Szymon Szott

A Survey of Medium Access Mechanisms for Providing QoS in Ad-Hoc Networks

In this survey we attempt to describe the Quality of Service (QoS) mechanisms employed by Medium Access Control (MAC) protocols designed for ad-hoc networks. We begin with background information: an overview of the related work, the definition of QoS and QoS-related metrics, a general description of contention-free and contention-based protocols for wireless networks, a discussion of issues affecting QoS provisioning in ad-hoc networks, as well as a novel classification of the QoS mechanisms. Then, each mechanism is briefly explained and implementation examples from different protocols are provided. Furthermore, a separate section is devoted to the completed and ongoing standardization work in the field. Afterwards, an extensive comparison of salient features, advantages and disadvantages of all described MAC mechanisms is given in order to guide future protocol designers. Finally, we comment on the most probable future research directions. Based on the presented survey, we observe that QoS provisioning is not only challenging but also a significant contemporary research problem. The protocol designs presented in the literature usually involve trade-offs between certain metrics, and currently there is no ideal solution which deals with all the issues affecting ad-hoc networks. Therefore, we trust that this survey will be of great help to designers of future QoS-aware protocols.

Standardizing a reference model and autonomic network architectures for the self-managing future internet

Research efforts at network design in the area of Autonomic Networking and Self-Managing Networks have reached a maturity level that forms a strong foundation toward standardization of architectural principles of the Self-Managing Future Internet. Therefore, an Industry Specification Group (ISG) on Autonomic network engineering for the self-managing Future Internet (AFI) has been established under the auspices of the European Telecommunications Standards Institute (ETSI). Upon its creation, the main stakeholders agreed to harmonize the previous developments and the most recent trends in the very vital field of autonomic and self-managing networks. Particularly, the life cycle of AFI is structured by Work Items providing the foundation for ETSI Group Specifications. So far AFI has been focusing on scenarios, use cases, and requirements for the autonomic/selfmanaging Future Internet, as well as on architectural reference model for autonomic networking and self-management. Most recently, AFI has continued with a new Work Item on requirements analysis and specification of implementation-oriented solutions for autonomics and self-management. At the same time, as a part of the global ecosystem, AFI is establishing strategic liaisons with the standards developing organizations and research community.

Detecting backoff misbehaviour in IEEE 802.11 EDCA

In this paper, we suggest the use of the chi-square test for detecting backoff misbehaviour in IEEE 802.11 EDCA networks. A performance evaluation is performed to compare the chi-square test with two other methods, known in the literature. To perform a suitable comparison, these two methods are extended to support EDCA and the BEB mechanism. We assume a misbehaviour model, which can be easily executed by a selfish user. We show that the chi-square test outperforms the other methods in terms of the probability of misbehaviour detection and time required to positively identify a misbehaving node. Copyright

What's new for QoS in IEEE 802.11?

Two amendments to IEEE 802.11 have recently been published: 802.11aa and 802.11ae. Both enhance Quality of Service (QoS) provisioning in Wi-Fi networks by providing support for multicast transmission, enhanced audio video streaming, coping with inter-network interference, and improved prioritization of management frames. The proposed solutions either extend mechanisms already existing in the standard or introduce new ones. Therefore, it is important for researchers to understand the new functionalities. To this end we provide the first description of these latest mechanisms: we present the motivation behind them, explain their design principles, provide examples of usage, and comment on compatibility issues. Finally, we identify new research challenges related to the two new amendments.

An IEEE 802.11 EDCA model with support for analysing networks with misbehaving nodes

We present a novel model of IEEE 802.11 EDCA with support for analysing networks with misbehaving nodes. In particular, we consider backoff misbehaviour. Firstly, we verify the model by extensive simulation analysis and by comparing it to three other IEEE 802.11 models. The results show that our model behaves satisfactorily and outperforms other widely acknowledged models. Secondly, a comparison with simulation results in several scenarios with misbehaving nodes proves that our model performs correctly for these scenarios. The proposed model can, therefore, be considered as an original contribution to the area of EDCA models and backoff misbehaviour.

Impact of Misbehaviour on QoS in Wireless Mesh Networks

This paper analyzes the impact of misbehaviour on QoS provisioning in wireless mesh networks. Misbehaviour occurs when a network participant decides not to cooperate. Since cooperation is fundamental for distributed environments such as mesh networks, misbehaviour can be a serious threat to them. In this work, the authors focus on the IEEE 802.11 EDCA medium access function which provides QoS in mesh networks. Simulation studies have been performed to determine what realistic forms of misbehaviour can occur and what their impact is. From these results the most beneficial forms of MAC layer misbehaviour in multihop mesh networks are derived.

Impact of Contention Window Cheating on Single-Hop IEEE 802.11e MANETs

This paper presents a work in progress which deals with the important and unresolved problem of node misbehavior. A realistic approach is used to determine the impact of contention window manipulation on IEEE 802.11e ad-hoc networks. It is explained why such networks are more prone to misbehavior. Novel results pertaining to the 802.11e standard are presented. Simulation analysis is done for several scenarios with a distinction made for uplink and downlink traffic. It is shown that a misbehaving node can jeopardize network performance, therefore, countermeasures to this problem need to be developed.

Selfish insider attacks in ieee 802.11s wireless mesh networks

The IEEE 802.11s amendment for wireless mesh networks does not provide incentives for stations to cooperate and is particularly vulnerable to selfish insider attacks in which a legitimate network participant hopes to increase its QoS at the expense of others. In this tutorial we describe various attacks that can be executed against 802.11s networks and also analyze existing attacks and identify new ones. We also discuss possible countermeasures and detection methods and attempt to quantify the threat of the attacks to determine which of the 802.11s vulnerabilities need to be secured with the highest priority.

SDN@home: A method for controlling future wireless home networks

Recent advances in wireless networking technologies are leading toward the proliferation of novel home network applications. However, the landscape of emerging scenarios is fragmented due to their varying technological requirements and the heterogeneity of current wireless technologies. We argue that the development of flexible software-defined wireless architectures, including such efforts as the wireless MAC processor, coupled with SDN concepts, will enable the support of both emerging and future home applications. In this article, we first identify problems with managing current home networks composed of separate network segments governed by different technologies. Second, we point out the flaws of current approaches to provide interoperability of these technologies. Third, we present a vision of a software-defined multi-technology network architecture (SDN@home) and demonstrate how a future home gateway (SDN controller) can directly and dynamically program network devices. Finally, we define a new type of flexibility enabled by SDN@home. Wireless protocols and features are no longer tied to specific technologies but can be used by general-purpose wireless SDN devices. This permits satisfaction of the requirements demanded by home owners and service providers under heterogeneous network conditions.

Improving QoS and security in wireless ad hoc networks by mitigating the impact of selfish behaviors: a game‐theoretic approach

Selfish users are known to be a severe security threat for wireless ad hoc networks. In particular, they can exploit mechanisms designed to assure quality of service (QoS) in the network. In this paper, the problem of backoff misbehavior in IEEE 802.11 enhanced distributed channel access (EDCA) networks is studied using a game-theoretic approach. First, it is shown how this selfish behavior can disrupt traffic differentiation. Then, a solution is proposed, which encourages standard-compliant behavior and thus proper QoS provisioning. This solution is based on punishing selfish nodes by degrading their throughput proportionally to the degree of misbehavior. A practical application of the solution is proposed, which is verified through simulations. Results show that the suggested mechanism considerably improves QoS provisioning in IEEE 802.11 EDCA ad hoc networks in the presence of selfish nodes. Furthermore, it is shown that the mechanism is adaptive, does not have a negative impact on the throughput of well-behaving nodes, and provides legacy node support. Copyright