Recent technological advances in wireless communications offer new opportunities and challenges for wireless ad hoc networking. In the absence of the fixed infrastructure that characterizes traditional wireless networks, control and management of wireless ad hoc networks must be distributed across the nodes, thus requiring carefully designed medium access control (MAC) layer protocols. In this article we survey, classify, and analyze 34 MAC layer protocols for wireless ad hoc networks, ranging from industry standards to research proposals. Through this analysis, six key features emerge: (1) channel separation and access; (2) topology; (3) power; (4) transmission initiation; (5) traffic load and scalability; and (6) range. These features allow us to characterize and classify the protocols, to analyze the tradeoffs produced by different design decisions, and to assess the suitability of various design combinations for ad hoc network applications. The classification and the tradeoff analysis yield design guidelines for future wireless ad hoc network MAC layer protocols.

A survey, classification and comparative analysis of medium access control protocols for ad hoc networks

We present Colorwave, a medium access control (MAC) protocol designed for wireless sensor networks such as radio frequency identification (RFID) reader networks. A network of readers will collaborate for a common application such as item-level monitoring in supply chain management. Readers may be deployed in an ad hoc manner, and readers must not interfere with one another's reader-to-tag communication. Colorwave capitalized on the localized nature of reader-to-tag communications to provide an on-line, distributed, and localized MAC protocol that minimized reader-to-reader interference.

Colorwave: a MAC for RFID reader networks

Shortest path distance vs. least directional change: Empirical testing of space syntax and geographic theories concerning pedestrian route choice behaviour

Most previous work on medium access control (MAC) protocols for wireless ad hoc networks has focused on the twin goals of maximising throughput and minimising average packet delay as required for general-purpose applications.In this paper we describe a new MAC protocol for use in multi-hop ad hoc networks whose goal is to provide, with high probability, time-bounded access to the wireless medium for applications with guaranteed response time requirements.The Time-Bounded Medium Access Control (TBMAC) protocol is based on time-division multiple access with dynamic but predictable slot allocation. TBMAC uses a light-weight atomic multicast protocol to achieve distributed agreement on slot allocation and employs location information to minimise contention for slots.TBMAC is the first time-bounded MAC protocol for multi-hop wireless ad hoc networks. In this paper we describe the protocol and provide a number of time bounds for the transmission of messages.

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Time bounded medium access control for ad hoc networks

We examine the relation between the finite and the infinite population models for a class of random access algorithms. The algorithms in the class are a combination of random access and reservation techniques, they are synchronous, and they are studied under the condition that each of the users can monitor the channel feedback continuously (full feedback sensing). For any finite number of independent and identical users in the system, and any i.i.d. arrival process per user, the algorithms are stable, provided that the total input rate is less than one. However, as the population size increases, the stability of an algorithm in the class is determined by its throughput in the presence of the infinite population model for all practical purposes.

On the relation between the finite and the infinite population models for a class of RAA's

Addressing the problem of timely packet transmission in a wireless soft real-time system such as one would find on the battlefield we present five splitting protocols that take packet deadlines into account. Three are blocked access and two are free access algorithms. Mathematical models of the algorithms are developed, and compared with simulations. We show, as expected, that the blocked access algorithms usually offer higher success rates than the free access versions. Of the two best performing blocked access protocols, performance differences are slight on a lightly loaded channel. Under heavy load, however, one is shown to have better performance, and thus would be the best choice for implementation.

http://ieeexplore.ieee.org/iel3/5148/13984/00645033.pdf

Wireless MAC protocols for real-time battlefield communications

As ad hoc wireless networks become more common, the need for real time services on these networks is emerging. However little work has focused on supporting real time requirements in such a demanding environment where the medium of transmission is noisy and protocols must be fully decentralized. Addressing this, we present a MAC protocol, preemptive in nature, that supports the transmission of hard, soft and non real time data. To guarantee stability even in overloaded conditions and still offer support for deadlines, we use splitting protocols. A protocol model is presented and analyzed, showing its performance under a wide range of offered loads with various fractions of real time types. We show that the protocol is easily implemented without making unreasonable hardware demands and so could be used as the basis for building real time services in an ad hoc wireless network.

Fully distributed wireless MAC transmission of real-time data

Communication between current military real-time systems and future interconnection of general purpose, embedded real-time systems will often require wireless communications. However, there has been little work undertaken to offer support for real-time applications on wireless networks. We present and evaluate three protocols; variations of two published protocols by Paterakis and Gallager as well as our new one, the Sliding Partition (SP) collision resolution algorithm (CRA). In a real-time setting, the modified Gallager CRA consistently performs worst of the three we consider. We observe that when the deadline range is small, the Sliding Partition CRA performs best. When the deadline range is large, however, the Paterakis CRA performs slightly better than the SP CRA. Both analytic and simulation results are obtained to study the maximum input traffic rates that can be sustained for various laxities, delay bounds, and message loss rates.

/pdf/evaluation-of-wireless-soft-real-time-protocols-242e8y00xc.pdf

Evaluation of wireless soft real-time protocols

Using wireless systems to transport real-time data is becoming increasingly common as wireless networks themselves are used more. However, in most instances, real-time data is generated by applications and ultimately transmitted by a MAC layer protocol with no support for deadlines. We describe a MAC layer protocol that transmits data taking into consideration its real-time properties. This would appear to be the first wireless MAC protocol offering support for hard, soft, and non-real-time data in a preemptive manner. Numerical results of the mathematical model (not presented here) are graphed and evaluated.

Fully distributed wireless transmission of heterogeneous real-time data

Addressing the challenge of packet transmission in a wireless soft real-time system, we present five splitting protocols that take packet deadlines into account. With them, connectionless service with real-time QoS guarantees at the MAC layer can be offered. Three protocols are blocked access and two are free access algorithms. Mathematical models are developed and results compared with simulations. As is the case with non real-time splitting algorithms, the blocked access versions offer higher success rates than the free access versions. We further show that of the two best performing blocked access protocols, under moderate to heavy loads, the Sliding Partition CRA outperforms the Two Cell CRA.

Michael J. Markowski

Papers

Wireless MAC protocols for real-time battlefield communications

Fully distributed wireless MAC transmission of real-time data

Evaluation of wireless soft real-time protocols

Fully distributed wireless transmission of heterogeneous real-time data

Blocked and Free Access Real-Time Splitting Protocols