scholarly journals Performance Analysis of the IEEE 802.11ax MAC Protocol for Heterogeneous Wi-Fi Networks in Non-Saturated Conditions

Sensors ◽  
2019 ◽  
Vol 19 (7) ◽  
pp. 1540 ◽  
Author(s):  
Kyu-haeng Lee
Keyword(s):  
Performance Analysis ◽  
Multiple Access ◽  
Network Performance ◽  
Mac Protocol ◽  
Analytical Framework ◽  
Frequency Division ◽  
Delay Performance ◽  
Traffic Conditions ◽  
Ieee 802.11Ax ◽  
Proposed Model

The IEEE 802.11ax standard, which realizes multi-user transmission based on orthogonal frequency division multiple access (OFDMA), has been highlighted as a key technology to meet high future demand for Wi-Fi systems. Since this standard is still being developed, performance analysis through mathematical modeling is of paramount importance; however, existing studies have several limitations. Firstly, most of these consider only the saturation network throughput, whereas for 802.11ax in particular, the access delay of the nodes needs to be studied carefully, since they no longer acquire the medium independently but depend solely on the access point’s (AP’s) schedule. Secondly, since the network performance may be affected to a greater extent by legacy nodes than by 802.11ax nodes, it is desirable to consider various heterogeneous cases of networks with existing legacy nodes. In this paper, a new analytical framework for the 802.11ax MAC protocol is provided. Markov-chain-based models are developed to represent the behavior of the 802.11ax nodes, and both non-saturated traffic conditions and co-existence with the legacy nodes are considered. Through both analysis and MATLAB simulations, it is shown that the proposed model accurately evaluates the throughput and the delay performance under various network conditions.

scholarly journals Implementing a Flexible Testbed Using Dynamic FFR Scheme in OFDMA Based Cognitive Radio Networks

2021 ◽  
Author(s):  
Joydev Ghosh
Keyword(s):  
Cognitive Radio ◽  
Multiple Access ◽  
Network Performance ◽  
Carrier Frequency Offset ◽  
Analytical Framework ◽  
Radio Networks ◽  
Superior Performance ◽  
Frequency Division ◽  
Performance Parameters ◽  
Frequency Reuse Factor

<div>In this paper, the femtocell resource allocation in the Orthogonal Frequency Division Multiple Access (OFDMA) integrated cognitive radio (CR) networks has been demonstrated to optimize the network performance, while reducing the outage users at cell edges. The sub-band sharing flexibility not only improves the spectral efficiency of the dynamic FFR scheme against conventional approach but also it alleviates outage probability and further noticeable amount of improvement can be found in superior performance parameters such as capacity, CDF of SINR and overall cell throughput. We yield an analytical framework to ascertain the orthogonality of the subcarriers by compensating carrier frequency offset (CFO) to ensure better OFDMA performance in the proposed network model and illustrates the influence of frequency reuse factor (FRF) at cell edges via simulation results. </div>

scholarly journals Implementing a Flexible Testbed Using Dynamic FFR Scheme in OFDMA Based Cognitive Radio Networks

2021 ◽  
Author(s):  
Joydev Ghosh
Keyword(s):  
Cognitive Radio ◽  
Multiple Access ◽  
Network Performance ◽  
Carrier Frequency Offset ◽  
Analytical Framework ◽  
Radio Networks ◽  
Superior Performance ◽  
Frequency Division ◽  
Performance Parameters ◽  
Frequency Reuse Factor

<div>In this paper, the femtocell resource allocation in the Orthogonal Frequency Division Multiple Access (OFDMA) integrated cognitive radio (CR) networks has been demonstrated to optimize the network performance, while reducing the outage users at cell edges. The sub-band sharing flexibility not only improves the spectral efficiency of the dynamic FFR scheme against conventional approach but also it alleviates outage probability and further noticeable amount of improvement can be found in superior performance parameters such as capacity, CDF of SINR and overall cell throughput. We yield an analytical framework to ascertain the orthogonality of the subcarriers by compensating carrier frequency offset (CFO) to ensure better OFDMA performance in the proposed network model and illustrates the influence of frequency reuse factor (FRF) at cell edges via simulation results. </div>

scholarly journals Time Slot Utilization for Efficient Multi-Channel MAC Protocol in VANETs

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 3028 ◽  
Author(s):  
VanDung Nguyen ◽  
Tran Anh Khoa ◽  
Thant Zin Oo ◽  
Nguyen H. Tran ◽  
Choong Seon Hong ◽  
...  
Keyword(s):  
Multiple Access ◽  
Vehicular Ad Hoc Networks ◽  
Ad Hoc ◽  
Mac Protocol ◽  
Media Access Control ◽  
Delivery Ratio ◽  
Media Access ◽  
Traffic Conditions ◽  
Hoc Networks ◽  
Transmission Overhead

In vehicular ad hoc networks (VANETs), many schemes for a multi-channel media access control (MAC) protocol have been proposed to adapt to dynamically changing vehicle traffic conditions and deliver both safety and non-safety packets. One such scheme is to employ both time-division multiple access (TDMA) and carrier-sense multiple access (CSMA) schemes (called a hybrid TDMA/CSMA scheme) in the control channel (CCH) interval. The scheme can adjust the length of the TDMA period depending on traffic conditions. In this paper, we propose a modified packet transmitted in the TDMA period to reduce transmission overhead under a hybrid TDMA/CSMA multi-channel MAC protocol. Simulation results show that a MAC protocol with a modified packet supports an efficient packet delivery ratio of control packets in the CCH. In addition, we analyze the hybrid TDMA/CSMA multi-channel MAC protocol with the modified packet under saturated throughput conditions on the service channels (SCHs). The analysis results show that the number of neighbors has little effect on the establishment of the number of time slots in TDMA periods and on SCHs under saturated throughput conditions.

A PERFORMANCE MODEL OF DISHA ROUTING IN K-ARY N-CUBE NETWORKS

2007 ◽  
Vol 17 (02) ◽  
pp. 213-228 ◽  
Author(s):  
A. KHONSARI ◽  
A. SHAHRABI ◽  
M. OULD-KHAOUA
Keyword(s):  
Network Performance ◽  
Routing Algorithm ◽  
Adaptive Routing ◽  
Routing Algorithms ◽  
Performance Model ◽  
Analytical Models ◽  
Traffic Conditions ◽  
Proposed Model ◽  
Fully Adaptive ◽  
Wormhole Routed

A number of analytical models for predicting message latency in k-ary n-cubes have recently been reported in the literature. Most of these models, however, have been discussed for adaptive routing algorithms based on deadlock avoidance, e.g. Duato's routing. Several research studies have empirically demonstrated that routing algorithms based on deadlock recovery offer maximal adaptivity that can result in considerable improvement in network performance. Disha is an example of a true fully adaptive routing algorithm that uses minimal hardware to implement a simple and efficient progressive method to recover from potential deadlocks. This paper proposes a new analytical model of Disha in wormhole-routed k-ary n-cubes. Simulation experiments confirm that the proposed model exhibits a good degree of accuracy for various networks sizes and under different traffic conditions.

A Queuing Model for IEEE 802.11 DCF Performance Analysis

2013 ◽  
Vol 380-384 ◽  
pp. 1202-1209
Author(s):  
Xuan Chen ◽  
Yu Bin Xu ◽  
Lin Ma
Keyword(s):  
Ieee 802.11 ◽  
Network Performance ◽  
Distributed Coordination ◽  
Queuing Model ◽  
Traffic Conditions ◽  
Ieee 802.11 Dcf ◽  
802.11 Dcf ◽  
Proposed Model ◽  
Distributed Coordination Function ◽  
Coordination Function

A queuing model is proposed to analyze the performance of IEEE 802.11 Distributed Coordination Function (DCF). By regarding the network performance in the unsaturated case as the expected mean of the network performance in the different saturated cases, the proposed model extends the application scenarios from the saturated case to the nonsaturated case. The queuing model can be used to analyze the network performance and QoS parameters of the stations for different traffic conditions. In addition, this model also applies to the cases in shadow channels. Compared to the existing work based on the classic Markov model, the proposed model is more general and can be used in more complex and practical scenarios.

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