Carrier Sense Multiple Access With Collision Avoidance Research Articles

Learning-Based Autonomous Channel Access in the Presence of Hidden Terminals

We consider the problem of autonomous channel access (AutoCA), where a group of terminals tries to discover a communication strategy with an access point (AP) via a common wireless channel in a distributed fashion. Due to the irregular topology and the limited communication range of terminals, a practical challenge for AutoCA is the hidden terminal problem, which is notorious in wireless networks for deteriorating throughput and delay performances. To meet the challenge, this paper presents a new multi-agent deep reinforcement learning paradigm, dubbed MADRL-HT, tailored for AutoCA in the presence of hidden terminals. MADRL-HT exploits topological insights and transforms the observation space of each terminal into a scalable form independent of the number of terminals. To compensate for the partial observability, we put forth a look-back mechanism such that the terminals can infer behaviors of their hidden terminals from the carrier-sensed channel states as well as feedback from the AP. A window-based global reward function is proposed, whereby the terminals are instructed to maximize the system throughput while balancing the terminals' transmission opportunities over the course of learning. Considering short-packet machine-type communications, extensive numerical experiments verified the superior performance of our solution benchmarked against the legacy carrier-sense multiple access with collision avoidance (CSMA/CA) protocol.

A Torpor-based Enhanced Security Model for CSMA/CA Protocol in Wireless Networks

Mobile wireless networks enable the connection of devices to a network with minimal or no infrastructure. This comes with the advantages of ease and cost-effectiveness, thus largely popularizing the network. Notwithstanding these merits, the open physical media, infrastructural-less attributes, and pervasive deployment of wireless networks make the channel of communication (media access) vulnerable to attacks such as traffic analysis, monitoring, and jamming. This study designed a virtual local area network (VLAN) model to circumvent virtual jamming attacks and other intrusions at the Media Access Control (MAC) layer of the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol. A Torpor VLAN (TVLAN) Data Frame Encapsulation and the algorithm for T-VLAN security in CSMA/CA were formulated and presented. A simulation experiment was conducted on the model using OMNeT++ software. The performance metrics used to evaluate the model were packet delivery ratio, network throughput, end-to-end channel delay, and channel load. The simulation results show that the TVLAN defence mechanism did not increase the channel load arbitrarily during TVLAN defence. similarly, the system throughput was shown to be 82% during TVLAN defence. Nevertheless, the network delay of the system during TVLAN defence was significantly high but the channel load was 297 when the TVLAN security mechanism was launched. These results demonstrate the model’s ability to provide a survivability mechanism for critical systems when under attack and add a security layer to the CSMA/CA protocol in wireless networks. Such a remarkable performance is required of a CSMA/CA infrastructure for improving the cybersecurity posture of a wireless network.

Effects Investigation of MAC and PHY Layer Parameters on the Performance of IEEE 802.15.6 CSMA/CA

The recently released IEEE 802.15.6 standard specifies several physical (PHY) layer and medium access control (MAC) layer protocols for variety of medical and non-medical applications of Wireless Body Area Networks (WBAN). The most suitable way for enhancing network performance is to be the choice of different MAC and PHY parameters based on quality of service (QoS) requirements of different applications. The impact of different MAC and PHY parameters on the network performance and the tradeoff relationship between the parameters are essential to overcome the limitations of exiting carrier sense multiple access with collision avoidance (CSMA/CA) scheme of IEEE 802.15.6 standard. To address this issue, we develop a Markov chain-based analytical model of IEEE 802.15.6 CSMA/CA for all user priorities (UPs) and apply this general model to different network scenarios to investigate the effects of the packet arrival rate, channel condition, payload size, access phase length, access mechanism and number of nodes on the performance parameters viz. reliability, normalized throughput, energy consumption and average access delay. Moreover, we conclude the effectiveness of different access phases, access mechanisms and user priorities of intra-WBAN.

Dynamic adaptation of contention window boundaries using deep Q networks in UAV swarms

In flying ad hoc networks (FANET), medium access layer (MAC) protocols play an essential role in ensuring better network performance. The effective utilization of network resources and providing access fairness are key research issues in this area, and the contention window size directly influences these factors. This paper mainly focuses on addressing the upper and lower boundaries of the contention window in Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) with a binary exponential back-off algorithm. Existing solutions include static and dynamic window adjustment techniques only to update the upper boundary of the contention window size. However, the static window adjustment technique is unsuitable for changing network conditions, while the dynamic window adjustment technique may need to be more efficient in dense network environments. The proposed solution uses a Deep Q-learning algorithm(DQN) framework to adjust the contention window adaptively based on the reward function, resulting in efficient and dynamic adaptation to changing network conditions among unmanned aerial vehicles (UAV). The proposed methodology is evaluated through simulations, and performance is measured using channel utilization, efficiency, delay, and collision rate. The simulation findings show that, in comparison to generic MAC protocols, the proposed algorithm is 5% more efficient in throughput and incurs a four-fold reduction in delay.

Analysis of the Efficiency of Various Receipting Multiple Access Methods with Acknowledgement in IoT Networks

An Internet of things (IoT) network is a distributed set of “smart” sensors, interconnected via a radio channel. The basic method of accessing the radio channels for these networks is Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA), in which access is carried out on the basis of contention, and confirmation of the correct reception of the packet is achieved using a receipt. If the sizes of information packets are small and comparable to the sizes of receipts, then the transmission of receipts requires a significant bandwidth of the channel, which reduces the efficiency of the network. This problem exists not only for IoT networks but also for monitoring systems, operational management of fast processes, telemetry, short messaging and many other applications. Therefore, an urgent task is to develop effective methods of multiple random access in the transmission of short information packets, the size of which is comparable to the size of receipts. To solve this problem, the authors proposed modifications of CSMA/CA random access in which, when packet collisions are detected, a diagnostic message (DM) is generated and transmitted in the broadcast mode. Based on simulation modeling, it is shown that in a wide range of network loads, the proposed random access options provide an increase in network capacity (the number of connected subscribers) of 1.5–2 times compared to the basic CSMA/CA access method when the size of the information packet is an order of magnitude larger than the size of receipts. The variant of access without acknowledgment is also considered, in which, as shown by the simulation results, at sufficiently large loads, the network can go into an unstable state.

Distributed Batteryless Access Control for Data and Energy Integrated Networks: Modeling and Performance Analysis

Radio-frequency (RF) signals are capable of simultaneously transferring data and energy from a hybrid access point (HAP) toward battery-powered and batteryless wireless devices. Battery-powered and batteryless wireless devices with the capability of RF energy harvesting need a distributed access control protocol with collision avoidance to achieve higher energy efficiency. We study the performance of a data and energy integrated network (DEIN) that adopts an enhanced carrier sensing multiple access with collision avoidance (CSMA/CA) protocol. Each device in this network can switch to RF energy harvesting mode or data reception mode according to HAP’s instruction, and freezes its backoff counter when energy storage is insufficient. By invoking a three-dimensional (3D) Markov chain, we model the operating behaviors of batteryless wireless devices and an HAP in a DEIN. Apart from backoff operations of devices, the 3D Markov chain also depicts their dynamic energy changes, including RF energy harvesting and energy consumption. Wireless devices consume energy harvested from the HAP’s downlink transmissions for powering their data upload and random backoff. With the aid of the 3D Markov chain, the upload throughput of devices can be obtained in semi-closed-form. Moreover, a decoupling method is proposed to approximate throughput performance with low complexity. The accuracy of our theoretical model is validated by simulation results. By characterizing the impact of various parameters on throughput performance, a design guideline for a DEIN with a distributed batteryless access protocol is provided.

Use of Logarithmic Rates in Multi-Armed Bandit-Based Transmission Rate Control Embracing Frame Aggregations in Wireless Networks

Herein, we propose the use of the logarithmic values of data transmission rates for multi-armed bandit (MAB) algorithms that adjust the modulation and coding scheme (MCS) levels of data packets in carrier-sensing multiple access/collision avoidance (CSMA/CA) wireless networks. We argue that the utilities of the data transmission rates of the MCS levels may not be proportional to their nominal values and suggest using their logarithmic values instead of directly using their data transmission rates when MAB algorithms compute the expected throughputs of the MCS levels. To demonstrate the effectiveness of the proposal, we introduce two MAB algorithms that adopt the logarithmic rates of the transmission rates. The proposed MAB algorithms also support frame aggregations available in wireless network standards that aim for a high throughput. In addition, the proposed MAB algorithms use a sliding window over time to adapt to rapidly changing wireless channel environments. To evaluate the performance of the proposed MAB algorithms, we used the event-driven network simulator, ns-3. We evaluated their performance using various scenarios of stationary and non-stationary wireless network environments including multiple spatial streams and frame aggregations. The experiment results show that the proposed MAB algorithms outperform the MAB algorithms that do not adopt the logarithmic transmission rates in both the stationary and non-stationary scenarios.

A score based link delay aware routing protocol to improve energy optimization in wireless sensor network

The Wireless Sensor Network (WSN) is the most appearing expertise that has potential applications broad ranges that include environment examining, smart spaces, medical systems, and robotic study. Energy efficiency is a consideration of vital design for WSN. The collision is occurred owing to the transmission of data from the sensor nodes and the traffic at the SINK node is high because of the excess data transmission by the sensor nodes. An essential division of the consumption of resources in a WSN is managed by the mechanism of Medium Access Control (MAC). An existing MAC protocols initiated for the utilization of WSNs single channel for data transmission. The deployment of wireless sensor nodes is concerned in the harsh environment in which the drastic change of conditions suffers from sudden changes in the status of a node and the quality of a link. With limited energy, the sensor nodes are supplied and a major concern is towards improving the lifetime of a network. To deal with these issues, a novel and simple routing mechanism Score based Link Delay Aware Routing (SBLDAR) is proposed, which utilizes the multi-channel MAC procedure comprises of Carrier Sense Multiple Access/ Collision Avoidance (CSMA/CA), to exchange the data, the activity of Time Division Multiple Access (TDMA) sequencing nodes and also Frequency Division Multiple Access FDMA) to allow collision-free exchange simultaneously. Also, in order to overcome this issue, an approach has been put out in this work that involves leveraging a variety of trust variables to identify malicious nodes and then using fuzzy based Modified Sun Flower Optimization (FMSFO) algorithm to elect an effective cluster head. The score based route selection increases the network lifetime and improves network performance. By comparing with the other protocols, the proposed SBLDAR combined with the technique of multi-MAC protocol has shown that it increases the network’s overall performance based on the simulation studies.

Timeliness of wireless sensor networks with random multiple access

In this paper, we consider a wireless sensor network in which N sensor nodes deliver the observed information of interest to a remote receiver by competing for a sharing channel through the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol or the slotted ALOHA protocol. For this network, we evaluate the information freshness of the two random multiple access protocols using the age of information (AoI) metric. In order to explicitly express the average AoI of the CSMA/CA based network, we establish an equivalent and tractable transmission model for the network, in which the transmission probabilities and the collision probabilities are assumed to be identical over time and among sensor nodes. For the slotted ALOHA based network, we derive the average AoI by focusing on a randomly chosen reference node. Our theoretical results show that 1) the transmission probability and collision probability of the two networks increase with both the arrival rate and the number of sensor nodes; 2) with the same transmission probability, the average AoI of the CSMA/CA based network is always smaller than that of the slotted ALOHA based network, no matter how the arrival rate and the number of nodes change. Our Monte Carlo simulation results also validate the correctness of our theoretical calculations.

CSMA Protocol performance with dynamic spreading factor in LPWAN networks with LoRa RF transceivers

Long Range (LoRa) is a spread spectrum modulation technology designed for Low-Power Wide-Area Networking (LPWAN) with a growing application in Internet of Things (IoT), which plays an important role in the global digitalization process. The expansion of LORAWAN networks demands careful circuit, system and network design to improve energy efficiency and quality of service. To support this task, advanced CAD tools can offer reliable network simulations results, where the effects of building blocks can be found. LoRaSim, one of the most popular simulators available for LoRa and LoraWan, had solely implemented an ALOHA access model protocol, which is not the most common protocol in real life scenarios. To mitigate this limitation and taking advantage of the open-source nature of both LoRaWAN and LoRaSim, it is proposed a Carrier Sense Multiple Access/ Collision Avoidance (CSMA/CA) protocol extension, as well as active adaptive parameters selection to cope with collisions. To demonstrate the effectiveness of these additions to the base solution, a comparison between both on different scenarios and their simulated performance key indicators will be presented.

Graph-based conflict-free MAC protocol and conflict analysis for a two-layer ultraviolet communication network

To efficiently exploit the space division multiplexing of ultraviolet (UV) communication, we apply link coverage characteristics to construct a conflict graph and design conflict-free protocols for a two-layer UV communication network. The network is divided into two layers: the first-layer network forms a backbone and the second-layer network serves as local access. We construct a routing model and medium-access control (MAC) model. Then we propose Routing-MAC joint scheduling for the first-layer network based on the conflict graph. We investigate the system throughput and delay of joint scheduling under different node intensities. For second-layer networks, we propose a multi-link conflict-free protocol adopting protocol frames of carrier sense multiple access with collision avoidance (CSMA/CA). Numerical results show that the multi-link conflict-free protocol can improve the system throughput by more than 100% compared with CSMA/CA. Moreover, we perform a conflict analysis on the proposed protocols to investigate the influence of conflict intensity. According to the conflict analysis, we optimize the path planning of Routing-MAC joint scheduling to reduce the average delay of the network. Numerical results show that the optimized Routing-MAC joint scheduling leads to larger system throughput and lower delay.

Sensors Scheduling for Remote State Estimation Over an Unslotted CSMA/CA Channel

This article investigates the sensor selection problem for remote state estimation. A set of sensors measures a process's state and sends the measurements to a remote estimator over an unslotted carrier sense multiple access/collision avoidance (CSMA/CA) channel in IEEE 802.15.4-based wireless body area networks. This article aims to answer which sensors should be selected according to probability so that the state estimation error covariance and the energy consumption of sensors can be optimized. A common assumption in most existing methods about sensor scheduling is that the packet loss process is unrelated to the channel input. This article analyzes the relationship between channel input and packet loss rate by modeling the communication process. A scheduling scheme is proposed to increase channel utilization from the perspective of sensor information fusion. Then the constraint on the performance metrics is presented. By transforming the sensor selection problem into a constrained optimization problem, the solution to the optimization problem is obtained by a numerical algorithm. Finally, the validity of the model and the feasibility of the sensor scheduling are demonstrated by a numerical simulation.

A novel ultraviolet communication channel access protocol based on competition mechanism

Media Access Control (MAC) protocol in the Ultraviolet (UV) communication plays an important role in mobile Ad-hoc networks. However, the throughput of the existing UV MAC competitive protocol will decline with a large number of nodes. In this paper, a novel UVCA channel access protocol (UV Conflict Avoidance protocol) is proposed based on the principle of ultraviolet power superposition. The UVCA protocol can reduce the conflict loss of multi-node competing access by a special control frame. Using MATLAB, throughput and delay performance of the UVCA protocol are simulated and analyzed under the difference of nodes number, transmission probability and frame length. Compared with Carrier Sense Multiple access with Collision Avoidance (CSMA/CA) protocol, the UVCA protocol has some features of simple implementation, low protocol complexity, higher channel utilization and strong anti-collision ability. When the number of nodes change from 2 to 20, the maximum throughput of UVCA protocol is 1.02–1.27 times than that of CSMA/CA, it indicates the new UVCA protocol can meet to the requirements of the multi-node UV-ad hoc network communication.

Starvation mitigation and priority aware of CSMA/CA in WSN with implementing Markov chain model

In the domain of wireless networking, the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) has a wide range of applications. Based on CSMA/CA, the IEEE 802.15.6 MAC protocol is used for the body network area. For reduction of the collision’s probability, the accessing the medium, the CSMA/CA uses a distributed coordination function. For a node to transmit the data in CSMA/CA, the channel is sensed and then the transmission is initiated if it happens to be idle. For a contention period, the node is deferred for transmission, if the channel happens to be busy. When the multiple nodes attempt to access a channel, their issue of contention will be solved by this mechanism. As a side effect, there is starvation of the decaying nodes, and the data latency is noticeably increased. For a delay-sensitive application, CSMA/CA protocol becomes inapplicable as the higher risk of fatality is associated with the delay critical applications, such as vehicle cohesion avoidance system and the health-care system.In the modeling process, the channel load is not taken into account at first. For high-priority services, channel detection is performed once. For low priority services, channel detection is performed twice. Markov chain model is used to analyze the influence of algorithm parameter setting on network performance, and it shows great efficiency. Accidents may become inevitable with the exponential latency in the receiving of an emergency notification. Hence, for backing up the loopholes of IEEE 802.15.6 MAC protocol and uprising the response rate of the emergency and warning cases, the author substitutes back off the procedure by proposing a solution that considers the level of emergency or the priority of the message with the help of associated contention window and level of emergency. This reduces the chances of starvation as well. The techniques for CSMA/CA that are priority aware, surely outperform the state of the art back off and this is proved by simulation that the model has enhanced the efficiency of the channel in regards to throughput, delays in transmission, utilization of the bandwidth.

A CSMA/CA based MAC protocol for hybrid Power-line/Visible-light communication networks: Design and analysis

Hybrid Power-line/Visible-light Communication (HPVC) network has been one of the most promising Cooperative Communication (CC) technologies for constructing Smart Home due to its superior communication reliability and hardware efficiency. Current research on HPVC networks focuses on the performance analysis and optimization of the Physical (PHY) layer, where the Power Line Communication (PLC) component only serves as the backbone to provide power to light Emitting Diode (LED) devices. So designing a Media Access Control（MAC) protocol remains a great challenge because it allows both PLC and Visible Light Communication (VLC) components to operate data transmission, i.e., to achieve a true HPVC network CC. To solve this problem, we propose a new HPC network MAC protocol (HPVC MAC) based on Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) by combining IEEE 802.15.7 and IEEE 1901 standards. Firstly, we add an Additional Assistance (AA) layer to provide the channel selection strategies for sensor stations, so that they can complete data transmission on the selected channel via the specified CSMA/CA mechanism, respectively. Based on this, we give a detailed working principle of the HPVC MAC, followed by the construction of a joint analytical model for mathematical-mathematical validation of the HPVC MAC. In the modeling process, the impacts of PHY layer settings (including channel fading types and additive noise feature), CSMA/CA mechanisms of 802.15.7 and 1901, and practical configurations (such as traffic rate, transit buffer size) are comprehensively taken into consideration. Moreover, we prove the proposed analytical model has the solvability. Finally, through extensive simulations, we characterize the HPVC MAC performance under different system parameters and verify the correctness of the corresponding analytical model with an average error rate of 4.62% between the simulation and analytical results.

A Grouping Algorithm for Random Access Networks and Supermartingale Evaluation

Wireless communications play a critical role in the applications of Internet of Things (IoT). The Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) is a well-proven wireless random access protocol. A crucial factor affecting the performance of random access networks is “hidden node collision,” which incurs performance degradation and lower resource utilization. Grouping is an efficient strategy for hidden node avoidance. In current IoT networks, the terminals usually have different traffic load, so load balance should be considered when grouping algorithm is designed. To mitigate hidden nodes and achieve load balance simultaneously, we propose a grouping algorithm based on the game theory. By introducing the supermartingale theory, the delay performance of the completed groups is analyzed. Simulations prove that the proposed algorithm alleviates collision, balances traffic, and promotes the efficient guarantee for Quality of Service (QoS).

F-802.11P: A Fuzzy Enhancement for IEEE 802.11P in Vehicle-to-Everything Communications

Vehicle-to-Everything communications (V2X) are becoming increasingly popular as a solution for safer roads and better traffic management. One of the essential protocols in V2X is the Dedicated Short Range Communication (DSRC) protocol suite. DSRC includes the IEEE 802.11p protocol that operates at the medium access control (MAC) and physical (PHY) layers. Upon collision, the IEEE 802.11p MAC layer applies a carrier sense multiple access/collision avoidance (CSMA/CA) mechanism that randomly selects a backoff time to re-check the channel activity and then retransmit. However, the random selection of the backoff time may lead to further packet collisions that decrease the utilization of the communication channel, which suffers from a limited bandwidth in the first place. This paper proposes a fuzzy model based on rational decision-making, which we call F-802.11p, to improve the IEEE 802.11p protocol backoff time selection by limiting the IEEE 802.11p beacon messages to better use of the available bandwidth. A simulation study presents the evaluation of our work compared to IEEE 802.11p. We deployed the simulation software in two scenarios: the Veins Framework map and the map of New Administrative Cairo in Egypt. We base our comparison on slots backoff, times into backoff, PHY busy time, MAC busy time, total lost packets, and generated/received beacon messages. Simulation results show that both protocols have comparable results in slots backoff, times into back off, and the generated beacon messages. At the same time, our F-802.11p significantly outperforms the IEEE 802.11p in PHY busy time, MAC busy time, total lost packets, and the received beacon messages in both scenarios.

Parallel Access Scheme for Wireless and Power Line Dual-Connection Communication

Hybrid communication of power line and wireless can improve the performance without dedicated communication lines and meet the requirements of in-vehicle communication. Aiming at the medium access control (MAC) design of dual-connection architecture, we propose a parallel access scheme for power line and wireless hybrid communication suitable for parallel diversity transmission, and establish transmission and collision probability equations on the basis that the two channel conditions are consistent. Further, the influences of the carrier sense multiple access with collision avoidance (CSMA/CA) and time division multiple access (TDMA) on the performance of the parallel access scheme are analyzed. Based on numerical results, it is shown that the proposed scheme can significantly improve the performance of throughput and delay when compared to power line and wireless network alone.

Implementation of CSMA/CA and ALOHA random-access protocols for packetizing wireless networks with model-based design

Because of the reliability of deployment, cost efficiency, and flexibility of ad-hoc wireless local networks (WLAN). These wireless networks have grown to be the everywhere connection solution in residential and public access networking protocols. It is important to know which strategy performs better with the least amount of delay. The Multiple Access Control protocols (MAC) that are relied on ALOHA, and Carrier Sense Multiple Access with collision avoidance (CSMA/CA) as random access techniques, have substantially aided the rapid growth of such wireless access networks. This work provides a model-based design approach for modeling CSMA/CA and ALOHA random-access protocols for packetizing wireless networks. We analyze the TX and Back-off waveforms of the PHY/MAC transceiver of three radio nodes under CSMA/CA and ALOHA operation modes and compare the obtained results of the PHY/MAC Transceiver for the network nodes according to these modes. Every node is within a range such that the communication between each couple of nodes can be interfered with and received data from the third node. The MAC layer and the logical link control function composed the data link layer. Since the same radio band is used for TX and RX, the MAC function employed here is CSMA/CA and ALOHA, which had also called a random back-off. The MAC layer sends a control signal to the TX block to transmit either a data frame or an acknowledgment frame. The frame contents are loaded in the look-up tables. The contents can be changed in the workspace. The output of this block is a complex baseband IQ signal. The obtained results show the effectiveness of CSMA/CA over ALOHA modes when comparing the corresponding Back-off waveforms and when calculating the throughput values of the three network nodes

Collision-Based Window-Scaled Back-Off Mechanism for Dense Channel Resource Allocation in Future Wi-Fi

Wireless local area networks (WLANs), known as Wi-Fi, are widely deployed to meet the enhanced needs of data-centric internet applications, such as wireless docking, unified communications, cloud computing, interactive multimedia gaming, progressive streaming, support of wearable devices, up-link broadcasts and cellular offloading. Wi-Fi networks typically adopt the Distributed Coordination Function (DCF)-based Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA), which uses the Binary Exponential Back-off (BEB) algorithm at the MAC layer mechanism to access channel resources. Currently deployed Wi-Fi networks face huge challenges towards efficient channel access for denser environments due to the blind exponential increase/decrease of a contention window (CW) procedure that is inefficient for a higher number of contending stations. Several modifications and amendments have been proposed to improve the performance of the MAC layer channel access based on a fixed or variable CW size. However, a more realistic network density-based channel resource allocation solution is still missing. An efficient channel resource allocation is one of the most critical challenges for future highly dense WLANs, such as High-Efficiency WLAN (HEW). In this paper, we propose a Channel Collision-based Window Scaled Back-off (CWSB) mechanism for channel resource allocation in HEW. In our proposed CWSB, all contending stations select an optimized CW size for each back-off stage for collided or successfully transmitted data frames. We affirm the performance of the proposed CWSB mechanism with the help of an Iterative Discrete Time Markov Chain (I-DTMC) model. This paper evaluates the performance of our proposed CWSB mechanism in HEW Wi-Fi networks using an NS3 simulator in terms of the normalized throughput and channel access delay compared to the state-of-the-art BEB and a recently proposed mechanism.