Contention-free Medium Access Control Research Articles

TMPAD: Time-Slot-Based Medium Access Control Protocol to Meet Adaptive Data Requirements for Trusted Nodes in Fog-Enabled Smart Cities

The popularity of fog-enabled smart cities is increasing due to the advantages provided by modern communication and information technologies, which contribute to an improved quality of life. Wireless networks make them more vulnerable when the network is under malicious attacks that cause a collision in the medium. Furthermore, diverse applications of smart cities demand a contention-free medium access control (MAC) protocol to meet adaptive data requirements. In this work, a time-slot-based medium access control protocol to meet adaptive data requirements (TMPAD) for IoT nodes in fog-enabled smart cities is proposed. TMPAD proposes a trust mechanism to differentiate malicious and legitimate data requests. In addition, it accommodates more legitimate data-requesting nodes to transfer their data during a session by applying the technique for order performance by similarity to ideal solution (TOPSIS) and 0/1 knapsack algorithm. The performance of TMPAD is compared with well-known techniques such as first come first serve (FCFS), shortest job first (SJF), and longest job first (LJF) in different prospective scenarios. The results show that TMPAD scrutinizes more data-requesting nodes in slot allocation, allowing more data transmission in a session, with better mean trust value, as compared to other algorithms.

CAMELAMA: Cooperative awareness and spaceborne monitoring enabled by location-assisted medium access

In beaconing systems such as AIS or ADS-B, used by ships and aircraft, each node periodically broadcasts its navigational state to nearby nodes to increase traffic safety. Nowadays, these beacons are also used as a source for satellite-based global traffic monitoring. This dual use imposes competing needs on the medium access control protocol as the size of the collision domains varies by a large factor between the use cases. Even the subproblem of solely avoiding terrestrial nodes’ packets to collide from the perspective of a receiving satellite is not trivial to solve if the satellite’s collision domain spans multiple hops in the terrestrial network. Based on ideas of the LAMA protocol, we propose CAMELAMA, a novel contention-free medium access control protocol for position awareness beaconing. Our low-overhead approach uses neither forwarding of node state nor handshakes but only the navigational data that is shared between the terrestrial nodes anyway. CAMELAMA provides local cooperative awareness while at the same time desynchronizing transmissions within a satellite’s collision domain even in terrestrially disconnected topologies. In a simulation-based performance evaluation we find that CAMELAMA outperforms SO-TDMA (the MAC protocol of AIS) and also scales better with respect to high node densities.

Improvised Protocol for Enhancement of Security in Internet of Vehicles

Background: Vehicular Ad-Hoc Network (VANET) is integral to lessen road mishappenings and to effortlessly control huge traffic on highways. Numerous protocols are researched and implemented for creating a secure medium between vehicular nodes. Objective: One of the visible problems is the loss of data between the nodes, which leads to delay, collision, and accidents in the VANET. This paper investigates traffic security and safety problems faced in VANET and provides a solution for them. Methods: For analyses of traffic safety issues, 3 types of Medium Access Control (MAC) protocols were compared, namely Conventional, Contention-Based and Contention-Free MAC Protocols. Plentiful of performance metrics have been studied under the transportation security issues, including signal received with error, throughput, and MAC Overhead and Packet loss. Results and Conclusion: By comparing the MAC Protocols, it can be concluded that Contention-Free multi-channel SD-TDMA is better with a security mechanism for continuous and safe communication between the vehicular nodes. It can be utilized in moderate to heavy traffic scenarios to have faster and safe communication.

A survey on recent contention-free MAC protocols for static and mobile wireless decentralized networks in IoT

Medium Access Control (MAC) protocols for wireless decentralized networks in IoT have attracted a lot of attention in both academic and industrial fields. They aim to coordinate access among IoT devices to the shared wireless medium. More specifically, contention-free MAC protocols are known to be more efficient than contention-based ones in the case of high traffic load and dense networks. To face the main communication challenges between IoT devices such as collisions and conflicts as well as mobility, it is crucial to design an efficient MAC protocol. To do so, several solutions have been proposed in the literature. Among recent proposed solutions, Machine Learning (ML) algorithms and game theory models were used to revolutionize the communication in IoT networks, especially for devices with high mobility degree. In our survey, we first start by studying the challenges and requirements of communication in wireless networks. Then, we provide a comprehensive survey on recent contention-free MAC protocols existing in the literature. Next, we compare these solutions based on important metrics such as QoS, robustness, fairness etc., and discuss the relationship between MAC protocols, network type and network mobility. Finally, we investigate a future research direction to solve a major problem, which is the network disruption and delay tolerance in IoT wireless mobile networks.

Cluster-based interference-free MAC protocol with load aware in software defined VANET

In order to reduce the interference, a novel, cluster-based medium access control (MAC) protocol with load aware for VANETs is proposed in this paper. First, all vehicles on roads are grouped into stable clusters in the light of their direction, number of neighbors, link reliability, and traffic load. By utilizing the advantages of centralized control in software defined VANETs (SDVN), cluster stability can be maintained in real-time. Second, a contention-free MAC mechanism composed of inter-cluster multi-channel allocation and intra-cluster dynamic TDMA frame allocation is proposed to prevent co-channel interference and hidden terminal interference. Simulation results show that the proposed protocol outperforms some existing protocols in cluster stability, delivery ratio, throughput and delay performance.

Cooperative Coevolution Design of Multilevel Fuzzy Logic Controllers for Media Access Control in Wireless Body Area Networks

Fuzzy logic techniques have been successfully employed in wireless body area networks (WBANs) for media access control (MAC). However, most of the existing research work considered only single-level fuzzy logic controls (FLCs) for either contention-based or contention-free MAC, neglecting the importance of utilizing both contention-based and contention-free MAC to improve the reliability and performance of the network. This paper introduces a two-level FLC control scheme at both the coordinator level and the sensor level to further enhance communication quality in WBANs. The sensor-level FLC controls contention-based channel access and the coordinator-level FLC controls contention-free channel access. This two-level FLC architecture can effectively improve the cooperation between sensors and the coordinator such that both the performance and reliability of the network can be significantly improved. We also proposed a cooperative coevolutionary approach to design of our proposed two-level control scheme automatically. With the goal of effectively designing useful FLCs, we have particularly developed two new collaborator selection methods for our cooperative coevolutionary approach, which enable us to effectively select collaborators while evaluating the candidate FLC design in each subpopulation. Specifically, we demonstrate that, by employing network knowledge, our collaborator selection methods can judge the suitability of potential collaborator designs and notably improve the effectiveness of our evolutionary design approach. Empirically the FLCs designed by our approach clearly outperformed several state-of-the-art MAC schemes from recent literature and the IEEE 802.15.4 standard.

An Energy-Conserving Collision-Free MAC Protocol for Underwater Sensor Networks

An underwater sensor network (UWSN) has recently attracted considerable attention due to its ability to discover and monitor the aquatic environment. However, its acoustic communication has posed several inherent characteristics, such as high latency, low available bandwidth, and high bit error rate. These unique characteristics have made contention-based medium access control (MAC) protocols inefficient for UWSNs. They are most expensive and are not as effective as they are in terrestrial networks. Through this principle, a contention-free MAC protocol is, therefore, considered to be more reliable and flexible to overcome the consequences of applying acoustic signals and also to achieve a high performance (improving the energy efficiency and throughput across the network) by eliminating the chance of collision. In this paper, we propose a novel energy-conserving and collision-free depth-based layering MAC (DL-MAC) protocol for UWSNs. DL-MAC is able to deal with the underwater MAC challenges, such as the near-far effect, spatial-temporal uncertainty, and hidden/exposed terminal problems. It is able to efficiently schedule the transmission and reception operations in each side by using the concept of layering and a distributed clustering algorithm. By using a TDMA-based principle, DL-MAC can assign separate time slots to every sensor node individually to access the medium without any possibility of collision. Our extensive simulation study shows that DL-MAC outperforms other protocols in terms of throughput, packet delivery ratio, energy consumption, and packets lost under varying traffic rates and the numbers of nodes.

Hybrid centralised MAC protocol for reliable broadcast of safety messages in vehicular ad hoc network

Several medium access control (MAC) protocols were proposed to provide high-performance for vehicular ad hoc network (VANET). For instance, the contention-free MAC allows several vehicles to share the same communication channel. However, contention-based MAC protocols do not require any predefined schedule where each node competes for channel access when it needs to transmit data without any guarantee of success transmission. Hence, a hybrid MAC protocol that adopts time division multiple access (TDMA) and carrier sense multiple access (CSMA/CA) is required to enhance the network performance. Nevertheless, hybrid MAC protocols cannot ensure services differentiation so that critical messages and non-security messages have the same priority. To overcome such limitation, this paper focuses on the design of a novel access method integrating TDMA and enhanced distributed channel access (EDCA) in unique architecture called QoS-aware centralised hybrid MAC protocol (QCH-MAC). To prove the efficiency of our proposal, the latter was implemented in ns-3.

Cluster-Based Beaconing Process for VANET

In this paper we introduce the Cluster-Based Beacon Dissemination Process (CB-BDP) that aims to provide vehicles with a local vehicle proximity map of their vicinity. Based on this map, safety applications can be used for accident prevention by informing drivers about evolving hazardous situations. The CB-BDP is designed under the two following objectives. First, since it is used for safety applications, we want the map to be detailed and accurate as much as possible. Second, we want the map to be coordinated with nearby vehicles, thereby allowing synchronized and coordinated reactions of nearby vehicles to evolving hazardous situations. We design a cluster based aggregation–dissemination beaconing process that uses an optimized topology to distribute the vehicle proximity map. The topology is adaptive and robust in order to meet the challenging VANET conditions. An accurate and detailed map results in a heavy load of beacon messages. Our proposed scheme deals with this problem by integrating a contention-free medium access control (MAC) strategy for reliable communication.

A Hierarchical Time Division Multiple Access Medium Access Control Protocol for Clustered Underwater Acoustic Networks

A hierarchical time division multiple access (HTDMA) medium access control (MAC) protocol is proposed for clustered mobile underwater acoustic networks. HTDMA consists of two TDMA scheduling protocols (i.e., TDMA1 and TDMA2) in order to accommodate mobile underwater nodes (UNs). TDMA1 is executed among surface stations (e.g., buoys) using terrestrial wireless communication in order to share mobility information obtained from UNs which move cluster to cluster. TDMA2 is executed among UNs, which send data to their surface station as a cluster head in one cluster. By sharing mobility information, a surface station can instantaneously determine the number of time slots in a TDMA2 frame up to as many as the number of UNs which is currently residing in its cluster. This can enhance delay and channel utilization performance by avoiding the occurrence of idle time slots. We analytically investigate the delay of HTDMA, and compare it with that of wellknown contention-free and contention-based MAC protocols, which are TDMA and Slotted-ALOHA, respectively. It is shown that HTDMA remarkably decreases delay, compared with TDMA and Slotted-ALOHA.

A detailed review of energy-efficient medium access control protocols for mobile sensor networks

This article reviews the state-of-the-art energy-efficient contention-based and scheduled-based medium access control (MAC) protocols for mobile sensor networks (MSNs) by first examining access schemes for wireless sensor networks (WSNs). Efficient and proper mobility handling in sensor networks provides a window of opportunity for new applications. Protocols, such as S-MAC, reduce energy consumption by putting nodes to sleep after losing to channel contention or to prevent idling. Sleeping is a common method for energy-efficient MAC protocols, but delay depends on sleep duration or frame time, and longer delays lead to higher packet lost rate when nodes are unsynchronized due to network mobility. MS-MAC extends S-MAC to include mobility-awareness by decreasing this sleep duration when mobility is detected. S-MAC with extended Kalman filter (EKF) reduces mobility-incurred losses by predicting the optimal data frame size for each transmission. MMAC utilizes a dynamic mobility-adaptive frame time to enhance TRAMA, a scheduled-based protocol, with mobility prediction. Likewise, G-MAC utilizes TDMA for cluster-based WSNs by combining the advantages of contention and contention-free MACs. Z-MAC also combines both methods but without clustering and allows time slot re-assignments during significant topology changes. All of the above MAC protocols are reviewed in detail.

Clustering-Based Multichannel MAC Protocols for QoS Provisionings Over Vehicular Ad Hoc Networks

Making the best use of the dedicated short range communications multichannel architecture, we propose a cluster-based multichannel communications scheme that can support not only public-safety message delivery but also a wide range of future multimedia (e.g., video/audio) and data (e.g., e-maps, road/vehicle traffic/weather information) applications. Our proposed scheme integrates clustering with contention-free and/or -based medium access control (MAC) protocols. In our scheme, the elected cluster-head vehicle functions as the coordinator to collect/deliver real-time safety messages within its own cluster and forward the consolidated safety messages to the neighboring cluster heads. In addition, the cluster-head vehicle controls channel assignments for cluster-member vehicles transmitting/receiving nonreal-time traffics, which makes the wireless channels more efficiently utilized for vehicle-to-vehicle (V2V) nonreal-time data transmissions. Our scheme uses the contention-free MAC within a cluster and the contention-based IEEE 802.11 MAC among cluster-head vehicles such that the real-time delivery of safety messages can be guaranteed. Under our proposed scheme, we develop an analytical model to study the delay for the consolidated safety messages transmitted by the cluster-head vehicles. Based on this analytical model, we derive the desirable contention-window size, which can best balance the tradeoff between the delay of safety messages and the successful rate of delivering safety messages. The extensive simulation results show that, under various highway traffic scenarios, our proposed scheme can efficiently support the nonreal-time traffics while guaranteeing the real-time delivery of the safety messages.