A mobile ad hoc network (MANET) is a collection of wireless mobile nodes that form a dynamic network without the need for any infrastructure. Due to the dynamic nature of MANET, it is prone to different kinds of malicious attacks. In order to pursue secure communication in such networks, there are many research solutions proposed for detecting and avoiding such malicious activities. As we know, MANET works properly if participating nodes cooperate in routing and forwarding. However, a node may decide not to cooperate just to save its resources but still use network to relay its traffic. In this scenario, we propose a reputationbased strategy to detect non-cooperative or selfish nodes and to select proper forwarder node for improving overall packet delivery of the network. Moreover, our proposed solution ensures data integrity. We have also done survey and performance analysis on some existing malicious attacks detection and prevention techniques available. The entire simulation has been done using the Network Simulator (NS-2) (http://www.isi.edu/nsnam/ns/) and simulation results show better delivery compared to some of other existing techniques discussed in the papers by Khamayseh et
WIFI and WiMAX became popular worldwide due to simplicity of installation and cost reduction compared with traditional DSL cable. The key challenge of WiFi is the restricted mobility of the user whereas mobile WiMAX (IEEE 802.16m) provides ubiquitous environment to the user. The recent challenges of WiMAX is managing radio resources (both licensed and unlicensed) efficiently through different QoS service classes, implementing proper modulation and coding schemes at PHY, proper antenna selection in MIMO to achieve better QOS. User can avail the benefits of speed and mobility through an integrated architecture comprising WiFi and WiMAX. This chapter provides an in depth performance evaluation of Mobile WiMAX and WiFi under various Modulation and Coding Schemes (MCS), cyclic prefixes and different path-loss models under integrated environment. Moreover, we present an optimized adaptive modulation scheme that senses the SNR and adaptively switches to required MCS to achieve desired level of QoS and link stability.
Due to lack of features of traditional network characteristics, DTN becomes one of the promising research paradigms of wireless network. As there are intermittent connectivity and store-carry-forward features, end-to-end acknowledgement is not possible. DTN is also named as 'opportunistic network'. But interestingly, intermediate nodes may always not behave fairly. Sometimes, due to limited resources (bandwidth and memory) intermediate nodes may behave 'selfish'. Intermediate nodes may also behave unfairly to next hop node intentionally. This behaviour is known as 'misbehaving behaviour'. Recent studies on 'selfish node' and 'misbehaving node' show us the negative impact on network performance (delivery ratio, delivery cost, delivery latency). So we design a slightly new concept inspired by real-life application in our paper showing the positive aspect of the involved nodes in the network. Apart from participating in data forwarding, node may behave as 'traffic node' trying to show the right path towards destination.
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