Protocol Enhancements And Performance Analysis Of WiFi Networks

10.32920/ryerson.14654946 ◽

2021 ◽

Author(s):

M. Zulfiker Ali ◽

Jelena Misic

Keyword(s):

Analytical Model ◽

Performance Metrics ◽

Mac Protocol ◽

Multiple Input Multiple Output ◽

Access Point ◽

Collision Probability ◽

Queuing Model ◽

Wifi Networks ◽

Extensive Simulation ◽

Performance Improvements

The 802.11ac version of the popular IEEE 802.11 protocol aims to boost performance by increasing the channel bandwidth and allowing simultaneous transmission to multiple clients in the downlink direction. This dissertation presents an innovative approach of performance evaluation of downlink multi-user multiple input multiple output (DL-MUMIMO) technique for differentiated quality of service (QoS) based traffic categories in IEEE 802.11ac protocol. We propose a novel analytical model based on discrete Markov chain (DMC) and E-limited M/G/1 queuing model to evaluate the performance improvements of multi-user transmission opportunity (MU-TXOP) sharing in DL-MU-MIMO under non-saturated load and non-ideal channel condition. We also evaluate MU-TXOP sharing probabilities among different QoS nodes to assess the performance improvement of different traffic categories. In this dissertation, we propose an Access Point controlled MAC protocol (A-MAC) that enables simultaneous transmissions from multiple stations (STA) in uplink to eliminate under utilization of network resources in uplink transmission due to single user communication. The protocol uses enhanced distributed channel access (EDCA) technique to initiate multi-user transmission and orthogonal frequency division multiple access (OFDMA) method to transmit multiple Ready-To-Send (RTS) messages simultaneously. The proposed protocol also introduces explicit channel sounding technique by using dedicated OFDM subcarrier blocks for each user. We evaluate the performance of the proposed protocol using a noble analytical model and validate the performance metrics by extensive simulation in different traffic conditions. In this dissertation we also propose the increase of carrier sensing threshold (CSTH) of nodes during association with access point (AP) to mitigate collision probability due to hidden nodes during uplink transmission and validate our proposal through extensive simulation. Finally, we propose a noble analytical model to evaluate the performance of restricted access window (RAW) mechanism of IEEE 802.11ah as the MAC layer protocol for internet of things (IoT) network. We evaluate detailed performance metrics of non-QoS IoT network and investigate the feasibility of using RAW mechanism to support differentiated QoS based heterogeneous IoT network

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The Integration Of IEEE 802.11 (WLAN) With RFID Systems in ISM (2.45 GHz) Frequency Band Environment Using Framed Slotted ALOHA And IEEE 802.15.4

10.32920/ryerson.14657274.v1 ◽

2021 ◽

Author(s):

Haleh Khojasteh

Keyword(s):

Ieee 802.11 ◽

Frequency Band ◽

Ieee 802.15.4 ◽

Performance Metrics ◽

Access Point ◽

Collision Probability ◽

Time Sharing ◽

Slotted Aloha ◽

Framed Slotted Aloha ◽

Ieee 802.15.4 Standard

In this thesis, we attempt to solve the problem of WLAN/RFID coexistence and integration in frequency band of GHz or ISM band. Our solution to this problem is to allow the WLAN access and RFID access in a time-sharing manner by making the WLAN Access Point aware of the RFID neighbor-network at MAC layer. The time-sharing function is implemented using IEEE 802.11 PCF mechanism. RFID network is implemented using two different standards. The first one is Framed Slotted Aloha standard and the second one is IEEE 802.15.4 standard. We have simulated both models using Artifex simulator and compared their performance using some performance metrics like collision probability and average number of collision in each superframe. It is shown that IEEE 802.15.4 based model outperforms the Framed Slotted Aloha based model.

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The Integration Of IEEE 802.11 (WLAN) With RFID Systems in ISM (2.45 GHz) Frequency Band Environment Using Framed Slotted ALOHA And IEEE 802.15.4

10.32920/ryerson.14657274 ◽

2021 ◽

Author(s):

Haleh Khojasteh

Keyword(s):

Ieee 802.11 ◽

Frequency Band ◽

Ieee 802.15.4 ◽

Performance Metrics ◽

Access Point ◽

Collision Probability ◽

Time Sharing ◽

Slotted Aloha ◽

Framed Slotted Aloha ◽

Ieee 802.15.4 Standard

In this thesis, we attempt to solve the problem of WLAN/RFID coexistence and integration in frequency band of GHz or ISM band. Our solution to this problem is to allow the WLAN access and RFID access in a time-sharing manner by making the WLAN Access Point aware of the RFID neighbor-network at MAC layer. The time-sharing function is implemented using IEEE 802.11 PCF mechanism. RFID network is implemented using two different standards. The first one is Framed Slotted Aloha standard and the second one is IEEE 802.15.4 standard. We have simulated both models using Artifex simulator and compared their performance using some performance metrics like collision probability and average number of collision in each superframe. It is shown that IEEE 802.15.4 based model outperforms the Framed Slotted Aloha based model.

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An Efficient Distributed Single-hop Relay Supporting (EDSRS) MAC Protocol for Wireless Sensor Networks

International Journal of Sensors Wireless Communications and Control ◽

10.2174/2210327908666180801125223 ◽

2019 ◽

Vol 9 (2) ◽

pp. 153-164

Author(s):

Arvind Kakria ◽

Trilok Chand Aseri

Keyword(s):

Energy Efficiency ◽

Cooperative Communication ◽

Mimo Systems ◽

Mac Protocol ◽

Multiple Input Multiple Output ◽

Relay Node ◽

Base Stations ◽

Destination Node ◽

Distributed Coordination ◽

Hardware Complexity

Background & Objective: Wireless communication has immensely grown during the past few decades due to significant demand for mobile access. Although cost-effective as compared to their wired counterpart, maintaining good quality-of-service (QoS) in these networks has always remained a challenge. Multiple-input Multiple-output (MIMO) systems, which consists of multiple transmitter and receiver antennas, have been widely acknowledged for their QoS and transmit diversity. Though suited for cellular base stations, MIMO systems are not suited for small-sized wireless nodes due to their hardware complexity, cost, and increased power requirements. Cooperative communication that allows relays, i.e. mobile or fixed nodes in a communication network, to share their resources and forward other node’s data to the destination node has substituted the MIMO systems nowadays. To harness the full benefit of cooperative communication, appropriate relay node selection is very important. This paper presents an efficient single-hop distributed relay supporting medium access control (MAC) protocol (EDSRS) that works in the single-hop environment and improves the energy efficiency and the life of relay nodes without compensating the throughput of the network. Methods: The protocol has been simulated using NS2 simulator. The proposed protocol is compared with energy efficient cooperative MAC protocol (EECOMAC) and legacy distributed coordination function (DCF) on the basis of throughput, energy efficiency, transmission delay and an end to end delay with various payload sizes. Result and Conclusion: The result of the comparison indicates that the proposed protocol (EDSRS) outperforms the other two protocols.

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A spatial queuing model for the location decision of emergency medical vehicles for pandemic outbreaks: the case of Za'atari refugee camp

Journal of Humanitarian Logistics and Supply Chain Management ◽

10.1108/jhlscm-07-2020-0058 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Felix Blank

Keyword(s):

Queuing Theory ◽

Emergency Service ◽

Performance Metrics ◽

Service System ◽

Refugee Camps ◽

Location Decision ◽

Stress Tests ◽

Queuing Model ◽

Content Type ◽

Emergency Medical

PurposeRefugee camps can be severely struck by pandemics, like potential COVID-19 outbreaks, due to high population densities and often only base-level medical infrastructure. Fast responding medical systems can help to avoid spikes in infections and death rates as they allow the prompt isolation and treatment of patients. At the same time, the normal demand for emergency medical services has to be dealt with as well. The overall goal of this study is the design of an emergency service system that is appropriate for both types of demand.Design/methodology/approachA spatial hypercube queuing model (HQM) is developed that uses queuing-theory methods to determine locations for emergency medical vehicles (also called servers). Therefore, a general optimization approach is applied, and subsequently, virus outbreaks at various locations of the study areas are simulated to analyze and evaluate the solution proposed. The derived performance metrics offer insights into the behavior of the proposed emergency service system during pandemic outbreaks. The Za'atari refugee camp in Jordan is used as a case study.FindingsThe derived locations of the emergency medical system (EMS) can handle all non-virus-related emergency demands. If additional demand due to virus outbreaks is considered, the system becomes largely congested. The HQM shows that the actual congestion is highly dependent on the overall amount of outbreaks and the corresponding case numbers per outbreak. Multiple outbreaks are much harder to handle even if their cumulative average case number is lower than for one singular outbreak. Additional servers can mitigate the described effects and lead to enhanced resilience in the case of virus outbreaks and better values in all considered performance metrics.Research limitations/implicationsSome parameters that were assumed for simplification purposes as well as the overall model should be verified in future studies with the relevant designers of EMSs in refugee camps. Moreover, from a practitioners perspective, the application of the model requires, at least some, training and knowledge in the overall field of optimization and queuing theory.Practical implicationsThe model can be applied to different data sets, e.g. refugee camps or temporary shelters. The optimization model, as well as the subsequent simulation, can be used collectively or independently. It can support decision-makers in the general location decision as well as for the simulation of stress-tests, like virus outbreaks in the camp area.Originality/valueThe study addresses the research gap in an optimization-based design of emergency service systems for refugee camps. The queuing theory-based approach allows the calculation of precise (expected) performance metrics for both the optimization process and the subsequent analysis of the system. Applied to pandemic outbreaks, it allows for the simulation of the behavior of the system during stress-tests and adds a further tool for designing resilient emergency service systems.

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Analytical model of the LPL with wake up after transmissions MAC protocol for WSNs

10.1109/iswcs.2009.5285320 ◽

2009 ◽

Cited By ~ 4

Author(s):

Cristina Cano ◽

Boris Bellalta ◽

Jaume Barcelo ◽

Miquel Oliver ◽

Anna Sfairopoulou

Keyword(s):

Analytical Model ◽

Mac Protocol

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Location-Aided Uplink Transmission for User-Centric Cell-Free Massive MIMO Systems: A Fairness Priority Perspective

10.21203/rs.3.rs-1202385/v1 ◽

2022 ◽

Author(s):

Chen Wei ◽

Kui Xu ◽

Zhexian Shen ◽

Xiaochen Xia ◽

Wei Xie ◽

...

Keyword(s):

Large Scale ◽

Mean Squared Error ◽

Mimo Systems ◽

Multiple Input Multiple Output ◽

Access Point ◽

Estimation Accuracy ◽

Minimum Mean Squared Error ◽

Input Multiple Output ◽

User Centric ◽

Assignment Scheme

Abstract In this paper, we investigate the uplink transmission for user-centric cell-free massive multiple-input multiple-output (MIMO) systems. The largest-large-scale-fading-based access point (AP) selection method is adopted to achieve a user-centric operation. Under this user-centric framework, we propose a novel inter-cluster interference-based (IC-IB) pilot assignment scheme to alleviate pilot contamination. Considering the local characteristics of channel estimates and statistics, we propose a location-aided distributed uplink combining scheme based on a novel proposed metric representing inter-user interference to balance the relationship among the spectral efficiency (SE), user equipment (UE) fairness and complexity, in which the normalized local partial minimum mean-squared error (LP-MMSE) combining is adopted for some APs, while the normalized maximum ratio (MR) combining is adopted for the remaining APs. A new closed-form SE expression using the normalized MR combining is derived and a novel metric to indicate the UE fairness is also proposed. Moreover, the max-min fairness (MMF) power control algorithm is utilized to further ensure uniformly good service to the UEs. Simulation results demonstrate that the channel estimation accuracy of our proposed IC-IB pilot assignment scheme outperforms that of the conventional pilot assignment schemes. Furthermore, although the proposed location-aided uplink combining scheme is not always the best in terms of the per-UE SE, it can provide the more fairness among UEs and can achieve a good trade-off between the average SE and computational complexity.

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An Asynchronous Multi-Channel MAC Protocol Based on Cooperation Mechanism in Vehicular AdHoc Network

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.713-715.1294 ◽

2015 ◽

Vol 713-715 ◽

pp. 1294-1298

Author(s):

Xin Yun Li ◽

Lun Tang

Keyword(s):

Network Reliability ◽

Mac Protocol ◽

High Mobility ◽

Collision Probability ◽

Delivery Ratio ◽

Adhoc Network ◽

Cooperation Mechanism ◽

Hidden Terminals ◽

Hidden Terminal ◽

Channel Environment

To solve the problem of vehicle adhoc network reliability is not high and multi-channel hidden terminals, we propose a multi-channel MAC protocol CAMP(cooperation-based asynchronous multi-channel MAC protocol) based mechanism for asynchronous cooperation in VANET. CAMP add to cooperation mechanisms in asynchronous multi-channel environment, the proposed scheme nodes cooperation in order to obtain the channel state information and status information to other nodes, thus a good solution to the hidden terminal problem multichannel transmission process, to achieve high mobility environment under the reliable transmission of data. The simulation results show that CAMP has better performance than IEEE 1609.4 standard, AMCP protocol, AMCMAC protocol on collision probability of SCH, safety messages delivery ratio.

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