Contention-free Medium Access Control Protocol Research Articles

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.

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.

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.