Multiple Access Control Protocol Research Articles

The Design of Clustering Algorithm and MAC Protocol for Low Delay Underwater Acoustic Sensor Networks

Underwater acoustic sensor networks (UASNs), which are popular in various application fields, including marine resources development, environmental exploration, seismic monitoring, etc., have made great progress in recent years. To maintain good scheduling performance, clustering algorithms and multiple access control (MAC) protocols have been widely used in sensor networks to improve network efficiency. However, the existing algorithms and protocols still have many shortcomings. For example, many clustering algorithms consider the delay performance little, the cluster structures are not always fully utilized by MAC protocols, and the cluster maintenance strategies are not considered. This article is devoted to solving those problems. By taking the node traffic and distances into account simultaneously, we design the cluster structure reasonably. And based on this structure, we plan a conflict-free handshake protocol with minimal idle time gaps. Besides, we also design a joining-cluster strategy for the free nodes to maintain the network without interference. Simulation results show that our work can perform well in network uniformity and end-to-end delay.

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

A TDMA-Based Data Gathering Protocol for Molecular Communication via Diffusion-Based Nano-Sensor Networks

This paper explores the application of molecular communication via diffusion-based nano-sensor networks (MCSNs) for data gathering applications in in-body medical systems. For MCSNs, the large and varying propagation delay in the channel presents a fundamental challenge for channel access, leading to packet collisions. Although packet collisions are well-studied for traditional wireless sensor networks, to date, there are no such studies conducted for MCSNs. Another fundamental challenge is the limited capabilities of the nano-sensors, rendering the existing solutions inefficient. Therefore, a novel light-weight time-division multiple access (TDMA)-based data gathering multiple access control (MAC) protocol is proposed. Light-weight here implies that long information, such as timestamps, is not exchanged. TDMA-based here implies that each nano-sensor is designated an exclusive time-slot. The lack of a channel model for spherical transmitters impairs theoretical analysis of the probability of packet collisions. To overcome this, the propagation delay is approximated as a Normal distribution. The model is validated using the widely popular particle-based simulation, which is also used to determine the packet duration considering ON-OFF shift keying. Building upon these analyses, a system-level simulator is developed to evaluate the proposed MAC protocol. For the first time, the packet collision probability is characterized under varied distances and diffusion coefficients. A key finding is the correlation between the channel utilization and the time-slot occupancy ratio, which can be used as a tool to optimize the performance of an MCSN. Finally, comparisons with conventional TDMA reveals that the proposed protocol can offer better performance.

A collision feedback based multiple access control protocol for very high frequency data exchange system in E-navigation

AbstractThe very high frequency data exchange system (VDES) is promising in promoting electronic navigation (E-navigation) and improving navigation safety. The multiple access control (MAC) protocol is crucial to the transmission performance of VDES. The self-organising time division multiple access (SOTDMA) protocol, as the only access mode given by current recommendations, leads to a high rate of transmission collisions in the traditional automatic identification system (AIS), especially with heavy traffic loads. This paper proposes a novel feedback based time division multiple access (FBTDMA) protocol to address the problems caused by SOTDMA, such that collision of transmissions can be avoided in information transmission among vessels. Simulation results demonstrate that the proposed FBTDMA outperforms the traditional SOTDMA in terms of channel utilisation and throughput, and significantly reduces the transmission collision rate. The study is expected to provide insights into VDES standardisation and E-navigation modernisation.

RECCE: Deep Reinforcement Learning for Joint Routing and Scheduling in Time-Constrained Wireless Networks

Time Division Multiple Access-based Medium Access Control protocols tend to be the choice for wireless networks that require deterministic delay guarantees, as is the case in many Industrial Internet of Things (IIoT) applications. As the optimal joint scheduling and routing problem for multi-hop wireless networks is NP-hard, heuristics are generally used for building schedules. However, heuristics normally result in sub-optimal schedules, which may result in packets missing their deadlines. In this paper, we present RECCE, a deep REinforcement learning method for joint routing and sCheduling in time-ConstrainEd networks with centralised control. During training, RECCE considers multiple routes and criteria for scheduling in any given time slot and channel in a multi-channel, multi-hop wireless network. This allows RECCE to explore and learn routes and schedules to deliver more packets within the deadline. Simulation results show that RECCE can reduce the number of packets missing the deadline by as much as 55% and increase schedulability by up to 30%, both relative to the best baseline heuristic. RECCE can deal well with dynamic network conditions, performing better than the best baseline heuristic in up to 74% of the scenarios in the training set and in up to 64% of scenarios not in the training set.

Performance Analysis and Optimization for the MAC Protocol in UAV-Based IoT Network

Unmanned aerial vehicles (UAVs) have played an important role in air-ground integration network. Especially in Internet of Things (IoT) services, UAV equipped with communication equipments is widely adopted as a mobile base station (BS) for data collection from IoT devices on the ground. In this paper, we consider an air-ground network in which the UAV flies straightly to collect information from the IoT devices in a 2-D plane based on the CSMA/CA protocol. Due to UAV's continuous mobility, the communication durations of devices in different locations with UAV are not only time-limited, but also vary from each other. To analyze the throughput performance of uplink multiple access control (MAC) protocol, we propose a new analysis model to deal with the communications heterogeneity in the network. Firstly, we divide the devices in the coverage into different clusters according to their communication durations. Then, a quitting probability indicating the probability that a device quits the UAV's coverage at each time slot is clarified. A modified three-dimensional Markov chain model adopting the quitting probability and cluster division is developed for the performance analysis. Besides, we also propose a modified CSMA/CA protocol which fully considers the heterogeneity of the access time and adaptively allocates the time resource among the devices in different clusters. Finally, the effects of retry limit, initial contention window size, the density of the devices, UAVs speed and coverage area are discussed in the simulation section.

A Spatial Group-Based Multi-User Full-Duplex OFDMA MAC Protocol for the Next-Generation WLAN.

The Wireless Local Area Network (WLAN) has become a dominant piece of technology to carry wireless traffic for Internet of Things (IoT). The next-generation high-density WLAN scenario is very suitable for the development trend of the industrial wireless sensor network. However, in the high-density deployed WLAN scenarios, the access efficiency is low due to severe collisions, and the interference is diffused due to the scattered locations of the parallel access stations (STAs), which results in low area throughput, i.e., low spatial reuse gain. A spatial group-based multi-user full-duplex orthogonal frequency division multiple access (OFDMA) (GFDO) multiple access control (MAC) protocol is proposed. Firstly, the STAs in the network are divided into several spatial groups according to the neighbor channel sensing ability. Secondly, a two-level buffer state report (BSR) information collection mechanism based on P-probability is designed. Initially, intra-group STAs report their BSR information to the group header using low transmission power. After that, group headers report both their BSR information collected from their members and inter-group interference information to the access point (AP). Finally, AP schedules two spatial groups without mutual interference to carry on multi-user full duplex transmission on the subchannels in cascading mode. The closed-form formulas are theoretically derived, including the number of uplink STAs successfully collected by AP, the network throughput and area throughput under saturated traffic. The simulation results show that the theoretical analysis coincide with the simulation results. The system throughput of the GFDO protocol is 16.8% higher than that of EnFD-OMAX protocol.

A Distributed Ambient Backscatter MAC Protocol for Internet-of-Things Networks

Ambient backscatter communication enabling device-to-device (D2D) communications via the ambient radio frequency (RF) signal has revealed its numerous application potential in the Internet-of-Things (IoT) networks. However, the work on the link layer for the backscatter communication is in its infancy due to the constraints of ultralow power and cost in such a system, especially a channel access protocol in the backscatter communication system for IoT networks is rarely mentioned. In this article, a distributed multiple access control (MAC) protocol is presented, which allows multiple backscatter devices (BDs) to connect with each other by relying on the ambient RF signal. By combining an analog channel sensing strategy with the dual-backoff mechanism, each BD can switch among the transmission, receiving, and energy harvesting (EH) states. Specifically, each BD starts a randomly designated time for EH once the channel is sensed to be busy. As the timer expires, the BD ceases the EH and continues its sensing and backoff procedures. With the consideration of the false alarm and the miss detection problems occurring while sensing, an enhanced 3-D Markov model is built to analyze the saturation throughput performance of the proposed MAC protocol. Extensive simulations verify the analysis and demonstrate the advantage of the proposed backscatter MAC protocol.

An efficient multiple access control protocol for directional dense urban traffic surveillance system

Artificial intelligence (AI) methods for traffic video analysis have been widely identified as potential solutions for solving hard problems in intelligent transport systems (ITS). To exploit the advantages of AI, dense cameras to monitor the traffic are required to be deployed along the road and at the intersections. The captured videos of these cameras should be back-hauled to the control center, acting as the inputs of the AI methods. To bear such large data traffic load and to cover long transmission range, directional communication technology can be employed, which concentrate the energy of the wireless signal in a specified direction to provide high data rate and long transmission range (up to hundreds of kilometers). In this paper, the communication time extension problem (CTEP) is identified when directional transmission is applied to the dense urban traffic surveillance system, where the wireless signal propagation time approximates the data transmission time. A link distance division-based time division multiple access (LDD-TDMA) protocol is proposed to address the identified CTEP. Firstly, the directional wireless communication links are classified into categories according to the link distance, where nodes located in the same communication ring belong to the same category. Then a link distance aware (LDA)-based slot allocation algorithm is proposed to assign the time slots to the links. The optimal communication rings’ radius is derived in closed form formula, and the minimum average links’ distance is derived. Simulation results show that LDD-TDMA outperforms TDMA by 13.37% when the ring number is 4.

Implementation and performance analysis of random multiple access protocol with variable collision length of multimedia video information

In recent years, multimedia video services have developed rapidly. However, the increasing number and variety of videos is likely to cause packet loss and delay during video transmission. Therefore, how to use channel resources more effectively becomes an urgent problem to be solved. This paper improves the existing random multiple access protocol and designs the 1-persistent CSMA (Carrier Sense Multiple Access) protocol with variable collision length. At the same time, considering the different requirements of different video services, multi-priority 1-persistent CSMA random multiple access control protocol with variable collision length is proposed, which sets different priorities and then competes fairly. Finally, the paper analyzes the performance of the multimedia video service access algorithm: the 1-persistent CSMA access protocol with variable collision length is higher than the traditional 1-persistent CSMA throughput, the performance is better, at the same time, in the case of a relatively high arrival rate, the advantage of throughput is more obvious.

A Black-Burst Based Time Slot Acquisition Scheme for the Hybrid TDMA/CSMA Multichannel MAC in VANETs

In the hybrid time division multiple access (TDMA)/carrier sense multiple access multichannel medium access control protocols for vehicular ad hoc networks, each vehicle randomly selects a time slot from available ones for the transmission of safety message in the TDMA-based part. However, the access collision will occur when two or more vehicles within two-hop range of each other attempt to acquire an identical idle slot, which degrades the performance of access process. In this letter, we propose a novel time slot acquisition scheme based on jamming signal, also known as black-burst. To reduce access collisions, each vehicle tries to send a randomly shifted black-burst to inform its one and two hop neighbors when it reserves an idle time slot. Simulation results show that the proposed scheme outperforms the state-of-the-art scheme in terms of time slot acquisition efficiency.

Intruder Attacks on Wireless Sensor Networks: A Soft Decision and Prevention Mechanism

Because of the wide-ranging of applications in a variety of fields, such as medicine, environmental studies, robotics, warfare and security, and so forth, the research on wireless sensor networks (WSNs) has attracted much attention recently. WSNs offer economical, flexible, scalable and pragmatic solutions in many situations. Sensor nodes are tiny and have a limited, non-rechargeable battery source, small memory/computational abilities and low transmitter power. Energy resources are vital as once the battery is depleted, the node is no longer usable. Multiple medium access control (MAC) protocols are designed to increase the life cycle of a node by minimizing its unnecessary energy consumption. In some critical applications like the surveillance of enemy movements on a battlefield, opponents deploy adversary nodes to disturb the performance of WSNs by mainly depleting the battery sources of legitimate nodes. In this work, an intrusion detection mechanism has been adapted to detect different kinds of intruders’ attacks in MAC protocols of WSN’s. A soft decision mechanism has been implemented to detect collision and exhaus-tion attacks. A preventative mechanism has also been introduced, which helps a node to avoid these intrusive attacks. Results show how the lifetime of a node increases and network performance also increases with better throughput and reduced delay.

Multiple Access Control for Cognitive Radio-Based IEEE 802.11ah Networks

The proliferation of Internet-of-Things (IoT) technology and its reliance on the license-free Industrial, Scientific, and Medical (ISM) bands have rendered radio spectrum scarce. The IoT can nevertheless obtain great advantage from Cognitive Radio (CR) technology for efficient use of a spectrum, to be implemented in IEEE 802.11af-based primary networks. However, such networks require a geolocation database and a centralized architecture to communicate white space information on channels. On the other hand, in spectrum sensing, CR presents various challenges such as the Hidden Primary Terminal (HPT) problem. To this end, we focus on the most recently released standard, i.e., IEEE 802.11ah, in which IoT stations can first be classified into multiple groups to reduce collisions and then they can periodically access the channel. Therein, both services are similarly supported by a centralized server that requires signaling overhead to control the groups of stations. In addition, more regroupings are required over time due to the frequent variations in the number of participating stations, which leads to more overhead. In this paper, we propose a new Multiple Access Control (MAC) protocol for CR-based IEEE 802.11ah systems, called Restricted Access with Collision and Interference Resolution (RACIR). We introduce a decentralized group split algorithm that distributes the participating stations into multiple groups based on a probabilistic estimation in order to resolve collisions. Furthermore, we propose a decentralized channel access procedure that avoids the HPT problem and resolves interference with the incumbent receiver. We analyze the performance of our proposed MAC protocol in terms of normalized throughput, packet delay and energy consumption with the Markov model and analytic expressions. The results are quite promising, which makes the RACIR protocol a strong candidate for the CR-based IoT environment.

On the successful transmission probability of cooperative cognitive radio ad hoc networks

We study the successful transmission probability of cognitive radio ad hoc networks in which secondary users assist primary users on transmitting packets. We propose a half-slotted ALOHA multiple access control protocol. Primary transmitters sacrifice second half slot for the reliability improved by the cooperative transmission of secondary users. We derive the closed-form expression of successful transmission probability for both primary and secondary network in the first-half slot. In the second half, we obtain the bounds of successful transmission probability for primary network and the closed-form expression of successful transmission probability for secondary network. Numerical results show that the successful transmission probability of both networks could achieve a maximum by optimizing the intensity of secondary users in the whole time slot.

Operational State Scheduling of Relay Nodes in Two-Tiered Wireless Sensor Networks

Operation state scheduling of relay nodes (RNs) in two-tiered wireless sensor networks is the focus of this paper. From multiple access control (MAC) viewpoint, scheduling of transmit, receive, and sleep operation states of RNs is formulated as an optimization problem under the objective of energy cost minimization. This problem is computationally intractable to solve optimally for practical problem sizes. With the perspective of a synchronous and schedule access MAC protocol, the problem is tackled using dual decomposition, and the solution is achieved collaboratively by RNs continually over time. To make the solution practically possible, a stochastic approximation iteration is provided, which results in an energy-aware MAC protocol with linear complexity. This protocol attains statistical convergence with respect to the time-varying channel state information in the time of its scope. Numerical results demonstrate the effectiveness of this protocol in terms of consumed energy in comparison with classical protocols as a result of eliminating idle listening in the network.

MAC Protocols Design for Smart Metering Network

The new generation of power metering system - i.e. Advanced Metering Infrastructure (AMI) - is expected to enable remote reading, control, demand response and other advanced functions, based on the integration of a new two-way communication network, which will be referred as Smart Metering Network (SMN). In this paper, we focus on the design principles of multiple access control (MAC) protocols for SMN. First, we list several AMI applications and its benefits to the current power grid and user experience. Next, we introduces several features of SMN relevant to the design choice of the MAC protocols, including the SMN architecture and candidate communication technologies. After that, we propose some performance evaluation metrics, such as scalability issue, traffic types, delay and etc, and give a survey of the associated research issues for the SMN MAC protocols design. In addition, we also note progress within the new IEEE standardization task group (IEEE 802.11ah TG) currently working to create SMN standards, especially in the MAC protocols aspect.

Grouping-Based MAC Protocols for EV Charging Data Transmission in Smart Metering Network

The next-generation advanced metering infrastructure, with the aid of two-way smart meters, is expected to support advanced functions such as remote reading and control and demand response. In this paper, we thus focus on the design of a smart metering network (SMN) for a future scenario where data from residences/customer premises are dominated by electric vehicle charging traffic. Therefore, the well-suited multiple access control (MAC) protocol design for such event-driven data is an emerging research area. However, because the number of smart meters (communication nodes) involved in such a single SMN is much larger than those in today's local area networks, the traditional random access MAC protocol is unlikely to perform well. In order to solve this problem, we propose two grouping-based MAC protocols, namely, TDMA-DCF and group leader DCF-TDMA schemes, in this paper. These two schemes are directed at 802.11-type networks operating at frequencies below 1 GHz, which has been adopted by a new IEEE 802.11ah standardization task group. We also conduct the comprehensive throughput and delay analysis on these schemes for unsaturated traffic conditions and hidden node events. The numerical results show that these two grouping-based MAC protocols significantly outperform the traditional random access protocol DCF in a densely populated network with large coverage such as SMN.

Adaptive low-power listening MAC protocol based on transmission rates.

Even though existing low-power listening (LPL) protocols have enabled ultra-low-power operation in wireless sensor networks (WSN), they do not address trade-off between energy and delay, since they focused only on energy aspect. However, in recent years, a growing interest in various WSN applications is requiring new design factors, such as minimum delay and higher reliability, as well as energy efficiency. Therefore, in this paper we propose a novel sensor multiple access control (MAC) protocol, transmission rate based adaptive low-power listening MAC protocol (TRA-MAC), which is a kind of preamble-based LPL but is capable of controlling preamble sensing cycle adaptively to transmission rates. Through experiments, it is demonstrated that TRA-MAC enables LPL cycle (LC) and preamble transmission length to adapt dynamically to varying transmission rates, compensating trade-off between energy and response time.

An event-driven WSN MAC protocol design based on active node and dynamic time slot allocation

The unique features of wireless sensor networks (WSNs) make them suitable for a wide range of applications in many different areas. However, with many of the protocols and algorithms used in traditional wireless networks, it is usually neither feasible nor possible to apply them directly to WSNs due to the strict resource constraints of tiny sensor nodes. Moreover, application-specific approaches for communication protocols are usually imposed since WSN applications have distinct requirements. In this study, event-driven WSN applications, where a number of sensor nodes are randomly and densely deployed in remote and difficult to reach locations, are targeted. In such applications, energy efficiency and latency are crucial design parameters since replacing or recharging the batteries of sensor nodes is extremely difficult, and any sensed data should be transmitted eventually. Considering this aspect, conventional time division multiple access-based medium access control (MAC) protocols are not well suited, although there are a few MAC protocols specifically designed for event-driven WSNs. In this paper, we introduce a MAC protocol, named modified bit-map--assisted (M-BMA), for event-driven WSN applications, designed by employing a new active node determination method (ANDM) and dynamic time slot allocation approach. Utilizing the proposed ANDM, we present that the M-BMA well supersedes its classical counterpart, offering up to approximately 49% better energy usage as well as up to about 68% fewer message delays.

On combining network coding with duty-cycling in flood-based wireless sensor networks

Network coding and duty-cycling are two major techniques for saving energy in wireless sensor networks. To the best of our knowledge, the idea to combine these two techniques for even more aggressive energy savings, has not been explored. This is not unusual, since these two techniques achieve energy efficiency through conflicting means, e.g., network coding saves energy by exploiting overhearing (i.e., nodes are awake), whereas duty-cycling saves energy by reducing idle listening (i.e., nodes sleep). In this article, we thoroughly investigate if network coding and duty cycling can be used together for more aggressive energy savings in flood-based wireless sensor networks.Our main idea is to exploit the redundancy sometimes present in flooding applications that use network coding, and put a node to sleep (i.e., duty cycle) when a redundant transmission takes place (i.e., the node has already received and successfully decoded a sequence of network-coded packets). We propose a scheme, called DutyCode, in which a multiple access control (MAC) protocol implements packet streaming and allows the network coding-aware application to decide when a node can sleep. We also present an algorithm for deciding the optimal coding scheme for a node to further reduce energy consumption by minimizing redundant packet transmissions. Finally, we propose an adaptive switching technique between DutyCode and an existing duty-cycling MAC protocol. We investigate our proposed solutions analytically and implement them on mote hardware. Our performance evaluation results, obtained from a 42-node indoor testbed, show that our scheme saves 30–46% more energy than network coding-based solutions.