Traditional Medium Access Control Research Articles

2DMAC: A Sustainable and Efficient Medium Access Control Mechanism for Future Wireless NoCs

Wireless Network-on-Chip (WNoC) requires a Medium Access Control (MAC) mechanism for an interference-free sharing of the wireless channel. In traditional MAC, a token is circulated among the Wireless Interfaces (WIs) in a Round Robin manner. The WI with the token holds the channel for a fixed number of cycles. However, the channel requirement of the individual WIs dynamically changes over time due to the varying traffic density across the WNoC. Moreover, the conventional WNoCs give equal importance to all the traffic taking the wireless path and transmit it in an oldest-first manner. Nevertheless, the critical data can degrade the system performance to a large extent by delaying the application runtime if not served promptly. We propose 2DMAC, which can change the token arbitration pattern and tune the channel hold time of each WI based on its runtime traffic density and criticality status. Moreover, 2DMAC prioritizes the critical traffic over the non-critical traffic during the wireless data transfer. The proposed mechanism improves the wireless channel utilization by 15.67% and the network throughput by 29.83% and reduces the critical data latency by 29.77% over the traditional MAC.

DR-ALOHA-Q: A Q-Learning-Based Adaptive MAC Protocol for Underwater Acoustic Sensor Networks.

Underwater acoustic sensor networks (UASNs) are challenged by the dynamic nature of the underwater environment, large propagation delays, and global positioning system (GPS) signal unavailability, which make traditional medium access control (MAC) protocols less effective. These factors limit the channel utilization and performance of UASNs, making it difficult to achieve high data rates and handle congestion. To address these challenges, we propose a reinforcement learning (RL) MAC protocol that supports asynchronous network operation and leverages large propagation delays to improve the network throughput.he protocol is based on framed ALOHA and enables nodes to learn an optimal transmission strategy in a fully distributed manner without requiring detailed information about the external environment. The transmission strategy of sensor nodes is defined as a combination of time-slot and transmission-offset selection. By relying on the concept of learning through interaction with the environment, the proposed protocol enhances network resilience and adaptability. In both static and mobile network scenarios, it has been compared with the state-of-the-art framed ALOHA for the underwater environment (UW-ALOHA-Q), carrier-sensing ALOHA (CS-ALOHA), and delay-aware opportunistic transmission scheduling (DOTS) protocols. The simulation results show that the proposed solution leads to significant channel utilization gains, ranging from 13% to 106% in static network scenarios and from 23% to 126% in mobile network scenarios.oreover, using a more efficient learning strategy, it significantly reduces convergence time compared to UW-ALOHA-Q in larger networks, despite the increased action space.

Survey of Reinforcement-Learning-Based MAC Protocols for Wireless Ad Hoc Networks with a MAC Reference Model.

In this paper, we conduct a survey of the literature about reinforcement learning (RL)-based medium access control (MAC) protocols. As the scale of the wireless ad hoc network (WANET) increases, traditional MAC solutions are becoming obsolete. Dynamic topology, resource allocation, interference management, limited bandwidth and energy constraint are crucial problems needing resolution for designing modern WANET architectures. In order for future MAC protocols to overcome the current limitations in frequently changing WANETs, more intelligence need to be deployed to maintain efficient communications. After introducing some classic RL schemes, we investigate the existing state-of-the-art MAC protocols and related solutions for WANETs according to the MAC reference model and discuss how each proposed protocol works and the challenging issues on the related MAC model components. Finally, this paper discusses future research directions on how RL can be used to enable MAC protocols for high performance.

Node Classification-Based Bandwidth Allocation: A New Scheduling Algorithm for TDMA-Based LANs

Local area networks often comprise nodes that run applications that belong to different traffic classes, with each class having different bandwidth requirements. Traditional Medium Access Control (MAC) protocols treat all nodes in the same manner. This may lead to a disproportionate allocation of bandwidth to the nodes and, consequently, to significant performance degradation. In this paper, a new MAC algorithm, is presented, that allocates different amounts of bandwidth to the nodes according to their traffic class. The bandwidth allocated to the nodes of each traffic class is proportional to the bandwidth requirements of the nodes of that class. The performance of the proposed Node Classification-based Bandwidth Allocation (NCBA) algorithm is studied via extensive simulation results, which indicate that it achieves a significant performance improvement compared to the well-known TDMA scheme. Overall, the new protocol achieves higher throughput, lower delay and exhibits a higher delay Fairness compared to TDMA for various network configurations, under asymmetric bursty traffic.

An intelligent hybrid MAC protocol for a sensor-based personalized healthcare system

Sensors based on personalized healthcare systems have been widely used in the medical field. However, energy limitations have greatly hindered the further development of medical sensors. For the traditional Medium Access Control (MAC) protocol, the duration of low-power listening is fixed because it ignores that the available energy of sensors is different in some situations, which leads to a high delay and low energy utilization. In this paper, a Maximum Listening Length MAC (MLL-MAC) protocol is proposed to fully utilize the energy in the sensor-based systems. The MLL-MAC protocol is an improvement of the Receiver-Initiated (RI) MAC protocol. The main advance is that the sensor node performs the following additional operations: (1) The sender sends a beacon when it wakes up and sends data, thus establishing a communication link with the receiver in the listening state; (2) The receiver keeps listening as long as possible to reduce the delay when it wakes up and listens to the channel, which is different from the previous strategy in which the node turns into a sleep state immediately without receiving data. Furthermore, the sensor node can dynamically determine whether to send beacons and prolong listening duration according to its available energy level. The MLL-MAC protocol is evaluated through theoretical analysis and experimental results. The results show that, compared with the RI-MAC protocol, the MLL-MAC protocol can reduce the average end-to-end delay by 41.4% and improve the energy utilization by 15.1%.

Research on the multi-channel operation of MAC protocol in wireless sensor networks

This paper briefly introduced Wireless Sensor Network (WSN) and the competitive Medium Access Control (MAC) protocol for assisting the multi-channel operation in WSN. Then, the avoidance operation of the traditional competitive MAC protocol was improved. The WSN that adopted two MAC protocols was simulated in the MATLAB software, and the performance of WSN under different node number was tested. The results showed that the WSN that adopted the traditional MAC protocol had decreased throughput and channel utilization and increased average time delay with the increase of node number in the WSN; the WSN that adopted the improved MAC protocol had decreased throughput and relatively stable average time delay and channel utilization with the increase of node number in the WSN; under the same number of nodes, the WSN that adopted the improved MAC protocol had higher throughput and channel utilization and lower average time delay.

A Q-Learning-Based Adaptive MAC Protocol for Internet of Things Networks

In Internet of Things (IoT) applications, sometimes the quality of service (QoS) of throughput for transmitting video or the QoS of bounded delay for control of a sensor node is required. A traditional contention-based medium access control (MAC) protocol cannot meet the adaptive traffic demands of these networks and confers delay-related constraints. Q-learning (QL) is one of the reinforcement learning (RL) mechanisms and can potentially be the future machine learning scheme for spectrum MAC protocols in IoT networks. In this study, a QL-based MAC protocol is proposed to facilitate adaptive adjustment of the length of the contention period in response to the ongoing traffic rate in IoT networks. The novelty of QL-based MAC lies in its use of RL to dynamically adjust the length of the contention period according to the traffic rate. The QL-based MAC will solve the models without additional input information to adapt to environmental variations during training. We confirm that the proposed QL-based MAC protocol with node contention is robust. In addition, we showed that our proposed QL-based MAC protocol has higher system throughput, lower end-to-end delay, and lower energy consumption in MAC contention than those of contention-based MAC protocols.

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.

DCN-MAC: A Dynamic Channel Negotiation MAC Mechanism for Underwater Acoustic Sensor Networks.

In the design of media access control (MAC) mechanism in underwater acoustic sensor networks (UASNs), due to the propagation characteristic of low-speed underwater acoustic signals, it is necessary to solve the spatial–temporal uncertainty problem. In order to avoid the multi-user access conflict in underwater networks, reduce the energy cost and improve the throughput and fairness across the network, a dynamic channel negotiation MAC mechanism based on spatial–temporal mapping of receiving queue (DCN-MAC) was proposed. DCN-MAC uses a duty cycle mechanism and implements a network management based on dynamic single node wake-up. The awakening node collects the request to send (RTS) and network status information in the network to solve the problem of space-temporal uncertainty and the highly dynamic needs of network access nodes and access services. The simulation results show that in different network scenarios, especially in those featuring high density and heavy network load, compared with the traditional underwater acoustic network MAC protocols, this protocol can effectively improve the network throughput and reduce the packet loss probability caused by multi-node conflict.

Improving Medium Access Efficiency With Intelligent Spectrum Learning

Through machine learning, this paper changes the fundamental assumption of the traditional medium access control (MAC) layer design. It obtains the capability of retrieving the information even the packets collide by training a deep neural network offline with the historical radio frequency (RF) traces and inferring the STAs involved collisions online in near-real-time. Specifically, we propose a MAC protocol based on intelligent spectrum learning for the future wireless local area networks (WLANs), called SL-MAC. In the proposed MAC, an access point (AP) is installed with a pre-trained convolutional neural network (CNN) model to identify the stations (STAs) involved in the collisions. In contrast to the conventional contention-based random medium access methods, e.g., IEEE 802.11 distributed coordination function (DCF), the proposed SL-MAC protocol seeks to schedule data transmissions from the STAs suffering from the collisions. To achieve this goal, we develop a two-step offline training algorithm enabling the AP to sense the spectrum with the aid of the CNN. In particular, on receiving the overlapped signal(s), the AP firstly predicts the number of STAs involving collisions and then further identifies the STAs' ID. Furthermore, we analyze the upper bound of throughput gain brought by the CNN predictor and investigate the impact of the inference error on the achieved throughput. Extensive simulations show the superiority of the proposed SL-MAC and allow us to gain insights on the trade-off between performance gain and the inference accuracy.

Full-duplex medium access control protocols in wireless networks: a survey

Medium Access Control (MAC) protocol plays an important role in full-duplex wireless networks. Theoretically, full-duplex communications have this ability to increase the capacity of traditional half-duplex wireless systems by up to twice. However, designing and implementing an efficient MAC protocol is a central issue in this way. Increasing throughput, collision avoidance, and fairness are common challenges in designing an efficient full-duplex MAC protocol. After giving a short introduction to the general classification of traditional MAC protocols, IEEE 802.11 MAC protocol, and the identified challenges of full-duplex communications in wireless networks, this review paper provides a comprehensive survey of current major MAC protocols for full-duplex wireless communications and classifies them in to three categories i.e. distributed wireless local area networks, centralized wireless local area networks, and other types of networks. This paper also explores and gives a comparative analysis of current full-duplex MAC protocols with stating their advantages and disadvantages as well as comparing them one with another.

Throughput performance of NOMA in WLANs with a CSMA MAC protocol

The existing medium access control (MAC) protocols are not able to utilize the full opportunities from power-domain non-orthogonal multiple access (NOMA) technique in wireless local area networks (WLANs). In this paper, we propose a carrier sense multiple access (CSMA) MAC protocol to increase downlink throughput by utilizing the opportunities offered by NOMA technique in downlink access of WLANs. For downlink transmission, an algorithm is developed to select an optimal user-set with appropriate power allocation from a randomly selected user-set. We then develop an analytical model to compute the uplink and downlink throughputs of a WLAN under the proposed MAC protocol by modelling the WLAN system as a discrete time Markov chain. The uplink and downlink throughputs of a WLAN under the proposed MAC protocol are determined by means of the analytical model and the accuracy of the analytical model is verified via extensive simulation. It is demonstrated that the proposed NOMA based MAC protocol improves the downlink throughput significantly compared to an orthogonal multiple access (OMA) based traditional CSMA MAC protocol without reducing the uplink throughput considerably. For a reasonable configuration, the downlink throughput gain is found to be more than 250%. We also study the throughput performance of the proposed MAC protocol for different transmit power levels, user medium access rates, data rates, path loss exponents and number of users in WLAN. We find that the throughput gain obtained by the proposed MAC protocol increases with increasing the transmit power and decreases with increasing the data rates and path loss. However, the change in the throughput gain obtained by the proposed MAC protocol is not significant for increasing the number of users and the user medium access rate.

A Full-Duplex MAC Tailored for 5G Wireless Networks

The increasing demands for high-data rate traffic stimulated the development of the fifth-generation (5G) mobile networks. The envisioned 5G network is expected to meet its challenge by devising means to further improve spectrum usage. Many alternatives to enhance spectrum usage are being researched, such as massive MIMO, operation in mmWave frequency, cognitive radio, and the employment of full-duplex antennas. Efficient utilization of the potential of any of these technologies faces a set of challenges related to medium access control (MAC) schemes. This work focuses on MAC schemes tailored for full-duplex antennas, since they are expected to play a major role in the foreseeable 5G networks. In this context, this paper presents a MAC layer technique to improve total transmission time when full-duplex antennas are employed. Several evaluations in different scenarios are conducted to assess the proposed MAC scheme. Numerical results show that the proposed scheme provides gains up to 156% when compared to a state-of-the-art full-duplex antenna MAC protocol. Compared to traditional half-duplex antenna MAC protocols, the proposed scheme yields gain up to 412%.

Location based transmission using a neighbour aware with optimized EIFS MAC for ad hoc networks

In a typical Ad Hoc network, participating nodes have scarce shared bandwidth and limited battery life resources, so resource optimization and enhancing the overall network performance are the primary aims to maintain functionality. This paper proposes a new cross layer Medium Access Control (MAC) algorithm called Location Based Transmission using a Neighbour Aware with optimized Extended Inter-Frame Spacing (EIFS) for Ad Hoc Networks MAC (LBT-NA with optimized-EIFS MAC) that aims to reduce the transmission power when communicating with the next hop receiver based on node's location which is made available during node deployment. However, node mobility is not taken into account in the study of this paper. According to the algorithm the node dynamically adjusts its transmission power, if there is an active neighbour located beyond the communicating source and destination pair to avoid hidden nodes. The new protocol also defines an optimized EIFS when frame collision, frame error or frame capture takes place, in-order to maintain a fair channel access among the contending nodes. The proposed MAC also uses a modified range of random backoff values, based on the degree of contention unlike IEEE 802.11 series which uses a fixed random backoff value for fresh frames irrespective of the degree of contention. Simulation results indicate that in a random topology with a random source and destination, when the two sources are separated by a minimum distance of 200m, the performance gain of power controlled MAC over IEEE 802.11b ranges from 30% to 70% depending on the type of traffics in the network and the degree of fairness ranges from 62% to 99.99% for a location based MAC with minimum power transmission, whereas LBT-NA with optimized-EIFS MAC secures fairness index ranging from 75% to 99.99%. Communication with a node that is 20m away can save 40% of the battery life in comparison to the traditional transmission power MAC from 802.11b. The validation tests demonstrate that the proposed algorithm increases battery life and reduces the interference impact on shorter distance communication and increases the probability of parallel transmission. The proposed protocol also provides a scope for active nodes to transmit with a higher degree of probability, providing higher degree of overall network throughput in the environment and alleviate the starvation of hidden node by using Dynamic EIFS scheme.

Dynamic time slot allocation and stream control for MIMO STDMA in ad hoc networks

Multiple-input multiple-output (MIMO) technologies have been shown to potentially improve the performance of network. Many traditional medium access control (MAC) protocols, such as spatial time division multiple access (STDMA), may not support MIMO technologies directly and not make full use of the feature of MIMO, which may be a limitation in the practical application in ad hoc networks. Therefore, in this paper, we propose a dynamic time slot allocation and stream control for MIMO STDMA (DTSMS) protocol to improve STDMA in performance. Utilizing stream control technology of MIMO and reservation scheme, DTSMS makes improvement on network throughput and avoids the mutual interference of neighbor links. Thus, DTSMS can support both unicast and multicast simultaneously. Moreover, we implement the dynamic time slot allocation scheme in DTSMS to guarantee the transmission efficiency of packets with high cross-layer transmission parameters, such as the packet priority, neighbor node density, or link quality. Utilizing the collected cross-layer information, the proposed scheme allocates time slots for all nodes dynamically according to the changes of network topology and nodes’ transmission parameters. Finally, the effectiveness of the protocol is demonstrated by numerical analysis and simulations. The results show that DTSMS outperforms STDMA in terms of network throughput and delay. Furthermore, compared to our previous TTS-MIMO, DTSMS can decrease the delay of packets with high transmission parameters and improve the quality of service (QoS).

Potential of Wake-Up Radio-Based MAC Protocols for Implantable Body Sensor Networks (IBSN)-A Survey.

With the advent of nano-technology, medical sensors and devices are becoming highly miniaturized. Consequently, the number of sensors and medical devices being implanted to accurately monitor and diagnose a disease is increasing. By measuring the symptoms and controlling a medical device as close as possible to the source, these implantable devices are able to save lives. A wireless link between medical sensors and implantable medical devices is essential in the case of closed-loop medical devices, in which symptoms of the diseases are monitored by sensors that are not placed in close proximity of the therapeutic device. Medium Access Control (MAC) is crucial to make it possible for several medical devices to communicate using a shared wireless medium in such a way that minimum delay, maximum throughput, and increased network life-time are guaranteed. To guarantee this Quality of Service (QoS), the MAC protocols control the main sources of limited resource wastage, namely the idle-listening, packet collisions, over-hearing, and packet loss. Traditional MAC protocols designed for body sensor networks are not directly applicable to Implantable Body Sensor Networks (IBSN) because of the dynamic nature of the radio channel within the human body and the strict QoS requirements of IBSN applications. Although numerous MAC protocols are available in the literature, the majority of them are designed for Body Sensor Network (BSN) and Wireless Sensor Network (WSN). To the best of our knowledge, there is so far no research paper that explores the impact of these MAC protocols specifically for IBSN. MAC protocols designed for implantable devices are still in their infancy and one of their most challenging objectives is to be ultra-low-power. One of the technological solutions to achieve this objective so is to integrate the concept of Wake-up radio (WuR) into the MAC design. In this survey, we present a taxonomy of MAC protocols based on their use of WuR technology and identify their bottlenecks to be used in IBSN applications. Furthermore, we present a number of open research challenges and requirements for designing an energy-efficient and reliable wireless communication protocol for IBSN.

Performance optimization of duty‐cycled MAC in delay‐energy constrained sensor network under uniform and nonuniform traffic generation

SummaryDuty‐cycle at the media access control (MAC) layer plays a key role in energy savings and network lifetime extension. It consists in putting a node's radio in the sleep state as soon as it has no communication activity. Traditional wireless sensor network MAC protocols are designed with short duty‐cycles at the cost of long delays. Careful design is required for joint energy‐delay constrained applications, where the optimal parameters should be thoroughly derived. The present paper deals with this issue and mathematically derives optimal values of key MAC parameters under low data rate applications for 3 well‐known duty‐cycled MAC protocols, WiseMAC, SCP‐MAC, and LMAC as representatives of 3 MAC protocol categories, respectively, preamble‐sampling, slotted contention‐based, and frame‐based. The analysis provides also the optimum traffic sampling rate that guarantees the minimum energy consumption. It shows the role of these parameters in achieving the targeted end‐to‐end delay constraints under network models with uniform traffic generation, for ring and grid topologies. As a second contribution, the model is extended to nonuniform traffic scenarios, where a certain percentage of deployed nodes are relays whose role is to balance traffic forwarding and save the overall network energy. The results reveal that different optimal internal MAC parameters and traffic generation rates can be found for different configurations of relay nodes deployment, which achieve minimal network energy consumption while satisfying the application required end‐to‐end delay threshold.

DAP-MAC: A delay-aware probability-based MAC protocol for underwater acoustic sensor networks

The long propagation delay of underwater acoustic communications has made traditional handshaking-based medium access control (MAC) protocols inefficient for underwater sensor networks (UWSNs). We envision that this unique feature, although often taken as negative, can be leveraged to improve the parallelism between multiple senders, i.e., transmitting data simultaneously so as to achieve higher channel utilization. In this paper, we propose a novel Delay-Aware Probability-based MAC protocol, DAP-MAC, which eliminates the handshaking process and utilizes concurrent transmissions to significantly improve the network throughput. Compatibility relation among senders based on their distances to the common receiver is derived at run-time. A utility-optimization framework uses this compatibility relation to determine the best transmission strategies for senders. Our extensive simulations demonstrate that DAP-MAC achieves better system throughput than the existing representative underwater MAC protocols.

An On-Demand Emergency Packet Transmission Scheme for Wireless Body Area Networks.

The rapid developments of sensor devices that can actively monitor human activities have given rise to a new field called wireless body area network (BAN). A BAN can manage devices in, on and around the human body. Major requirements of such a network are energy efficiency, long lifetime, low delay, security, etc. Traffic in a BAN can be scheduled (normal) or event-driven (emergency). Traditional media access control (MAC) protocols use duty cycling to improve performance. A sleep-wake up cycle is employed to save energy. However, this mechanism lacks features to handle emergency traffic in a prompt and immediate manner. To deliver an emergency packet, a node has to wait until the receiver is awake. It also suffers from overheads, such as idle listening, overhearing and control packet handshakes. An external radio-triggered wake up mechanism is proposed to handle prompt communication. It can reduce the overheads and improve the performance through an on-demand scheme. In this work, we present a simple-to-implement on-demand packet transmission scheme by taking into considerations the requirements of a BAN. The major concern is handling the event-based emergency traffic. The performance analysis of the proposed scheme is presented. The results showed significant improvements in the overall performance of a BAN compared to state-of-the-art protocols in terms of energy consumption, delay and lifetime.

Access granularity control of multichannel random access in next-generation wireless LANs

As the next-generation Wireless LANs (WLANs) will provide the ubiquitous high-data-rate network coverage, the traditional contention-based Medium Access Control (MAC) scheme may be unable to fulfill the requirement of efficient channel access. To address this problem, several research works have proposed the random access systems combined with Orthogonal Frequency Division Multiplex Access (OFDMA) technology. Access granularity control is a crucial issue in this combination. Specifically, this issue focuses on how to tune the subchannel bandwidth and the number of accessible subchannels towards the maximum channel utilization. This paper analyzes access granularity control in an OFDMA system that adopts a multichannel Carrier Sensing Multiple Access (CSMA) MAC and resolves contention by the frequency-domain backoff. The theoretical analysis verifies the significance of access granularity control. In addition, the simulation experiments demonstrate that the proposed dynamic access granularity control algorithms notably outperform the traditional ones that divide channel band statically and adjust the number of accessible subchannels empirically.