Medium Access Control Protocol Design Research Articles

Analysis and Design of a MAC Protocol and Vehicular Traffic Simulator for Multimedia Communication on Motorways

This paper aims to guarantee the quality of service (QoS) to motorway drivers with regard to multimedia (triple play-video, voice, and data) communications, which requires substantial analysis of the characteristics of vehicular traffic profiles on motorways. We therefore perform an analysis of real vehicular traffic data taken from inductive loops on a motorway and then develop our own simulator to study real-time vehicular traffic scenarios on the medium access control (MAC) layer, where a wireless local area network (WLAN) base station (BS) is responsible for multimedia communication between vehicles and the backbone network. Access to this BS is managed by a modified version of the packet-reservation multiple access (M-PRMA) protocol, which we have integrated into the simulator. Finally, we use our developed simulator, which is built upon extensive analysis of vehicular traffic data, to evaluate the multimedia services offered to motorway drivers.

A Study of MAC Protocols for WBANs

The seamless integration of low-power, miniaturised, invasive/non-invasive lightweight sensor nodes have contributed to the development of a proactive and unobtrusive Wireless Body Area Network (WBAN). A WBAN provides long-term health monitoring of a patient without any constraint on his/her normal dailylife activities. This monitoring requires the low-power operation of invasive/non-invasive sensor nodes. In other words, a power-efficient Medium Access Control (MAC) protocol is required to satisfy the stringent WBAN requirements, including low-power consumption. In this paper, we first outline the WBAN requirements that are important for the design of a low-power MAC protocol. Then we study low-power MAC protocols proposed/investigated for a WBAN with emphasis on their strengths and weaknesses. We also review different power-efficient mechanisms for a WBAN. In addition, useful suggestions are given to help the MAC designers to develop a low-power MAC protocol that will satisfy the stringent requirements.

Medium access control protocols in cognitive radio networks

AbstractIn cognitive radio (CR) networks, medium access control (MAC) protocols play an important role to exploit the spectrum opportunities, manage the interference to primary users (PUs), and coordinate the spectrum access amongst secondary users (SUs). In this paper, we first introduce the challenges in the design and implementation of CR MAC protocols. Then, we make a comprehensive survey of the state‐of‐the‐art CR MAC protocols and categorize them on the basis of spectrum sharing modes, i.e., overlay and underlay modes. We also introduce some other classification metrics such as architecture (centralized or distributed), sharing behaviors (cooperative or non‐cooperative), and access modes (contention based or contention free). Through the study, we find out that most CR MAC protocols are designed for the overlay mode. The CR MAC protocols in underlay mode could yield higher spectrum utilization efficiency with the cost of more complicated power and admission control schemes. The centralized CR MAC protocols are more suitable to do spectrum sensing using quiet period of whole network, while the distributed CR MAC protocols are more flexible to deploy. We identify several future directions, such as more practical CR MAC protocols for underlay mode, MAC protocols considering security, MAC protocols considering heterogeneous coexistence, etc. Copyright © 2009 John Wiley & Sons, Ltd.

Efficient MAC protocol for ultra-wideband networks

Ultra-wideband communication is a promising enabling technology for future broadband wireless multimedia services. A simple and robust medium-access-control (MAC) protocol is of critical importance to utilize the large bandwidth of UWB channels and to enable numerous new applications and services cost effectively. In this article, we introduce an efficient MAC protocol design for both centralized and distributed multihop UWB networks, based on the exclusive region concept. By reserving a small ER surrounding the receivers to assure successful transmissions, the ER-based MAC protocol can exploit the spatial multiplexing gain of UWB networks and enable multiple users to efficiently and fairly share network resources.

A survey on MAC protocols for cognitive radio networks

In cognitive radio (CR) networks, identifying the available spectrum resource through spectrum sensing, deciding on the optimal sensing and transmission times, and coordinating with the other users for spectrum access are the important functions of the medium access control (MAC) protocols. In this survey, the characteristic features, advantages, and the limiting factors of the existing CR MAC protocols are thoroughly investigated for both infrastructure-based and ad hoc networks. First, an overview of the spectrum sensing is given, as it ensures that the channel access does not result in interference to the licensed users of the spectrum. Next, a detailed classification of the MAC protocols is presented while considering the infrastructure support, integration of spectrum sensing functionalities, the need for time synchronization, and the number of radio transceivers. The main challenges and future research directions are presented, while highlighting the close coupling of the MAC protocol design with the other layers of the protocol stack.

Distributed cooperative MAC for multihop wireless networks

This article investigates distributed cooperative medium access control protocol design for multihop wireless networks. Cooperative communication has been proposed recently as an effective way to mitigate channel impairments. With cooperation, single-antenna mobile terminals in a multi-user environment share antennas from other mobiles to generate a virtual multiple-antenna system that achieves more reliable communication with a higher diversity gain. However, more mobiles conscribed for one communication inevitably induces complex medium access interactions, especially in multihop wireless ad hoc networks. To improve the network throughput and diversity gain simultaneously, we investigate the issues and challenges in designing an efficient MAC scheme for such networks. Furthermore, based on the IEEE 802.11 DCF, a cross-layer designed cooperative MAC protocol is proposed. The MAC scheme adapts to the channel condition and payload length.

Survey on joint power control and multi-rate MAC protocols

This article carried out a survey of the power control technique for energy-saving and the multi-rate feature in MANETs, with particular emphasis on typical Medium Access Control (MAC) protocols with combined techniques of power-control and multi-rate capabilities. Their characteristics, performance and deficiency were compared adequately in terms of optimization goal selection, process method and information exchange. The difficulties in designing MAC protocols taking account of both power-control and multi-rate capabilities including the status of wireless nodes is hard to be fully explored by other nodes and the control metrics cannot accurately achieve the optimization goal. Finally, future trends were predicted.

Exploration of energy conservation MAC protocol of WSNs for ubiquitous environment

According to analyzing the facade phenomenon of wireless sensor networks(WSNs), this paper proposes a feasible method to state clearly and improve the power control efficiency of wireless sensor networks(WSNs). One of the crucial problems for WSNs is the design of medium access control (MAC) protocol. Our method wants to adjust the activities of the MAC protocols control to achieve the enery conservation when the wireless communication module of sensor nodes is running, which is the major consumer of energy consumed by sensors’ energy. The energy efficiency of MAC protocol makes a strong impact on the network performance. To some extent,our research work describes and analyzes the sources of energy consumption in the MAC layer and simultaneously presents an optimal method for the design of MAC protocol. Then we discusses some factors impacting on the performance of MAC protocol and metrics of performance evaluation. Eventually, the coming research direction is summarized.

Utilizing acoustic propagation delay to design MAC protocols for underwater wireless sensor networks

AbstractLong propagation delay is one of the most important characteristics in underwater wireless sensor networks (UWSNs) and poses a great challenge for medium access control (MAC) protocol design, especially for contention‐based MAC protocols due to intolerable delay caused by unpredictable retransmissions in UWSNs. Recently, some MAC protocols for UWSNs have been suggested in the literature, and most of them are based on random access with their capabilities to compensate propagation delay. However, two issues should still be resolved in these protocols: (a) they need to make measurements to realize duty cycle synchronization and (b) packet collisions exist, which not only reduce the throughput (thus increasing delays) but also waste energy. In this paper, we propose a novel MAC protocol explicitly designed for UWSNs, which makes the best use of the propagation delay to resolve collision problem and reduce overhead of control‐packet to save energy. The proposed MAC protocol can assure that the number of retransmissions is not more than one. To validate the analytical results, simulations have been conducted to show that the proposed MAC protocol can offer a low energy consumption while avoiding collisions in UWSNs. Copyright © 2008 John Wiley & Sons, Ltd.

Capacity analysis and MAC enhancement for UWB broadband wireless access networks

We analyze the capacity of ultra-wide band (UWB) wireless access networks supporting multimedia services by calculating the number of multimedia connections that can be supported in a UWB access network with IEEE 802.15.3 Medium Access Control (MAC) protocol, considering the overheads from different layers. We then propose how to increase the capacity by improving the MAC protocol design and parameter setting. We also quantify the effectiveness of different approaches and derive the appropriate MAC protocol parameters such as the duration of contention period and contention free period in a superframe . Simulation results are given to demonstrate the accuracy of the analysis.

Medium Access Control Protocol Design for Vehicle–Vehicle Safety Messages

We propose a medium access control protocol design for a vehicle to send safety messages to other vehicles. We develop a Quality-of-Service (QoS) model for safety messages that are consistent with the active vehicle safety systems literature. Each message has a range and useful lifetime. The QoS target has each message received with high probability within its specified lifetime by each vehicle within its specified range. The protocol design is based on rapidly rebroadcasting each message multiple times within its lifetime in combination with the 802.11 Distributed Coordination Function. This makes the design compatible with emerging standards for Dedicated Short-Range Communication. Six different design variations are proposed. We derive equations and develop a simulation tool to assess the performance of the designs. Using these, we identify the best and most easily implemented designs. Design performance depends on the number of rebroadcasts, power, modulation, coding, and vehicular traffic volumes. We show that under certain assumptions on the loss probability tolerated by safety applications, the design is able to transport safety messages in vehicular ad hoc networks

Optimal Power Control, Scheduling, and Routing in UWB Networks

Ultra-wideband (UWB) is an emerging wireless physical layer technology that uses a very large bandwidth. We are interested in finding the design objectives of the medium access [medium-access control (MAC), namely, power control and scheduling] and routing protocols of a multihop, best-effort, UWB network. Our objective is to maximize flow rates (more precisely, log-utility of flow rates) given node power constraints. The specificity of UWB is expressed by the linear dependence between rate and signal-to-noise ratio at the receiver. It is known that, in wireless networks, different routing strategies can imply differences in MAC protocol design. Hence, we search for the jointly optimal routing, scheduling and power control. We find that the optimal solution is characterized by the following. 1) When data is being sent over a link, it is optimal to have an exclusion region around the destination, in which all nodes remain silent during transmission, whereas nodes outside of this region can transmit in parallel, regardless of the interference they produce at the destination. Additionally, the source adapts its transmission rate according to the level of interference at the destination due to sources outside of the exclusion region. 2) The optimal size of this exclusion region depends only on the transmission power of the source of the link, and not on the length of the link nor on positions of nodes in its vicinity. 3) Each node in a given time slot either sends data at the maximum power, or does not send at all. As for the routing, we restrict ourselves to a subset of routes where on each successive hop we decrease the distance toward the destination, and we show that 4) relaying along a minimum energy and loss route is always better than using longer hops or sending directly, which is not obvious since we optimize rate and not power consumption. Finally 5), the design of the optimal MAC protocol is independent of the choice of the routing protocol. For narrowband networks, 2), 4), and 5) do not hold, which shows that the design of an UWB network should be addressed in a different way than for narrowband. Our technical approach is based on expressing the design requirements as a mathematical optimization problem. We solve it exactly for simple networks on a line and approximately on random topologies in a plane with up to 50 nodes with various power constraints, traffic matrices, and mobility parameters.

Design of MAC protocols with fast collision resolution for wireless local area networks

Development of efficient medium access control (MAC) protocols providing both high throughput performance for data traffic and good quality of service (QoS) support for real-time traffic is the current major focus in distributed contention-based MAC protocol research. In this paper, we propose an efficient contention resolution algorithm for wireless local area networks, namely, the fast collision resolution (FCR) algorithm. The MAC protocol with this new algorithm attempts to provide significantly higher throughput performance for data services than the IEEE 802.11 MAC algorithm and more advanced dynamic tuning backoff (DTB) algorithm. We demonstrate that this algorithm indeed resolves collisions faster and reduces the idle slots more effectively. To provide good fairness performance and to support good QoS for real-time traffic, we incorporate the self-clocked fair queueing algorithm and a priority scheme into the FCR algorithm and come up with the real-time FCR (RT-FCR) algorithm, and show that RT-FCR can simultaneously achieve high throughput and good fairness performance for nonreal-time traffic while maintaining satisfactory QoS support for real-time traffic.

Medium access control protocols for wireless mobile ad hoc networks: issues and approaches

AbstractIn this article, a comprehensive survey of the medium access control (MAC) approaches for wireless mobile ad hoc networks is presented. The complexity in MAC design for wireless ad hoc networks arises due to node mobility, radio link vulnerability and the lack of central coordination. A series of studies on MAC design has been conducted in the literature to improve medium access performance in different aspects as identified by the different performance metrics. Tradeoffs among the different performance metrics (such as between throughput and fairness) dictate the design of a suitable MAC protocol. We compare the different proposed MAC approaches, identify their problems and discuss the possible remedies. The interactions among the MAC and the higher layer protocols such as routing and transport layer protocols are discussed and some interesting research issues are also identified. Copyright © 2003 John Wiley & Sons, Ltd.

Measurements of a wireless link in an industrial environment using an IEEE 802.11-compliant physical layer

The design and simulation of coding schemes, medium access control (MAC), and link-layer protocols for future industrial wireless local area networks can be supported by some understanding of the statistical properties of the bit error patterns delivered by a wireless link (which is an ensemble of transmitter, channel, receiver, modems). The authors present results of bit error measurements taken with an IEEE 802.11-compliant radio modem in an industrial environment. In addition to reporting the most important results, they draw some conclusions for the design of MAC and link-layer protocols. Furthermore, they show that the popular Gilbert/Elliot model and a modified version of it are a useful tool for simulating bit errors on a wireless link, despite their simplicity and failure to match certain measured statistics.

Uplink–downlink design issues for next generation satellite networks

AbstractNext Generation Mobile Systems will implement one's dream of anywhere, anytime communications. Providing global coverage and mobility, satellite systems will play an important role in order for this to be achieved. The design options of satellite systems include several choices. The basic ones are the choice of orbit, processing and switching, intersatellite links, and link layers technologies. In addition to the network architecture, the protocols must be developed for efficient use of the satellite radio resources. The most important protocol design issues concentrate on Medium Access Control (MAC) techniques, routing and traffic management. In this paper some of the special features of satellite systems are considered. Emphasis is given in MAC protocols design, as well as in research programmes that led to their development. Finally, an adaptive hybrid access scheme that combines CDMA technology and random access techniques is presented. This new scheme is called CDMA/PRMA and from the results obtained it is a very promising access technique for next generation satellite systems. Copyright © 2002 John Wiley & Sons, Ltd.