Time division multiple access scheduling strategies for emerging vehicular ad hoc network medium access control protocols: a survey

[EN] Vehicular ad hoc network (VANET) is an emerging and promising technology, which allows vehicles while moving on the road to communicate and share resources. These resources are aimed at improving traffic safety and providing comfort to drivers and passengers. The resources use applications that have to meet high reliability and delay constraints. However, to implement these applications, VANET relies on medium access control (MAC) protocol. Many approaches have been proposed in the literature using time division multiple access (TDMA) scheme to enhance the efficiency of MAC protocol. Nevertheless, this technique has encountered some challenges including access and merging collisions due to inefficient time slot allocation strategy and hidden terminal problem. Despite several attempts to study this class of protocol, issues such as channel access and time slot scheduling strategy have not been given much attention. In this paper, we have relatively examined the most prominent TDMA MAC protocols which were proposed in the literature from 2010 to 2018. These protocols were classified based on scheduling strategy and the technique adopted. Also, we have comparatively analyzed them based on different parameters and performance metrics used. Finally, some open issues are presented for future deployment.Tambawal, AB.; Noor, RM.; Salleh, R.; Chembe, C.; Anisi, MH.; Michael, O.; Lloret, J. (2019). Time division multiple access scheduling strategies for emerging vehicular ad hoc network medium access control protocols: a survey. Telecommunication Systems. 70(4):595-616. https://doi.org/10.1007/s11235-018-00542-8S59561670

Energy-efficient wireless communication

In this chapter we present an energy-efficient highly adaptive network interface architecture and a novel data link layer protocol for wireless networks that provides Quality of Service (QoS) support for diverse traffic types. Due to the dynamic nature of wireless networks, adaptations in bandwidth scheduling and error control are necessary to achieve energy efficiency and an acceptable quality of service. In our approach we apply adaptability through all layers of the protocol stack, and provide feedback to the applications. In this way the applications can adapt the data streams, and the network protocols can adapt the communication parameters

Medium Access Control Protocols for Ad-Hoc Wireless Networks: A Survey

Studies of ad hoc wireless networks are a relatively new field gaining more popularity for various new applications. In these networks, the Medium Access Control (MAC) protocols are responsible for coordinating the access from active nodes. These protocols are of significant importance since the wireless communication channel is inherently prone to errors and unique problems such as the hidden-terminal problem, the exposed-terminal problem, and signal fading effects. Although a lot of research has been conducted on MAC protocols, the various issues involved have mostly been presented in isolation of each other. We therefore make an attempt to present a comprehensive survey of major schemes, integrating various related issues and challenges with a view to providing a big-picture outlook to this vast area. We present a classification of MAC protocols and their brief description, based on their operating principles and underlying features. In conclusion, we present a brief summary of key ideas and a general direction for future work

On the Medium Access Control Protocols Suitable for Wireless Sensor Networks – A Survey

A MAC (Medium Access Control) protocol has direct impact on the energy efficiency and traffic characteristics of any Wireless Sensor Network (WSN). Due to the inherent differences in WSN’s requirements and application scenarios, different kinds of MAC protocols have so far been designed especially targeted to WSNs, though the primary mode of communications is wireless like any other wireless network. This is the subject topic of this survey work to analyze various aspects of the MAC protocols proposed for WSNs. To avoid collision and ensure reliability, before any data transmission between neighboring nodes in MAC layer, sensor nodes may need sampling channel and synchronizing. Based on these needs, we categorize the major MAC protocols into three classes, analyze each protocol’s relative advantages and disadvantages, and finally present a comparative summary which could give a snapshot of the state-of-the-art to guide other researchers find appropriate areas to work on. In spite of various existing survey works, we have tried to cover all necessary aspects with the latest advancements considering the major works in this area

Medium access control design for all-IP and ad hoc wireless network

Medium Access Control (MAC) protocol in a wireless network controls the access of wireless medium by mobile terminals, in order to achieve its fair and efficient sharing. It plays an important role in resource management and QoS support for applications. All-IP wireless WAN is fully IP protocol-based and it is a strong candidate beyond 3G (Third Generation Wireless Network). Ad hoc wireless network has recently been the topic of extensive research due to its ability to work properly without fixed infrastructure. This dissertation is composed of two main parts. The first part pursues a Prioritized Parallel Transmission MAC (PPTM) design for All-IP Wireless WAN. Two stages are used and each packet is with a priority level in PPTM. In stage 1, a pretransmission probability is calculated according to the continuous observation of the channel load for a certain period of time. In stage 2, a packet is prioritized and transmitted accordingly. It is modeled and analyzed as a nonpreemptive Head-Of-the-Line prioritized queueing system with Poisson arrival traffic pattern. Its performance is analyzed under three other traffic patterns, which are Constant Bit Rate, Exponential On/Off, and Pareto On/Off, by using a NS-2 simulator, and compared with that of Modified Channel Load Sensing Protocol. PPTM supports dynamic spread code allocation mechanism. A mobile terminal can apply for a spreading code according to the current channel condition. To use the idea of dynamic bandwidth allocation in PPTM for adhoc wireless network, a Dynamic-Rate-with-Collision-Avoidance (DRCA) MAC protocol is proposed in the second part of the dissertation. DRCA is based on spread spectrum technology. In DRCA, a terminal sets the spreading factor for a packet according to the activity level of neighboring nodes. If the total number of usable spreading codes with this spreading factor is less than the total number of mobile terminals in the network, to avoid collision, the spreading code id is broadcast such that other terminals can avoid using it when the packet is being transmitted. The performance of DRCA is theoretically analyzed in a slotted, single-hop, multi-user environment. To evaluate DRCA\u27s performance in an environment closed to a real one, a simulator that supports multi-hop, random mobility pattern is created with OPNET. Both theoretical and simulation results show that DRCA outperforms MACA/CT (Multiple Access with Collision Avoidance with Common Transmitter-based) in case if there are more than one communication pair and the ratio of inactive mobile terminals to active ones is high

A critical analysis of research potential, challenges and future directives in industrial wireless sensor networks

In recent years, Industrial Wireless Sensor Networks (IWSNs) have emerged as an important research theme with applications spanning a wide range of industries including automation, monitoring, process control, feedback systems and automotive. Wide scope of IWSNs applications ranging from small production units, large oil and gas industries to nuclear fission control, enables a fast-paced research in this field. Though IWSNs offer advantages of low cost, flexibility, scalability, self-healing, easy deployment and reformation, yet they pose certain limitations on available potential and introduce challenges on multiple fronts due to their susceptibility to highly complex and uncertain industrial environments. In this paper a detailed discussion on design objectives, challenges and solutions, for IWSNs, are presented. A careful evaluation of industrial systems, deadlines and possible hazards in industrial atmosphere are discussed. The paper also presents a thorough review of the existing standards and industrial protocols and gives a critical evaluation of potential of these standards and protocols along with a detailed discussion on available hardware platforms, specific industrial energy harvesting techniques and their capabilities. The paper lists main service providers for IWSNs solutions and gives insight of future trends and research gaps in the field of IWSNs

Controlo de acesso ao meio em comunicações veiculares de tempo-real

Despite several preventive measures, the number of roadway accidents is still very high, being considered even a problem of public health by some entities. This thesis has as global purpose of contributing to the reduction of that number of accidents, and consequent fatalities, by using safety-related applications that use communication among vehicles. In particular, the primary goal is guaranteeing that communication between users in vehicular environments is done with appropriate time bounds to transfer safety-critical information. In detail, it is studied how to manage the scheduling of message’s transmissions (medium access control - MAC), in order to define precisely who will communicate and when is the appropriate instant. The preferable situation where a communication infrastructure is present with full coverage (RSUs) is also studied, from which medium access control is defined precisely, and vehicles (OBUs) become aware of medium utilization. Also, sporadic situations (e.g., absence of RSUs) are studied in which the communication network is “ad hoc” and solely formed by the current vehicles. It is used the recently WAVE / IEEE 802.11p standard, specific for vehicular communications, and it is proposed a TDMA based solution, with appropriate coordination between RSUs in order to effectively disseminate a critical safety event. It is taken into account two different ways of choosing the instant for the initial broadcast, and both cases are compared. In case there is no infrastructure available, methods are derived to minimize communication medium access collisions, and to maximize the available bandwidth. The results reflect the total end-to-end delay, and show that adequate times are attained, and meet with the requisites for the type of applications being considered. Also, enhancements are obtained when using the alternate choice for the initial broadcast instant.Apesar de diversas medidas preventivas, o número de acidentes rodoviários continua a ser muito elevado, sendo mesmo considerado uma questão de saúde pública por algumas entidades. Esta tese tem como objetivo geral contribuir para a redução desse número de acidentes, e consequentes fatalidades, através da utilização de aplicações de segurança que envolvem comunicação entre veículos. Em particular, o objetivo principal é garantir que a comunicação entre utentes, em ambientes veiculares, seja efetuada com limites temporais apropriados à transferência de informações críticas. De forma mais detalhada, é estudada a gestão do escalonamento das transmissões (controlo de acesso ao meio – MAC) que irá definir quem vai comunicar e quando o pode fazer. São estudadas situações (desejadas) onde há uma infra-estrutura de comunicações com cobertura integral (RSUs), a partir da qual se faz a coordenação do acesso ao meio pelos veículos (OBUs), e situações (esporádicas, por ausência de RSU) em que a rede de comunicação é “ad hoc” e apenas constituída pelos veículos presentes. Utiliza-se a recente norma WAVE / IEEE 802.11p, específica para comunicações veiculares, e propõe-se uma solução baseada em TDMA, com coordenação apropriada entre RSUs para disseminação efetiva de um evento crítico de segurança. A escolha do instante para o broadcast inicial do evento de segurança também é tida em conta, e são comparados dois casos distintos. No caso da ausência de infraestrutura, derivam-se métodos para minimizar colisões no acesso ao meio de comunicação, e maximizar a largura de banda disponível. Os resultados refletem o atraso total end-to-end, mostrando tempos apropriados para os requisitos das aplicações em causa, e evidenciando melhorias aquando da escolha alternativa para o instante do broadcast inicial.Programa Doutoral em Engenharia Eletrotécnic

Elastic hybrid MAC protocol for wireless sensor networks

The future is moving towards offering multiples services based on the same technology. Then, billions of sensors will be needed to satisfy the diversity of these services. Such considerable amount of connected devices must insure efficient data transmission for diverse applications. Wireless sensor network (WSN) represents the most preferred technology for the majority of applications. Researches in medium access control (MAC) mechanism have been of significant impact to the application growth because the MAC layer plays a major role in resource allocation in WSNs. We propose to enhance a MAC protocol of WSN to overcome traffic changes constraints. To achieve focused goal, we use elastic hybrid MAC scheme. The main interest of the developed MAC protocol is to design a medium access scheme that respect different quality of services (QoS) parameters needed by various established traffic. Simulation results show good improvement in measured parameters compared to typical protocol