Acknowledgement Frame Research Articles

VoWiFi Cell Capacity Evaluation using WiFi 7 considering VBR Traffic

Deployment for Wireless Local Area Network (WLAN) technology is experiencing substantial growth. The transmission of Voice over WiFi (VoWiFi) is half-duplex due to its single-talk nature. In order to mitigate the inefficient utilization of available bandwidth, the technique of silent suppression is employed. This feature decreases the level of ambient noise and provides Variable Bit Rate (VBR) communication. To enhance the VoWiFi cell capacity, we utilized VBR traffic instead of Constant Bit Rate (CBR) traffic. In this study, we developed a mathematical model to find the number of VoWiFi users possible within a WLAN Access Point (AP) considering G.729 vocoder. Arbitration inter-frame space (AIFS) has been utilized in our study to evaluate the channel state prior to transmitting real-time data between user equipment (UE) devices. Additionally, short inter-frame spacing (SIFS) has been employed to transmit Request To Send (RTS)/Clear To Send (CTS) and Acknowledgement (ACK) frames, enabling an examination of the VoWiFi cell capacity. Again, to increase the VoWiFi cell capacity, we incorporated the compressed RTP (cRTP) protocol. Further, we conducted an analysis on the impact of retransmission on VoWiFi cell capacity. This analysis involved a comparison of the results using VBR traffic with the previous WLAN standards, namely IEEE 802.11b/g/n/ac/ax. We observed that the improvement in VoWiFi cell capacity in VBR traffic is approximately 2.6 times more than the CBR traffic. Further, our research revealed that the enhancement in VoWiFi cell capacity is approximately 1.5% higher when utilizing AIFS compared to Distributed Coordination Function (DCF) inter-frame spacing (DIFS).

Framing Revolution: Multiframe News Themes in Lebanon’s October 2019 Uprising

This study examines news framing of partisan media during uprisings. Through mixed methods, it studies the framing of Lebanon’s October 2019 protests, compares frames across political divides, and interprets story themes based on associations between multiple frames. First, the qualitative media framing analysis (MFA) inductively interprets issue-specific frames. Then, the quantitative content analysis deductively examines the developed issue-specific frames and the generic frames across five partisan news channels and tests the relationship between them and across the pro- and anti-protests media. Finally, multiple associated frames are grouped together into news story themes. Results from the MFA reveal six frames: solidarity, head-to-head, individualization, acknowledgment, disruption, and peace through violence frames. The study detected the frequent deployment of the solidarity, conflict, and acknowledgment frames and a significant framing difference between pro- and anti-protest channels. Pro-protest channels more often deployed the solidarity frame, while anti-protest channels more frequently used the conflict, acknowledgment, disruption, and economic consequence frames. Finally, the study developed four story themes based on associations between frames: Blame the protestors or the politicians; protestor violence begets government violence; divided they suffer; and politicians may not only be the culprits but also the solution. The resulting multiframe news themes offer nuanced meaning to generic frames that frequently appear with issue-specific frames and highlight the different roles a singular news frame can play when combined with other frames.

Enhanced Energy-Saving Mechanisms in TSCH Networks for the IIoT: The PRIL Approach

Lifetime of motes in wireless sensor networks can be enlarged by decreasing the energy spent for communication. Approaches like time slotted channel hopping pursue this goal by performing frame exchanges according to a predefined schedule, which helps reducing the duty cycle. Unfortunately, whenever the receiving radio interface is active but nobody in the network is transmitting, idle listening occurs. If the traffic pattern is known in advance, as in the relevant case of periodic sensing, proactive reduction of idle listening (PRIL) noticeably lowers energy waste by disabling receivers when no frames are expected for them. Optimal PRIL operation demands that, at any time, the transmitter and receiver sides of a link have a coherent view of its state (either enabled or disabled). However, this is not ensured in the presence of acknowledgment frame losses. This paper presents and analyzes some strategies to cope with such events. An extensive experimental campaign has been carried out through discrete event simulation to determine what consequences above errors may have from both a functional and performance viewpoint. Results show that, although no strategy is optimal in all circumstances, different solutions can be profitably adopted depending on the specific operating conditions.

Adversarial Reinforcement Learning-Based Coordinated Robust Spatial Reuse in Broadcast-Overlaid WLANs

Broadcast services for wireless local area networks (WLANs) are being standardized in the IEEE 802.11 task group bc. Envisaging the upcoming coexistence of broadcast access points (APs) with densely-deployed legacy APs, this paper addresses a learning-based spatial reuse with only partial receiver-awareness. This partial awareness means that the broadcast APs can leverage few acknowledgment frames (ACKs) from recipient stations (STAs). This is in view of the specific concerns of broadcast communications. In broadcast communications for a very large number of STAs, ACK implosions occur unless some STAs are stopped from responding with ACKs. Given this, the main contribution of this paper is to demonstrate the feasibility to improve the robustness of learning-based spatial reuse to hidden interferers only with the partial receiver-awareness while discarding any re-training of broadcast APs. The core idea is to leverage robust adversarial reinforcement learning (RARL), where before a hidden interferer is installed, a broadcast AP learns a rate adaptation policy in a competition with a proxy interferer that provides jamming signals intelligently. Therein, the recipient STAs experience interference and the partial STAs provide a feedback overestimating the effect of interference, allowing the broadcast AP to select a data rate to avoid frame losses in a broad range of recipient STAs. Simulations demonstrate the suppression of the throughput degradation under a sudden installation of a hidden interferer, indicating the feasibility of acquiring robustness to the hidden interferer.

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

Research on TCP Performance Model and Transport Agent Architecture in Broadband Wireless Network

The problems of Internet stability, heterogeneity, fairness of bandwidth sharing among streams, efficiency of use and congestion control have been solved in this article. This paper proposes an improved scheme of TCP proxy acknowledgement based on Automatic Repeat Request (ARQ), which improves throughput, reduces delay and saves uplink bandwidth of wireless link, and is more suitable for future asymmetric networks. The substantial improvement is observed during the experimentation as processing efficiency of protocol. The observed results revealed that overall processing time for each packet is approximately equals to one fourth of the transfer control protocol and the reduction of 59% is also observed in the utility of resources. The protocol also incorporates various simple techniques for the recovery of loss to improve the throughput in noisy wireless conditions. The results show that the adoption of the average diversity combining technology is helpful to improve the throughput and effective factor performance, and can reduce the requirement of radio link protocol (RLP) maximum retransmission times. As nearly 90% of uplink acknowledgement frames are filtered, the uplink bandwidth utilization rate is significantly improved. Decomposing large data frames into small data frames is also helpful to improve system performance.

Modified QUIC protocol with congestion control for improved network performance

In the networks, a transport layer is responsible for reliable data with guaranteed Quality of Service. A Modified-QUIC protocol provides improved throughput and reduced latency of the network. This work proposes a modification in handshaking mechanism for QUIC protocol to minimize overhead due to control signals and time required to update the congestion-window size. This modification fine-tunes the window update mechanism with the acknowledgment frame, which results in a smooth variation in the congestion-window size. This leads to the control congestion by regulating traffic in the network. In the proposed mechanism, unnecessary time out events are avoided by updating the congestion-window on receipt of the acknowledgment frame. This work has been carried out using two different testbed setups to verify the transport layer and a browser network performance. It has been observed that a Modified-QUIC protocol is easy to deploy, improves the throughput and data rate by 35% and 3.43%, respectively, over the QUIC protocol. The average fairness index is increased with a file size and for the long live traffic.

Pushing the Limits of Transmission Concurrency for Low Power Wireless Networks

Concurrent transmission (CT) has been widely adopted to optimize the throughput of various data transmissions in wireless networks, such as bulk data dissemination and high-rate data collection. In CT, besides the possible data frame collision at receivers, we observe that acknowledgment frame (ACK) collision at senders can also significantly diminish concurrency opportunities. In this article, to avoid the potential ACK collision in CT, we propose ALIGNER which develops a new transmission pattern to coordinate concurrent senders in a distributed manner. The key idea is to align the silent periods of concurrent transmitters. To achieve this goal, we align the end of data frames concurrently transmitted by several senders. Therefore, the potentially arriving ACKs can avoid a collision with ongoing data transmissions because the concurrent senders are in a listening state to wait for receivers’ ACKs for a short and fixed period. ALIGNER can be applied for both deterministic and opportunistic forwarding protocols. It optionally uses a random back-off and slotted ACK mechanism to avoid a potential collision among simultaneously arrived ACKs in opportunistic forwarding. In addition, ALIGNER adopts a tailor-made metrics to analyze the throughput benefit of concurrent transmission for both deterministic and opportunistic data collection protocols. We have implemented ALIGNER in TinyOS and conducted extensive experiments on a real testbed. Experimental results show that ALIGNER can significantly increase the concurrency opportunities in both deterministic (up to 105%) and opportunistic (up to 89.7%) forwarding compared with the state-of-the-art CT methods.

Self-Forming Multiple Sub-Nets Based Protocol for Tactical Networks Consisting of SDRs

The paper presents a novel approach for tactical networks in which radios form self-regulatory virtual sub-nets on the basis of control messages. The design uses hybrid of frequency division multiple access (FDMA) and time division multiple access (TDMA) approaches with less call setup delays and increases in network throughput. This multiple sub-nets based distributed algorithm exploits available spectrum resources, provides collision-free simultaneous transmissions and autonomous selection of time slots over different frequency sub-bands with self-organizing and self-forming network capabilities. We propose two schemes which provide multi-channel medium access control with autonomous scheduling of time slots for software-defined radios (SDRs). The schemes use request and acknowledgment frames as control messages to devise a distributed solution. These control messages alone help to form virtual sub-nets, preserve frequency channels and schedule transmissions over multiple time slot intervals, depend on the type of data messages. In order to demonstrate the behavior of sub-nets for tactical networks, theoretical findings are exploited with experimental analysis to provide practical implementation of schemes using contention-free time slotted common control channel for nodes coordination and time slotted collision-free multi-channel environment for data transmissions. The results show the effective coexistence of multiple transmissions in a network with increase in network throughput and lower the data latency up-to 76.8%, when compare to conventional MAC protocols. The design is workable for time sensitive, mission critical networks and expected to support multi-hop transmissions in similar manner.

Covert Jamming Using Fake ACK Frame Injection on IEEE 802.11 Wireless LANs

When a transmitter node sends a data frame in an IEEE 802.11 distributed coordinated function (DCF) network, the receiver sends an acknowledgment (ACK) frame within a short inter-frame space (SIFS) interval if a data frame is successfully received. If the transmitter node fails to receive this ACK frame, it considers the transmission a failure and attempts to retransmit the data frame. We consider a data frame jamming scenario in which an attacker transmits a jamming signal while a transmitter is sending a data frame. In this scenario, the transmitter does not receive the ACK frame from its intended receiver and may suspect the presence of signal jammers if it experiences repeated failures. We propose a covert jamming method that deceives a transmitter into believing that the transmission was successful by injecting a fake ACK frame to pretend to be its intended receiver.

A Reinforcement-Learning-Based Distributed Resource Selection Algorithm for Massive IoT

Massive IoT including the large number of resource-constrained IoT devices has gained great attention. IoT devices generate enormous traffic, which causes network congestion. To manage network congestion, multi-channel-based algorithms are proposed. However, most of the existing multi-channel algorithms require strict synchronization, an extra overhead for negotiating channel assignment, which poses significant challenges to resource-constrained IoT devices. In this paper, a distributed channel selection algorithm utilizing the tug-of-war (TOW) dynamics is proposed for improving successful frame delivery of the whole network by letting IoT devices always select suitable channels for communication adaptively. The proposed TOW dynamics-based channel selection algorithm has a simple reinforcement learning procedure that only needs to receive the acknowledgment (ACK) frame for the learning procedure, while simply requiring minimal memory and computation capability. Thus, the proposed TOW dynamics-based algorithm can run on resource-constrained IoT devices. We prototype the proposed algorithm on an extremely resource-constrained single-board computer, which hereafter is called the cognitive-IoT prototype. Moreover, the cognitive-IoT prototype is densely deployed in a frequently-changing radio environment for evaluation experiments. The evaluation results show that the cognitive-IoT prototype accurately and adaptively makes decisions to select the suitable channel when the real environment regularly varies. Accordingly, the successful frame ratio of the network is improved.

A Full-Duplex MAC Protocol Based on Buffer Status Report for Successive Full-Duplex Link Setup

Full-duplex radio is the next-generation wireless technology that can transmit and receive frames simultaneously over the same channel. Recently, as self-interference cancellation technologies have evolved, full-duplex radio has become possible. In this letter, we propose a new medium access control (MAC) protocol designed for full-duplex radio. In the proposed MAC protocol, the downlink station on a full-duplex link uses an acknowledgment frame to report its buffer status information to the access point (AP). Then, the AP can establish a successive full-duplex link to provide a transmission opportunity to the station without contention. Our performance analysis and simulation results indicate that the proposed MAC protocol achieves throughput gains compared to existing studies.

Link adaptation strategies for IEEE 802.15.4 WPANs: Protocol design and performance evaluation

This paper proposes two link adaptation strategies for IEEE 802.15.4 wireless personal area networks (WPANs), using a multi-rate signaling set. In the proposed link adaptation strategies, the most adequate modulation and coding scheme (MCS) satisfying the target bit error rate (BER) of the end device is selected based on the signal-to-interference-plus-noise ratio (SINR) of either a beacon or an acknowledgement (ACK) frame. The beacon-based link adaptation scheme has low complexity and overhead, given that it performs link adaptation only once per superframe. In contrast, the ACK-based strategy performs link adaptation at every ACK frame, and therefore provides a faster and more effective link adaptation, but at the expense of a larger overhead. The specific protocol design for the proposed link adaptation strategies is developed by constructing the signal flow based on the service primitives between the protocol stack layers. The network simulator OPNET is used to implement an accurate IEEE 802.15.4 WPAN protocol stack and the simulation environment required for performance evaluation. The simulation results show that the received throughput of IEEE 802.15.4 WPANs can be improved by exploiting the proposed link adaptation strategies instead of auto-rate fallback, the conventional WPAN strategy.

Enhanced Dual Carrier Sensing With Transmission Time Control for Fair Spatial Reuse in Heterogeneous and Dense WLANs

In this paper, we focus on fairness and spatial reuse in heterogeneous and dense wireless local area networks (WLANs) where stations (STAs) have different capabilities of carrier sensing and basic service sets (BSSs) are densely deployed. First, we show a serious problem of unfairness arising when STAs with different carrier sensing threshold (CSTH) coexist and compete for channel access. To cope with this problem, a dual carrier sensing mechanism has been proposed in the on-going IEEE 802.11ax standardization. This mechanism uses two differentiated CSTHs: a conservative CSTH for fairness among intra-BSS STAs and an aggressive CSTH for spatial reuse by inter-BSS STAs. This dual carrier sensing mechanism may be effective in improving fairness. However, we show that its gain is marginal in terms of spatial reuse because an acknowledgment (ACK) frame is liable to be corrupted due to interference from a data frame transmitted by an inter-BSS STA. In order to avoid ACK corruption, we enhanced the dual carrier sensing mechanism by controlling the transmission time of the data frame. Depending on the receiving signal strength of data frame transmitted by an inter-BSS STA, the proposed mechanism selectively adjusts the concurrent transmission time of the data frame so that ACK frames can be successfully delivered. Results from simulation confirmed the outstanding performance of the proposed mechanism in heterogeneous and dense WLANs; compared with conventional mechanisms, the total throughput was considerably increased by more than two-fold while the fairness among the STAs was improved.

Probe/PreAck: A Joint Solution for Mitigating Hidden and Exposed Node Problems and Enhancing Spatial Reuse in Dense WLANs

In dense wireless local area networks (WLANs), the primary causes of interference and hindrance to spatial reuse are the well-known hidden node problem (HNP) and the exposed node problem (ENP). In this paper, we propose a joint solution to these problems. The proposed mechanism, referred to as Probe/PreAck (PR/PA), utilizes the concept of a two-way handshake for efficient channel reservation and spatial reuse by means of two control frames called PR and PA. The PR frame is designed for the semi-reservation of a channel initiated by a transmitting node, while the PA frame is used for the receiver-oriented permission of a channel reservation. Once a transmitting node advertises a PR frame, the channel is temporarily reserved, and the channel reservation is finally completed after the node receives the corresponding PA frame. Otherwise, the channel reservation is immediately released. Unlike the ready-to-send/clear-to-send mechanism, which is a well-known solution to HNP, the proposed mechanism does not unnecessarily prevent nodes from accessing the channel but selectively blocks transmitting and receiving nodes when they overhear the PA and PR frames transmitted by neighboring nodes, respectively. In this way, the proposed PR/PA mechanism effectively deals with both HNP and ENP in a unified framework. We further enhance the PR/PA mechanism by devising an immediate destination switching scheme, which is implemented in access points (APs) to improve the downlink throughput. If an AP fails to complete the exchange of PR and PA frames with a specific destination, it sends another PR frame to a different destination node without performing a new back-off procedure. Moreover, we adopt the transmission time control scheme to assure successful spatial reuse in multiple basic service set (BSS) WLANs. By adjusting the transmission time of the data frames simultaneously transmitted in different BSSs, severe interference between the data and acknowledgment frames can be avoided. The results of a simulation study confirmed that the proposed mechanism outperformed conventional mechanisms in dense multi-BSS WLANs; the downlink throughput was increased by more than 10 times while the overall network throughput was increased by approximately 50%.

Cloud-Based Wi-Fi Network Using Immediate ACK in Uplink Data Transmissions

In a cloud-based network architecture, the central unit (CU) at the cloud coordinates wireless nodes such as the remote access units (RAUs) at the edges of the network and manages most functions for providing wireless connectivity services to clients. The CU facilitates efficient communication resource management such as radio frequency or transmission power of RAUs by global resource coordination. In this paper, we propose a cloud-based Wi-Fi network architecture consisting of a CU and RAUs as an improvement on the conventional Wi-Fi architecture with traditional access points (APs). We then propose a method for uplink data transmission in a cloud-based Wi-Fi network. In a conventional Wi-Fi network with independently operating APs, APs close to each other may not be able to utilize the same frequency band efficiently because of significant amounts of interference. However, in a cloud-based Wi-Fi network, the CU coordinates RAUs so that they can operate in the same frequency band by transmitting or receiving signals through the shared wireless medium to improve spectral efficiency. For each frequency band, the proposed system utilizes a diversity combining that combines multiple signals and introduces a single improved signal with high signal-to-noise ratio for uplink transmission in the cloud-based Wi-Fi network. In our proposed uplink transmission method for a cloud-based Wi-Fi network, we utilize diversity combining with the immediate acknowledgement (ACK) transmission method that transmits the ACK frame to the client immediately before decoding. The proposed uplink data transmission method mitigates the performance degradation caused by the fronthaul propagation delay between the CU and RAUs, without significant modification of the IEEE 802.11 standard. Using an IEEE 802.11n standard-compliant simulation and experiments with software-defined radio equipment, we verify the goodput performance of the proposed method for a cloud-based Wi-Fi network architecture.

SINR-Based MCS Level Adaptation in CSMA/CA Wireless Networks to Embrace IoT Devices

This paper presents an automatic modulation and coding scheme (MCS) level adaptation algorithm to embrace Internet of Things (IoT) devices by improving the area spectral efficiency of carrier-sense multiple access with collision avoidance (CSMA/CA) wireless networks. In the proposed algorithm, senders of CSMA/CA wireless networks use the signal to interference plus noise ratio of acknowledgment frames from their receivers to estimate channel statuses between the senders and the receivers. Using the estimated channel status of each receiver, senders control sending rates of traffic by adjusting MCS levels of packets destined for each receiver. We use Poisson point processes (PPPs) to model the locations of participating nodes (i.e., access points and wireless devices) in a given area. We evaluate the effectiveness of the proposed algorithm using an event-driven ns-2 simulator for various PPP densities of access points and wireless devices.

Modelling and analysis data fragmentation in IEEE 802.15.4 slotted CSMA/CA protocol without ACK mode

The low-rate wireless personal area networks (WPANs), as wireless sensor networks (WSNs), suffer from many constraints. The IEEE 802.15.4 standard proposes the slotted CSMA/CA as a communication channel access mechanism with collision avoidance that take into account the constraints of WPANs. In this paper, we propose to introduce a data fragmentation mechanism into slotted CSMA/CA to improve a bandwidth utilisation. The novelty, in this paper, is the use of the fragmentation mechanism to replace an acknowledgement frame after the transmission of the fragment and the remaining frame. The beacon frame is used to confirme the success transmission of a data fragment. To evaluate the performances of our proposition, we have developped a three dimension Markov chain which modelises the behaviour of the node using IEEE 802.15.4 with data fragmentation mechanism without using an ACK frame. The analytical results of the network throughput and the transmission success delay demonstrate the improvement of the bandwidth occupation.

Mitigation of packet duplication in VANET unicast protocols

Vehicular ad hoc networks (VANETs) are self-organized networks designed to improve the drivers’ safety and the efficiency of vehicular traffic management. In this kind of networks, packet losses are common in the path from source to destination, mainly due to the high mobility of the nodes (i.e., vehicles). Reliability mechanisms at different layers are used to mitigate the impact of this issue. In this work, we explain how the loss of acknowledgment frames (ACK) at the medium access control (MAC) layer with the recovery procedure of VANET routing protocols lead to an unexpected generation of duplicate packets. We propose two incoming filters with different levels of detection of duplicate packets at routing layer to prevent the propagation of unnecessary packet copies, so that the available bandwidth will increase as a consequence. To evaluate the behavior of our proposals, we employed two VANET routing protocols: the topological iAODV [1] and the geographical MMMR [2]. We carried out simulations with three vehicle densities in an urban scenario and with two different mechanisms to adapt the size of the contention window (CW), which is an important factor in VANETs to avoid collisions. The extensive statistical analysis of the results show that our approaches are effective to reduce the traffic load in both routing protocols in terms of routing operations, idle time, duplicate packets and end-to-end delay. We also observed an expected minimum degradation of the packet delivery ratio in the geographical routing protocol, thus the benefits of the proposal are clear.

ETEEM- Extended Traffic Aware Energy Efficient MAC Scheme for WSNs

Idle listening issue arises when a sensor node listens to medium despite the absence of data which results in consumption of energy. ETEEM is a variant of Traffic Aware Energy Efficient MAC protocol (TEEM) which focuses on energy optimization due to reduced idle listening time and much lesser overhead on energy sources. It uses a novel scheme for using idle listening time of sensor nodes. The nodes are only active for small amount of time and most of the time, will be in sleep mode when no data is available. ETEEM reduces energy at byte level and uses a smaller byte packet called FLAG replacing longer byte SYNC packets of S-MAC and SYNCrts of TEEM respectively. It also uses a single acknowledgement packet per data set hence reducing energy while reducing frequency of the acknowledgment frames sent. The performance of ETEEM is 70% better comparative to other under-consideration MAC protocols.