Denoising-enhanced differential chaos shift keying with joint dual orthogonal codes and time-frequency index modulation

A code is said to be locally testable if an algorithm can distinguish between a codeword and a vector being essentially far from the code using a number of queries that is independent of the code's length. The question of characterizing codes that are locally testable is highly complex. In this work we provide a sufficient condition for linear codes to be locally testable. Our condition is based on the weight distribution (spectrum) of the code and of its dual. Codes of (large) length n and minimum distance n/2 - /spl Theta/(/spl radic/n) have size which is at most polynomial in n. We call such codes almost-orthogonal. We use our condition to show that almost-orthogonal codes are locally testable, and, moreover, their dual codes can be spanned by words of constant weights (weight of a codeword refers to the number of its non-zero coordinates). Dual-BCH(n, t) codes are generalizations of the well studied Hadamard codes (t = 1 is Hadamard). Alon et al. (2003) raised the question whether Dual-BCH(n, t) codes are locally testable for constant t. As these codes are known to be almost-orthogonal, we solve this question. We further show that BCH(n, t) code is spanned by its almost shortest words, that is by codewords of weight at most 2t + 2, while the minimum weight is 2t + 1. Our results can be straightforwardly extended to Goppa codes and trace subcodes of algebraic-geometric codes.

Comparing with orthogonal space time block code (OSTBC), quasi orthogonal space time block code (QOSTBC) can achieve high transmission rate with partial diversity. In this paper, we present a QOSTBC concatenated Reed-Solomon (RS) error correction code structure. At the receiver, pairwise detection and error correction are first implemented. The decoded data are regrouped. Parallel interference cancellation (PIC) and dual orthogonal space time block code (OSTBC) maximum likelihood decoding are deployed to the regrouped data. The pure concatenated scheme is shown to have higher diversity order and have better error performance at high signal-to-noise ratio (SNR) scenario than both QOSTBC and OSTBC schemes. The PIC and dual OSTBC decoding algorithm can further obtain more than 1.3 dB gains than the pure concatenated scheme at 10 -6 bit error probability.

Dual film-like organelles enable spatial separation of orthogonal eukaryotic translation

This paper proposes a forward link unbalancing power control algorithm which is based on a channel modulation scheme for wireless multimedia CDMA mobile systems. The forward channel adopts dual orthogonal spreading codes and a multicode modulation scheme to meet different data rate traffic requirements. The proposed power control algorithm is the integration of a priority scheme and forward link power allocation and adjustment. The numerical results show that the unbalancing power control can guarantee the QoS requirements of traffic with higher priority even for the condition of heavy traffic.

It has been shown that quasi orthogonal space time block codes (QOSTBC) can achieve high transmission rate with partial diversity. Constellation rotational QOSTBC can achieve full diversity. In this paper, we present a constellation rotational QOSTBC concatenates Reed-Solomon (RS) error correction code structure. At the receiver, pairwise detection and error correction are first implemented. The decoded data are regrouped. Parallel interference cancellation (PIC) and dual orthogonal space time block code (OSTBC) decoding are deployed to the regrouped data. The dual OSTBC decoding can obtain better error performance than constellation rotational QOSTBC. The pure concatenated scheme is shown to have higher diversity order and have better error performance at high signal-to-noise ratio (SNR) scenario than both QOSTBC and OSTBC schemes. The PIC and dual OSTBC decoding algorithm can further obtain approximate 1.0 dB gains than pure concatenated scheme at 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> bit error probability (BEP). The BEP performance of the proposed algorithm is very close to that of dual OSTBC scheme with perfect interference cancellation.

This study proposes a new energy-efficient and high data-rated communication technique by combining media-based modulation (MBM) and differential chaos shift keying technique (DCSK), called DCSK–MBM. The MBM technique, which forms the infrastructure of this proposed system, is one of the newest members of the index modulation family, while DCSK offers considerable performance improvements for fading channels. Communication comprises two stages in the DCSK system. In the first stage, only the reference symbol is transmitted to the receiver side, whereas in the second stage, information is carried along with the reference symbol. The negative aspect of this method is that it reduces both transmission data rate and spectral efficiency. The MBM technique provides a significant increase in both spectral efficiency and data rate because it performs index modulation with reconfigurable antennas and transmits extra information bits. To minimize the disadvantages of the DCSK technique and create a more energy-efficient and high data-rated technique, the MBM technique is combined with the DCSK technique. Thus, considerable progress is made. All performance analyses are performed over Rayleigh fading channels for M-ary phase shift keying/quadrature amplitude modulation. Cite this article as: Önal B, Çögen F, Aydın E. Differential Chaos Shift Keying-Assisted Media-Based Modulation. Electrica, 2021; 21(1): 66-73.

In this paper, we determine self dual and self orthogonal codes arising from negacyclic codes over the group ring (Fq + υFq) G. By taking a suitable Gray image of these codes we obtain many good parameter quantum error-correcting codes over Fq.

A new M-ary differential chaos shift keying with index modulation (IM-MDCSK), which has the advantages of high data rate and low energy consumption, is proposed in this paper. In the proposed scheme, each data frame is divided into several time slots where the reference signal is placed in the first time slot and the rest time slots with specific indices are provided for information bearing signals. More exactly, the information bearing signals with active indices are modulated by M-ary DCSK symbols, and the active indices are determined by mapped bits via the combination number mapping method. At the receiver, the absolute values of decision variables in all branches are used to find the indices of active time slots, while M-ary DCSK demodulation is applied to recover the modulated bits. Moreover, we derive the analytical bit-error-rate (BER) expressions for the proposed scheme over additive white Gaussian noise (AWGN) and multipath Rayleigh fading channels, and then simulation results verify our theoretical derivations. Finally, the performance of IM-MDCSK scheme is compared with M-ary DCSK and other up-to-date chaotic modulation schemes based on index modulation (IM). IM-MDCSK scheme is proved to be competitive and preeminent.

Orthogonal frequency division multiplexing with index modulation (OFDM-IM), stands out among conventional communication technologies, as it uses the indices of the available transmit entities. Thanks to such an approach, it offers a novel method for the transmission of extra data bits. Recent years have seen a great interest in chaos-based communications. The spectrum-spreading signals used in chaotic signal modulation technologies are orthogonal to the existing mixed signals. This paper presents how well a non-coherent differential chaos shift keying communication system performs across an AWGN. Different types of detection methods are simulated, bit error rate and power spectral density are calculated and then compared with standard OFDM with index modulation. The results of simulations concerning the performance of a DCSK system, adding to the security of the proposed solution and offering a comparable bit error rate performance, are presented in the paper as well.

In this paper, we investigate conventional communication-based chaotic waveforms in the context of wireless power transfer (WPT). Particularly, we present a differential chaos shift keying (DCSK)-based WPT architecture, that employs an analog correlator at the receiver, in order to boost the energy harvesting (EH) performance. We take into account the nonlinearities of the EH process and derive closed-form analytical expressions for the harvested direct current (DC) under a generalized Nakagami- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$m$</tex-math></inline-formula> block fading model. We show that, in this framework, both the peak-to-average-power-ratio of the received signal and the harvested DC, depend on the parameters of the transmitted waveform. Furthermore, we investigate the case of deterministic unmodulated chaotic waveforms and demonstrate that, in the absence of a correlator, modulation does not affect the achieved harvested DC. On the other hand, it is shown that for scenarios with a correlator-aided receiver, DCSK significantly outperforms the unmodulated case. Based on this observation, we propose a novel DCSK-based signal design, which further enhances the WPT capability of the proposed architecture; corresponding analytical expressions for the harvested DC are also derived. Our results demonstrate that the proposed architecture and the associated signal design, can achieve significant EH gains in DCSK-based WPT systems. Furthermore, we also show that, even by taking into account the nonlinearities at the transmitter amplifier, the proposed chaotic waveform performs significantly better in terms of EH, when compared with the existing multisine signals.

In this work, we investigate differential chaos shift keying (DCSK), a communication-based waveform, in the context of wireless power transfer (WPT). Particularly, we present a DCSK-based WPT architecture, that employs an analog correlator at the receiver in order to boost the energy harvesting (EH) performance. By taking into account the nonlinearities of the EH process, we derive closed-form analytical expressions for the peak-to-average-power-ratio of the received signal as well as the harvested power. Nontrivial design insights are provided, where it is shown how the parameters of the transmitted waveform affects the EH performance. Furthermore, it is demonstrated that the employment of a correlator at the receiver achieves significant EH gains in DCSK-based WPT systems.

This paper studies the performance of a differential chaos shift keying (DCSK)-based wireless power transfer (WPT) setup in a frequency selective scenario. Particularly, by taking into account the nonlinearities of the energy harvesting (EH) process and a generalized frequency selective Nakagami-m fading channel, we derive closed-form analytical expressions for the harvested energy in terms of the transmitted waveform and channel parameters. A simplified closed-form expression for the harvested energy is also obtained for a scenario, where the delay spread is negligible in comparison to the transmit symbol duration. Nontrivial design insights are provided, where it is shown how the power delay profile of the channel as well as the parameters of the transmitted waveform affect the EH performance. Our results show that a frequency selective channel is comparatively more beneficial for WPT compared to a flat fading scenario. However, a significant delay spread negatively impacts the energy transfer.

In this paper, we investigate conventional communication-based chaotic waveforms in the context of wireless power transfer (WPT). Particularly, we present a differential chaos shift keying (DCSK)-based WPT architecture, that employs an analog correlator at the receiver, in order to boost the energy harvesting (EH) performance. We take into account the nonlinearities of the EH process and derive closed-form analytical expressions for the harvested direct current (DC) under a generalized Nakagami-m block fading model. We show that, in this framework, both the peak-to-average-power-ratio of the received signal and the harvested DC, depend on the parameters of the transmitted waveform. Furthermore, we investigate the case of deterministic unmodulated chaotic waveforms and demonstrate that, in the absence of a correlator, modulation does not affect the achieved harvested DC. On the other hand, it is shown that for scenarios with a correlator-aided receiver, DCSK significantly outperforms the unmodulated case. Based on this observation, we propose a novel DCSK-based signal design, which further enhances the WPT capability of the proposed architecture; corresponding analytical expressions for the harvested DC are also derived. Our results demonstrate that the proposed architecture and the associated signal design, can achieve significant EH gains in DCSK-based WPT systems. Furthermore, we also show that, even by taking into account the nonlinearities at the transmitter amplifier, the proposed chaotic waveform performs significantly better in terms of EH, when compared with the existing multisine signals.

In this work, we investigate differential chaos shift keying (DCSK), a communication-based waveform, in the context of wireless power transfer (WPT). Particularly, we present a DCSK-based WPT architecture, that employs an analog correlator at the receiver in order to boost the energy harvesting (EH) performance. By taking into ac-count the nonlinearities of the EH process, we derive closed-form analytical expressions for the peak-to-average-power-ratio of the received signal as well as the harvested power. Nontrivial design in-sights are provided, where it is shown how the parameters of the transmitted waveform affects the EH performance. Furthermore, it is demonstrated that the employment of a correlator at the receiver achieves significant EH gains in DCSK-based WPT systems.

In this paper, a permutation-based chaos system, named as Single Reference Permutation Index with Dual Modulation Differential Chaos Shift Keying (SR-PIDM-DCSK), is developed and tested. The proposed system uses the chaotic segment and its reversed version to modulate two pairs of data sets simultaneously. It uses the same reference for multiple symbol modulation. This significantly reduces bit energy requirement and enhances the Bit Error Rate (BER). In addition, it reduces the complexity of the system. At the transmitter, the reference signal is sent first, then the same reference is delayed and permutated to send the first information set of bits, while the same version is time reversed and permutated to modulate the second set of bits. Both segments are added together on the same symbol duration slot for transmission. This process is repeated for multiple symbols in a frame. At the receiver, the incoming reference signal is delayed for several symbol durations for demodulation. The BER of the system is evaluated in various channel environments. Moreover, a theoretical prediction for BER formula is developed for the suggested model. Results show that the proposed system has superior BER performance compared with other standard chaos based systems by an average of 2 dB. It is evident that the BER performance is enhanced with the increase in the spreading factor and the number of symbols in a frame. The theoretical formula for BER prediction is validated by computer simulation. Excellent matching was found between the theoretical formula and simulation results.