Abstract: In WiMAX networks, the biggest challenge is to overcome the effects of fading especially when nodes are mobile. The multipath nature of channel leads to ISI (Inter Symbol Interference) and the severity of ISI effects increases with bandwidth increase and this might get worse when nodes are moving . The radio link between the Base Station and Service Station/Mobile Station can be a LOS or it can be a NLOS. The environmental objects and features like buildings, weather conditions can severely obstruct NLOS signal. In this paper the effect of pedestrian multipath and node mobility in WiMAX network is studied under different codecs schemes in order to evaluate the effect of multipath channel fading when nodes are moving on the QoS parameters end to end delay, jitter, mean opinion score and throughput of a VoIP application. The obtained results showed that multipath fading with mobile nodes has sever effect on throughput and MOS value for all studied codecs and on the other parameters the effect varies depending on the implemented codecs. arabic 14 English 71
N. Aboalgasm, I. Almerhag , A. Daeri(3-2018)

Even though it is an essential requirement of any computer system, there is not yet a standard method to measure data security, especially when sending information over a network. However, the most common technique used to achieve the three goals of security is encryption. Three security metrics are derived from important issues of network security in this chapter. Each metric demonstrates the level of achievement in preserving one of the security goals. Routing algorithms based on these metrics are implemented to test the proposed solution. Computational effort and blocking probability are used to assess the behavior and the performance of these routing algorithms. Results show that the algorithms are able to find feasible paths between communicating parties and make reasonable savings in the computational effort needed to find an acceptable path. Consequently, higher blocking probabilities are encountered, which is the price to be paid for such savings. arabic 3 English 22
Ibrahim Almerhag(3-2014)

Network availability is a key consideration in disaster planning, but it also has critical impacts on everyday life and work. For organizations, network downtime or sluggishness equates to business downtime, at considerable cost to organizations through inefficiency, lost sales, lack of critical data for decisions, and other harmful effects. First hop redundancy protocols (FHRP) are an essential tool for improving the availability of IP networks. In this paper, we evaluate the three particular protocols of FHRPs, namely the Hot Standby Router Protocol (HSRPv6), Virtual Router Redundancy Protocol (VRRPv3), and Gateway Load Balancing (GLBPv6) using GNS3 tools. The First Hop Redundancy Protocols have been implemented, tested, optimized, and compared to one another in terms of CPU Utilization, Traffic flow, packet loss and convergence time. The comparison indicates which protocol is best in which scenario and which is best among the three protocols.
Mahmud Mansour, Mohamed Alamin Alqomati, Mohmed K. Al-said(3-2022)