Existing Medium Access Control Protocols Research Articles

Variable rate power-controlled batch-based channel assignment for enhanced throughput in cognitive radio networks

The number of users in wireless networks, such as mobile and Internet-of-Things networks, is witnessing a tremendous increase, turning the available frequency spectrum into a scarce resource that needs to be efficiently utilized. Cognitive radio (CR) is a key technology for achieving spectrum efficiency by continuously sensing and detecting frequency bands that are not used by licensed primary users (PU) and allowing unlicensed secondary users (SUs) to use them. One of the main challenges in CR is the design of a medium access control (MAC) protocol that ensures efficient spectrum sharing by SUs without disrupting the connectivity of PUs. To achieve that, many of the existing MAC protocols in the literature allow multiple SU transmissions to proceed simultaneously by performing batch-based power control decisions to limit mutual interference between them. Interestingly, the majority of such protocols are demand-rate unaware; i.e., all SUs are granted the same data rate, regardless of their data rate demand. In this paper, we highlight the severe drawbacks of demand-rate unawareness and propose the rate-aware power-controlled channel assignment (RPCCA) MAC protocol, which performs batch-based simultaneous channel assignment decisions to competing SUs along with power control to limit mutual interference, while taking into account the variable demand-rate across SUs. Simulation experiments have demonstrated that the RPCCA protocol offers substantial performance improvements over existing demand-rate unaware CR-based MAC protocols.

Q-Learning and Efficient Low-Quantity Charge Method for Nodes to Extend the Lifetime of Wireless Sensor Networks

With the rapid development of the Internet of Things (IoT), improving the lifetime of nodes and networks has become increasingly important. Most existing medium access control protocols are based on scheduling the standby and active periods of nodes and do not consider the alarm state. This paper proposes a Q-learning and efficient low-quantity charge (QL-ELQC) method for the smoke alarm unit of a power system to reduce the average current and to improve the lifetime of the wireless sensor network (WSN) nodes. Quantity charge models were set up, and the QL-ELQC method is based on the duty cycle of the standby and active times for the nodes and considers the relationship between the sensor data condition and the RF module that can be activated and deactivated only at a certain time. The QL-ELQC method effectively overcomes the continuous state–action space limitation of Q-learning using the state classification method. The simulation results reveal that the proposed scheme significantly improves the latency and energy efficiency compared with the existing QL-Load scheme. Moreover, the experimental results are consistent with the theoretical results. The proposed QL-ELQC approach can be applied in various scenarios where batteries cannot be replaced or recharged under harsh environmental conditions.

FDOE: Exploit Concurrent Communication Opportunities in Full-Duplex Wireless Mesh Networks

In recent years, full-duplex communications in a single frequency channel have become a practical technology. However, existing full-duplex medium access control (MAC) protocols can hardly take full advantages of full-duplex transmission opportunities, because they are not capable of adding one more half-duplex link on an on-going half-duplex link to form a full-duplex link. Besides, the exposed node and hidden node issues in multi-hop wireless networks limit flexible establishment of full-duplex links. Such limitations waste full-duplex transmission opportunities, and thus degrade network performance. In this paper, an efficient full-duplex link establishment protocol called full-duplex opportunity exploitation (FDOE) is developed to exploit full-duplex transmission opportunities in a wireless mesh network. FDOE leverages rateless coding and pseudo-noise (PN) sequences to establish a full-duplex link whenever a full-duplex transmission opportunity is available. Such a distinct feature leads to significant improvement of network performance. FDOE is evaluated through theoretical analysis and extensive simulations. Performance results show that FDOE exploits full-duplex transmission opportunities efficiently in wireless mesh networks, and thus significantly outperforms existing MAC protocols.

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

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

A Traffic-Aware Fair MAC Protocol for Layered Data Collection Oriented Underwater Acoustic Sensor Networks

Underwater acoustic channels are characterized by long propagation delay, limited available bandwidth and high energy costs. These unique characteristics bring challenges to design media access control (MAC) protocol for underwater acoustic sensor networks (UASNs). Especially in data-collection-oriented UASNs, data generated at underwater nodes are transmitted hop-by-hop to the sink node. The traffic loads undertaken by nodes of different depths are different. However, most existing MAC protocols do not consider the traffic load imbalance in data-collection-oriented UASNs, resulting in unfairness in how the nodes transmit their own generated data. In this paper, we propose a novel traffic-aware fair MAC protocol for layered data-collection-oriented UASNs, called TF-MAC. TF-MAC accesses a medium by assigning time slots of different lengths to each layer via different traffic loads to achieve traffic fairness of nodes. To improve throughput and avoid collision in the network, an overlapping time slot division mechanism for different layers and multi-channel allocation scheme within each single layer is employed. Considering the time-varying traffic loads of the nodes, an adaptive packet length algorithm is proposed by taking advantage of the spatial-temporal uncertainty of underwater channels. A sea experiment was conducted to prove the spatial-temporal uncertainty of UASNs, which provides a feasibility basis for the proposed algorithm. Simulation results show that TF-MAC can greatly improve the network performance in terms of throughput, delay, energy consumption, and fairness in the layered data-collection-oriented UASNs.

Optimal Achievable Transmission Capacity Scheme for Full-Duplex Multihop Wireless Networks.

Full-duplex (FD) communication has been attractive as the breakthrough technology for improving attainable spectral efficiency since the 5G mobile communication system. Previous research focused on self-interference cancellation and medium access control (MAC) protocol to realize the FD system in wireless networks. This paper proposes an optimal achievable transmission capacity (OATC) scheme for capacity optimization in the FD multihop wireless networks. In this paper, the proposed OATC scheme considers the temporal reuse for spectral efficiency and the spatial reuse with transmit power control scheme for interference mitigation and capacity optimization. OATC scheme controls the transmit power to mitigate interference and optimizes the transmission capacity, which leads to the optimal achievable network capacity. We conduct the performance evaluation through numerical simulations and compare it with the existing FD MAC protocols. The numerical simulations reveal that considering only the concurrent transmissions in the FD system does not guarantee optimal transmission capacity. Moreover, the hybrid mechanism, including the sequential transmissions, is also crucial because of the interference problem. Besides, numerical simulation validates that the proposed OATC scheme accomplishes the optimal achievable network capacity with lower interference power and higher achievable throughput than the existing MAC protocols.

An adaptive and cooperative MAC protocol for safety applications in cognitive radio enabled vehicular Ad-hoc networks

Rapid broadcast of safety message (sm) is critical for real-time applications in cognitive radio vehicular ad hoc networks (CR-VANETs). The arrival of primary users (PU) and the relative unpredictability of traffic emerge as network bottleneck constraints, resulting in unreliable broadcast services. The requirement is for a Medium Access Control (MAC) protocol that allows for fair contention, is adaptive, and includes a makeup strategy for rebroadcasting failed transmissions. There are intricate tradeoff optimisation relationships in which a value for the contention window that is inadequate will not result in optimal network performance. In this paper, we develop a dynamic contention window backoff mechanism using Karush–Kuhn–Tucker (KKT) conditions that enhances network performance by modifying the backoff time according to traffic density. Then we amalgamate this algorithm with a cooperative makeup strategy to design a novel adaptive and cooperative MAC protocol that is operable in a dynamic CR-VANET paradigm (ACCRV-MAC). A Markov chain decision model characterises the protocol, and Network Simulator -2 analyses various performance parameters. The study reveals that ACCRV-MAC improves throughput by 38.3% and reduces network latency by 49% compared to existing MAC protocols.

A novel cooperative MAC protocol for safety applications in cognitive radio enabled vehicular ad-hoc networks

Recent developments in intelligent transportation system (ITS) require a reliable medium access control (MAC) protocol to support the high-priority safety message broadcast. The rapid increase in spectrum demand is addressed by implementing cooperation in cognitive radio-based vehicular ad-hoc networks (CR-VANETs). In this paper, a novel cooperative MAC for CR-VANET (CCRV-MAC) is proposed for safety applications. CCRV facilitates collaboration among vehicles to exchange channel status reports for pro-active channel switching in the case of primary user (PU) appearance. Additional control signals are introduced to enable transmission mode selection. The helper nodes rebroadcast failed transmission by employing the proposed cooperative makeup strategy. The protocol is modelled using a Markov chain and is analyzed for various performance parameters using NS-2. It is also compared with two existing MAC protocols. In the results, CCRV shows enhanced throughput and packet delivery ratio. The average delay in CCRV MAC is reduced by approximately 37% compared to existing cognitive radio network (CRN) and vehicular ad-hoc network (VANET) based MAC approaches. Analysis of overhead and delay illustrates the reliability of CCRV as it suffers a maximum average delay of 69 ms under adverse conditions which is well below the permissible limit of 100 ms.

PrEEMAC: Priority based energy efficient MAC protocol for Wireless Body Sensor Networks

Wearable wireless sensors, or Wireless Body Sensor Network (WBSN), is one of the most recent fields of research in healthcare applications. The sensors are placed on the human body to detect the critical medical parameters and transmit the collected data to a centralized node. Though the devices work at low energy and power constraints, maintenance of such devices is a crucial aspect. In light of this requirement, an efficient medium access control (MAC) protocol should be utilized to extend the life time of the network. In this paper, we propose a new “Priority based Energy Efficient (PrEE) MAC protocol” incorporated with various priorities in predefined devices based on data sensing and normal devices changing to priority when the value is more than the threshold, by modifying IEEE 802.15.4 header bits. The PrEE MAC protocol is designed based on the IEEE 802.15.4 and its Superframe structure. The simulation results show that the energy efficiency and lifetime of the proposed MAC protocol is more as compared to the existing MAC protocol.

Medium Access Control Protocols for Flying Ad Hoc Networks: A Review

Recently, flying ad hoc networks (FANETs) have been broadly applied to various civilian and military applications. Medium access control (MAC) protocols have attracted significant attention because of their impact on overall network performance. Owing to peculiar features such as high mobility and dynamic topology, however, the design of a MAC protocol for FANETs confronts challenges. Several MAC protocols for FANETs have been reported in literature. In early MAC protocols for FANETs, delay, throughput, and collision detection were the key design concerns. Recently, however, the design of an energy-efficient MAC protocol has become a new research focus. To the best of the authors’ knowledge, there exists no survey on MAC protocols for FANETs. This study extensively investigates the existing MAC protocols for FANETs. In this paper, the MAC design issues in FANETs are presented first. Subsequently, the existing MAC protocols are reviewed and discussed from the perspective of major features, operational principles, advantages, and limitations. The MAC protocols are then qualitatively compared in terms of major features, characteristics, and performance factors. Furthermore, open issues and research challenges are summarized and discussed.

Determining node duty cycle using Q-learning and linear regression for WSN

Wireless sensor network (WSN) is effective for monitoring the target environment, which consists of a large number of sensor nodes of limited energy. An efficient medium access control (MAC) protocol is thus imperative to maximize the energy efficiency and performance of WSN. The most existing MAC protocols are based on the scheduling of sleep and active period of the nodes, and do not consider the relationship between the load condition and performance. In this paper a novel scheme is proposed to properly determine the duty cycle of the WSN nodes according to the load, which employs the Q-learning technique and function approximation with linear regression. This allows low-latency energy-efficient scheduling for a wide range of traffic conditions, and effectively overcomes the limitation of Q-learning with the problem of continuous state-action space. NS3 simulation reveals that the proposed scheme significantly improves the throughput, latency, and energy efficiency compared to the existing fully active scheme and S-MAC.

A Dual Channel Medium Access Control (MAC) Protocol for Underwater Acoustic Sensor Networks Based on Directional Antenna

Medium access control (MAC) protocol is an important link for achieving networks function in any wireless networks; an efficient and reliable MAC protocol is crucial for an effective underwater acoustic sensor networks (UASNs). Significant differences between UASNs and terrestrial sensor networks (TSNs) render the traditional MAC protocols applied on land inapplicable underwater. Existing MAC protocols for UASNs use the omnidirectional antenna, which wastes energy, restricts the network’s coverage range, and brings about unnecessary interferences in neighbor nodes. This paper proposes a dual channel MAC protocol for UASNs based on directional antenna (DADC-MAC), which increases the network coverage range, efficiently utilizes space, and reduces node interference compared to the omnidirectional antenna. The DADC-MAC protocol divides the channel into a data transmission channel and busy prompt message channel; the node uses the former to transmit the control frame and DATA package while the sending node and receiving node use the latter channel to inform the neighbor nodes of on-going communications to prevent DATA package collision. A neighbor discovery mechanism and directional network allocation vector are applied to resolve hidden terminal and deafness problems. Simulation results show that the DADC-MAC protocol could improve network throughput and reduce end-to-end delay, is efficient, performs well, and is well suited to both symmetrical and asymmetrical UASNs topology.

Fuzzy Based Enhanced Medium Access Control protocol for Wireless Sensor Networks

Wireless Sensor Networks (WSNs) have increased huge consideration because of their wide scope of utilizations. In these networks, the sensor hubs gather various kinds of information from the general condition. During the transmission of collected data packets, some of them will be dropped due to the collision of packets. So, collide packets are retransmitted which may lead the network to high energy consumption. As Medium Access Control (MAC) protocol has responsible for reliable communication in WSN, an enhanced MAC protocol has to be proposed for improving energy efficiency of the network. By considering this solution, Fuzzy Based Enhanced Medium Access Control protocol (Fuzzy-MAC) is proposed in this paper. Before transmission, data packets are prioritized using the Fuzzy system. Then the packets are transmitted in light of the need of the parcels. Simulation results show that the exhibition of the proposed Fuzzy-MAC beats that of existing MAC protocols as far as energy utilization, delivery ratio and throughput.

SAFE-MAC: Speed Aware Fairness Enabled MAC Protocol for Vehicular Ad-hoc Networks.

Highly dynamic geographical topology, two-direction mobility, and varying traffic density can lead to fairness issues in Vehicular Ad-hoc Networks (VANETs). The Medium Access Control (MAC) protocol plays a vital role in sharing the common wireless channel efficiently between vehicles in a VANET system. However, ensuring fairness between vehicles can be a challenge in designing MAC protocols for VANET systems. The existing protocol, IEEE 802.11 DCF, ensures that the packet transmission rate for a particular vehicle is directly proportional to the amount of time a vehicle spends within a service area, but it does not guarantee that faster vehicles will be able to send the minimum number of packets. Other existing MAC protocols based on IEEE 802.11 are able to provide a minimum amount of data transmission regardless of velocity, but are unable to provide an amount of data transmission that is more proportionate to the time a vehicle spends in the service area. To address the above limitations, we propose a Speed Aware Fairness Enabled MAC (SAFE-MAC) protocol that calculates the residence time of a vehicle in a service area by using mobility metrics such as position, direction, and speed to synthesize the transmission probability of each individual vehicle with respect to its residence time. This is achieved by dynamically altering the values of parameters such as minimum contention window, maximum backoff stage, and retransmission limit in the MAC protocol. We then develop an analytical model to compare the performance of our proposed protocol with contemporary MAC protocols. Numerical analysis results show that our proposed protocol significantly improves fairness among the speed-varying vehicles in VANET.

A Cooperative and Reliable RSU-Assisted IEEE 802.11P-Based Multi-Channel MAC Protocol for VANETs

Vehicle ad-hoc networks (VANETs), which support various important applications for intelligent transportation systems (ITSs), consist of vehicle-to-vehicle and vehicle-to-infrastructure communications based on vehicles and roadside units (RSUs). Medium access control (MAC) plays a critical role in providing efficient broadcast services for VANETs. Unlike other types of networks, VANETs suffer from rapid changes in topology, resulting in frequent network disconnections caused by the high mobility of nodes. Hence, adaptive MAC protocols, which dynamically adjust the interval according to the traffic conditions, are essential to VANETs. This study proposes a cooperative and reliable RSU-assisted IEEE 802.11p-based multi-channel MAC protocol for VANETs, called RAM. In our proposal, an RSU is used to both calculate the optimized interval and keep track of the safety packet transmission. We also present a cooperative scheme for the retransmission of safety packets that failed to broadcast because of hidden nodes. The simulation results show that the RAM not only allows safety packets to be broadcast more efficiently using the existing MAC protocols, but also outperforms the existing MAC protocols in terms of the packet delivery ratios for safety and control packets.

A Novel Capture-Aware TDMA-Based MAC Protocol for Safety Messages Broadcast in Vehicular Ad Hoc Networks

Since broadcast communication is considered the highly appropriate technique for the dissemination of safety messages in vehicular ad hoc networks (VANETs), it is vital to design a high-efficient medium access control (MAC) protocol for vehicles accessing wireless channel. However, the characteristics of VANETs, such as high-velocity vehicles, highly dynamic topology and very unstable communication link, lower the performance of existing MAC protocols. In this paper, we propose a novel Capture-aware TDMA-based MAC (CT-MAC) protocol, which can better utilize the channel resource than the existing MAC protocols by setting the optimal frame length with taking capture effect into account. To obtain the realistically optimal frame length, the closed form expression of probability of capture effect is derived under Nakagami-m fading channel which is proper to model the small-scale fading channel in VANETs. Besides, a discrete Markov chain is introduced to analyze the impact of capture effect on channel utilization. The theoretical analyses and the simulation results show that the reliability of broadcast and the efficiency of channel utilization are significantly improved.

A QoS Based Adaptive Backoff Scheme for Vehicular Ad Hoc Networks.

The media access control (MAC) protocol is a key element in the design of vehicular ad hoc networks (VANETs) that directly affects the network performance. The backoff schemes of existing MAC protocols apply the single backoff process and therefore are not suitable for multi-class data transmission. Additionally, they cannot satisfy the delay requirements of emergency data in the case of varying number of vehicles, causing an adverse effect to the intelligent transportation system (ITS). This paper presents a priority-based adaptive backoff scheme that can enhance the binary exponential backoff (BEB) algorithm as well as the polynomial backoff (QB) algorithm. This system distinguishes priority data with different delay requirements first and designs different backoff schemes for each type of data later. The two-dimensional Markov Chain is used to analyze the backoff scheme and determine the expressions for throughput and delay. The simulation results show that the backoff scheme provided by this paper can reduce the average data delay and regulate each kind of data delay adaptively, according to the varying number of vehicles and different delay requirements.

A Taxonomy for MAC Protocols in Wireless Sensor Networks Based on Traffic Prioritization

Various media access control (MAC) protocols have been developed to deal with the heterogenous traffic in wireless sensor networks (WSN). In many emerging applications, it is regarded essential to prioritize the heterogeneous traffic for reliable performance of WSN. This work categorizes the recently developed traffic prioritization MAC protocols in the classes of ‘Adaptive Contention’, ‘Duty-Cycle Adaptation’, ‘Queue Management’ and ‘Hybrid’. A taxonomy has been developed based on the categorization and detailed overview of each protocol is presented. The performance benefits and gaps are described for each of the protocols and the future research directions are suggested based on the analysis. It has been identified that most of the existing MAC protocols, although provide early channel access to high priority traffic, fail to offer true preemptive priority. There exists no mechanism which could pause/interrupt the ongoing transmission of the low priority traffic to facilitate the immediate channel access for high priority data. The analysis provided by this article is expected to aid the future researchers in identifying the trends of MAC protocol development in the context of traffic prioritization.

DCO-MAC: A Hybrid MAC Protocol for Data Collection in Underwater Acoustic Sensor Networks.

In underwater acoustic sensor networks (UASNs), medium access control (MAC) is an important issue because of its potentially significant effect on the network performance. However, designing a suitable MAC protocol for the UASN is challenging because of the specific characteristics of the underwater acoustic channel and network, such as limited available bandwidth, long propagation delay, high bit-error-rate, and sparse network topology. In addition, as the traffic load is non-uniformly distributed in a UASN for data collection, it is essential to consider the application feature for the MAC protocol. In this paper, we propose a MAC protocol in a data-collection-oriented UASN, abbreviated as the DCO-MAC protocol. In the proposed protocol, the network is partitioned into two kinds of sub-networks according to the traffic load. A contention-based MAC protocol is used in the sub-network with a light traffic load, while a reservation-based MAC protocol is used in the sub-network with a heavy traffic load. Meanwhile, the DCO-MAC protocol supports the access of mobile nodes. The theoretical analysis and simulation results demonstrate that, in a UASN for data collection, the proposed MAC protocol outperforms the other existing MAC protocols, in terms of the network throughput, end-to-end packet delay, energy overhead, and fairness.

Geometry Distance Estimated MAC Protocol for TV White Space

Regulatory bodies worldwide have quite recently approved the dynamic access of unlicensed networks to the TV white space (TVWS) spectrum. In TVWS, secondary users (SUs) are required to access a database periodically to acquire information on the spectrum usage of primary users (PUs). The spectrum database querying of SUs will solve the spectrum scarcity problem. A key technology in efficiently using the TVWS spectrum is designing an efficient medium access control (MAC) protocol. In this paper, we propose a geometry distance estimated medium access control (GMAC) protocol to mitigate the hidden and exposed terminal problems in TVWS. GMAC provides an efficient means of channel database querying to obtain the list of available channels to overcome interference with PUs. We develop a Markov chain model to characterize the saturation normalized throughput of our proposed GMAC protocol for the TVWS. In this study, transmitter power control is based on the geometrically estimated distance between SU communication pairs; this increases channel spatial reuse and throughput, and reduces PU outage probability. We also compare our proposed scheme with existing MAC protocols for TVWS. We show that the GMAC will improve the channel spatial reuse and normalized throughput, and reduce PU outage probability.