70 research outputs found
Thwarting Selfish Behavior in 802.11 WLANs
The 802.11e standard enables user configuration of several MAC parameters,
making WLANs vulnerable to users that selfishly configure these parameters to
gain throughput. In this paper we propose a novel distributed algorithm to
thwart such selfish behavior. The key idea of the algorithm is for honest
stations to react, upon detecting a selfish station, by using a more aggressive
configuration that penalizes this station. We show that the proposed algorithm
guarantees global stability while providing good response times. By conducting
a game theoretic analysis of the algorithm based on repeated games, we also
show its effectiveness against selfish stations. Simulation results confirm
that the proposed algorithm optimizes throughput performance while discouraging
selfish behavior. We also present an experimental prototype of the proposed
algorithm demonstrating that it can be implemented on commodity hardware.Comment: 14 pages, 7 figures, journa
A Media Access Control Protocol for Wireless Adhoc Networks with Misbehaviour Avoidance
The most common wireless Medium Access Control (MAC) protocol is IEEE 802.11. Currently IEEE 802.11 standard protocol is not resilient for many identified MAC layer attacks, because the protocol is designed without intention for providing security and with the assumption that all the nodes in the wireless network adhere to the protocol. However, nodes may purposefully show misbehaviours at the MAC layer in order to obtain extra bandwidth con-serve resources and degrade or disrupt the network performance. This research proposes a secure MAC protocol for MAC layer which has integrated with a novel misbehaviour detection and avoidance mechanism for Mobile Ad Hoc Networks (MANETs). The proposed secure MAC protocol the sender and receiver work collaboratively together to handshakes prior to deciding the back-off values. Common neighbours of the sender and receiver contributes effectively to misbehaviours detection and avoidance process at MAC layer. In addition the proposed solution introduces a new trust distribution model in the network by assuming none of the wireless nodes need to trust each other. The secure MAC protocol also assumes that misbehaving nodes have significant levels of intelligence to avoid the detectio
CSMA Local Area Networking under Dynamic Altruism
In this paper, we consider medium access control of local area networks
(LANs) under limited-information conditions as befits a distributed system.
Rather than assuming "by rule" conformance to a protocol designed to regulate
packet-flow rates (e.g., CSMA windowing), we begin with a non-cooperative game
framework and build a dynamic altruism term into the net utility. The effects
of altruism are analyzed at Nash equilibrium for both the ALOHA and CSMA
frameworks in the quasistationary (fictitious play) regime. We consider either
power or throughput based costs of networking, and the cases of identical or
heterogeneous (independent) users/players. In a numerical study we consider
diverse players, and we see that the effects of altruism for similar players
can be beneficial in the presence of significant congestion, but excessive
altruism may lead to underuse of the channel when demand is low
Applications of Repeated Games in Wireless Networks: A Survey
A repeated game is an effective tool to model interactions and conflicts for
players aiming to achieve their objectives in a long-term basis. Contrary to
static noncooperative games that model an interaction among players in only one
period, in repeated games, interactions of players repeat for multiple periods;
and thus the players become aware of other players' past behaviors and their
future benefits, and will adapt their behavior accordingly. In wireless
networks, conflicts among wireless nodes can lead to selfish behaviors,
resulting in poor network performances and detrimental individual payoffs. In
this paper, we survey the applications of repeated games in different wireless
networks. The main goal is to demonstrate the use of repeated games to
encourage wireless nodes to cooperate, thereby improving network performances
and avoiding network disruption due to selfish behaviors. Furthermore, various
problems in wireless networks and variations of repeated game models together
with the corresponding solutions are discussed in this survey. Finally, we
outline some open issues and future research directions.Comment: 32 pages, 15 figures, 5 tables, 168 reference
Detection of selfish manipulation of carrier sensing in 802.11 networks
Recently, tuning the clear channel assessment (CCA) threshold in conjunction with power control has been considered for improving the performance of WLANs. However, we show that, CCA tuning can be exploited by selfish nodes to obtain an unfair share of the available bandwidth. Specifically, a selfish entity can manipulate the CCA threshold to ignore ongoing transmissions; this increases the probability of accessing the medium and provides the entity a higher, unfair share of the bandwidth. We experiment on our 802.11 testbed to characterize the effects of CCA tuning on both isolated links and in 802.11 WLAN configurations. We focus on AP-client(s) configurations, proposing a novel approach to detect this misbehavior. A misbehaving client is unlikely to recognize low power receptions as legitimate packets; by intelligently sending low power probe messages, an AP can efficiently detect a misbehaving node. Our key contributions are: 1) We are the first to quantify the impact of selfish CCA tuning via extensive experimentation on various 802.11 configurations. 2) We propose a lightweight scheme for detecting selfish nodes that inappropriately increase their CCAs. 3) We extensively evaluate our system on our testbed; its accuracy is 95 percent while the false positive rate is less than 5 percent. © 2012 IEEE
Enhanced Medium Access Control Protocol for Resolving Node Misbehavior in Wireless Networks
In this research, two schemes that enhance the existing misbehavior handling
strategy are proposed. The first scheme correlates misbehavior with the traffic
characteristics generated by the node deviating from the stipulated protocol. It
eliminates the stereotyping of deviation by deriving a multi-scale deviation
definition ranging from misbehavior to the underestimation of resource
allocation. The scale adaptively enables varying types of misbehavior
according to resource requirement. From the performance analysis, it was
determined that the scheme is successful in differentiating between
misbehavior due to selfishness and under-allocation of resource. In addition,
the scheme also enables nodes that are allocated with inadequate resource to
achieve higher share of throughput as per its requirement. The second proposed scheme further extends the existing misbehavior
handling strategy by detecting excessive allocation of resources. This scheme
effectively diminishes the wastage of resources by re-distributing them among
the rest of the nodes. The allocation of the resources is carried out on a First-
Come-First-Serve basis in order maintain fair characteristics of the 802.11
access mechanism. From the analysis, it was found that when this scheme is
employed, the presence of nodes that are over-allocated with resources enables
the rest of the nodes to increase their throughput share.
The performance analysis of the proposed schemes was conducted with the
use of a discrete-event simulator. The simulator was specifically developed for
wireless networks incorporating the proposed schemes. It simulates a wireless
network comprising non-deviating nodes and nodes that deviate from the
MAC protocol due to selfishness, under-allocation and over-allocation of
resources. The metrics employed to measure the performance of the proposed
algorithms are average throughput, fairness index, channel utilization and
throughput ratio.
From the analysis of the metrics, it is concluded that with the employment of
the proposed scheme, if a node deviates from the protocol and it is allocated
with inadequate resources, the scheme will adaptively allow the node to gain
the resource as per the degree of its resource under-allocation. On the other
hand, if it deviates due to over-allocation, the excess resources will be distributed to other nodes, hence, enabling for the increase of overall network
throughput
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