In identity (ID)-based cryptosystems, a user can use his/her identity as the public key, which simplifies the key management procedure compared to certificate-based cryptosystems. Authentication is a desired property in cryptographic protocols. The signature scheme provides this property. Notion of pairing reduces the computation overheads and makes the system simple and efficient. In this survey, we have tried to cover some ID-based signature schemes based on bilinear pairings with their protocol and security analysis to the best of our knowledge. We hope this survey will provide a ready reference to work in the related area.

Cognitive radio (CR) is a promising technology. The most fundamental problem of CR is spectrum sensing. Energy detector is often considered for spectrum sensing in CR, and if the noise power is exactly known, energy detector has admirable performance. However, in practice, noise power is always inexactly known. To solve this problem, Dandawate [Dandawate et al. IEEE Transactions on Signal Processing, 1994, 42(9): 2355–2369] has proposed a nonparametric single-cycle detector based on cyclostationarity, which is robust to noise uncertainty. In this paper, based on Dandawate’s single-cycle detector, a joint multi-cycle detector is further proposed, which is also nonparametric and immune from noise uncertainty. Simulation results have shown the validity and superiority over single-cycle detector of the proposed detector.

Multi-constrained quality of service (QoS) routing aims at finding an optimal path that satisfies a set of QoS parameters, as an NP complete problem, which is also a big challenge for wireless mesh networks (WMNs). Heuristic algorithms with polynomial and pseudo-polynomial-time complexities are often used to deal with this problem. However, existing solutions, most of which suffered either from excessive computational complexities or from low performance, were proposed only for wired networks and cannot be used directly in wireless mesh networks. In this paper, we propose a novel routing scheme based on mean field annealing (MFA-RS) to solve this problem. MFA-RS first uses a function of two QoS parameters, wireless link’s delay and transmission success rate as the cost function, and then seeks to find a feasible path by MFA. Because MFA-RS uses a set of deterministic equations to replace the stochastic process in simulated annealing (SA) and uses saddle point approximation in the calculation of the stationary probability distribution at equilibrium, the convergence time is much less than the routing scheme based on SA (SA-RS). Simulation results demonstrate that MFA-RS is an effective algorithm and is very fit for WMNs.

Collaborative transmission among evolved Node-Bs (eNBs) is one of the promising techniques for LTE-Advanced to provide broader coverage and higher spectral efficiency. The interference among multi-cell transmission can be mitigated by joint precoding, such as multi-cell block diagonalization (BD) at cooperative eNBs. The major difference between multi-cell and single-cell transmission is that the power constraint has to be considered on a per-eNB basis. To satisfy per-eNB power constraint (PePC), a simplified power allocation algorithm for the multi-cell BD based collaborative transmission is proposed in this paper. The algorithm provides a power allocation coefficient matrix for BD to meet PePC. Simulation results demonstrate that the proposed algorithm has a near-optimal performance with simplicity.

In orthogonal frequency division multiplexing (OFDM) system, the time variation of a wireless channel destroys orthogonality among the sub-carriers, and this induces inter-carriers interference (ICI) and degrades system performance severely in mobile environment. In this paper, a new method of ICI cancellation based on delay diversity (DD) was proposed, which provides a way to mitigate the negative effect from the time variation of the wireless paths, thus improve the system performance greatly. The new method was called time-domain self-interference cancellation (TDSIC) algorithm, which is different from other existing methods, such as frequency-domain method. In a cyclically extended OFDM system, the fading characteristics of extended OFDM symbols with different cyclic delay are different with each other, so in our TDSIC method, a new diversity collection scheme at the receiver end is proposed, which can be used to improve the system performance by suppressing ICI through selecting appropriate parameters. Moreover, the cyclically extended OFDM symbol at the transmitter side and diversity collection with different delay added OFDM symbols at the receiver side are used in the TDSIC method with the tradeoff of time-expense, so the well-known fixed delay for symbol at the transmitter side may be detected by the receiver side through estimating several parameters of wireless channels. In summary, the key of the TDSIC method is to improve the system performance with the cost of time. Based on performance analysis, simulation has proved that TDSIC may effectively improve the performance of the time-variant wireless channel.

Rain and snow seriously degrade outdoor video quality. In this work, a primary-secondary background model for removal of rain and snow is built. First, we analyze video noise and use a sliding window sequence principal component analysis de-nosing algorithm to reduce white noise in the video. Next, we apply the Gaussian mixture model (GMM) to model the video and segment all foreground objects primarily. After that, we calculate von Mises distribution of the velocity vectors and ratio of the overlapped region with referring to the result of the primary segmentation and extract the interesting object. Finally, rain and snow streaks are inpainted using the background to improve the quality of the video data. Experiments show that the proposed method can effectively suppress noise and extract interesting targets.

Distributed video coding (DVC) is a new video coding architecture. Compared with traditional video coding schemes, DVC has a simple encoder and complex decoder, which makes it suitable for circumstances where the encoder equipments are simple but the decoder equipments are complex. Most of the existing DVC architectures use decoder rate allocation method with the help of feedback channel. According to the results of the current decoding round, the decoder informs the encoder by feedback channel whether more parity bits are needed. The use of feedback channel not only increases the system delay, but also limits the use of DVC to instances where there is no feedback channel. In this paper, we propose a novel encoder rate allocation method. First, the simple three-step motion estimation is introduced into the encoder to estimate the side information of the decoder, and then the number of parity bits the decoder needs for each bit-plane is allocated at the encoder according to the difference of the estimated side information and the current Wyner-Ziv (WZ) frame. Experiment results indicate that the accuracy of the proposed method is 5.18%–52.93% higher than that of the method proposed by Morbee.

To solve the frame delay problem and match the previous frame, Plapous et al. [IEEE Transactions on Audio, Speech, and Language Processing, 2006, 14(6): 2098–2108] introduced a novel approach called two-step noise reduction (TSNR) technique to improve the performance of the speech enhancement system. However, TSNR approach results in spectral peaks of short duration and the broken spectral outlier, which degrade the spectral characteristics of the speech. To solve this problem, a cepstral smoothing step is added in order to remove these spectral peaks brought by TSNR approach. Theory analysis shows that the proposed approach can effectively smooth the spectral peaks and keep the spectral outlier so as to protect the speech characteristics. Experiment results also show that the proposed approach can bring significant improvement compared to decision-directed (DD) and TSNR approaches, especially in non-stationary noisy environments.

Using an energy-based Hamiltonian function method, this paper investigates the robust excitation control of multi-machine multi-load power systems described by a set of uncertain differential algebraic equations. First, we complete the dissipative Hamiltonian realization of the power system and adjust its operating point by the means of pre-feedback control. Then, based on the obtained Hamiltonian realization, we discuss the robust excitation control of the power system and put forward an H∞ excitation control strategy. Simulation results demonstrate the effectiveness of the control scheme.

The electron gun with rotational surface cathode is presented to improve the laminarity of the converging electron beams in this paper, and the function expression of the rotational surfaces is given. The results of particle in cell (PIC) simulation indicate that anode-hole spherical aberration is the major cause for the nonlaminarity of the electron beams. By properly choosing the size of the shape, rotational surface cathode can effectively counteract the effect of the anode-hole spherical aberration and enhance the laminarity of the electron beams. The theoretical analysis was carried out for the explanation of the phenomenon that appeared in the PIC simulation.

Wearable, textile-based antennas get more and more attention for body-centric communications because it could be easily worn on body and integrated into clothes. Electro-textiles (e-textiles) are used as antenna patch and ground plane. The electromagnetic properties of the textiles play important roles in antenna design and performance. This paper focuses on the study of the electromagnetic properties of e-textiles for wearable antennas applications and mainly discusses the electromagnetic properties of e-textile cell and the influences of different woven densities and different e-textile materials to antenna performances. Simulation and measurement results show that if the e-textiles adopt woven pattern, then when the distance between two conductive fibers is within 2 mm, the e-textiles could be regarded as metal plane to design antennas. In addition, the results show that metal-plated woven fabric could be used as metal plane to design antennas, while non-woven fabric shows distinct differences.

Conventional control systems used for regulated power supplies, including the proportional integral and derivation (PID) controller, have some serious disadvantages. The PID controller has a delayed feedback associated with the control action and requires a lot of mathematical derivations. This paper presents a novel controlling system based on the artificial neural network (ANN), which can be used to regulate the output voltage of the DC power supply. Using MATLAB^TM, the designed control system was tested and analyzed with two types of back-propagation algorithms. This paper presents the results of the simulation that includes sum-squared error (SSE) and mean-squared error (MSE), and gives a detailed comparison of these values for the two algorithms. Hardware verification of the new system, using RS232 interface and Microsoft Visual Basic 6.0, was implement- ed, showing very good consistency with the simulation results. The proposed control system, compared to PID and other conventional controllers, requires less mathematical derivation in design and it is easier to implement.