Performance of a SIMO-CDSK System over Rayleigh Fading Channels

This paper proposes a single-input multiple-output (SIMO) architecture for correlation delay shift keying (CDSK) modulation technique, and the bit error rate (BER) formula is derived under the assumption of the proposed system over Rayleigh fading channels. The new system employs multiple antennas at the receiver end to form a SIMO structure so as to obtain a diversity gain. Theoretical analysis and simulations show that, at a higher signal-to-noise ratio (SNR), the proposed SIMO-CDSK architecture has an outstanding bit error rate (BER) performance in contrast to the conventional single-input single-output (SISO) CDSK and GCDSK communication system; for the given SNR, the diversity gain of the proposed system will be improved with the number of receiver antennas increasing; for different SNRs, the best performance of the proposed system can be obtained by selecting the reasonable spreading factor; because the performance of SIMO-CDSK system is independent of the time delay, the proposed system has better security than GCDSK system

An Oversampling-based Correlator-type Receiver for DCSK Communication Systems Over Generalized Flat Rayleigh Fading Channels

This paper proposes an oversampling-based correlator-type receiver for Differential Chaos-shift Keying (DCSK) communication systems, which can exploit the flat-fading characteristic of multipath channels in order to improve the system performance. At the receiver, the incoming signal is sampled with a sampling rate higher than chip rate before feeding to a correlator. This oversampling step aims to specifically determine delayed-signal components from fading multipath channels, which can be combined together by the correlator in order to increase the ratio of signal-to-noise at its output. In particular, the performance of the proposed receiver is investigated by means of a generalized flat Rayleigh fading channel which has one primary path (i.e., the path having the shortest transmission period) and multiple secondary paths (i.e., the other remaining paths with delays). Mathematical models in discrete-time domain for the conventional transmitter, generalized channel, and proposed receiver are proposed and analyzed. The theoretical bit-error-rate (BER) expression is first derived and then distribution histogram for the ratio of variable bit energy to noise power spectral density is computed. The BER performance is finally estimated by integrating the BER expression over all possible values of the histogram. Numerical simulations with specific parameters are carried out and then simulated performances are shown in comparison to estimated ones. Obtained results point out that the system performance is significantly improved when the number of secondary paths increases

Optimal sub-carriers power allocation in MC-DCSK communication system

研究了多载波差分混沌移位键控(MulTI-CArrIEr dIffErEnTIAl CHAOS SHIfT kEyIng,MC-dCSk)调制中的子载波功率分配问题,基于功率分配模型,推导了MC-dCSk以子载波功率为参数的误比特率(bIT ErrOr rATE,bEr)表达式,基于该表达式,建立了最小化误比特率的最优化问题,并用凸优化方法获得了子载波最优功率的分配策略。通过仿真,比较了最优功率分配与等功率分配情况下,MC-dCSk在加性高斯白噪声(AddITIVE WHITE gAuSSIAn nOISE,AWgn)和rAylEIgH多径衰落信道下的性能,仿真结果验证了最优功率分配策略对系统性能的重要改进,尤其当子载波数较大时,其性能增益更为明显。In this paper,power allocation strategy on sub-carriers of Multi-carrier Differential Chaos Shift Keying( MC-DCSK) is studied.At first,the MC-DCSK system model with power allocated reference and information sub-carriers is presented.Then bit error rate( BER) expression of sub-carriers power allocated MC-DCSK system is derived.Based on the BER expression,the optimal sub-carriers power allocation strategy is obtained by convex optimization.The BER performance of the sub-carriers power allocated MC-DCSK system is evaluated and compared with the conventional MC-DCSK system with equal power allocations under additive white Gaussian noise( AWGN) and Rayleigh multipath fading channels.Simulation results confirm the significant advantages of the optimal sub-carriers power allocation when the number of sub-carriers is large.重庆工程学院校内自然科学基金(2013xzky06)~

Journal of Telecommunications and Information Technology

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