A vehicular ad hoc network (VANET) is an emerging and promising wireless technology aimed to improve traffic safety and provide comfort to road users. However, the high mobility of vehicles and frequent topology changes pose a considerable challenge to the reliable delivery of safety applications. Clustering is one of the control techniques used in VANET to make the frequent topology changes less dynamic. Nevertheless, research has shown that most of the existing clustering algorithms focus on cluster head (CH) election with very few addressing other critical issues such as cluster formation and maintenance. This has led to unstable clusters which could affect the timely delivery of safety applications. In this study, enhanced weight-based clustering algorithm (EWCA) was developed to address these challenges. We considered any vehicle moving on the same road segment with the same road ID and within the transmission range of its neighbour to be suitable for the cluster formation process. This was attributed to the fact that all safety messages are expected to be shared among the vehicles within the vicinity irrespective of their relative speedto avoid any hazardous situation. To elect a CH, we identified some metrics on the basis of the vehicle mobility information. Each vehicle was associated with a predefined weight value based on its relevance. A vehicle with the highest weight value was elected as the primary cluster head (PCH). We also introduced a secondary cluster head (SeCH) as a backup to the PCH to improve the cluster stability. SeCH took over the leadership whenever the PCH was not suitable for continuing with the leadership. The simulation results of the proposed approach showed a better performance with an increase of approximately40%– 45% in the cluster stability when compared with the existing approaches. Similarly, cluster formation messages were significantly minimized, hence reducing the communication overhead to the system and improving the reliable delivery of the safety applications.

Software fault localization is one of the most tedious and costly activities in program debugging in the endeavor to identify faults locations in a software program. In this paper, the studies that used spectrum-based fault localization (SBFL) techniques that makes use of different multiple fault localization debugging methods such as one-bug-at-a-time (OBA) debugging, parallel debugging, and simultaneous debugging in localizing multiple faults are classified and critically analyzed in order to extensively discuss the current research trends, issues, and challenges in this field of study. The outcome strongly shows that there is a high utilization of OBA debugging method, poor fault isolation accuracy, and dominant use of artificial faults that limit the existing techniques applicability in the software industry.

Vehicular Ad hoc Network (VANET) is an emerging and promising technology, which allows vehicles to communicate and share resources. These resources use applications that have to meet high reliability and delay constraints. However, to implement these applications, VANET relies on medium access control (MAC) protocol. Many approaches have been proposed in literature using Time Division Multiple Access (TDMA) scheme to enhance the efficiency of MAC protocol. Nevertheless, this technique is faced with some challenges including access and merging collisions due to inefficient time slot allocation strategy and hidden terminal problem. In this paper, we relatively examined the most prominent TDMA MAC protocols proposed in the literature from the year 2010 to 2017. We classify them based on scheduling strategy and the technique they adopt. We also comparatively analysed them based on different parameters and performance metrics used.Finally, some open issues are presented for future deployment.

VoIP is becoming more and more popular and as such a potential target for hackers. Providing security for VoIP services is therefore pertinent for telecommunications. Without correct mechanisms to ensure callers' authentication, transmission confidentiality and availability of the service, security of the VoIP users is at risk. The fact that VoIP relies on IP infrastructure make it vulnerable to any attack that targets the network. Consequently, whatever may be the nature of the attack, there is a good chance that the attacker is capitalizing on a weakness in the VoIP protocol being used. VoIP is different from other IP services in the sense that its security is normally treated as one of the service properties configurable by the user. This article provides an overview of the VoIP security configuration requirement, aimed at empowering public VoIP user With the strategies to mitigate threats.