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1

Modeling and Analysis of Additional Clear Channel Assessment to Improve Performance of IEEE 802.15.4-based MAC Protocol

Asuti Manjunath G., Basarkod Prabhugoud I.

Journal of Telecommunications and Information Technology

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2020

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nr 3

10--21

EN

Design of the MAC protocol is crucial in all wireless sensor networks (WSNs) due to its inﬂuence on the performance of the transceiver, i.e. the most energy-consuming component of each sensor node. A mechanism known as “carrier sense multiple access with collision avoidance” (CSMA/CA) is used for accessing the wireless channel in the IEEE 802.15.4 standard-based MAC protocol in order to avoid collisions between the network’s communicating nodes. CSMA/CA relies on two clear channel assessments (CCA=2) for checking the status of the channel. In this paper, we develop an additional CCA algorithm for the two scenarios encountered in star topology-enabled WSNs. Next, we investigate the impact of an additional clear channel assessment (CCA=3) on performance in IEEE 802.15.4. We develop a Markov chain model for the proposed methodology, and validate it using Matlab. Simulation results show that there is a signiﬁcant improvement of performance metrics in the IEEE 802.15.4 standard-based MAC protocol with an additional CCA.

2

Projekt INVOCOM - nauczanie na odległość wykorzystujące internet i interaktywne strony www

Kotrys R., Remlein P., Stelter A., Szulakiewicz P.

Zeszyty Naukowe Politechniki Poznańskiej. Elektryka

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2004

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Nr 48

85-101

PL

W artykule opisano wybrane rezultaty trzyletniego projektu INVOCOM realizowanego w Instytucie Elektroniki i Telekomunikacji w ramach europejskiego programu Leonardo da Vinci. Politechnika Poznańska pełni funkcję koordynatora międzynarodowego zespołu realizatorów z Francji, Finlandii i Portugalii, którzy przygotowują dostępne w Internecie interaktywne materiały dydaktyczne dotyczące wybranych zagadnień technologii informacyjnych i telekomunikacyjnych. Po krótkiej charakterystyce projektu, który wprowadzono półtora roku temu, opisano dwa kursy przygotowywane przez autorów artykułu. Jeden z nich dotyczy algorytmów dekodowania, a drugi - protokołów wielodostępu do medium transmisyjnego w bezprzewodowych sieciach komputerowych.

EN

In this paper, there are described the selected results of the international project named INVOCOM, realized in the frame of the EU Leonardo daVinci program. After short introduction to the project there are described two interactive courses. The first one concerns the decoding algorithms (VA and Max-Log-MAP). The second course concerns the MAC protocols.

3

Application of a hash function to discourage MAC-layer misbehaviour in wireless LANs

Konorski J., Kurant M.

Journal of Telecommunications and Information Technology

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2004

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nr 2

38-46

EN

Contention-based MAC protocols for wireless ad hoc LANs rely on random deferment of packet transmissions to avoid collisions. By selfishly modifying the probabilities of deferments greedy stations can grab more bandwidth than regular stations that apply standard-prescribed probabilities. To discourage such misbehaviour we propose a protocol called RT-hash whereby the winner of a contention is determined using a public hash function of the channel feedback. RT-hash is effective in a full hearability topology, assuming that improper timing of control frames is detectable and that greedy stations do not resort to malicious actions. Simulation experiments show that RT-hash protects regular stations' bandwidth share against various sophisticated greedy strategies of deferment selection; as such it may contribute to MAC-layer network security.

4

Fair access to shared radio channel in IEEE 802.11 networks

Janczak T., Woźniak J.

Systems Science

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2002

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Vol. 28, nr 2

131-140

EN

n computer networks based on a shared communication medium. the MAC (medium access control) protocol is the key element of ensuring service fairness. This element is particularly critical in wireless local area networks (WLANs), where partially hidden topologies are often encountered; for example, due to natural obstacles. The most popular wireless solutions, like IEEE 802.11 and ETSI HIPERLAN, are subject to the channel capture effect in the presence of hidden nodes. Under such conditions, the centrally located stations can send packets so frequently that the hidden nodes are jammed and cannot access the radio channel. In this paper, we analyse the channel capture phenomenon and introduce a modification of the standard 802.11 MAC protocol that attempts to alleviate this problem. Our simulation results show that the modified algorithm can significantly improve service fairness in IEEE 802.11 networks.