mahdieh ghazvini

Smartphones are now well integrated with advanced capabilities and technologies such as the Internet. Today, due to the facilities and capabilities and the widespread use of smart mobile devices, mobile security has become a vital issue worldwide. Smartphones are not properly protected compared to computers and computer networks, and users do not consider security updates. Recently, mobile devices and networks have been targeted by one of the most dangerous cyber threats known as botnets. Mobile Bantent An enhanced example of Boutons has the ability to perform malicious operations such as denial of service attacks, data theft, eavesdropping, and more. Bunters use three communication protocols: HTTP, SMS and Bluetooth to communicate with each other; So when users are not connected to the Internet, botnets are able to communicate with each other. In this study, to identify mobile batonet from 14 Android baton families, including 1932 samples of Android mobile devices applications and 4304 samples of safe and secure Android mobile devices applications have been used. Application permissions were extracted for reverse engineering to automatically classify and detect types of botnets, then based on these permissions, each application was converted to an equivalent image using the proposed method. Labeled images were then used to train convolutional neural networks. The results of evaluation and comparison of this method with classical methods including backup vector machine and decision tree showed that the proposed method is able to achieve higher efficiency in detecting different types of botnets and separating it from healthy programs

The modern processors that consist of large caches are very vulnerable to transient errors. Due to the importance of this problem, coding methods are adopted for protection against errors. The cost of reliability should be incurred to optimize the use of energy and area. This paper proposes an approach to dependability enhancement in unprotected caches of processors. For this purpose, the low-cost tag error mitigation mechanism is adopted to analyze the reliability of caches in modern processors. Benefiting from the tag Hamming distance increase technique, the proposed approach has a much lower overhead and decreases the false hit rate to zero.

Transmission opportunity and contention window are two important parameters in media access in IEEE 802.11e-based networks. and determine how to access the channel, as well as the length of time the channel is used. In these networks, each wireless station determines its media access probability by adjusting its contention window size. After winning in the contention, with respect to the duration of its transmission opportunity, transmits its data packets without re-contention. In multi hop networks, because of long distances between the source nodes and the destination nodes, the middle nodes are used to relay the data. Therefore, the middle nodes, in their transmission and receiving range, see more nodes as neighboring nodes, which makes it possible to increase traffic intensity and higher collision rates than other nodes. In this paper, the length of the queue, data arrival rate and the amount media access delay are exploited in order to a dynamic setting of the transmission opportunity and contention window to reduce the rate of packet loss and end to end delay.Simulation results show the proposed method improves media access and reduce the amount of packet loss and delay.

IEEE 802.11e is standardized to enhance real time multimedia applications’ quality of service (QoS). This standard introduces two access mechanisms called Enhanced distributed channel access (EDCA) and HCF Controlled Channel Access (HCCA) as well as four Access Categories (ACs) for different types of applications. Each AC has four adjustable parameters : Arbitrary Inter-Frame Space Number(AIFSN), minimum Size of Contention Window(CWmin), maximum size of Contention Window (CWmax), and TXOP_limit. A TXOP_limit (TXOP) is time interval, in which a wireless station can transmit a number of frames consecutively, without releasing the channel and any further contention with other wireless stations. TXOP improves network throughput as well as service differentiation. Proper TXOP adjustment can lead to better bandwidth utilization and QoS provisioning. This paper studies the determination of TXOP in EDCA mode of IEEE 802.11e using a game theory based approach called GDTXOP. Based on GDTXOP, each wireless node chooses its appropriate TXOP according to its queue length and media access delay. OPNET simulator simulated the proposed method and its accuracy is evaluated and verified. The results of the simulation indicate that tuning TXOP appropriately improves both channel utilization for all levels of traffic priority and fairness. This improvement does not impair the quality of high-priority traffics. The proposed approach improves channel utilization, while preserving fairness and efficiency in WLANs and minimizing selfishness behaviours of stations in a distributed environment. Simulation results show the proposed method improves fairness while not disrupting the quality of service.

Transmission opportunity limit and contention window are two influenced parameters in accessing the media in the networks based IEEE 802.11e standard. In these networks¡ every wireless station by setting of its contention window value¡ determines the chance of access to wireless media. Furthermore¡ a transmission opportunity limit provides a period of transmission without contact for a station. In order to increase the productivity of the wireless media¡ these two parameters can be determined by considering the network variable conditions in the dynamic form. In this regard¡ since Games Theory is a robust tool for modeling¡ analysis and optimization of competitive environment with shared resources¡ in this research¡ the problem of simultaneous setting of transmission opportunity and contention window in the framework of Game theory have been surveyed and this problem has been modeled in the format of a game. In this Game¡ by defining the consequence function¡ every wireless station plays a role of a player and selects its strategy in setting these two parameters by maximizing its consequence function and in accordance with the quality of services requirements and increasing the productivity of wireless media. Simulation results show that the proposed method has caused to improve access to the channel and relative fairness retention.

New generation of wireless networks, LTE and WiMAX, supports many services which consume a lot of resources (such as VOIP, Video Conference, Digital Video, Multimedia streams and online Multi-player Games). Supporting multi-media services in wireless communication systems provide new resource allocation challenges. Because of high loads in downlink, efficient resource allocation is vital in downlink rather than uplink. In LTE networks, different services need different Quality of Services (QoS). The aim of this article is evaluation of scheduling policies for real time and non-real time services in terms of three parameters. These parameters are throughput, fairness, and packet loss rate. The evaluations and comparisons of these parameters are done by simulation of the scheduling algorithms for a video traffic as a real time service and a web browsing traffic as a non-real time service.