Current linguistic steganography techniques have achieved promising results in terms of resistance to steganalysis. However, they still face significant challenges in maintaining robustness against various forms of attacks, particularly paraphrasing attacks. To address this issue, this paper proposesKeyword-basedRobust LinguisticSteganography against paraphrasing attacks (KR-stega). First, to improve robustness, we leverage keywords as robust features of sentences while introducing locality-sensitive hashing (LSH) to partition the semantic space of words. By generating sentences conditioned on keywords, the method ensures accurate extraction of the secret message. Second, to improve imperceptibility, this paper introduces an imperceptible-enhancing sampling strategy. This strategy enhances the diversity of stegotext, thereby significantly lowering the risk of detection by steganalysis models. Experimental results demonstrate that this method not only enhances the robustness of stegotext against paraphrasing attacks, but also effectively improves the capability to resist steganalysis attacks.

Scene text detection is currently a popular research topic in the computer vision community. However, it is a challenging task due to the variations of texts and clutter backgrounds. In this paper, we propose a novel framework for scene text localization. Based on the region proposal network, a Strip-based Text Detection Network (STDN) is developed with vertical anchor mechanism to predict the text/non-text strip-shaped proposals. Meanwhile, we incorporate the recurrent neural network layers in the proposed network to refine the predicted results. Specifically, hard example mining is performed to train the STDN with cascade learning, which has a remarkable improvement in precision. Besides, we exploit a clustering algorithm to generate anchor dimensions spontaneously without hand-picking, which is portable and time-saving. The text detection framework achieves the state-of-the-art performance on ICDAR2013 with 0.89 F-measure.

This study investigates the security of the two‐way relaying system with untrusty relay nodes. Cooperative jamming schemes are considered for bi‐directional secrecy communications. The transmit power of each source node is divided into two parts corresponding to the user and jamming signals, respectively. Two different assumptions of the jamming signals are considered. When the jamming signals are a priori known at the two source nodes, closed‐form power allocation expressions at two source nodes are derived. Under the assumption of unknown jamming signals, it is proven that the cooperative jamming is useless for the system secrecy capacity, because that all the power should be allocated to the user signals at each source node. Relay selection is also investigated based on the analysis of cooperative jamming. Simulation results are presented to compare the system secrecy capacities under the two jamming signal assumptions.

The security of the two-way relaying system with an eavesdropper is investigated in this paper. A cooperative jamming and power allocation scheme is proposed to enhance the system secrecy capacity. Both user and pre-defined jamming signals are transmitted by each source node simultaneously. The optimum power allocation between the user and jamming signals at each source node is derived. Our analytical results suggest that the proposed cooperative jamming scheme improves on the system secrecy capacity, especially when the channel gains of the two source-relay links are of large difference. Simulation results in close agreement with analytical results clearly demonstrate the advantage of the proposed cooperative jamming scheme.

The security of the three-phase two-way relaying system with an eavesdropper is investigated in this paper. A cooperative jamming and power allocation scheme is proposed to enhance the system secrecy capacity. When a source node transmits user signals to the relay node, the other source node interferes the relay node with pre-defined jamming signals simultaneously. Optimum power allocation between the user and jamming signals at each source node is analyzed. Our analytical results suggest that the proposed cooperative jamming scheme improves on the system secrecy capacity, especially when the channel gains of the two source-relay links are of large difference. Simulation results in close agreement with analytical results clearly demonstrate the advantage of the proposed cooperative jamming scheme.

The secrecy capacity of relay communications is investigated in this paper, where an eavesdropper is present. Distributed precoding through multiple relay nodes can be used to enhance the received signal power at the destination node and to mitigate the signal leakage to the eavesdropper, simultaneously. Due to individual power constraints at relay nodes, the distributed precoding scalar at each relay node is equivalent to a distributed precoding angle. An iterative algorithm is proposed to find the suboptimum distributed precoding angles at all the relay nodes, where the channel state information (CSI) sharing overhead among the relay nodes can also be substantially reduced. Each relay node receives the equivalent CSI from its preceding relay node, computes its distributed precoding angle, and updates the equivalent CSI for the next relay node. Compared with the simple decode-and-forward relaying protocol with random distributed precoding, the proposed iterative distributed precoding algorithm is able to further improve on the secrecy capacity of the multirelay wiretap system with an acceptable CSI sharing overhead.

Carrier aggregation is one of the key techniques for the advancement of long-term evolution (LTE- Advanced) networks. This article proposes a quality- of-experience (QoE)-based carrier scheduling scheme for networks with multiple services. The proposed scheme aims at maximizing the user QoE, which is determined by both the application-level and network-level quality of services. Packet delay, as an essential factor affecting QoE, is first discussed under the context of QoE optimization as well as the data rate. The component carriers are dynamically scheduled according to the network traffic load by the proposed novel scheme. Simulation results show that our approach can achieve significant improvement in QoE and fairness over conventional approaches.

In this paper, a novel non-saturation analytical model for enhanced distributed channel access (EDCA) in IEEE 802.11e wireless local area network (WLAN) is proposed. Unlike previous work focused on saturation conditions, this model uses Markov and M/M/1/K theories to predict MAC delay, service time, throughput and loss. Moreover, the EDCA technique resets the default contention window (CW) of stations statically after each successful transmission. The static behavior which can not adapt to the network state results in bad performance. Consequently, we introduce an enhancement scheme based on quality of experience (QoE) perceived by users to adjust CW adaptively. Instead of solely relying on technical parameters such as loss and delay, our scheme is based on QoE which contains the parameters inherently. Simulations validate this model and demonstrate better performance of our scheme compared with traditional EDCA regarding QoS parameters and user satisfaction.

In wireless sensor networks, several relay nodes can be used to support multiple transmission links between source and destination nodes simultaneously to achieve higher spectral efficiency. A channel state information sharing scheme among multiple relay nodes is presented in this letter, where only one angle per source-destination pair is sent from one relay node to another. Then, to enhance received signal powers, a distributed multiuser precoding scheme is presented to be used at each relay node with the angles sent by another relay node. Simulation results demonstrate that the proposed distributed precoding scheme enhances the capacity performance with slight overhead.