This paper introduces a new algorithm named C2-ESPRIT to estimate the direction of narrow band signals which are not coherent. The new technique estimates direction of arrival (DOA) by dividing the received signals into two sub-array and performing sub-array processing where a new diagonal matrix is obtained. As the elements of this matrix are associated with the main angles of arrival signals, it can be used to estimate the DOA of signals. The main idea in this paper is how the signal’s sub-array are obtained and a processing method is used. Unlike the two algorithms named ESPRIT and C-SPRIT, where the result of processing the signals were a diagonal matrix and diagonal conjugated matrix, in C2-ESPRIT it may appears in the form of the square conjugate diagonal matrix. The advantages of this method compared to ESPRIT and C-SPRIT, are the reduction of the variance, high resolution and requirement of fewer samples in the receiver. MATLAB is used to compare and verify new C2-ESPRIT algorithm efficiency with three known algorithms: Root-Music, ESPRIT and C-SPRIT. تفاصيل المقالة

The IP Multimedia Subsystem (IMS) is a platform for the exchange of multimedia communications that was proposed by 3GPP as of the year 2002. The 3GPP proposal called for the integration of mobile cellular networks and internet technology using a completely IP-based structure. The IMS uses the protocols defined by the IETF, such as SIP, RTP and others. SIP is the backbone of the IMS network, where it is used for signaling and multimedia services control. However, security vulnerabilities are inherent in such integration. When the IMS architecture is opened for easy network access and the use of SIP, it is far more vulnerable to SIP flooding attacks. This has presented a significant security problem in new networks. In the presented method for detection, network traffic is captured in two phases, being the training phase and the test phase. The distance between the probable distributions of SIP messages in these two phases is then measured using the Kullback-Leibler divergence. Then, an adaptive threshold is defined for the Kullback-Leibler divergence which, when passed, means that an attack has occurred. The adaptive threshold is accounted for by the use of a Triple Exponential Moving Average (TEMA), and the performance of the presented detection method in various situations of normal traffic and massive attacks is evaluated. The parameters α, β, ε, and γ are used for estimating the threshold and setting a safe margin for authorized traffic. In addition, the effect of changes of the estimate and setting parameters is evaluated. تفاصيل المقالة

A management protocol level connection line with universal mobile telecommunications system (UMTS) terrestrial radio access network is required in order to enable user’s connection in UMTS networks which is performed by transferring data streams among some pre-shared channels. In this paper international mobile subscriber identity (IMSI) is obtained by an intelligence supervise interception so that if the user identity is not allowed, the connection would be terminated by supervisor. The advantage of this method in comparison with traditional approaches is in attacking connection while it is not in safe layer. In other words, rejection of connection will be performed before any network capacity loss. Our investigation proved that the proposed method results in reduction of computational complexity and energy usage of networks. Furthermore, the probability of network intrusion is also improved. تفاصيل المقالة