Abstract-This paper introduces a cooperation-based database caching system for Mobile Ad Hoc Networks (MANETs). The heart of the system is the nodes that cache submitted queries. The queries are used as indexes to data cached in nodes that previously requested them. We discuss how the system is formed and how the requested data is found if cached or retrieved from the external database and then cached. Analysis is performed, and expressions are derived for the different parameters, including the upper and lower bounds for the number of query caching nodes and the average load they experience, generated network traffic, node bandwidth consumption, and other performance-related measures. Simulations with the ns-2 software were used to study the performance of the system in terms of average delay and hit ratio and to compare it with the performance of two other caching schemes for MANETs, namely, CachePath and CacheData. The results demonstrate the effectiveness of the proposed system in terms of achieved hit ratio and low delay.

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Routing protocols are the binding force in mobile ad hoc network (MANETs) since they facilitate communication beyond the wireless transmission range of the nodes. However, the infrastructure-less, pervasive, and distributed nature of MANETs renders them vulnerable to security threats. In this paper, we propose a novel clusterbased trust-aware routing protocol (CBTRP) for MANETs to protect forwarded packets from intermediary malicious nodes. The proposed protocol organizes the network into one-hop disjoint clusters then elects the most qualified and trustworthy nodes to play the role of cluster-heads that are responsible for handling all the routing activities. The proposed CBTRP continuously ensures the trustworthiness of cluster-heads by replacing them as soon as they become malicious and can dynamically update the packet path to avoid malicious routes. We have implemented and simulated the proposed protocol then evaluated its performance compared to the clustered based routing protocol (CBRP) as well as the 2ACK approach. Comparisons and analysis have shown the effectiveness of our proposed scheme.

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IEEE 802.16 standard defines the specifications for emerging WiMAX networks. It did not however define the scheduling algorithms that determine the uplink and downlink bandwidth allocation. This paper proposes a Preemptive Deficit Fair Priority Queue (PDFPQ) scheduling architecture for QoS management for the IEEE 802.16 standard. The proposed scheduling architecture is an extension of the DFPQ scheduling technique found in the literature. It enhances the QoS requirements of real time polling service (rtPS) flow class, and improves its delay and throughput. Compared to DFPQ, preliminary results show that a significant rtPS delay reduction and throughput increase can be realized with our new scheduling technique.