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Cognitive radio technology free authorization through the use of opportunistic spectrum to improve spectrum utilization. Because in the cognitive wireless network, the communication between nodes must be without causing interference to the activities of the authorized user so you need to balance performance of cognitive wireless networks. This article puts forward a measurable spectrum joint routing algorithms, can in the spectrum sensing stage can't detect the level of the user's receiver to provide protection, and put onto a control channel routing information transmission, and from the perspective of energy efficiency design the routing discovery process, so that all in the middle of the forwarding nodes can get the spectrum or the network information, so in the destination node calculation consumption is also reduced.

This paper proposes an improved wireless communication channel reservation policy to address the impact on network performance cannot be analyzed under the original model with the primary and secondary users communication channel occupancy rates, and the problem that the secondary user blocking state is significantly higher than the primary user blocking probability under the original model. Simulation results show that improvement in network performance can be done by increasing the primary user communication channel occupy completion rate and the secondary user communication channel occupy completion rate. Also different users channel using request blocking probability can be reduced. It is more effective. That to improve the mixing network performance by improvement of secondary user communication channel occupy completion rate. The new improved model is important in ensuring the coal mine communication system (primary user) as the coal mine wireless communication system for emergency protection. Also the blocking probability of secondary users was reduced. The network access performance of the secondary user was enhanced and improved. The fairness among different users access to the hybrid network was ensured.

In the recent years we have huge development of wireless technology. We are presently getting more subject to wireless technology. As we know wireless networks have broadcast nature so there are different security issues in the wireless communication. The security conventions intended for the wired systems can't be extrapolated to wireless systems. Hackers and intruders can make utilization of the loopholes of the wireless communication. In this paper we will mull over the different remote security dangers to wireless systems and conventions at present accessible like Wired Equivalent Privacy (WEP), Wi-Fi Protected Access (WPA) and Wi-Fi Protected Access 2 (WPA2). WPA2 is more hearty security convention as compared with WPA on the grounds that it utilizes the Advanced Encryption Standard (AES) encryption. There are few issues in WPA2 like it is helpless against brute force attack and MIC bits could be utilized by programmer to compare it with the decoded content. So in this paper we will concentrate on different sorts of wireless security dangers.

The separate situation of research has area coverage or target coverage in wireless sensor networks. Based on directional sensing model the algorithm used the virtual potential field to make the sensor nodes shift positions and change directions automatically in monitoring area, With the completion of multiple prior coverage of hot targets which needed higher quality requirements the algorithm could maximize the coverage rate throughout the monitoring area Simulation experiments show that the algorithm has a good ability of self-organizing. It can satisfy the requirements of coverage quality of the hot targets and the whole monitoring area and save resources effectively of the network.

Many different factors, such as topology, routing technique, selection function, flow control policy, complexity of router design, contribute to the performance of networks on chip (NoCs). Among these factors, the choice of topology and routing function has a significant effect on the average packet latency and saturation behavior. Torus is popular in many application domains, while the problem of virtual channel misbalance caused by its deadlock avoidance scheme brings lots of performance pathologies. In this paper, we present a novel deadlock avoidance scheme based on draining scheme, and propose a deadlock-free routing scheme for torus networks. We quantify the effects of the proposed routing scheme on the overall network performance by presenting simulation results for 1-D torus and 2-D torus NoCs. Experimental results show that the novel routing algorithm for torus networks could make more efficient use of virtual channel resources, and hence cutting down packet latency and boosting throughput. Note although this paper has considered 1-D and 2-D torus networks in the experimental evaluation, the new scheme is flexible enough to support high-radix torus networks.

To ensure the Quality of Service (QoS) of the high-priority requests, the paper proposes a Congestion Control Algorithm of Multi-Priority (CCAMP) which differentiates the QoS according to the priorities, CCAMP reserves queue buffer for the high-priority packets by dropping the low-priority packets in a certain probability. Moreover, the paper presents an improved EDF (Earliest Deadline First) schedule of multi-priority with the sliding window which sorts the packets according to the estimated completion time, the sliding window defines the time similarity, and the high-priority packets are scheduled in priority in the sliding window. The results of the experiments prove that CCAMP and the improved EDF schedule reduces the delay and the loss rate of the high-priority packages, they realize the QoS differentiation by priorities effectively.

Inter-cell interference is a serious issue in Long Term Evolution (LTE/LTE-Advanced) system. Coordinated Multi-Point (CoMP) operation has been considered as a powerful technology targeted for LTE-A standard to reduce interference, improve spectrum efficiency, increase data throughput and enhance effective coverage area, in particular for cell-edge users, by exploiting the interference signals from different transmission points. In this context, this paper provides a holistic overview of CoMP operation in LTE-A system. Here, we consider the downlink operation, e.g. CoMP transmission, as it is more convenient to explain the system effectively. The technical operation challenges, advantages and operation complexities of different CoMP schemes, CoMP architectures and CoMP sets are described in details in terms of backhaul traffic, synchronization effect and feedback design. Moreover, this article provides clear evidence of CoMP benefits in terms of throughput gain and compares the results with no-CoMP scenario. In addition, it is intended for a wide range of readers as it covers the topic from basics to advanced aspects.

Random Early Drop (RED) is widely applied in Mobile Ad-hoc NETworks (MANETs) for congestion control. It randomly drops packets to prevent congestion from occurring, while keeping proper queue size of Route Request (RREQ) packets at the same time. Unfortunately, in the case of severe congestion and large amounts of RREQ packets in the queue, RED algorithm with tune parameters is not able to improve the congestion status properly. This paper proposes a Dynamic RED (DRED) mechanism based on the fitting curve of packet delivery ratio and packet sending rate, which can be readily achieved in practice. DRED presupposes threshold value for initiating and dynamically changes it according to the function regression. Compared to First In First Out (FIFO) and RED with tune parameters mechanisms, simulation results show that DRED has better performance in terms of average end-to-end delay, Hello packet overhead and packet delivery ratio, while avoiding obvious increase of routing discovery frequency.

A complex network is a interaction network of entities where global behavior is not deductible from the individual behaviors of each entities, leading to new properties emergence. Our problem is the network analysis ad modeling. Network analysis needs a formalism to assemble together the structure (static approach) and the function (dynamic approach), and to have a better understanding of the networks characteristics. In this paper, we introduce common used network modeling based on graph theory, having the role to simulate complex networks.

An H-U-E shaped slotted microstrip antenna with improved bandwidth is presented in this paper. The antenna resonates in the frequency range of (2.0–6.3) GHz with the center frequency of 4.2 GHz. The proposed antenna provides return loss approximately -30 dB. The antenna is fed with coaxial feeding yields an impedance bandwidth of 103.6% and VSWR of less than 1.07. The proposed antenna is simulated using Ansoft's HFSS software. The proposed H-U-E slotted microstrip antenna is suitable for wireless communications.

Heterogeneous networks are consisted of the networks with different Radio Access Technologies (RAT). Vertical handoffs would be triggered while mobile users moving across two cells implemented different RATs during the session. Thus, some serious problems will be caused due to characteristics of different RATs. Numerous solutions have been proposed to solve these problems. However, most of existing solutions only take into account single traffic, e.g. vertical handoffs (VHO). In this paper, an analytical model is proposed, with which VHO is taken into account, but also new services (NS). Simulation results illustrate that the performance could be significantly improved with the algorithms in the proposed model. Compared with existing strategies, i.e. Signal to Interference and Noise (SINR) and Vertical Handoff Management (VHOM), for NS, the blocking probability could be improved by 33% and 40%, respectively; for VHO, the blocking probability could be improved by 17% and 19%, respectively; and the resource utilization could be improved by approximately 8% and 11%, respectively.

This project deals with a method of enhancing the degraded detail in the fingerprint images. The term adaptive implies that the parameters of this method are automatically adjusted based on the input fingerprint image. In this method, five processing blocks are involved. The process of fingerprint image enhancement is based on integrating the functionalities of each block. The five blocks are Pre processing, Global analysis, Local analysis, matched filtering and Image segmentation. In the Pre processing and Local analysis blocks, a nonlinear dynamic range adjustment method is used. In the Global analysis and Matched filtering blocks, various forms of order statistic filters are applied. These processing blocks yield an enhanced and new adaptive fingerprint image processing method.

In IEEE 802.11p protocol of Vehicular Ad-Hoc network (VANET), the multiple channels are divided into one control channel (CCH) and six service channels (SCHs). CCH is used for broadcasting safety messages related to road conditions, so that CCH access algorithm has great influence on efficiency of VANET. This paper proposes a contention-free bandwidth partition algorithm, which can dynamically partition the CCH interval and bandwidth assigned to on board units (OBUs) located in vehicles according to real-time VANET environments. Meanwhile, a frequency hopping communication scheme based on chaos scrambling is applied to our algorithm to improve the reliability of VANET. The performance of proposed algorithm are verified by theoretical analysis, the results show that it is able to enhance the transmission efficiency of safety packets in CCH with high reliability.

This paper presents the resonant characteristics of rectangular microstrip antenna printed on anisotropic substrate. The anisotropic substrates are characterized by both permittivity and permeability tensors. The analysis is performed in the spectral domain method by using Green’s function technique. Numerical results concerning the effects of electric anisotropy and antennas parameters on the resonant characteristics of rectangular microstrip antenna are presented and discussed. Results are compared with previously published data and are found to be in good agreement.

This article introduce the genetic algorithm to solve the routing problem with QoS requirements, solve the traditional routing algorithms in completely the limitation of the NP problem. QoS routing optimization model is given, and the detailed design of genetic algorithm encoding scheme, fitness function, selection operator, crossover operator and mutation operator. Finally, the simulation experiment algorithm according to have better convergence and stability, in solving the problem of QoS routing is feasible.