 분석하였다. 기존의 카오스 동기화 및 카오스 변조통신 알고리즘을 개선하여 통신환경에서 발생하는 다양한 조건들을 적용하여 음성신호의 복원능력을 모의실험 하였다. 일반적인 PC(Pecora ＆ Carroll) 제어기법과 제안한 SFB(Self-FeedBack) 마스킹 기법을 사용하여 송신단에서 음성신호를 카오스 신호로 마스킹하여 변조하고, 통신채널에 잡음신호를 추가하여 전송하였다. 수신단에서는 카오스 응답시스템을 이용하여 음성신호를 복조하고, 복원성능을 계산하기 위하여 아날로그 복원 에러 신호의 평균전력을 제안하여 계산하였다. 실험결과 마스킹 정도, 파라미터들의 민감성, 채널잡음 등에 대하여 PC 제어기법보다 피드백 제어기법의 복원성능이 우수함을 정량적인 데이터로 확인할 수 있었다. 또한 로렌쯔 카오스 비화통신시스템에 사용할 경우 파라미터들의 조합으로 암호키를 구성해야 하므로 파라미터 변화율에 대응하는 복원에러율의 관계를 모의실험 값으로 구하였다. This paper presents analog secure communication system about safe speech transmission using chaotic signals. We applied various conditions that happen in actuality communication environment modifying chaotic synchronization and chaotic communication schemes and analyzed restoration performance of speech signal to computer simulation. In transmitter, we made the chaotic masking signal which is added voice signal to chaotic signal using PC(Pecora ＆ Carroll) and SFB(self-feedback) control techniques and transmitted encryption signal to noisy communication channel And in order to calculate the degree of restoration performance, we proposed the definition of analog average power of recovered error signals in receiver chaotic system. The simulation results show that feedback control techniques can certify that restoration performance is superior to quantitative data than PC method about masking degree, susceptibility of parameters and channel noise. We experimentally computed the table of relation of parameter fluxion to restoration error rate which is applied the encryption key values to the chaotic secure communication.

In this paper, we mainly propose a chaotic secure communication scheme which is based on the synchronization of double-layered and multiple complex dynamical networks. Compared with the previous chaotic secure communication schemes, in which only two chaotic systems or just a single-layer network composed of multiple chaotic systems is used, the introduction of a double-layered and multiple complex networks model composed of many encryption/encryption units can not only reflect the complex characteristics of different nodes, but also can improve the complexity and security of information encryption. By using a clustering method, nodes with the same characteristics belong to the same subnet, while the nodes with different characteristics belong to different ones. The subnets in the transmitter and receiver are one-to-one correspondence and form a pair of matching subnets, but the node size of each subnet can be inconsistent. Each subnet is only responsible for encrypting a certain part of information, and thus, the synchronization between each pair of matching subnets plays a crucial role on the correct recovery of information. Multiple encryption/decryption units operating in parallel way can speed up the encryption of information, and the key space can grow with the number of nodes in the transmitter. The proposed scheme utilizes the chaotic signals generated by many chaotic systems as the key sequences and adopts the one-time-one-cipher encryption method. Moreover, this scheme is not subject to the constraint that the amplitude of the encrypted signal should be much smaller than that of the chaotic signal, and it is particularly suitable for the big data encryption. Both theoretical analysis and numerical simulation demonstrate the feasibility and effectiveness of the proposed scheme.

In cognitive radio networks, each cognitive transmission process typically requires two phases: the spectrum sensing phase and data transmission phase. In this paper, we investigate cognitive transmissions with multiple relays by jointly considering the two phases over Rayleigh fading channels. We study a selective fusion spectrum sensing and best relay data transmission (SFSS-BRDT) scheme in multiple-relay cognitive radio networks. Specifically, in the spectrum sensing phase, only the initial spectrum sensing results, which are received from the cognitive relays and decoded correctly at a cognitive source, are selected and used for fusion. In the data transmission phase, only the best relay is utilized to assist the cognitive source for data transmissions. Under the constraint of satisfying a required probability of false alarm of spectrum holes (for the protection of the primary user), we derive an exact closed-form expression of the spectrum hole utilization efficiency for the SFSS-BRDT scheme, which is used as a measure to quantify the percentage of spectrum holes utilized by the cognitive source for its successful data transmissions. For the comparison purpose, we also examine the spectrum hole utilization efficiency for a fixed fusion spectrum sensing and best relay data transmission (FFSS-BRDT) scheme, where all the initial spectrum sensing results are used for fusion without any refined selection. Numerical results show that, under a target probability of false alarm of spectrum holes, the SFSS-BRDT scheme outperforms the FFSS-BRDT scheme in terms of the spectrum hole utilization efficiency. Moreover, the spectrum hole utilization efficiency of the SFSS-BRDT scheme always improves as the number of cognitive relays increases, whereas the FFSS-BRDT scheme's performance improves initially and degrades eventually after a critical number of cognitive relays. It is also shown that a maximum spectrum hole utilization efficiency can be achieved through an optimal allocation of the time durations between the spectrum sensing and data transmission phases for both the FFSS-BRDT and SFSS-BRDT schemes.

A DS‐CDMA system with both a circuit‐switching scheme for voice transmission and a packet‐switching scheme for data transmission is effective in multimedia communication required to transmit a variety of media. Although the Slotted‐ALOHA system is believed to be an effective packet‐switched system from the perspectives of transmission efficiency and interference power, only open loop transmit power control is used because of the difficulty in using closed loop transmit power control in the ALOHA system. In this paper, we analyze the performance of open loop transmit power control that uses a power margin to obtain the quality required even in packet‐switched terminals, and propose wireless packet transmission with variable processing gain control as the method to achieve high‐speed transmission by more effectively using the free channels. The results of computer simulations showed that the system capacity of circuit‐switched terminals is not damaged when an appropriate power margin is set, and the additional effect of the packet‐switched terminals is increased. In addition, the proposed system can greatly shorten the average delay time of packet‐switched terminals. © 2001 Scripta Technica, Electron Comm Jpn Pt 1, 84(10): 16–26, 2001

We discuss the performance of several data transmission schemes over measured MIMO-channels using four transmit antennas. We analyze uncoded and prefiltered data transmission with schemes using simple extended Alamouti codes, with and without partial feedback. Our simulations are based on channel measurements and measurement based channel models. It is shown that the extended Alamouti scheme using partial feedback is extremely robust against channel correlation and thus outperforms other transmission schemes.

This paper presents a current-mode triline ternarylevel coded differential signaling scheme for high-speed data transmission across on-chip global interconnects. An energy efficient current-mode triline transceiver pair suitable for this signaling scheme has been proposed. Compared with a voltage mode receiver with resistive termination, the proposed active terminated current-mode receiver reduces the signal current by 7.8 times and the signaling power by 2.6 times. Two data transmission schemes are proposed for using this transceiver pair. In the first scheme, two data streams are directly transmitted over the three lines link, thereby having a wire efficiency of 67%. In the second scheme, five data streams at half rate are encoded and serialized to send over the three lines, thereby having a wire efficiency of 83%. A prototype design has been implemented in a UMC 0.18-μm technology for an interconnect of length 5 mm. The measured energy efficiency of the triline transceiver in a direct transmission scheme for the data rate of 7.4 Gb/s is 0.61 pJ/bit. With the encoding scheme, the energy efficiency is 1.24 pJ/bit for a total data transmission of 9.25 Gb/s.

The Bit Error Rate (BER) performance of common data transmission schemes is quite poor when operating over the Rayleigh-fading mobile radio channel. This is due to the very high BER during fades. In (1) it is shown that Orthogonal Frequency Division Multiplexing (OFDM), a parallel transmission method, can provide improved performance by spreading the effects of a fade over many bits. This paper examines the performance of OFDM transmitted over an FM channel (OFDM/FM). Simulation results comparing OFDM/FM to Non-Coherent Frequency Shift Keying (NCFSK) indicate performance gains of 5 to 9 dB at a Bit Error Rate (BER) of 10-3but negligible improvements at a BER of 10-2.

In this paper, a novel strategy for data transmission that is based on prediction revision dynamic adjustment data gathering algorithm (PRDA) is proposed in WSNs. The key idea of the PRDA is to separate the data prediction and model computing, and the autoregressive process model is employed for prediction revision algorithm. The model computing of PRDA is conducted by sink node firstly according to sampling data sequence from sensor nodes, then, sink node sends the parameters of model to sensor node. Each sensor node predicts the values of the data with parameters, and then, determines whether the current sampling data are sent out or not according to the comparison results of predicting data and sampling data. The dynamic adjustment mechanism of model computing is used to fit the variety of sampling data. Simulation results show that PRDA is able to reduce the amount of data transmission and lead to more significantly energy saving than the traditional approach.

Mobile crowd sensing, as a new paradigm, means that mobile users equipped with smart devices to solve large-scale mobile sensing tasks through wireless communication. Data transmission schemes with opportunistic network in mobile crowd sensing have attracted widespread attention recently, which attempt to reach high delivery and low consumption. However, most transmission schemes resort to users’ trajectory and connection history that are dynamic and difficult to calculate, causing it so hard to establish stable connection channel. For achieving energy-efficient transmission, an energy-efficient data transmission protocol is proposed in this paper, which deploys static nodes to assist in information transmission based on Archimedes curve. Meanwhile, the significant performance of the proposed protocol is demonstrated through extensive simulations based on the ONE platform.

In this paper, we study the problem of delay-constrained data transmission in mobile opportunistic device-to-device networks. In contrast to the deterministic or greedy single-copy single-path (SCSP) and multicopy multipath (MCMP) routing schemes that have been discussed in the literature, we develop a planned opportunistic routing scheme that aims to determine the optimal single-copy multipath (SCMP) transmission strategy that satisfies the delay requirement and, at the same time, minimizes communication cost. We first address the unicast by formulating the optimization problem and developing a distributed routing algorithm under practical network settings. Then, we explore optimal multicast strategies based on the SCMP transmissions. We implement the proposed algorithms on Android tablets and carry out extensive experiments, each with 25 nodes, for a period of two weeks. Moreover, we extract the algorithm codes from our prototype and run simulations based on the Haggle trace to study performance trends under various network settings. The experimental and simulation results show that the proposed protocols achieve significant performance gain in comparison with their counterparts based on SCSP and MCMP transmissions.

Among other things, field-programmable gate arrays (FPGAs) available today contain numerous bit-serial transceivers for communication purposes. Unlike analog modulation schemes, such as quadrature amplitude modulation, bit-serial communication is relatively easy to implement in digital hardware, and is thus usually used for inter FPGA communication. In this view, only the data rate and frequency limit the bandwidth of the circuit. In order to overcome the bandwidth limit, this research proposes a pulse-width modulation (PWM) scheme for data transmission. The information is coded by modulating the length of the high and low voltage parts of the pulse. Although this approach is not new, existing PWM modulators have unsatisfactorial data rates due to their synchronous implementation nature. Therefore, this research implements both the modulator and demodulator by using asynchronous logic. The result is a proof-of-concept comprising two Terasic DE2-70 development boards and a 1 m coaxial cable. Both the PWM modulator and demodulator run at 333 MHz, and pulses are transmitted every 3 ns. Each pulse carries 3 to 4 bits of data. The experimental results indicate an achievable data rate of one gigabit per second, which is about 50 % larger than the FPGA's handbook states.

Two radio-over-fiber data transmission schemes are demonstrated in which the millimeter-wave carrier is generated by heterodyning two free-running DFB lasers, and detected by self-homodyning at receiver. The system is relatively simple and cheap to implement.

In the fog computing model of the IoT, subprocesses of an application process to handle sensor data are performed on fog nodes. Since the IoT is scalable, we have to reduce the electric energy consumption. In the tree-based fog computing (TBFC) model, fog nodes are hierarchically structured. In this paper, we propose a fault-tolerant TBFC (FTBFC) model. In addition, we newly propose a pair of fault-tolerant strategies. In one data transmission strategy, data processed by disconnected fog nodes is sent to a new parent fog node. Here, we propose a minimum energy (ME) algorithm to select a new parent fog node whose energy consumption is minimum. In another subprocess transmission strategy, the subprocess of the faulty fog node is sent to another fog node. In the evaluation, the energy consumption and execution time of a new parent fog node can be reduced by the ME algorithm.

This paper presents a secure chaotic communication scheme using observer-based synchronization of chaotic systems. A class of chaotic systems satisfying incremental quadratic constraints are considered as the transmitter. The original message is encrypted in the noise-like output of the system. A circle criterion-based observer is designed for the system as the receiver by using the linear matrix inequalities technique. The message is recovered at the receiver end from the estimation error of the observer. To design the observer, a general algorithm to calculate incremental multiplier matrices for nonlinearities in chaotic systems is presented. Moreover, the proposed observer-based chaotic secure communication scheme is feasible for many common chaotic systems with ellipsoidal bounds. The simulation results show the good performance of the proposed communication scheme through an example of image transmission.