In many applications, wireless ad-hoc networks are formed by devices belonging to independent users. Therefore, a challenging problem is how to provide incentives to stimulate cooperation. In this paper, we study ad-hoc games—the routing and packet forwarding games in wireless ad-hoc networks. Unlike previous work which focuses either on routing or on forwarding, this paper investigates both routing and forwarding. We first uncover an impossibility result—there does not exist a protocol such that following the protocol to always forward others’ traffic is a dominant action. Then we define a novel solution concept called cooperation-optimal protocols. We present Corsac, a cooperation-optimal protocol consisting of a routing protocol and a forwarding protocol. The routing protocol of Corsac integrates VCG with a novel cryptographic technique to address the challenge in wireless ad-hoc networks

Protecting the network layer from malicious attacks is an important yet challenging security issue in mobile ad hoc networks. In this paper we describe SCAN, a unified networklayer security solution for such networks that protects both routing and data forwarding operations through the same reactive approach. SCAN does not apply any cryptographic primitives on the routing messages. Instead, it protects the network by detecting and reacting to the malicious nodes. In SCAN, local neighboring nodes collaboratively monitor each other and sustain each other, while no single node is superior to the others. SCAN also adopts a novel credit strategy to decrease its overhead as time evolves. In essence, SCAN exploits localized collaboration and information cross-validation to protect the network in a self-organized manner. Through both analysis and simulation results we demonstrate the effectiveness of SCAN even in a highly mobile and hostile environment.

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Without sufficient nodes cooperating to provide relaying functions, a mobile ad hoc network cannot function properly. Consequently various proposals have been made which provide incentives for individual users of an ad hoc mobile network to cooperate with each other. In this paper we examine this problem and analyse the drawbacks of currently proposed incentive systems. We then argue that there may not be a need for incentive systems at all, especially in the early stages of adoption, where excessive complexity can only hurt the deployment of ad hoc networks. We look at the needs of different customer segments at each stage of the technological adoption cycle and propose that incentive systems should not be used until ad hoc networks enter mainstream markets. Even then, incentive systems should be tailored to the needs of each individual application rather than adopting a generalised approach that may be flawed or too technically demanding to be implemented in reality.

In wireless networks, it is often assumed that each individual wireless terminal will faithfully follow the prescribed protocols without any deviation – except, perhaps, for a few faulty or malicious ones. Wireless terminals, when owned by individual users, will likely do what is the most beneficial to their owners, i.e., act “selfishly”. Therefore, an algorithm or protocol intended for selfish wireless networks must be designed. In this paper, we specifically study how to conduct efficient multicast routing in selfish wireless networks. We assume that each wireless terminal or communication link will incur a cost when it transits some data. Traditionally, the VCG mechanism has been the only method to design protocols so that each selfish agent will follow the protocols for its own interest to maximize its benefit. The main contributions of this paper are two-folds. First, for each of the widely used multicast structures, we show that the VCG based mechanism does not guarantee that the selfish terminals will follow the protocol. Second, we design the first multicast protocols without using VCG mechanism such that each agent maximizes its profit when it truthfully reports its cost. Extensive simulations are conducted to study the practical performances of the proposed protocols regarding the actual network cost and total payment.

In wireless network, it is often assumed that each individual wireless terminal or link will faithfully follow the prescribed protocols without any deviation – except, perhaps, for the faulty or malicious ones. Wireless terminals or links, often owned by individuals, will likely do what is most beneficial to their owners – act “selfishly”. Thus, it is more reasonable to expect that each selfish terminal will try to manipulate the algorithms or protocols for its owners ’ benefit, instead faithfully follow the designed protocols. Therefore, an algorithm or protocol intended for selfish wireless terminals or links must be designed. In this paper, we specifically study how to conduct efficient multicast in selfish wireless networks. We assume that each wireless terminal or communication link (called agent) will incur a cost when it transits some data, and the cost is known to the wireless terminal or communication link itself. For each of the widely used structures for multicast, we design a strategyproof multicast mechanism without using the well known VCG mechanism such that each agent has to truthfully report its cost to maximize its profit. Extensive simulations are conducted to study the practical performances of the proposed protocols regarding the actually network cost and total payment.

We propose novel solutions for unicast routing in wireless networks consisted of selfish terminals: in order to alleviate the inevitable over-payment problem (and thus economic inefficiency) of the VCG (Vickrey-Clark-Groves) mechanism, we design a mechanism that results in Nash equilibria rather than the traditional strategyproofness (using weakly dominant strategy). In addition, we systematically study the unicast routing system in which both the relay terminals and the service requestor (either the source or the destination nodes or both) could be selfish. To the best of our knowledge, this is the first paper that presents social efficient unicast routing systems with proved performance guarantee. Thus, we call the proposed systems: Optimal Unicast Routing Systems (OURS). Our main contributions of OURS are as follows. (1) For the principal model where the service requestor is not selfish, we propose a

Mobile ad-hoc networks are deployed under the assumption that participating nodes are willing to forward other nodes’ packets. In reputation-based mechanisms cooperation is induced by means of a threat of partial or total disconnection from the network if a node is non-cooperative; however packet collisions and interference may make cooperative nodes appear selfish sometimes. In this paper we use a simple network model to first study the performance of some proposed reputation strategies and then present a new mechanism that we call DARWIN (Distributed and Adaptive Reputation mechanism for WIreless ad-hoc Networks). The idea is to avoid a retaliation situation after a node has been falsely perceived as selfish so cooperation can be restored quickly. We prove that our strategy is robust to imperfect measurements, is collusion-resistant and can achieve full cooperation among nodes.

We investigate the problem of sharing the cost of a multicast transmission in a wireless network in which each node (i.e., radio station) of the network corresponds to a (set of) user(s) potentially interested in receiving the transmission. As in the model considered by Feigenbaum et al. [2001], users may act selfishly and report a false “level of interest” in receiving the transmission trying to be charged less by the system. We consider the issue of designing so called truthful mechanisms for the problem of maximizing the net worth (i.e., the overall “satisfaction” of the users minus the cost of the transmission) for the case of wireless networks. Intuitively, truthful mechanisms guarantee that no user has an incentive in reporting a false valuation of the transmission. Unlike the “wired” network case, here the cost of a set of connections implementing a multicast tree is not the sum of the single edge costs, thus introducing a complicating factor in the problem. We provide both positive and negative results on the existence of optimal algorithms for the problem and their use to obtain VCG truthful mechanisms achieving the same performances.

In wireless ad hoc networks, routing requires cooperation of nodes. Since nodes often belong to different users, it is highly important to provide incentives for them to cooperate. However, most existing studies of the incentivecompatible routing problem focus on individual nodes ’ incentives, assuming that no subset of them would collude. Clearly, this assumption is not always valid. In this paper, we present a systematic study of collusion resistance in incentive-compatible routing schemes. In particular, we consider two standard solution concepts for collusion resistance in game theory, namely Group Strategyproofness and Strong Nash Equilibrium. We show that achieving Group Strategyproofness is impossible while achieving Strong Nash Equilibrium is possible. More specifically, we design a scheme that is guaranteed to converge to a Strong Nash Equilibrium. In addition, we give a cryptographic method that prevents profit transfer between colluding nodes, as long as they do not fully trust each other unconditionally. This method makes our scheme widely applicable in practice. Experiments show that our solution is collusion-resistant and has good performance.