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Summary: The rapid growth in wireless communication technology and the proliferation of multimedia applications, specifically Voice over Wireless Fidelity (VoWiFi), necessitate the exploration of innovative techniques for improving network performance and quality‐of‐service (QoS). This research paper presents an innovative approach to enhance VoWiFi cell capacity using aggregate medium access control protocol data unit (A‐MPDU) frame aggregation for variable bit rate (VBR) traffic. In this research article, we investigated the effect that the retransmission of voice packets has on the cell capacity of a wireless local area network (WLAN) standard that provides VoWiFi service while taking into account the A‐MPDU approach. When taking into consideration the constant bit rate (CBR) and VBR traffics, we compared the results obtained using WiFi 6 (i.e., IEEE 802.11ax) with older WLAN standards such as IEEE 802.11b/g/n/ac. [ABSTRACT FROM AUTHOR]

This work is to have a look at the successfulness of the PFMIPv6 protocol. EPMIPv6-AS over IEEE 802.11ax CMake delivers standard overall performance for advanced features like 4K or 8K films, increased capacity, high community apps, all wireless locations, and the Internet of Things (IoT) using Network Simulator (NS) version 3.36. The proxy mobile IPv6 for advanced sensor networks phase of the next-generation web protocol (EPMIPv6- AS) is an extension of the PFMIPv6 movability management. It permits nearby mobilitybased routing of IP datagrams to IPv6 hosts except station participation in the IP address signaling. A mobile node avoids the signaling expense and response times associated with modify IP addresses by maintaining its IP address while switching across links. Local mobility is still required, but IPv6 also adds additional specifications like Mobile Node, Advanced Sensor Mobile Access Gateway (ASMAG), and Advanced Sensor Local Mobility Anchor (ASLMA). While moving between serving networks during handover, the mobile station's IP remains consistent, hence location privacy may not be guaranteed. This paper carried out analytical comparison studies for the PFMIPv6 and EPMIPv6-AS mobile protocols. In order to compare costs, we raised the binding update cost value and packet delivery cost value. Wi-Fi 6 consumers in dense locations are available upgrades; it improves as high-efficient Wi-Fi. [ABSTRACT FROM AUTHOR]

The integration of virtual and augmented reality technologies in fields as diverse as medicine, engineering, education and marketing has enabled the establishment of new forms of learning, which necessarily require efficient connectivity. This article therefore analyses the fundamental role of Wi-Fi 6 (IEEE 802.11ax) in the improvement of immersive experiences, considering aspects such as its superior speed, capacity and efficiency, which respond to the growing demands of this type of applications. This research presents a bibliographic-descriptive study, for which a systematic review has been carried out on the impact of Wi-Fi 6 on virtual and augmented reality, defining variables and inclusion-exclusion criteria in databases such as: SCOPUS, Web of Science, IEEE Explore, Google Scholar, among others. There is no doubt that, in the medical area (surgical and dental), virtual and augmented reality have proven their efficiency in the training of students and professionals, which has improved clinical outcomes and user satisfaction, in relation to the above, Wi-Fi 6 amplifies these advantages by ensuring wireless connectivity with higher data rates and lower latency. As virtual and augmented reality applications evolve and position themselves in various industries, technologies such as Wi-Fi 6 are also required to establish a wireless network infrastructure with increased capacity, better performance in congested environments, faster data rates, reduced latency and energy efficiency.

Wireless network technology systems and application appear as a constantly developing network technology. Enterprise network infrastructures, where the number of users are intense and data transfer processes continue, needed new generation wireless network infrastructures with the developing technology. The latest generation wireless network technology, 802.11ax (Wi-Fi 6) will be the most important part of enterprise wireless network systems in the coming years. It is observed that the importance of speed, performance and security issues in wireless network areas is increasing as 802.11ax (Wi-Fi 6) and 5G technology are becoming widespread compared to being a new infrastructure. With the emergence of new technological network devices and end-user products, IEEE 802.11ax technology allows users to transfer data without loss of performance on their wireless connections with the more secure password encryption level WPA-3 and file transfer. 802.11ax (Wi-Fi 6) OFDMA, 1024-QAM, MU-MIMO support that allows users to stay in touch without losing performance on their wireless connections in file transfer. It reaches data rate reaching 10Gbps bandwidth. The fact that it works in this field to solve energy and security problems in IoT devices strengthens the adaptation to 802.11ax technology. In this study, while examining the IEEE 802.11ax standard technology, we will compare the old generation 802.11a, b, g, n, ac wireless network technologies and evaluate the future advantages of 802.11ax technology with an application on a live and working real world system. As a result of the evaluation, it has been understood that the IEEE 802.11ax standard technology is a better technology compared to the previous generation standards. [ABSTRACT FROM AUTHOR]

The increase in channel bandwidth and peak-to-average power ratio (PAPR) of modern communication standards poses a serious challenge to performing channel power (CP) and complementary cumulative distribution function (CCDF) measurements in real-time using standard measurement solutions based on spectrum analyzers (SA). Recently, Software Defined Radio (SDR) technology has become a viable alternative to the conventional real-time spectrum monitoring approach based on SA due to its reduced cost. Therefore, in this paper, we propose a novel, innovative, agile and cost-effective solution to enable both CP and CCDF measurements on a state-of-the-art SDR platform. The proposed solution exploits the ability of the SDR equipment to access signal samples in the time domain and defines both CP and CCDF-type measurements. The two measurement functions are software implemented in GNU Radio by designing customized blocks and integrated into a graphical user interface. The proposed system was first tested and parameterized in a controlled environment using emitted signals specific to the IEEE 802.11ax family of wireless local area networks. After parameterization, the SDR-based system was used for over-the-air measurements of signals emitted in the 4G+, 5G and 802.11ax communication standards. By performing the measurement campaign, we have demonstrated the capabilities of the measurement system in performing real-time measurements on broadband channels (up to 160 MHz for IEEE 802.11ax). Altogether, we have proved the usability of CP and CCDF measurement functions in providing valuable insights into the power distribution characteristics of signals emitted by the latest communication standards. By exploiting the versatility of SDR technology, we have enabled a cost-effective solution for advanced real-time statistical measurements of modern broadband signals. [ABSTRACT FROM AUTHOR]

The paper focuses on the optimization of IEEE 802.11ax dense networks. The results were obtained with the use of the NS-3 simulator. Various network topologies were analyzed and compared. The advantage of using MSDU and MPDU aggregations in a dense network environment was shown. The process of improving the network performance for changes in the transmitter power value, CCA Threshold, and antenna gain was presented. The positive influence of BSS coloring mechanism on overal network efficiency was revealed. The influence of receiver sensitivity on network performance was determined.

The IEEE 802.11ax standard defines High-Efficiency WLAN (HEW), which is known as 6th Generation Wi-Fi (Wi-Fi 6) network. HEW uses an up-link OFDMA-based Random Access (UORA) mechanism for channel access in dense multi-user transmissions. Similar to legacy Wi-Fi networks, UORA recommends adopting a random OFDMA Back-Off (OBO) procedure within the OFDMA contention window (OCW) range to access the available channel resources randomly. IEEE 802.11ax follows a centralized channel resource allocation mechanism, in which an access point (AP) is responsible for calculating and configuring the OCW range and notifying the respective Random Access stations (RA-STAs). However, IEEE 802.11ax does not specify a method to determine reasonable OCW ranges based on the number of RA-STAs for uplink transmissions. In a centralized UORA approach, one of the major challenges for an AP is to accurately and quickly evaluate the exact number of RA-STAs to minimize collision probabilities without the aid of a specific signaling mechanism. The centralized approach in Wi-Fi 6 can significantly degrade the performance of the UORA owing to an inappropriate range of OCW, particularly when the number of random access stations changes dynamically. In this study, a Collision-based Distributed OBO control (CODOBO_CTRL) scheme is proposed where each RA-STA independently determines its OBO counter, instead of an AP-guided centralized mechanism. The motivation for CODOBO_CTRL is to improve the performance of UORA in highly dynamic networks using primitive network parameters. Considering the success or failure of recent UORA transmissions, in the CODOBO_CTRL scheme, each random access station actively adjusts the OBO counter using the relationship between realistic network parameters: channel bandwidth and a collision factor. The results of a simulation study validate that the achieved throughput of the proposed scheme is almost equal to that of the OPT_UORA scheme in a static network, and 11% higher specifically in highly dynamic scenarios. Furthermore, compared to the standard UORA and OBO_CTRL schemes, the CODOBO_CTRL scheme demonstrates improvements of up to 207% and 12%, respectively, in terms of throughput performance.

There has been considerable amount of research to improve performance for a dense wireless local area network (WLAN) environment. While some studies focus on aggressive channel access, others highlight frequent channel state information (CSI) corruption by excessive transmissions. We pay attention to midamble, adopted in the IEEE 802.11ax standard specification, to overcome CSI corruption. If the transmitter inserts midamble symbols, the receiver can acquire new CSI periodically during a physical layer convergence protocol (PLCP) protocol data unit (PPDU) frame. In this paper, we propose a precise receiver performance model to describe the impact of CSI, and design a standard-compliant algorithm called REMEDY that works with conventional channel access schemes by handling CSI corruption and time-varying channels in high-density WLAN networks. REMEDY determines whether to use midamble considering overhead, estimates on-frame signal-to-interference and noise ratio (SINR) to notice channel environments, and cancels the effects of scrambling and incorrect descrambling. We evaluate the performance of the conventional schemes with and without REMEDY in 11ax task group (TGax) indoor simulation scenarios using the ns-3 simulator, considering time-varying channels and CSI corruption. REMEDY helps the existing channel access schemes to achieve up to $2.20\times $ higher throughput while improving the throughput of the lowest performing group, compared to the existing schemes without REMEDY.

The paper presents an analysis of BSS coloring scheme defined in IEEE 802.11ax standard. The efficiency of dense networks for different scenarios was analyzed and compared. This analysis covers various topologies and work configurations through the use of multiple parameters of the PHY and MAC layers. A positive impact of the coloring mechanism on the QoS was observed. The study also analyzed the impact of the RTS/CTS mechanism on the obtained network performance and adequate prioritization of various traffic classes. It was shown that the proper selection of the coloring mechanism parameters in the IEEE 802.11ax standard has a strong impact on QoS and the performance of dense networks.

This paper presents an analysis of the IEEE 802.11ax networks' coexistence with legacy stations, namely IEEE 802.11ac, IEEE 802.11n, and IEEE 802.11a. The IEEE 802.11ax standard introduces several new features that can enhance network performance and capacity. The legacy devices that do not support these features will continue to coexist with newer devices, creating a mixed network environment. This usually leads to a deterioration in the overall performance of such networks; therefore, in the paper, we want to show how we can reduce the negative impact of legacy devices. In this study, we investigate the performance of mixed networks by applying various parameters to both the MAC and PHY layers. We focus on evaluating the impact of the BSS coloring mechanism introduced to the IEEE 802.11ax standard on network performance. We also examine the impact of A-MPDU and A-MSDU aggregations on network efficiency. Through simulations, we analyze the typical performance metrics such as throughput, mean packet delay, and packet loss of mixed networks with different topologies and configurations. Our findings indicate that implementing the BSS coloring mechanism in dense networks can increase throughput by up to 43%. We also show that the presence of legacy devices in the network disrupts the functioning of this mechanism. To address this, we recommend using an aggregation technique, which can improve throughput by up to 79%. The presented research revealed that it is possible to optimize the performance of mixed IEEE 802.11ax networks. [ABSTRACT FROM AUTHOR]

In IEEE 802.11ax, orthogonal frequency division multiple access (OFDMA) is introduced in the uplink for multi-user transmission. The uplink resource units (RUs) can be allocated by the combination of random access (RA) and scheduled access (SA) with specific proportion. And the RU allocation ratio of RA to SA will affect the overall performance. In this paper, an adaptive uplink resource allocation scheme is proposed based on the analysis of access delay. To achieve minimum average delay, according to the distribution of different kinds of traffic and the number of stations (STAs) which have reserved RUs for the next uplink transmission, a specific proportion of RUs are allocated for SA and the remainders are for RA. The specific allocation of RUs is obtained by solving the objective function which aims to minimize the expected access delay. When the distribution of traffic or the number of reserved RUs changes, the allocation of RUs for SA and RA will be adjusted accordingly. In this manner, the RUs will be assigned with low access delay, and the utilization of RUs will be guaranteed. The simulation results show that the proposed adaptive allocation scheme outperforms the fixed allocation uplink OFDMA scheme in terms of throughput and access latency. [ABSTRACT FROM AUTHOR]

The paper studies the spatial reuse in IEEE 802.11ax networks over propagation models in ns3. The propagation models used in the study include the Friis model, the Nakagami model, and the combination of the two models. The results show that not all access points in an area benefit from the spatial reuse, and some even lose throughput. These results introduce the question of how to justify the spatial reuse for those access points who lose throughput, although the total throughput of the access points in the area benefits from the spatial reuse in general. The results also show that the total throughput gains heavily depend on the physical environment of the networks as the environment determines the signal propagation in the networks. The results show that an environment of significant attenuation plus multipath fading offers significant throughput gains for the access points as a whole. Our main contributions in the paper are the results of the ns3 simulations which were not found in the literature. [ABSTRACT FROM AUTHOR]

In this paper, the design, simulation, fabrication, and characterization study of a low-cost and directional hybrid four-element (2 × 2 configuration) Minkowski–Sierpinski fractal antenna array (MSFAA) for the high-efficiency IEEE 802.11ax WLANs (Wi-Fi 6E) and the sub-6 GHz 5G wireless system is presented. Each element of the array is separated by 0.7 λ0. The complete four-element fractal antenna array system includes designing the single-element Minkowski–Sierpinski fractal antenna using two different substrates for performance comparison and an equal-split Wilkinson power divider (WPD) to achieve power division and to form a feed network. The single-element antenna, four-element fractal antenna array, and WPDs are fabricated using a flame-resistant (FR4) glass epoxy substrate with a dielectric constant (εr) of 4.3 and thickness (h) of 1.66 mm. For performance comparison, a high-end Rogers thermoset microwave material (TMM4) substrate is also used, having εr = 4.5 and h = 1.524mm, respectively. The designed four-element fractal antenna array operates at the dual-band frequencies of 4.17 and 5.97 GHz, respectively. The various performance parameters of the antenna array, such as return loss, bandwidth, gain, and 2D and 3D radiation patterns, are analyzed using CST Microwave Studio. The fabricated four-element antenna array provides the bandwidth and gain characteristic of 85 MHz/4.19 dB and 182 MHz/9.61 dB at 4.17 and 5.97 GHz frequency bands, respectively. The proposed antenna array design gives an improvement in the bandwidth, gain, and radiation pattern in the boresight at both frequencies. In the IEEE 802.11 ax WLANs (Wi-Fi 6E) deployments and the upcoming 5G wireless and satellite communication systems, it is critical to have directional antenna arrays to focus the radiated power in any specific direction. Therefore, it is believed that the proposed dual-band four-element fractal antenna array with directional radiation patterns can be an ideal candidate for the high-efficiency IEEE 802.11ax WLANs (Wi-Fi 6E) and the upcoming 5G wireless and satellite communication systems. [ABSTRACT FROM AUTHOR]

With the growing quantity of wireless devices, the demands for wireless transmission are increasing exponentially. More and more WiFi access points (APs) have been built in the environment to serve these stations (STAs). As the density of devices increases, two or more basic service sets (BSSs) are too close to hear each other, which leads to overlapping BSS (OBSS) problems. When the OBSS problem occurs, the STAs in the OBSS area are interfered with by the AP signals from the overlapping BSSs, which causes the data transmission delay, and the quality of service of the user cannot be guaranteed. In this paper, we designed a scheme with a controller which maintains the Overlapping Area Record (OAR) of each BSS. By utilizing the OAR, we proposed a mechanism that reduces the transmission power of the interfering APs and extends the transmission opportunity limits of the low-QoS stations (LQ-STAs). Moreover, we give priority to the LQ-STAs in the multi-user multiple-input multiple-output transmission to deal with the OBSS problem. Through simulations, when the data arrival rate is 128 kbits/s, our method reduces the average downlink transmission delay of interfered high-efficiency STAs and legacy STAs by 21.4% and 25% compared to the base case scenario. When the data arrival rate is 512 kbits/s, our method outperforms the base case scenario up to 99%, which greatly ameliorates the OBSS problem in IEEE 802.11ax. [ABSTRACT FROM AUTHOR]

The paper focuses on the optimization of IEEE 802.11ax dense networks. The results were obtained with the use of the NS-3 simulator. Various network topologies were analyzed and compared. The advantage of using MSDU and MPDU aggregations in a dense network environment was shown. The process of improving the network performance for changes in the transmitter power value, CCA Threshold, and antenna gain was presented. The positive influence of BSS coloring mechanism on overal network efficiency was revealed. The influence of receiver sensitivity on network performance was determined. [ABSTRACT FROM AUTHOR]

The IEEE 802.11ax pave the way to deliver the high-speed communications in the Wi-Fi network even in the dense areas. In this regard, the most challenging task is to enhance the throughput as IEEE 802.11ax standard promises to provide four times improvement in average throughput per station. Unfortunately, none of the existing protocols could satisfy the demand of the standard yet. The performance of the IEEE 802.11ax protocol largely depends on the efficient and wise scheduling of resource units to the stations. The uplink scheduling is more challenging than the downlink since in the uplink path many stations send data to the access point where the stations must be synchronized for the OFDMA transmissions. This paper innovates an uplink scheduling protocol named Efficient Resource Allocation (ERA) that promises to provide a high-throughput to the Wireless LAN along with the reduction of retransmissions of the packets. The simulations and analyses show that the proposed protocol would be a robust one to satisfy the promises of the latest IEEE 802.11ax standard. To the best of our knowledge, the proposed protocol is the unique one of its kind where the resource units are distributed to the stations according to their available loads.

Machine learning (ML) has gained attention from the network research community because it can help solve difficult problems and potentially lead to groundbreaking achievements. In the Wi-Fi domain, ML is applied to solve challenges such as efficient channel access and fair coexistence with other technologies in unlicensed bands. In this paper, we address the performance of uplink orthogonal frequency division multiple random access (UORA) in IEEE 802.11ax networks. Optimization of UORA is a good case for applying ML because of its inherent complexity and dependence on situation and time-dependent parameters. In particular, we use deep reinforcement learning to tune UORA parameters. Our simulation results show that even though the ML-based solution leads to close to optimal results, its operation is comparable to a much simpler, non-ML heuristic. Therefore, we conclude that ML-based solutions to improve IEEE 802.11 performance need not exceed well-designed heuristics.

IEEE 802.11ax stations can use multi-user (MU) uplink OFDMA-based random access (UORA) to improve per-station throughput in dense deployments in comparison to legacy IEEE 802.11 single-user access. Unfortunately, UORA suffers from a high collision probability and low efficiency under high contention. In this paper, we address this problem by modifying the UORA backoff selection method. The proposed solution allows an access point to adjust the OFDMA random access backoff (OBO) countdown rate to decrease the probability of uplink transmission failures. The implemented changes considerably improve UORA performance. We show through extensive simulations, that the proposed efficient OFDMA random access backoff (E-OBO) ensures throughput, efficiency, and collision probability close to optimal and outperforms state-of-the-art solutions.

The widespread use of the Internet of Things makes it relevant to use public IP networks for simultaneous access by both users and wireless sensors. To achieve this, a significant reduction in the subscriber devices' energy consumption is required. This paper analyzes the application features of the collective dynamic routing method both with and without the use of a robust method for estimating the channel data rate for sensors' communication in wireless public networks. Based on the analysis, a novel modification of the collective dynamic routing method has been developed that reduces the sensors' energy consumption while keeping a high data rate and short delivery time for users. An analysis of the network load, the total data transfer rate over the network, and the parameters affecting the sensors' energy consumption was carried out for a segment of a seamless IEEE 802.11ax network. The simulation demonstrated a high efficiency of using a novel modification of the collective dynamic routing method for access to users and wireless sensors. [ABSTRACT FROM AUTHOR]

The paper presents an analysis of BSS coloring scheme defined in IEEE 802.11ax standard. The efficiency of dense networks for different scenarios was analyzed and compared. This analysis covers various topologies and work configurations through the use of multiple parameters of the PHY and MAC layers. A positive impact of the coloring mechanism on the QoS was observed. The study also analyzed the impact of the RTS/CTS mechanism on the obtained network performance and adequate prioritization of various traffic classes. It was shown that the proper selection of the coloring mechanism parameters in the IEEE 802.11ax standard has a strong impact on QoS and the performance of dense networks. [ABSTRACT FROM AUTHOR]

Wi-Fi is a popular wireless technology and is continuously extended to keep pace with requirements such as high throughput, real-time communication, dense networks, or resource and energy efficiency. The IEEE 802.11ax standard, also known as Wi-Fi 6, promises to provide data rates of up to almost 10 Gb/s, lower energy consumption, and higher reliability. Its capabilities go far beyond Wi-Fi 5 (802.11ac) and novel technical concepts have been introduced for this purpose. As such, the Wi-Fi 6 standard includes Multi-User Orthogonal Frequency Division Multiple Access (MU OFDMA), Multi-User Multiple-Input Multiple-Output (MU MIMO), new mechanisms for Spatial Reuse (SR), new mechanisms for power saving, higher-order modulation, and additional minor improvements. In this paper, we provide a survey of Wi-Fi 6. Initially, we provide a compact technological summary of Wi-Fi 5 and its predecessors. Then, we discuss the potential application domains of Wi-Fi 6, which are enabled through its novel features. Subsequently, we explain these features and review the related works in these areas. Finally, performance evaluation tools for Wi-Fi 6 and future roadmaps are discussed. [ABSTRACT FROM AUTHOR]

All the world now is depending on networks to share information between the users, where different data types are transferred wirelessly from network to network. Using wireless LANs are important to connect the users and share the data, these Wireless LANs have different types of obstacles that affect the data sharing or the wireless signal, such as, compatibility wireless protocol types, range coverage, walls penetration, moving devices, different routing protocols, data transferred types, weak signal, and many more. In this paper a practical analysis will be made to the latest IEEE 802.11ax wireless protocol to be compared with two types of Wi-Fi booster’s networks, Mesh and Extender Wi-Fi, while transferring 4k video size data rate, inside a room and on different rooms for wall penetration analysis, while measuring the throughput, delay, and signal strength metrics. The main importance of this paper is to give a more practical understanding and avoid the main problems of using the wireless protocol 802.11ax in different network types.

This paper presents an analysis of the IEEE 802.11ax networks’ coexistence with legacy stations, namely IEEE 802.11ac, IEEE 802.11n, and IEEE 802.11a. The IEEE 802.11ax standard introduces several new features that can enhance network performance and capacity. The legacy devices that do not support these features will continue to coexist with newer devices, creating a mixed network environment. This usually leads to a deterioration in the overall performance of such networks; therefore, in the paper, we want to show how we can reduce the negative impact of legacy devices. In this study, we investigate the performance of mixed networks by applying various parameters to both the MAC and PHY layers. We focus on evaluating the impact of the BSS coloring mechanism introduced to the IEEE 802.11ax standard on network performance. We also examine the impact of A-MPDU and A-MSDU aggregations on network efficiency. Through simulations, we analyze the typical performance metrics such as throughput, mean packet delay, and packet loss of mixed networks with different topologies and configurations. Our findings indicate that implementing the BSS coloring mechanism in dense networks can increase throughput by up to 43%. We also show that the presence of legacy devices in the network disrupts the functioning of this mechanism. To address this, we recommend using an aggregation technique, which can improve throughput by up to 79%. The presented research revealed that it is possible to optimize the performance of mixed IEEE 802.11ax networks.

In this study, we address the problem of downlink throughput degradation in dense wireless local area networks (WLANs) based on the IEEE 802.11ax standard. We demonstrate that this problem essentially results from the asymmetric characteristic of carrier sense multiple access between downlink and uplink transmissions in infrastructure WLANs, and it is exacerbated by a dynamic sensitivity control algorithm that aims to improve spatial reuse (SR) in IEEE 802.11ax. To solve this problem, we propose the interference-aware two-level differentiation mechanism consisting of the dual channel access (DCA) and supplemental power control (SPC) schemes. The proposed mechanism introduces a new measure called a spatial reusability indicator, which roughly estimates the signal-to-interference ratio from the received signal strength of beacon frames. Based on this measure, stations (STAs) are classified into the following two categories: spatial reusable STAs (SR-STAs) and non-spatial reusable STAs (NSR-STAs). Because SR-STAs are more robust to interference than NSR-STAs, the DCA scheme prioritizes transmissions to SR-STAs over those to NSR-STAs by using differentiated carrier sensing thresholds. Moreover, the SPC scheme selectively increases the transmission power to NSR-STAs to compensate for transmission failure due to interference. By combining the SPC and DCA schemes, the proposed mechanism effectively differentiates the downlink transmissions to SR-STAs and NSR-STAs in terms of channel access and transmission power, and it can boost the possibility of successful SR. The proposed mechanism can be easily implemented in IEEE 802.11ax without any complex calculation or significant signaling overhead. Moreover, we provide a practical guideline to determine appropriate parameter values for use in the proposed mechanism. The extensive simulation results obtained in this study confirm that the proposed mechanism increases the downlink throughput by more than several times without decreasing the overall throughput, compared to the existing mechanisms, and it maintains fairness between SR-STAs and NSR-STAs in terms of the ratio of successful transmission. [ABSTRACT FROM AUTHOR]

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 (C W) 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 C W 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 C W 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. [ABSTRACT FROM AUTHOR]

The IEEE 802.11ax pave the way to deliver the high-speed communications in the Wi-Fi network even in the dense areas. In this regard, the most challenging task is to enhance the throughput as IEEE 802.11ax standard promises to provide four times improvement in average throughput per station. Unfortunately, none of the existing protocols could satisfy the demand of the standard yet. The performance of the IEEE 802.11ax protocol largely depends on the efficient and wise scheduling of resource units to the stations. The uplink scheduling is more challenging than the downlink since in the uplink path many stations send data to the access point where the stations must be synchronized for the OFDMA transmissions. This paper innovates an uplink scheduling protocol named Efficient Resource Allocation (ERA) that promises to provide a high-throughput to the Wireless LAN along with the reduction of retransmissions of the packets. The simulations and analyses show that the proposed protocol would be a robust one to satisfy the promises of the latest IEEE 802.11ax standard. To the best of our knowledge, the proposed protocol is the unique one of its kind where the resource units are distributed to the stations according to their available loads. [ABSTRACT FROM AUTHOR]

The latest generation of IEEE 802.11ax wireless local area networks technology (Wi-Fi 6) is de-sined to improve the efficiency of channel resource utilization. The choice of bandwidth with the ability to puncture the preamble of the frames, introduced in Wi-Fi 6, is one of the mechanisms to achieve this goal. The IEEE 802.11be standard (Wi-Fi 7), which is being developed at the time of this writing, expands the capabilities of the preamble puncturing mechanism, making it more flexible. This article studies the efficiency of the preamble puncturing mechanism. An algorithm for choosing the bandwidth that considers preamble puncturing is proposed. It is shown that its efficiency is higher than that when using the standard rules for selecting the bandwidth. [ABSTRACT FROM AUTHOR]

In this paper, the joint access point (AP) association and transmission time allocation problem in densely deployed multirate WLANs based on time sharing medium access control (MAC) is considered. In our study, the centralized coordinated joint AP association and transmission time allocation problem with heterogeneous station (STA) throughput demands is first formulated as an NP-hard single non-zero programming (SNZP) optimization problem with proportionally fair (PF) throughput based objective function. To solve the NP-hard SNZP problem, two novel algorithms, the SNZP relaxation (SNZPR) algorithm and the iterative SNZPR (iSNZPR) algorithm, are proposed. The property and complexity of the proposed algorithms are analyzed. In addition, for dynamic network scenarios where there are new STAs arriving at and trying to join the network, a distributed joint admission, AP association and transmission time allocation (DAAA) algorithm is proposed to determine whether to admit a new STA arriving at the network or not. The performance of the proposed algorithms is then investigated and compared with that of some existing algorithms based on numerical results.

With the growing demand for wireless local area network (WLAN) applications that require low latency, orthogonal frequency-division multiple access (OFDMA) has been adopted for uplink and downlink transmissions in the IEEE 802.11ax standard to improve the spectrum efficiency and reduce the latency. In IEEE 802.11ax WLANs, OFDMA resource allocation that guarantees latency, called latency-bounded resource allocation, is more challenging than that in cellular networks because severe unmanaged interference from overlapping basic service sets is enhanced due to the concurrent-transmission mechanism newly employed in IEEE 802.11ax. To improve the downlink OFDMA resource allocation with the unmanaged interference caused by IEEE 802.11ax concurrent transmissions, we propose Lyapunov optimization-based latency-bounded allocation with reinforcement learning (RL). We focus on the transmission-queue size for each station (STA) at the access point that determines the STA latency. Using Lyapunov optimization, we formulate the resource-allocation problem with the queue-size constraints in a form that can be solved using RL (i.e., a Markov decision process) and prove the upper bound of the queue size. Our simulation results demonstrated that the proposed method, which uses an RL algorithm with a deep deterministic policy gradient, satisfied the queue-size constraints. This means that the proposed method met the latency requirements, while some baseline methods failed to meet them. Furthermore, the proposed method achieved a higher fairness index than the baseline methods.

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Internet of Things (IoT) is a kind of information carrier, which enables for all ordinary objects that can perform independent functions to realize interconnection. The standardization process of wireless local area networks (WLANs) which is an important network system of IoT is gradually advancing. IEEE 802.11ax will replace IEEE 802.11a/b/g/n/ac as the latest WLANs standard. The uplink transmission of IEEE 802.11ax adopts a hybrid access mode. The mode means that the stations (STAs) can access the network adopting either scheduling access mode or random access mode. Since the hybrid access mode supports both the scheduling and random access, how to allocate the resources among the STAs which adopt the two access modes is the first problem to be solved. In particular, IEEE 802.11ax focuses more on the network performance of the high-dense deployment scenarios. The characteristic of the interference of the overlapping basic service set (OBSS) situation is the key factor of the efficiency of resource allocation algorithm. Therefore, firstly, this paper combines capacity entropy multi-user access (CEM) with utility function, and defines a metric value to measure the utility of two kinds of users. Secondly, the simulation-assisted method is used to obtain the probability distribution characteristic of the interference power random variables from dense multi-cell scenarios of IEEE 802.11ax. Then, based on interference power random variables which generated by the probability density curve obtained by simulation, we propose an algorithm which can maximizetotal utility of scheduling and random access STAs, i.e., to maximize the total satisfaction of all STAs. The authors believe that the research can enhance the quality of experience (QoE) of users in dense multi-cell scenarios for the next generation WLANs. [ABSTRACT FROM AUTHOR]

IEEE 802.11ax supports orthogonal frequency division multiple access (OFDMA) for uplink (UL) transmissions where stations (STAs) access randomly chosen resource units (RUs) in a distributed manner. Nevertheless, as the number of STAs increases, frequent collisions can occur, which lead to throughput degradation in UL transmissions. To address this problem, we propose a multi-user multiple-input multiple-output (MU-MIMO) enabled UL OFDMA random access (MORA) protocol. MORA combines the ideas of OFDMA and MU-MIMO, and thus more than one STA can share the same RU, which can significantly reduce the collision probability in congested situations. Analytical and simulation results demonstrate that MORA improves the throughput of the standard OFDMA-only protocol significantly.

The ever-increasing demand for unlicensed spectrum has prompted regulators in the US and Europe to consider opening up the 6 GHz bands for unlicensed access. These bands will open up 1.2 GHz of additional spectrum for unlicensed radio access technologies (RATs), such as Wi-Fi and 5G New Radio Unlicensed (NR-U), in the US and if permitted, 500 MHz of additional spectrum in Europe. The abundance of spectrum in these bands creates new opportunities for the design of mechanisms and features that can support the emerging bandwidth-intensive and latency-sensitive applications. However, coexistence of unlicensed devices both with the bands’ incumbent users and across different unlicensed RATs present significant challenges. In this paper, we provide a comprehensive survey of the existing literature on various issues surrounding the operations of unlicensed RATs in the 6 GHz bands. In particular, we discuss how key features in next-generation Wi-Fi are being designed to leverage these additional unlicensed bands. We also shed light on the foreseeable challenges that designers of unlicensed RATs might face in the near future. Our survey encompasses key research papers, contributions submitted to standardization bodies and regulatory agencies, and documents presented at various other venues. Finally, we highlight a few key research problems that are likely to arise due to unlicensed operations in the 6 GHz bands. Tackling these research challenges effectively will be critical in ensuring that the new unlicensed bands are efficiently utilized while guaranteeing the interference-free operation of the bands’ incumbent users.

Energy efficiency is a significant challenge for modern wireless networking devices. It is crucial for the Internet of Things devices, is required for battery-supplied user devices such as smartphones, and is advisable for high-performance devices such as wireless VR headsets. This article examines the ability of modern Wi-Fi devices to achieve extremely low power consumption when they rarely send and receive data. Two recently developed mechanisms, namely Target Wake Time (TWT) and Wake-Up Radio (WUR), are studied. The first one allows stations to schedule the frame exchanges in advance, while the second one introduces a low-power radio for control information exchange. Although TWT and WUR differ significantly, they both suffer from the clock drift effect that significantly degrades their performance in the case of rare traffic. The paper describes these mechanisms, focusing on their revolutionary features, and presents mathematical models to evaluate the impact of this effect on TWT and WUR mechanism efficiency in terms of energy and channel time consumption. The paper also proposes and thoroughly examines various approaches to the joint and separate usage of TWT and WUR in Wi-Fi networks.

IEEE 802.11ax is a protocol being developed for high-density Wireless Local Area Networks (WLAN). Several algorithms have been proposed to improve the level of spatial reuse applied in IEEE 802.11ax. However, these algorithms are tentative and do not specify how to select the transmit power and carrier sense threshold in practice; It is unclear when and why the tuned parameters lead to better network performance. In this paper, we restricted the scale of transmit power tuning to prevent the case of backfire in which spatial reuse will result in transmission failure. If the restrictions cannot be satisfied, spatial reuse will be abandoned. This is why we named the proposed scheme as Arbitration based Spatial Reuse (ASR). We quantified the network performance after spatial reuse, and formulate a corresponding maximum problem whose solution is the optimal carrier sense threshold and transmit power. We verified our theoretical analysis by simulation and compared it with previous studies, and the results show that ASR improves the throughput up to 8.6% compared with 802.11ax. ASR can avoid failure of spatial reuse, while the spatial reuse failure rate of existing schemes can up to 36%. To use the ASR scheme in practice, we investigate the relation between the optimal carrier sense threshold and transmit power. Based on the relations got from ASR, the proposed Relation based Spatial Reuse (RSR) scheme can get a satisfactory performance by using only the interference perceived and the previously found relations. [ABSTRACT FROM AUTHOR]

Multi-User Multiple-Input and Multiple-Output (MU-MIMO) is a technique that allows concurrent transmissions between one access point (AP) and multiple clients to improve spectral efficiency. In practice, however, the MU-MIMO is sensitive to client mobility and is sometimes even harmful to the performance in networks with moving clients. In this paper, we identify that it is essential to optimize the MU-MIMO performance with moving clients by jointly selecting the sounding period, the number of spatial streams, and client grouping with the consideration of the client density of the network. We develop a data-driven model that estimates client throughput with the consideration of these parameters, as well as an algorithm that jointly determines the parameters for each client with low computational complexity. Using a commodity 802.11ax network, we experimentally demonstrate the significant impact of the key factors on MU-MIMO performance. Based on experimental data, we develop an emulation model to evaluate network performance with different client densities and mobility. Emulation results show that our proposed algorithm outperforms conventional schemes by over 20% in MU-MIMO networks with moving clients. [ABSTRACT FROM AUTHOR]

The IEEE 802.11ax standard defined a set of new specifications to improve spectrum efficiency, power efficiency, and reliability of future wireless local area networks (WLANs). Among these specifications, the uplink multi-user multiple-input, multiple-output (MU-MIMO) remedies the uplink shortcomings of existing WLANs and enables high-efficiency uplink transmissions. This paper considers the problem of adaptive modulation and coding (AMC) for uplink MU-single-input, multiple-output (MU-SIMO) in the upcoming WLANs. Our target is to select the appropriate modulation and coding scheme (MCS) for the existing users so as to maximize the throughput and at the same time guarantee that all users can satisfy a frame error constraint. We adopt a deep learning approach to tackle this problem. We propose to let the access point (AP) leverage the estimated channel state information (CSI) of all users along with the estimated noise standard deviation as the input features to a deep convolutional neural network (DCNN) that is trained to perform AMC. Simulation results reveal that the proposed DCNN for the uplink MU-SIMO AMC outperforms rival machine learning techniques such as fully-connected deep neural network (DNN), k-nearest neighbors (KNN), support vector machines (SVM), Gaussian Naive Bayes (GNB), and random forest (RF) in terms of the throughput and the frame error rate (FER). [ABSTRACT FROM AUTHOR]

As the demands for uplink traffic increase, improving the uplink throughput has attracted research attention in IEEE 802.11 networks. To avoid excessive competition among stations and enhance the uplink throughput performance, the IEEE 802.11ax standard supports uplink multi-user transmission scenarios, in which AP triggers certain stations in a network to transmit uplink data simultaneously. The performance of uplink multi-user transmissions highly depends on the scheduler, and station scheduling is still an open research area in IEEE-802.11ax-based networks. In this paper, we propose a transmission delay-based uplink multi-user scheduling method. The proposed method consists of two steps. In the first step, the proposed method makcreateses station clusters so that stations in each cluster have similar expected transmission delays. The transmission delay-based station clustering increases the ues of uplink data channels during the uplink multi-user transmission scenario specified in IEEE 802.11ax. In the second step, the proposed method selects cluster for uplink multi-user transmissions. The cluster selection can be performed with a proportional fair-based approach. With the highly channel-efficient station cluster, the proposed scheduling method increases network throughput performance. Through the IEEE 802.11ax standard compliant simulations, we verify the network throughput performance of the proposed uplink scheduling method. [ABSTRACT FROM AUTHOR]

The widespread use of the Internet of Things makes it relevant to use public IP networks for simultaneous access by both users and wireless sensors. To achieve this, a significant reduction in the subscriber devices’ energy consumption is required. This paper analyzes the application features of the collective dynamic routing method both with and without the use of a robust method for estimating the channel data rate for sensors’ communication in wireless public networks. Based on the analysis, a novel modification of the collective dynamic routing method has been developed that reduces the sensors’ energy consumption while keeping a high data rate and short delivery time for users. An analysis of the network load, the total data transfer rate over the network, and the parameters affecting the sensors’ energy consumption was carried out for a segment of a seamless IEEE 802.11ax network. The simulation demonstrated a high efficiency of using a novel modification of the collective dynamic routing method for access to users and wireless sensors.

Wi-Fi is a popular wireless technology and is continuously extended to keep pace with requirements such as high throughput, real-time communication, dense networks, or resource and energy efficiency. The IEEE 802.11ax standard, also known as Wi-Fi 6, promises to provide data rates of up to almost 10 Gb/s, lower energy consumption, and higher reliability. Its capabilities go far beyond Wi-Fi 5 (802.11ac) and novel technical concepts have been introduced for this purpose. As such, the Wi-Fi 6 standard includes Multi-User Orthogonal Frequency Division Multiple Access (MU OFDMA), Multi-User Multiple-Input Multiple-Output (MU MIMO), new mechanisms for Spatial Reuse (SR), new mechanisms for power saving, higher-order modulation, and additional minor improvements. In this paper, we provide a survey of Wi-Fi 6. Initially, we provide a compact technological summary of Wi-Fi 5 and its predecessors. Then, we discuss the potential application domains of Wi-Fi 6, which are enabled through its novel features. Subsequently, we explain these features and review the related works in these areas. Finally, performance evaluation tools for Wi-Fi 6 and future roadmaps are discussed.

Adopting OFDMA and MU-MIMO techniques for both downlink and uplink IEEE 802.11ax will help next-generation WLANs efficiently cope with large numbers of devices but will also raise some research challenges. One of these is how to optimize the channelization, resource allocation, beamforming design, and MCS selection jointly for IEEE 802.11ax-based WLANs. In this paper, this technical requirement is formulated as a mixed-integer non-linear programming problem maximizing the total system throughput for the WLANs consisting of unicast users with multicast groups. A novel two-stage solution approach is proposed to solve this challenging problem. The first stage aims to determine the precoding vectors under unit-power constraints. These temporary precoders help re-form the main problem into a joint power and radio resource allocation one. Then, two low-complexity algorithms are proposed to cope with the new problem in stage two. The first is developed based on the well-known compressed sensing method while the second seeks to optimize each of the optimizing variables alternatively until reaching converged outcomes. The outcomes corresponding to the two stages are then integrated to achieve the complete solution. Numerical results are provided to confirm the superior performance of the proposed algorithms over benchmarks. [ABSTRACT FROM AUTHOR]