The exponential usage of internet attracts cyber criminals to commit crimes and attacks in the network. The forensic investigator investigates the crimes by determining the series of actions performed by an attacker. Digital forensic investigation can be performed by isolating the hard disk, RAM images, log files etc. It is hard to identify the trace of an attack by collecting the evidences from network since the attacker deletes all possible traces. Therefore, the possible way to identify the attack is from the access log traces located in the server. Clustering plays a vital role in identifying attack patterns from the network traffic. In this paper, the performance of clustering techniques such as k-means, GA k-means and Self Organizing Map (SOM) are compared to identify the source of an application layer DDoS attack. These methods are evaluated using web server log files of an apache server and the results demonstrate that the SOM based method achieves high detection rate than k-means and GA k-means with less false positives.

Mobile ad hoc network is a wireless non-centralized network. This network includes a set of distributed nodes with any base or central management, develop a temporary network. Such a way, routing is of the basic challenges of these kinds of networks. Till now, various protocols have been provided for routing in these kinds of networks. One of the optimum routing techniques in these networks is stable routing. In the stable routing, the target is to use paths for send and receive that probably have a higher life period. This causes the data to be sent from a more confident path and the need to new routing will be less, due to liquidation of the current path. In this paper, the target is to provide a stable routing protocol with high efficiency for these kinds of networks, by improving the DSR routing protocol. In the provided protocol, beside the path stability, the energy of the path nodes and path length will be considered too, in order to discover a path with higher quality and use it. The provided protocol will be called as ST-DSR. The result of stimulation in the NS-2 environment shows that the ST-DSR has a better operation toward the base protocol, meaning DSR.

Mobile Ad Hoc Network has given importance in last few years by researchers. Implementations of Ad Hoc network in cognitive radio environment are emerging kind of wireless network [1, 5]. The communication is done by the secondary user in the free frequency band available in the spectrum of the primary user. In this paper, we have projected proficient routing solution by the maintenance of the link for AOMDV protocol for cognitive radio ad hoc Network. We have used ns2 Simulator for simulations. The link maintenance makes the system more efficient that is evaluated by simulation and comparing it with a classical routing protocol.

In this paper, a novel shaped patch antenna for triple band frequency of operation in X-band (radar) is defined. The antenna resonates under three frequency bands at 10 GHz, 10.93 GHz and 11.68 GHz respectively which are included in the X-band frequency range. The substrate material used as the dielectric between the patch and the ground is of Flame Retardant Version 4 (FR4) Epoxy. The DGS (Defected Ground Structure), usually included in the back conductor of the Microstrip patch antenna is used to tune the frequency and also to boost the characteristics of the antenna. The same is included in this depicted antenna with circular ring shaped slot to vary the performance. FEM (Finite Element Method) based Ansoft High Frequency Structural Simulator (HFSS) V.12 is used for designing and verifying the features of the proposed antenna. The size of the depicted model on the whole is of 31.34 × 28.33 × 1.6 mm3. For the first, second and third resonant frequency, a bandwidth of 480 MHz, 600 MHz and 420 MHz correspondingly is obtained with a return loss value of -18.47 dB, -42.22 dB and -19.74 dB. The other parameters of the antenna are also conferred in this paper.

Beamspace MIMO performs beam-selection which can substantially reduce the number of power-consuming radio frequency (RF) chains without perceptible performance deterioration. However, for capacity-approaching performance, accurate information of the beamspace-channel of large-size is required for beam-selection, which is contesting in case of little number of RF-chains. To overcome such problem, I proposed an efficient support-detection (SD) algorithm for channel-estimation with low pilot-overhead and short number of RF chains. The key idea of SD-algorithm is to divide the whole issue of beamspace channel-estimation into a series of sub-issues, where each of them considers only one sparse channel-component. The support of each channel component is detected reliably by deploying the sparse structure attributes of the beamspace-channel. The effect of this channel-component is eliminated from the whole channel-estimation issue. Thus, the sparse beamspace-channel can be estimated with low pilot-overhead. Simulation Results shows that the proposed schemes perform much better than the conventional compressed-sensing (CS) schemes.

A miniature sized microstrip UWB (ultra wideband) BPF (bandpass filter) having highly attenuated upper stop band performance using a dual MMR (multimode resonator) and the DGS (defected ground structure) is proposed. Combining these two topologies, a prototype of the proposed UWB BPF is fabricated using FR-4 substrate of 1.6 mm thickness with dielectric constant of 4.4. This BPF is modelled and simulated using Ansoft high frequency structure simulator (HFSS) Software. The simulated and measured results show a wide FBW (fractional bandwidth) of 119% .The insertion loss is less than -1.0 dB throughout the pass band of 2.78 to 10.95 GHz. All the ripples of return loss are lower than -14 dB in the passband. The BPF has a high rejection of more than -30 dB in the upper stop band up to 16.8 GHz. The simulated and measured group delays variation in the passband are found to be less than 0.2 ns. The overall length of the resonator is 7 mm.