Medium Access Control Parameters Research Articles

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.

Simulative Assessment of the Listen before Talk Adaptive Frequency Agility Medium Access Control Protocol for LoRaWAN Networks in IoT Scenarios

The work presents an extensive simulative assessment of a LoRaWAN network that adopts the Listen Before Talk (LBT) Adaptive Frequency Agility (AFA) channel access technique in compliance with the ETSI regulations. The paper presents the results obtained in several scenarios with a different number of nodes and different configurations of the LoRaWAN Medium Access Control (MAC) parameters. The aim of the paper is to give insights about the performance achievable by changing the configuration parameters. For example, in all the scenarios considered in this work, once the number of nodes is fixed, the impact on the message loss ratio of the considered MAC parameters is always lower than 7%. Conversely, the impact of such parameters on the end-to-end delay is much more significant. The methodology of this assessment is of general validity and can be exploited by the network designer during the network configuration phase to obtain the most suitable combination of the MAC parameters for the network under consideration, based on the number of nodes and the application requirements.

DADC: A Novel Duty-cycling Scheme for IEEE 802.15.4 Cluster-tree-based IoT Applications

The IEEE 802.15.4 standard is one of the widely adopted specifications for realizing different applications of the Internet of Things. It defines several physical layer options and Medium Access Control (MAC) sub-layer for devices with low-power operating at low data rates. As devices implementing this standard are primarily battery-powered, minimizing their power consumption is a significant concern. Duty-cycling is one such power conserving mechanism that allows a device to schedule its active and inactive radio periods effectively, thus preventing energy drain due to idle listening. The standard specifies two parameters, beacon order and superframe order, which define the active and inactive period of a device. However, it does not specify a duty-cycling scheme to adapt these parameters for varying network conditions. Existing works in this direction are either based on superframe occupation ratio or buffer/queue length of devices. In this article, the particular limitations of both the approaches mentioned above are presented. Later, a novel duty-cycling mechanism based on MAC parameters is proposed. Also, we analyze the role of synchronization schemes in achieving efficient duty-cycles in synchronized cluster-tree network topologies. A Markov model has also been developed for the MAC protocol to estimate the delay and energy consumption during frame transmission.

Cross-Layer Analysis of Multi-Static RFID Systems Exploiting Capture Diversity

In this paper, we propose a framework for cross-layer analysis of multi-static passive RFID systems. The model takes into account details of the shared wireless channel, including fading and capture effect, whereas, at the medium access control (MAC) layer, the anti-collision mechanism proposed in the EPC Generation 2 standard is taken as a reference. To address the complexity of the system model, we rely on a semi-analytical approach, that combines a moment matching approximation method to abstract the physical layer and Monte-Carlo simulations to describe the MAC dynamics. Furthermore, based on the space diversity feature offered by the multi-static settings, we introduce the concept of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">capture diversity</i> and propose a modification to the standard to fully support this form of diversity. Numerical results show the impact of deployment conditions and the relative positions of interrogator, tags, and detection points on the performance of tags’ identification. We show how the number of detection points impacts the system performance under various channel conditions and MAC parameters’ settings. Finally, we validate the proposed update of the MAC protocol, showing substantial performance improvement with respect to the standard collision resolution policy.

REO: A Reliable and Energy Efficient Optimization Algorithm for Beacon-Enabled 802.15.4–Based Wireless Body Area Networks

Nowadays, due to the advancements in microelectronics and wireless communications, Wireless Body Area Networks (WBANs) have gained significant attention. They have various application fields including telemedicine, military, sports, and entertainment, which require contradictory Quality of Service (QoS) in terms of reliability, delay, energy, and simplicity. Medium Access Control (MAC) protocols play an essential role in finding a solution to these tradeoffs. Many ongoing research activities, primarily based on the low power IEEE 802.15.4 standard, tried to improve the WBAN performance by MAC parameter adjustment but, to the authors' knowledge, none were able to properly satisfy delay and reliability requirements. In this paper, a numerical MAC optimization algorithm is proposed for the Beacon-enabled IEEE 802.15.4-based WBANs, optimizing the delay, reliability, and energy tradeoffs based on the existing traffic and QoS requirements. The simulation results show that in comparison with similar works, the energy efficiency and reliability are improved by at least 14% and 25%, respectively while reducing the delay substantially.

IEEE 802.11n/ac Üzerinden Çoklu Video Yayını Analizi ve Değerlendirilmesi

There is an ever-growing interest for video applications. It is well-known that video applications have very stringent quality of service (QoS) requirements and require high data rates. To meet ever growing demands for mobile video streaming applications and stringent QoS requirements, it is required to optimise the current networks. IEEE 802.11 is one of the most widely deployed networks in the world. Therefore, this paper investigates the performance of multicast video streaming over IEEE 802.11n/ac in a mobile outdoor scenario. To this end, an end-to-end system level simulator is developed to evaluate the performance of the perceived video quality at the receiver in terms of peak signal to noise ratio (PSNR) and resource efficiency in terms of total transmission times for different application layer - forward error correction (AL-FEC) and medium access control (MAC) layer parameters. Results show that without AL-FEC protection the legacy IEEE 802.11n/ac provides very poor quality of experience. However, the perceived video quality can be significantly improved by adding some extra repair symbols. Since video applications have very challenging QoS requirements, changing only MAC parameters are unable to meet these QoS requirements thus additional AL-FEC protection is required. Moreover, it is observed that with the use of the frame aggregate mechanism at the MAC layer, the total transmission times can be significantly reduced and hence the resource consumptions.

Intelligent MU-MIMO User Selection With Dynamic Link Adaptation in IEEE 802.11ax

IEEE 802.11ax high-throughput wireless access networks support multi-user multiple-input multiple-output (MU-MIMO)-based communication, where a set of spatially apart wireless stations forms a user group and uses different spatial streams for simultaneous transmission and reception. In this architecture, dynamic user group selection is an important aspect for maintaining high-throughput fair channel access. In addition, the physical and media access control parameters, like channel bonding levels, modulation, and coding schemes need to be tuned based on the selected user group to utilize the maximum available capacity. In this paper, we design an online learning-based approach over a centralized logical control architecture, called intelligent MU-MIMO user selection with link adaptation (IMMULA), where a central controller collects the performance statistics under various configuration space and applies a reinforcement learning strategy to select the best-suited configurations dynamically at periodic intervals. The performance of IMMULA is analyzed over a testbed consisting of 6 IEEE 802.11ac access points and 20 wireless stations. The results show that IMMULA improves network performances significantly compared to other baseline mechanisms.

Performance Evaluation and Delay-Power Trade-off Analysis of ZigBee Protocol

In this paper, we analyze the superframe structure of the Medium Access Control (MAC) sublayer of IEEE 802.15.4 protocol (ZigBee), designed for Low-Rate Wireless Personal Area Networks (LR-WPANs), and evaluate the effects of the inactive portion of a superframe on average delay, and average power consumption. The four-dimensional Markov chain-based analysis of the slotted Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) algorithm presented in this work considers backoff freezing and acknowledged packet transmission that are not studied in the existing works. The analytical results prove that the performance of LR-WPANs depends significantly on the length of a superframe's active portion. We introduce a variable-Superframe duration-Beacon interval Ratio (SBR), which is utilized by tuning a few MAC parameters to achieve 35 percent reduced delay, on an average, compared to the existing state of the art. The results show that the proposed model also yields improved performance in terms of power consumption, for short and medium contention windows. In addition to the proposed analysis, this work provides optimized superframe order values that achieve trade-offs between delay and power consumption as demanded by user-provided QoS requirements corresponding to different contexts.

Formal Methods for Stability Analysis of Networked Control Systems With IEEE 802.15.4 Protocol

Wireless networked control systems (WNCSs) with control loops closed over a wireless network are prevailing these days. However, due to uncertainties such as random accessing delays and possible packet drops, the stability analysis for a WNCS is a challenging task. Most previous studies on the communication network analysis either relied on Monte Carlo simulation or followed the multistate Markov chain framework. In this paper, our main contribution is to propose a formal method-based stability analysis in which the communication system is modeled as a probabilistic timed automaton. The underlying communication protocol is analyzed through probabilistic model checking. In particular, the stability condition of the WNCS is expressed in the probabilistic temporal logic formula as the quality of service requirement, which can be checked, and the satisfaction of the specification is equivalent to the stability guarantee of the WNCS. We then study the impact of different media access control (MAC) parameters on the satisfaction of the specification. Furthermore, if the specification is not satisfied initially, we propose a systematic way to tune the MAC parameters or redesign the controller so that the specification can be met. This paper presents an attempt and a new angle to the communication and control system codesign problem.

AP-STA Association Control for Throughput Maximization in Virtualized WiFi Networks

To manage and enable service customization among multiple internet service providers (ISPs) sharing the common physical infrastructure and network capacity in virtualized Wi-Fi networks, this paper models and optimizes access point-station (STA) association via airtime usage control. More specifically, an optimization problem is formulated on the STAs’ transmission probabilities to maximize the overall network throughput, while providing airtime usage guarantees for the ISPs. As the proposed optimization problem is inherently non-convex, an algorithm to reach the optimal solution is developed by applying monomial approximation and geometric programming iteratively. Based on the proposed 3-D Markov-chain model of the enhanced distributed channel access protocol, the detailed implementation of the optimal transmission probability of each STA is also discussed by manipulating medium access control parameters. The performance of the developed association and airtime control scheme is evaluated through numerical results. For both homogeneous and non-homogeneous STA distributions, numerical results reveal performance gains of the proposed algorithm in improving the throughput and keeping airtime usage guarantees.

Token-Based Adaptive MAC for a Two-Hop Internet-of-Things Enabled MANET

In this paper, a distributed token-based adaptive medium access control (TA-MAC) scheme is proposed for a two-hop Internet of Things (IoT)-enabled mobile ad hoc network. In the TA-MAC, nodes are partitioned into different one-hop node groups, and a time division multiple access (TDMA)-based superframe structure is proposed to allocate different TDMA time durations to different node groups to overcome the hidden terminal problem. A probabilistic token passing scheme is devised to distributedly allocate time slots to nodes in each group for packet transmissions, forming different token rings. The distributed time slot allocation is adaptive to variations of the number of nodes in each token ring due to node movement. To optimize the medium access control (MAC) design, performance analytical models are presented in closed-form functions of both MAC parameters and network traffic load. Then, an average end-to-end delay minimization framework is established to derive the optimal MAC parameters under a certain network load condition. Analytical and simulation results demonstrate that, by adapting the MAC parameters to the varying network condition, the TA-MAC achieves consistently minimal average end-to-end delay, bounded delay for local transmissions, and high aggregate throughput. Further, the performance comparison with other MAC schemes shows the scalability of the proposed MAC in an IoT-based two-hop environment with an increasing number of nodes.

End-to-End Throughput of Ad Hoc Multi-Hop Networks in a Poisson Field of Interferers

This paper proposes a novel approach to assess the performance in terms of end-to-end throughput of an ad hoc multi-hop wireless network, where each link is affected by interference coming from other multi-hop paths nearby. The approach captures the mutual impact of each path on all others. It can be applied to both, contention-based and scheduled, medium access control (MAC) protocols. Sources have data to send to destination nodes through $n$ relays. Nodes are assumed to be uniformly and randomly distributed in the 2-D infinite plane. The model shows the impact on the end-to-end throughput of $n$ ; it also captures the influence of node density, traffic generated, number of retransmissions, and other MAC parameters. Finally, the model provides the throughput-delay tradeoff. Unlike most previous approaches, the mathematical tool proposed appears to be scalable, allowing easy extension to any number of hops. Comparison with simulation results is provided to prove that the impact of the approximations introduced in the analysis is almost negligible.

AT-MAC: Adaptive MAC-Frame Payload Tuning for Reliable Communication in Wireless Body Area Networks

In wireless sensor networks, adaptive tuning of Medium Access Control (MAC) parameters is necessary in order to assure the QoS requirements. In this paper, we propose an adaptive MAC-frame payload tuning mechanism for wireless body area networks (WBANs) to maximize the probability of successful packet delivery or reliability of the associated sensor nodes based on real-time situation. The enabling algorithm, Adaptively Tuned MAC (AT-MAC), has been proposed to tune the MAC-frame payload of a WBAN sensor node, which is compliant with the IEEE 802.15.4 protocol. AT-MAC prioritizes sensor nodes based on the seriousness of the health parameters that are being measured by the respective sensor nodes. Further, we consider a Markov chain-based analytical approach that acknowledges the slotted CSMA/CA backoff mechanism with retry limits, as described in the IEEE 802.15.4 protocol. We derive expressions for reliability, power consumption, and throughput, which are the key metrics to evaluate the network performance of the proposed protocol, and analyze the impact of MAC parameters on them. Finally, results indicate that the low rate and low power IEEE 802.15.4 can be used effectively in case of WBANs if the payload is tuned properly through the proposed algorithm. The proposed AT-MAC algorithm yields around 70 percent increase in reliability of a critical node in a WBAN.

Adaptive management of energy consumption, reliability and delay of wireless sensor node: Application to IEEE 802.15.4 wireless sensor node.

Designing a Wireless Sensor Network (WSN) to achieve a high Quality of Service (QoS) (network performance and durability) is a challenging problem. We address it by focusing on the performance of the 802.15.4 communication protocol because the IEEE 802.15.4 Standard is actually considered as one of the reference technologies in WSNs. In this paper, we propose to control the sustainable use of resources (i.e., energy consumption, reliability and timely packet transmission) of a wireless sensor node equipped with photovoltaic cells by an adaptive tuning not only of the MAC (Medium Access Control) parameters but also of the sampling frequency of the node. To do this, we use one of the existing control approaches, namely the viability theory, which aims to preserve the functions and the controls of a dynamic system in a set of desirable states. So, an analytical model, describing the evolution over time of nodal resources, is derived and used by a viability algorithm for the adaptive tuning of the IEEE 802.15.4 MAC protocol. The simulation analysis shows that our solution allows ensuring indefinitely, in the absence of hardware failure, the operations (lifetime duration, reliability and timely packet transmission) of an 802.15.4 WSN and one can temporarily increase the sampling frequency of the node beyond the regular sampling one. This latter brings advantages for agricultural and environmental applications such as precision agriculture, flood or fire prevention. Main results show that our current approach enable to send more information when critical events occur without the node runs out of energy. Finally, we argue that our approach is generic and can be applied to other types of WSN.

A New Intelligent Approach for Optimizing 6LoWPAN MAC Layer Parameters

Fairness, low latency, and high throughput with low energy consumption are desired attributes for medium access control (MAC) protocols. The IEEE 802.15.4 standard defines the MAC and physical layers standard for IPv6 over low power personal area network (6LoWPAN). When a non-appropriate parameter setting is used, the default MAC parameters generate excessive collisions, packet losses, and high latency under high traffic when a large number of 6LoWPAN nodes being deployed. A search of the literature revealed few studies that investigate the impact of optimizing these parameters to achieve high throughput with minimum latency. This paper proposes a new intelligent approach to selecting the optimal 6LoWPAN MAC layer parameters set; the introduced mechanism depends on artificial neural networks, genetic algorithm, or particles swarm optimization to select and validate the optimized MAC parameters. The obtained simulation results showed that utilizing the optimal MAC parameters improved 6LoWPAN network throughput by 52–63% and reduced the end-to-end delay by 54–65% in which the enhancement percentage depends on the number of deployed sensor nodes in the network.

Comparison of the Device Lifetime in Wireless Networks for the Internet of Things

This paper presents a comparison of the expected lifetime for Internet of Things (IoT) devices operating in several wireless networks: the IEEE 802.15.4/e, Bluetooth low energy (BLE), the IEEE 802.11 power saving mode, the IEEE 802.11ah, and in new emerging long-range technologies, such as LoRa and SIGFOX. To compare all technologies on an equal basis, we have developed an analyzer that computes the energy consumption for a given protocol based on the power required in a given state (Sleep, Idle, Tx, and Rx) and the duration of each state. We consider the case of an energy constrained node that uploads data to a sink, analyzing the physical (PHY) layer under medium access control (MAC) constraints, and assuming IPv6 traffic whenever possible. This paper considers the energy spent in retransmissions due to corrupted frames and collisions as well as the impact of imperfect clocks. The comparison shows that the BLE offers the best lifetime for all traffic intensities in its capacity range. LoRa achieves long lifetimes behind 802.15.4 and BLE for ultra low traffic intensity; SIGFOX only matches LoRa for very small data sizes. Moreover, considering the energy consumption due to retransmissions of lost data packets only decreases the lifetimes without changing their relative ranking. We believe that these comparisons will give all users of IoT technologies indications about the technology that best fits their needs from the energy consumption point of view. Our analyzer will also help IoT network designers to select the right MAC parameters to optimize the energy consumption for a given application.

Boycott based enhanced correction scheme for mac layer misbehavior in wireless networks

In IEEE 802.11 standard, the wireless LAN Medium Access Control (MAC) provides transmission fairness to nodes in a network, but some nodes that called misbehaving nodes (MNs) can take advantage and modify its MAC parameters to improve its own performance at the expense of other nodes (honest nodes HNs). Many solutions have been proposed to solve this problem, but most of these solutions are based on the assumption that MNs misbehave just one time. Therefor, in this paper, we propose a boycott based enhanced correction scheme for mac layer misbehavior in wireless networks to correct and react against MNs and increasing the HNs throughput.To correct these MNs, HNs collectively react and correct the MNs. When the misbehavior is detected for the first time, HNs react in an appropriate way by decreasing the throughput of MNs, but if MNs misbehave for the second time HNs start to react aggressively and consequently decrease MNs throughput dramatically. In the third misbehavior, HNs boycott the MNs and reject all messages that came from these nodes. Simulation result shows the efficiency of our proposed scheme to improve HNs throughput and boycott MNs.

Dominant Channel Occupancy for Wi-Fi Backscatter Uplink in Industrial Internet of Things

This paper presents a dominant channel occupancy (DCO) mechanism for the Wi-Fi backscatter uplink in the industrial Internet of things (IIoT). The DCO provides high-priority channel access and reliable burst transmission to the Wi-Fi backscatter devices, thereby enabling the Wi-Fi backscatter tag to deliver its tag information to the Wi-Fi reader without interference from neighboring legacy Wi-Fi devices to guarantee the timeliness and reliability of the IIoT system. For the former, we consider three types of medium access control (MAC) configurations: “carrier sense multiple access with collision avoidance (CSMA/CA) starting with short inter-frame space (SIFS)”, “freezing of the backoff period”, and “reduced CWmin.” In addition, the DCO uses the SIFS between burst packets to guarantee reliable burst transmission. To verify the effectiveness of DCO and determine a proper value for MAC parameters, we conduct experimental simulations under IEEE 802.11n PHY/MAC environments. The simulation results show that the reduced CWmin has the most significant effect on the channel occupancy. The Wi-Fi backscatter devices achieve much higher throughput than the separate cases when two or more configurations are used simultaneously. Moreover, the results exhibit that the use of SIFS between consecutive packets supports reliable burst transmission regardless of the transmission of the legacy Wi-Fi devices in the vicinity.

Energy harvested roadside IEEE 802.15.4 wireless sensor networks for IoT applications

With the increasing deployment of the Internet of Things (IoT) applications, the demand for energy efficiency (EE) and quality-of-service (QoS) guarantee is on the rise. This paper considers the typically contradicting requirements for EE and QoS provisioning in an integrated manner for an IEEE 802.15.4-based wireless sensor network (WSN). Specifically, we consider variable traffic conditions of IoT applications in the presence of an energy harvesting technique based on the movement of vehicles. To this end, we introduce an adaptive energy-efficient algorithm, referred to as ABSD, that adapts the medium access control (MAC) parameters of IEEE 802.15.4 sensor nodes in response to the queue occupancy level of sensor nodes and the offered traffic load levels. By adapting the transmission parameters, the ABSD algorithm minimizes the network contention level which could in turn improve the EE as well as the network throughput. The ABSD algorithm is further enhanced by integrating with an energy harvesting technique and a new MAC parameter known as the ‘energy backoff’. The enhanced algorithm referred to as EH-ABSD offers priority to different classes of traffic by improving the battery lifetime and QoS values under variable traffic load conditions. Numerical results confirm that our proposed algorithms achieve high EE and QoS values while extending the lifetime of sensor nodes for outdoor applications.

사물인터넷 환경을 위한 IEEE 802.15.4 프로토콜 모델링과 최적화 방안

본 논문에서는 사물인터넷 환경에서 사용되는 저전력 통신 기술인 IEEE 802.15.4 MAC (Media Access Control) 프로토콜의 성능 분석을 수행한다. 사물인터넷 환경에서는 기기 종류가 다양하고 생성되는 트래픽 특성도 상이하기 때문에 기존 연구와는 달리 트래픽이 혼재되어 있는 heterogeneous traffic 환경을 고려한다. 마코프 체인을 통해 프로토콜의 성능을 MAC 파라미터의 함수로 도출하였고 이를 기반으로, 사용되고 있는 애플리케이션을 위한 에너지 효율적인 최적 MAC 파라미터를 실시간으로 찾는 프레임워크를 설계하였다. 제안 방식은 기존의 파라미터를 고정시켜 운용하는 방법 대비 에너지 이득이 있음을 애플리케이션 시나리오별 비교를 통해 보였고, 제안된 프레임워크가 연산 능력의 한계를 가지는 소형 기기에서도 충분히 사용될 수 있음을 정확도와 속도 측면에서 검증하였다. In this paper, we perform analysis of the performance of low-power communication technology, IEEE 802.15.4 MAC (Media Access Control) protocol used in internet of things. Wide variety of devices in internet of things generate different kinds of traffic characteristics and heterogeneous traffic environment is therefore considered in contrast to existing works. With the help of the Markov chain the performance of the protocol is derived as a function of the MAC parameters and based on the results a framework to determine energy-efficient optimal MAC parameters for applications in real time is proposed. Proposed method is shown to be more efficient in terms of energy consumption through performance comparison over application scenarios compared to operation with fixing MAC parameters, and its practicability on small devices with limited computing power is verified through evaluating the accuracy and speed of the proposed framework.