Data generated in wireless multimedia sensor networks (WMSNs) may have different importance and it has been claimed that the network exert more efforts in servicing applications carrying more important information. Nevertheless, importance of packets cannot generally be accurately represented by a static priority value. This article presents a dynamic priority based congestion control (DPCC) approach that makes two major innovations in WMSNs. First, DPCC employs dynamic priority to represent packet importance. Second, it prioritizes the local traffic of motes near the base station when WMSN is highly congested. Simulation results confirm the superior performance of the proposed approach with respect to energy efficiency, loss probability and latency as well.

In order to improve the efficiency and fairness of radio resource utilization, a scheme of dynamic cooperative subcarrier and power allocation based on Nash bargaining solution (NBS-DCSPA) is proposed in the uplink of a three-node symmetric cooperative orthogonal frequency division multiple access (OFDMA) system. In the proposed NBS-DCSPA scheme, resource allocation problem is formulated as a two-person subcarrier and power allocation bargaining game (SPABG) to maximize the system utility, under the constraints of each user’s maximal power and minimal rate, while considering the fairness between the two users. Firstly, the equivalent direct channel gain of the relay link is introduced to decide the transmission mode of each subcarrier. Then, all subcarriers can be dynamically allocated to the two users in terms of their selected transmission mode. After that, the adaptive power allocation scheme combined with dynamic subcarrier allocation is optimized according to NBS. Finally, computer simulation is conducted to show the efficiency and fairness performance of the proposed NBS-DCSPA scheme.

The paper proposes a prediction-mode-based filtering mechanism (PMF) to solve the problems of transmission energy wasting caused by time-redundant data in wireless sensor networks (WSN), according to the characteristic of spatio-temporal correlations on sampling series in data-collection. Prior works have suggested several approaches to decrease energy cost during data transmission process via data aggregation tree structure. Distinguish from those methods in above researches, our proposed scheme mainly focus on reducing the temporal redundant degree in event-source to achieve energy-saving effect via self-adaptive filtering structure. The framework of PMF for energy-efficient collection is composed of prediction module for mining the change law of time domain, self-learning module for updating model, and driving module for controlling data filtering operation. Combined with the design of error driving rule and threshold distributing rule, which is the middleware in the above filtering mechanism, the quantity of transmission load in networks can be greatly inhibited on the premise of quality of service (QoS) assurance and energy consumption can be reduced consequently. Finally, the experimental results show that the performance of PMF can significantly outperform some classical data-collection algorithms on energy-saving effect and self-adaptability

Heterogeneous network for long term evolution advanced (LTE-A) creates severe interference. It is an urgent task to overcome the interference in macro cellular with low-power base stations (BSs), such as relay, pico, and femto called subnet nodes. In this paper, the cognitive interference model in interference zone (IZ) of the practical heterogeneous scenario is proposed. Based on investigation of interaction between the macro BS and subnet nodes in this model, the strategy framework of the cognitive critical ratio and power reward factor is set up for interference management aiming to get the maximum net saving power. The study of interference management is transformed into a multiple objective non-linear programming (MONLP) of the maximum saving power for the macro BS and subnet nodes. To facilitate the best compromise solution for both, the MONLP is changed into single objective programming and genetic algorithm (GA) is employed to obtain the global optimum solution. In addition, the practical implementation using the proposed algorithm in heterogeneous network for LTE-A is designed. Finally, numerical evaluation is used to test the applicability of the proposed algorithm, and system level simulation results demonstrate the effectiveness of the proposed interference management scheme.

This paper reviews multi-channel media access control (MAC) protocols based on IEEE 802.11 in wireless Mesh networks (WMNs). Several key issues in multi-channel IEEE 802.11-based WMNs are introduced and typical solutions proposed in recent years are classified and discussed in detail. The experiments are performed by network simulator version 2 (NS2) to evaluate four representative algorithms compared with traditional IEEE 802.11. Simulation results indicate that using multiple channels can substantially improve the performance of WMNs in single-hop scenario and each node equipped with multiple interfaces can substantially improve the performance of WMNs in multi-hop scenario.

Website navigability is acquiring a growing importance in website design and redesign, quality evaluation, and improvement. Existing navigability measures mainly depend on site link structure, so that they only consider the impact of site link structure for navigability and ignore the impact of Web page content. A continuous Markov chain model which depicts the user’s surfing behavior can balance these two factors in the evaluation of website navigability, and it needs to estimate the page transition probabilities and user stay time according to user access log. In this way, we can obtain more reliable results for website navigability measure than the existed methods. Experiments show that our method is effective.

This article considers the two-way multiple-input multiple-output (MIMO) relaying channels with multiple users, in which multiple users are served simultaneously by the base station (BS) with the assistance of the relay. The transmission consists of only two phases, doubling the system throughout over traditional one-way half-duplex transmission. A zero-forcing dirty paper coding (ZFDPC) aided physical-layer network coding (PNC) scheme is proposed in this article and the achievable capacity of the ZFDPC aided PNC scheme is derived. Simulation results show that the proposed scheme outperforms the previous decode-and-forward (DF) and zero-forcing beamforming (ZFBF) aided PNC scheme due to more degrees of freedoms and the advantage of PNC. Moreover, we analyze the effect of the imperfect channel state information (CSI) from RS to users at BS side to show the robustness of the proposed ZFDPC aided PNC scheme.

In orthogonal frequency division multiple access (OFDMA) relay system, for supporting relay transmission, the base station (BS)-the relay station (RS) link must consume an extra part of resource, which may result in serious resource shortage. In order to improve resource utilization, this paper proposes a dynamic resource allocation scheme in adaptive frequency reused OFDMA-relay system based on adaptive modulation and coding (AMC) technology. In this scheme, relay nodes have two independent antennas and operate in decode-and-forward (DF) and full-duplex mode. Then the BS and RSs share the same subcarriers by spatial multiplexing by two independent antennas. The resource allocation problem is formulated for system downlink throughput maximization. Since the optimal solution couldn’t be obtained easily, a sub-optimal algorithm is proposed. The adaptive frequency reused algorithm with two independent antennas RS improves the system throughput about 24.3 % compared with the orthogonal frequency allocation with single-antenna model, and increases the system throughput 10.4 % compared with adaptive frequency reused algorithms with single-antenna RS. It is proved that both of the RS with two-antenna model and adaptive frequency reused scheme can improve the system throughput significantly.

In this paper, a distributed interference suppression scheme is proposed for multi-cell uplink orthogonal frequency division multiple access (OFDMA) system. Firstly, we model resource allocation process as a non-cooperative game. Then we show the concept of Nash equilibrium (NE) and investigate its existence and uniqueness in detail. To enhance the performance of multi-cell OFDMA system, the further improvement process based on NE is given. Several adjustable parameters are set to make the system achieve different tradeoffs between the total capacity and complexity. Simulation results show that the proposed scheme can greatly improve the system performance comparing with conventional scheme.

The investigation of inter-cell interference mitigation techniques is a key area in wireless communications. Coordinated multiple points (CoMP) transmission/reception is a candidate technique for interference cancellation in 3GPP LTE-Advanced system. However, the coordination scheme in CoMP remains a key research problem to be solved, which will have a strong influence on the performance of CoMP. In this paper, a novel coordinated transmission scheme is proposed for the uplink LTE-Advanced system. In our scheme, several base transceiver stations (BTS) and users are selected as coordination partners which form a CoMP cluster. Joint processing is used at the receiver to mitigate interference. From the perspective of coordinated partner selection, our scheme can be divided into static and dynamic coordination which are both considered to fully exploit the throughput gain of CoMP. The proposed schemes are evaluated by system level simulation and compared with the conventional LTE system based upon single cell processing. Our simulation results demonstrate that the proposed schemes attain superior performance as opposed to the conventional system in terms of cell average and cell edge throughput.

Dynamic spectrum access (DSA), consisting of spectrum sharing and spectrum trading stage, becomes a promising approach to increase the efficiency of spectrum usage and system performance. In this paper, from the perspective of individual interest optimization, we focus on strategy adaptation of network users and their interaction in spectrum trading process. Considering adverse effects on decision-making accuracy and the fairness among network users via local information acquirement, a hybrid game model based on global information of relevant spectrum is proposed to formulate intelligent behaviors of both primary and secondary users. Specifically, by using the evolutionary game theory, a spectrum-selection approach for the evolution process of secondary users is designed to converge to the evolutionary equilibrium gradually. Moreover, competition among primary users is modeled as a non-cooperative game and an iterative algorithm is employed to achieve the Nash equilibrium. The simulation results show that the proposed hybrid game model investigates network dynamics under different network parameter settings.

The computation of Chebyshev polynomial over finite field is a dominating operation for a public key cryptosystem. Two generic algorithms with running time of have been presented for this computation: the matrix algorithm and the characteristic polynomial algorithm, which are feasible but not optimized. In this paper, these two algorithms are modified in procedure to get faster execution speed. The complexity of modified algorithms is still , but the number of required operations is reduced, so the execution speed is improved. Besides, a new algorithm relevant with eigenvalues of matrix in representation of Chebyshev polynomials is also presented, which can further reduce the running time of that computation if certain conditions are satisfied. Software implementations of these algorithms are realized, and the running time comparison is given. Finally an efficient scheme for the computation of Chebyshev polynomial over finite field is presented.

The problem to improve the performance of resisting geometric attacks in digital watermarking is addressed in this paper. Based on the optimized support vector regression (SVR), a zero-bit watermarking algorithm is presented. The proposed algorithm encrypts the watermarking image by using composite chaos with large key space and capacity against prediction, which can strengthen the safety of the proposed algorithm. By using the relationship between Tchebichef moment invariants of detected image and watermarking characteristics, the SVR training model optimized by composite chaos enhances the ability of resisting geometric attacks. Performance analysis and simulations demonstrate that the proposed algorithm herein possesses better security and stronger robustness than some similar methods.

From the motivation of algebraic attacks on stream and block ciphers, the concept of algebraic immunity (AI) of a Boolean function was introduced and studied extensively. High algebraic immunity is a necessary condition for resisting algebraic attacks. In this paper, we give some lower bounds on the algebraic immunity of Boolean functions. The results are applied to give lower bounds on the AI of symmetric Boolean functions and rotation symmetric Boolean functions. Some balanced rotation symmetric Boolean functions with their AI near the maximum possible value ?n/2? are constructed.

Botnets are networks composed with malware-infect ed computers. They are designed and organized to be controlled by an adversary. As victims are infected through their inappropriate network behaviors in most cases, the Internet protocol (IP) addresses of infected bots are unpredictable. Plus, a bot can get an IP address through dynamic host configuration protocol (DHCP), so they need to get in touch with the controller initiatively and they should attempt continuously because a controller can’t be always online. The whole process is carried out under the command and control (C&C) channel. Our goal is to characterize the network traffic under the C&C channel on the time domain. Our analysis draws upon massive data obtained from honeynet and a large Internet service provider (ISP) Network. We extract and summarize fingerprints of the bots collected in our honeynet. Next, with the fingerprints, we use deep packet inspection (DPI) Technology to search active bots and controllers in the Internet. Then, we gather and analyze flow records reported from network traffic monitoring equipments. In this paper, we propose a flow record interval analysis on the time domain characteristics of botnets control traffic, and we propose the algorithm to identify the communications in the C&C channel based on our analysis. After that, we evaluate our approach with a 3.4 GB flow record trace and the result is satisfactory. In addition, we believe that our work is also useful information in the design of botnet detection schemes with the deep flow inspection (DFI) technology.

Compressed sensing (CS) is a new theory of signal processing for simultaneous signal sampling and compression. The optimization methods with components regularization have been proposed to perform CS reconstruction of the natural images which always contain various morphological components. In this paper, in order to solve the components regularized optimization problem more accurately, an iterative algorithm is proposed based on the Bregman iteration. The proposed algorithm is an inner-outer iterative procedure, with the two-variable Bregman iteration as its outer iteration and the alternating minimization as its inner iteration. Experimental results show the superiority of the proposed algorithm to other recently developed algorithms in terms of the visual quality improvement and the detail feature preserving capability.

In this paper, the impact of the interference from multiple ultra wideband (UWB) transmitters to a 3rd-generation (3G) terminal is evaluated under UWB emission power limit regulations of federal communications commission (FCC), european telecommunications standards institute (ETSI) and Japan respectively. A three-dimensional interference model is presented where a discrete spatial distribution of UWB transmitters is considered. It is assumed that a mobile terminal and a large number of UWB devices exist in one room simultaneously. A parameter which characterizes the link budget degradation at the victim receiver is defined to measure the UWB interference to 3G systems. The maximum acceptable density of UWB transmitters and the minimum acceptable distance between UWB transmitters and the 3G terminal are analyzed under different link budget degradations. The simulation results demonstrate that the performance of time division-synchronous code division multiple access (TD-SCDMA) is the best, the one of code division multiple access 2000 (CDMA2000) is the worst and the one of wideband code division multiple access (WCDMA) lies between them in presence of UWB interference.