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

2020 ◽  
Vol 3 ◽  
pp. 10-21
Author(s):  
Manjunath G. Asuti ◽  
Prabhugoud I. Basarkod
Keyword(s):  
Ieee 802.15.4 ◽  
Performance Metrics ◽  
Mac Protocol ◽  
Markov Chain Model ◽  
Wireless Channel ◽  
Chain Model ◽  
Clear Channel Assessment ◽  
Ieee 802.15.4 Standard ◽  
The Impact ◽  
Clear Channel

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

A Backoff Algorithm for LOWPAN Based on the Dynamically Backoff Exponent

2015 ◽  
Vol 713-715 ◽  
pp. 1389-1393
Author(s):  
Ya Jun Zhang ◽  
Jin Liang Shi ◽  
Guo Rong Chen
Keyword(s):  
Ieee 802.15.4 ◽  
Mac Protocol ◽  
Markov Chain Model ◽  
Poor Performance ◽  
System Throughput ◽  
Chain Model ◽  
Backoff Algorithm ◽  
The Poor ◽  
Mathematical Derivation ◽  
Transmission Status

A mechanism that the backoff exponent changes dynamically was proposed aiming at the poor performance of backoff algorithm in IEEE 802.15.4 MAC protocol. The algorithm could adjust the initial backoff exponent according to the previous transmission status and the backoff exponent. A Markov chain model for the algorithm was established and the mathematical derivation for the model was carried out. The theoretical analysis and simulation results show that the model increases the channel access probability and system throughput. The optimized algorithm improves the performance of LOWPAN effectively.

scholarly journals Performance Analysis of WBAN MAC Protocol under Different Access Periods

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Pervez Khan ◽  
Niamat Ullah ◽  
Md. Nasre Alam ◽  
Kyung Sup Kwak
Keyword(s):  
Performance Metrics ◽  
Mac Protocol ◽  
Markov Chain Model ◽  
Wireless Body Area Network ◽  
Heterogeneous Traffic ◽  
System Throughput ◽  
Area Network ◽  
Chain Model ◽  
Access Methods ◽  
Qos Differentiation

The IEEE 802.15.6 is a new standard on wireless body area network (WBAN) for short-range, extremely low power wireless communication with high data rates in the vicinity of, or inside, a human body. The standard defines two contention-based channel access schemes: slotted ALOHA and carrier sense multiple access with collision avoidance (CSMA/CA) using an alternative binary exponential backoff procedure. The standard supports quality of service (QoS) differentiation through user priorities and access phases. In this study, we develop an analytical model for the estimation of performance metrics such as energy consumption, normalized throughput, and mean frame service time, employing a Markov chain model under nonsaturated heterogeneous traffic scenarios including different access phases specified in the standard for different user priorities and access methods. We conclude that the deployment of exclusive access phase (EAP) is not necessary in a typical WBAN using CSMA/CA because it degrades the overall system throughput, consumes more energy per packet, and results in higher delay for nonemergency nodes.

New enhanced clear channel assessment method for IEEE 802.15.4 network

2015 ◽  
Author(s):  
Kyou Jung Son ◽  
Hanjin Cho ◽  
Sung Hyeuck Hong ◽  
Seong-Pil Moon ◽  
Tae Gyu Chang
Keyword(s):  
Ieee 802.15.4 ◽  
Assessment Method ◽  
Clear Channel Assessment ◽  
Clear Channel

scholarly journals COVID-19 and homelessness in England: a modelling study of the COVID-19 pandemic among people experiencing homelessness, and the impact of a residential intervention to isolate vulnerable people and care for people with symptoms

2020 ◽  
Author(s):  
Dan Lewer ◽  
Isobel Braithwaite ◽  
Miriam Bullock ◽  
Max T Eyre ◽  
Robert W Aldridge ◽  
...  
Keyword(s):  
Critical Care ◽  
Success Factors ◽  
Hospital Admissions ◽  
Markov Chain Model ◽  
Severe Disease ◽  
Sensitivity Analyses ◽  
Homeless Population ◽  
Chain Model ◽  
Scenario Analyses ◽  
The Impact

AbstractBackgroundThere is an ongoing pandemic of the viral respiratory disease COVID-19. People experiencing homelessness are vulnerable to infection and severe disease. Health and housing authorities in England have developed a residential intervention that aims to isolate those vulnerable to severe disease (COVID-PROTECT) and care for people with symptoms (COVID-CARE).MethodsWe used a discrete-time Markov chain model to forecast COVID-19 infections among people experiencing homelessness, given strong containment measures in the general population and some transmission among 35,817 people living in 1,065 hostels, and 11,748 people sleeping rough (the ’do nothing’ scenario). We then estimated demand for beds if those eligible are offered COVID-PROTECT and COVID-CARE. We estimated the reduction in the number of COVID-19 cases, deaths, and hospital admissions that could be achieved by these interventions. We also conducted sensitivity and scenario analyses to identify programme success factors.ResultsIn a ’do nothing’ scenario, we estimate that 34% of the homeless population could get COVID-19 between March and August 2020, with 364 deaths, 4,074 hospital admissions and 572 critical care admissions. In our ’base intervention’ scenario, demand for COVID-PROTECT peaks at 9,934 beds, and demand for COVID-CARE peaks at 1,366 beds. The intervention could reduce transmission by removing symptomatic individuals from the community, and preventing vulnerable individuals from being infected. This could lead to a reduction of 164 deaths, 2,624 hospital admissions, and 248 critical care admissions over this period. Sensitivity analyses showed that the number of deaths is sensitive to transmission of COVID-19 in COVID-PROTECT. If COVID-PROTECT capacity is limited, scenario analyses show the benefit of prioritising people who are vulnerable to severe disease.ConclusionSupportive accommodation can mitigate the impact of the COVID-19 pandemic on the homeless population of England, and reduce the burden on acute hospitals.

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