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For secure mobile wireless networks whose topologies are changed dynamically in insecure environments, mobile users need to keep in contact with each other for the purpose of user authentications. For instance, the network formed by a group of soldiers equipped with wireless devices in a battlefield. Maintaining a high connectivity is crucial in such networks in order to authenticate scattered individuals and to be able to communicate with each other. To establish connections, different mobile ad hoc network routing protocols have been developed. However, much research has shown that these protocols are incapable of maintaining high connectivity when the node density is lower in the network. This paper proposes a mechanism to enhance the node connectivity, which is specifically effective for mobile ad hoc networks with lower node densities. It selects some nodes with larger transmission power as strategic nodes to assist in establishing connections with remote nodes, which are unable to connect with otherwise. The strategic nodes have the ability to connect with each other. Whenever a remote mobile node has a request to connect to another remote mobile node, the strategic nodes function as normal mobile nodes and may forward the connection requests to the desired remote destination node. The mechanism is simulated in different scenarios with various node densities, and the results show that the node connectivity is generally enhanced with the benefit of lower node density network, gaining significant improvement.

Malicious nodes can seriously impair the performance of wireless ad hoc networks as a result of different actions such as packet dropping, ([1] and [2]). Secure routes are shortest paths on which every node on the route is trusted even if unknown. Secure route discovery requires the adoption of mechanisms of associating trust to nodes. Most existing secure route discovery mechanisms rely on shared keys and digital signature. In the absence of central nodes that act as certification authority, such protocols suffer from heavy computational burden and are vulnerable to malicious attacks. In this paper we shall review existing techniques for secure routing and propose to complement route finding with creditability scores. Each node would have a credit list for its neighbors. Each node monitors its neighbors' pattern of delivering packets and regularly credits are reviewed and updated accordingly. Unlike most existing schemes the focus of our work is based on post route discovery stage, i.e. when packets are transmitted on discovered routes. The level of trust in any route will be based on the credits associated with the neighbors belonging to the discovered route. We shall evaluate the performance of the proposed scheme by modifying our simulation system so that each node has a dynamic changing "credit list" for its neighbors' behavior. We shall conduct a series of simulations with and without the proposed scheme and compare the results. We will demonstrate that the proposed mechanism is capable of isolating malicious nodes and thereby counteracting black hole attacks.