A CSMA/CP MAC protocols for IP over WDM metropolitan area ring networks

DQDB (distributed queue dual bus) is a media access control (MAC) protocol which is being standardized in IEEE 802 as an 802.6 metropolitan area network (MAN) standard proposal. The authors analyze the major features responsible for unfairness in the DQDB MAC protocol with the bandwidth balancing mechanism disabled. For each of these factors mechanisms to reduce the unfairness are identified and analyzed. These new mechanisms are brought together in a unique MAC protocol named DQDB/FBS (fair bandwidth sharing) which, while preserving the DQDB distributed queue concept, implements a new reservation mechanism. The performance analysis of DQDB/FBS shows a remarkable improvement in fairness. In particular, ideal fair behavior is obtained under heavy loads. A comparison between DQDB (BWBMOD=8) and DQDB/FBS is provided, and the pros and cons of both MAC protocols are highlighted.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Power efficient ultra-wideband based wireless communication for wireless body area network applications

In this paper we propose a simple relay enabled medium access (SRMAC) protocol that enables cooperative relay transmissions. Due to the wireless signal power attenuation with distance, using a relay in a wireless network can make wireless networking more bandwidth efficient at the expense of requiring multiple transmissions for a single packet. Standard MAC protocols such as the IEEE 802.11 MAC protocol, while useable with relaying, however are not designed explicitly for relay communication. When IEEE 802.11 MAC protocol is used for cooperative communication such a relaying, each packet transmission would need to separately contend for the channel via a channel access procedure which can use significant resources (both energy and bandwidth). Because using a single relay requires two transmissions, an efficient medium access control (MAC) protocol that supports two hop transmission is needed. We introduce a protocol, SRMAC, which is a simple cooperative MAC protocol that utilizes information from the physical layer for the MAC operation of relay networks. We consider the bandwidth efficiency of SRMAC protocol considering both the physical layer and MAC layer. The SRMAC protocol includes the possibility of both cooperative transmission and direct transmission. With SRMAC, cooperative transmission (relaying) can be dynamically chosen when it is more beneficial than direct transmission. The SRMAC protocol can improve the throughput by up to 20% compared to conventional MAC protocols.

Since cognitive wireless network (CRN) has the characteristic of secondary use, it can enable the device to dynamically access available spectrum without interference to primary users (PUs), which can effectively alleviate contradiction between the lack of spectrum resources and the growing demand for wireless access. However, Medium Access Control (MAC) protocol as CRN core components, can achieve competition access of the licensed spectrum and coordination control, which will maximize spectrum utilization efficiency and network throughput. The contribution of this survey is threefold. First, we analyze the characteristics of the existed multi- channel MAC protocol in CRN; Second, according to the different ways of spectrum access in CRNs, the multi-channel MAC protocols are classified into time-slotted based MAC protocol, control channel based MAC protocol and hybrid MAC protocol, and the paper emphatically analyzed the advantages and disadvantages of these multi-channel MAC protocols; Finally, the paper explores the difficulties and the challenges of multi-channel MAC protocols design in cognitive wireless network.

High throughput and fair resource sharing are two of the most important objectives in designing a medium access control (MAC) protocol. Currently, most MAC protocols including IEEE 802.11 DCF adopt a random access based approach in a distributed manner in order to coordinate the wireless channel accesses among competing stations. In this paper, we first identify that a random access–based MAC protocol may suffer from MAC protocol overhead such as a random backoff for data transmission and a collision among simultaneously transmitting stations. Then, we propose a new MAC protocol, called sequential coordination function (SCF), which coordinates every station to send a data frame sequentially one after another in a distributed manner. By defining a service period and a joining period, the SCF eliminates unnecessary contentions during the service period, and by explicitly determining the sequence of frame transmission for each stations, it reduces collision occurrences and ensures fairness among stations in the service period. The performance of SCF is investigated through intensive simulations, which show that the SCF achieves higher throughput and fairness performances than other existing MAC protocols in a wide range of the traffic load and the number of stations.

Cognitive Radio (CR) exploits underutilized licensed spectrums to improve its bandwidth availability. Using CR technology, a node is able to adapt its transmission and reception radio parameters including channel frequency dynamically according to local spectrum availability. For channel access between wireless nodes, a cognitive Medium Access Control (MAC) protocol is necessary to coordinate the CRs. Multi-channel MAC protocol extensions have been proposed in IEEE802.11 to enable a node to operate in multiple channels in order to improve network-wide throughput. These multi-channel MAC protocols have several functions that can be leveraged by cognitive MAC protocols due to their similarities in certain aspects, though the CR has an additional requirement to cope with the existence of licensed users that have higher authority over the channels. Current research in cognitive MAC protocols assumes the availability of a common control channel at all times, which is an approach in the multi-channel MAC protocols. This approach has certain hardware requirements that may not be readily available at CR nodes. Hence, other approached may be necessary. In this paper, various types of multi-channel MAC protocols are reviewed, followed by discussion of their merits and demerits in multi-channel environments. The purpose is to show the additional functionalities and challenges that each multi-channel MAC protocol has to offer and address in order to operate in multihop CR networks. By providing discussion on possible technology leverage from multi-channel to cognitive MAC protocols, we aim to establish a foundation for further research and discussion.

Two important criteria of wireless body area networks (WBANs) are low power consumption and delay. These criteria can be met by designing efficient medium access control (MAC) protocols. In this paper, two TDMA-based MAC protocols are proposed. The first protocol, TM–MAC makes use of only a main radio. The second proposed protocol, TWM–MAC makes use of a WUR alongside the main radio. The two proposed protocols are compared with different categories of standard MAC protocols and it is shown that they outperform the standard ones by improving the power consumption and delay. The TWM–MAC consumes 55% less power consumption than the Scheduled Channel Polling MAC (SCP–MAC) protocol for a high traffic scenario on the high-rate platform while the TM-MAC consumes 85% less power consumption than the SCP–MAC. For a low traffic scenario, the TWM–MAC performs 53.5% better than the SCP–MAC protocol and 77.5% better than the very low power MAC (VLPM) protocol on the high and low-rate platforms respectively. An improvement in delay was observed with the TWM–MAC protocol for high traffic situations. The TWM–MAC protocol surpasses the VLPM protocol by 81.1% in terms of latency for a high traffic scenario and 3.2% for a low traffic scenario.

The key contributions of this paper are the proposed Pure Collective Aloha (PCA) medium access control (MAC) protocol with multilevel powers and its closed-form theoretical analysis. The PCA MAC protocol collects a batch of packets before transmitting these packets sequentially in the channel. The key idea in the design of this PCA MAC protocol with multilevel powers is to spread out the arrivals of each batch of packets in a channel and the multilevel powers of the packets received at the receiver allow capture for the case of the strongest signal power packet among the overlapping lower signal power packets to be successfully received at the receiver. If it is the only received packet, it is successfully received, regardless of its received power level. The PCA MAC protocol with multilevel powers is analyzed theoretically. The explicit closed-form expressions for the optimal offered loads and the maximum throughputs of the Pure Aloha, the Slotted Aloha and the PCA MAC protocols with multilevel powers are presented. The numerical results show that the throughput of the asynchronous PCA MAC protocol with multilevel powers is about 90.5% better than that of the asynchronous Pure Aloha MAC protocol with multilevel powers and can approach the maximum throughput bound of the synchronous Slotted Aloha MAC protocol with multilevel powers, without the need of any synchronization mechanism to slot boundaries.

Medium Access Control (MAC) protocol is one of the key network protocols that ensure Wireless Sensor Networks (WSNs) maintain high performance during communication. MAC protocol design plays an important role in improving the performances of the whole network. First, Wireless Passive Sensor Networks (WPSNs) and MAC protocols are introduced in this paper. Second, some existing MAC protocols are introduced. Sensor MAC (S-MAC) protocol is analyzed and existing improved backoff algorithms are introduced. A new MAC protocol called Improved Sensor MAC (IS-MAC) is then proposed to solve the problem that the contention window (CW) during carrier sense is fixed in S-MAC protocol. IS-MAC protocol is able to adjust CW in terms of network load, so energy consumption can be decreased. Finally, according to the simulation results on NS2, the proposed protocol has better performance in terms of throughput and energy consumption.

Design and performance evaluation of a metro WDM storage area network with IP datagram support

Radio Frequency Identification (RFID) has become widespread thanks to its important advantages over traditional identification technologies, like barcodes. Compared to this technology, RFID is, in fact, able to cover larger distance and does not require line-of-sight, that represent important improvements in the considered field of application. An RFID system is formed by a set of n tags, that represent clients in the identification process, and a tag reader, that is the identification server. Each tag is associated with an identifier (ID), that must be transmitted to the reader upon receipt of a suitable identification query. Tags can be active, i.e. provided with an independent power supply (like a battery), or passive. In the latter case, tags depend on energy provided by the tag reader through its queries (Want, 2006). For this reason, active tags can have some data processing ability, while passive tags are limited to doing only elementary operations and replying to the reader’s queries. An important issue in Radio Frequency Identification systems concerns the reading of colocated tags, that must be managed through suitable Medium Access Control (MAC) protocols, specifically designed for low power devices. Efficiency of MAC protocols for RFID systems directly influences the time needed by the tag reader for completely identifying a set of co-located tags, so it has great impact on the whole system performance. A deep analysis of the MAC technologies adopted in RFID is the aim of this chapter. We denote by Ttot(n) the time needed by the tag reader for completely identifying a set of n tags. Under ideal conditions, it should be Ttot(n) = nTpkt, where Tpkt is the time needed to transmit one identification packet. However, in order to ensure collision-free transmission to each tag, a MAC protocol is needed that, inevitably, produces a time waste with respect to the ideal condition. The time actually needed for identification depends on several factors, like the technology adopted, the working frequency, etc. So, RFID systems can exhibit very different reading rates, typically ranging between 100 Tag/s and 1000 Tag/s. The most common MAC protocols used in RFID systems can be grouped into two classes: deterministic protocols and stochastic protocols. Deterministic protocols basically coincide with tree traversal algorithms: all RFID tags form a binary tree on the basis of their identifiers, and the reader explores the tree in a systematic way, by repeating queries based on bit masks. Randomness is only in the tree structure (due to the choice of the co-located tag set), while the algorithm execution is pre-determined. Stochastic MAC protocols are instead based on the framed slotted Aloha (FSA) algorithm, that requires each tag to make a constrained pseudo-random choice of an integer number in order to reduce the probability of collisions.

A joint MIMO-OFDM transceiver and MAC design for mobile ad hoc networking

Storage area networks (SANs) are becoming an important part of optical metropolitan area networks (MANs). Growing storage and business-continuity needs; high-bandwidth, low latency requirements for SANs; storage infrastructure consolidation; and post-9/11 regulatory issues are among the several driving factors to push this trend. In this paper, we study network traffic in a proposed metro wavelength division multiplexing (WDM) ring architecture SAN with variable-length packets. The paper begins with a brief review of the relevant background information on SANs, data mirroring and network traffic analysis in the literature. Subsequently, the network architectures along with their medium access control (MAC) protocols are described. Network traffic analysis for the proposed network architectures is studied by means of discrete-event computer simulation. Network traffic characteristics are evaluated under self-similar asymmetric traffic scenarios.

Highly dynamic geographical topology, two-direction mobility, and varying traffic density can lead to fairness issues in Vehicular Ad-hoc Networks (VANETs). The Medium Access Control (MAC) protocol plays a vital role in sharing the common wireless channel efficiently between vehicles in a VANET system. However, ensuring fairness between vehicles can be a challenge in designing MAC protocols for VANET systems. The existing protocol, IEEE 802.11 DCF, ensures that the packet transmission rate for a particular vehicle is directly proportional to the amount of time a vehicle spends within a service area, but it does not guarantee that faster vehicles will be able to send the minimum number of packets. Other existing MAC protocols based on IEEE 802.11 are able to provide a minimum amount of data transmission regardless of velocity, but are unable to provide an amount of data transmission that is more proportionate to the time a vehicle spends in the service area. To address the above limitations, we propose a Speed Aware Fairness Enabled MAC (SAFE-MAC) protocol that calculates the residence time of a vehicle in a service area by using mobility metrics such as position, direction, and speed to synthesize the transmission probability of each individual vehicle with respect to its residence time. This is achieved by dynamically altering the values of parameters such as minimum contention window, maximum backoff stage, and retransmission limit in the MAC protocol. We then develop an analytical model to compare the performance of our proposed protocol with contemporary MAC protocols. Numerical analysis results show that our proposed protocol significantly improves fairness among the speed-varying vehicles in VANET.

Health monitoring using biomedical sensors has witnessed significant attention in recent past due to the evolution of a new research area in sensor network known as Wireless Body Area Networks (WBANs). In WBANs, a number of implantable, wearable, and off-body biomedical sensors are utilized to monitor various vital signs of patient’s body for early detection, and medication of grave diseases. In literature, a number of Medium Access Control (MAC) protocols for WBANs have been suggested for addressing the unique challenges related to reliability, delay, collision and energy in the new research area. The design of MAC protocols is based on multiple access techniques. Understanding the basis of MAC protocol designs for identifying their design objectives in broader perspective, is a quite challenging task. In this context, this paper qualitatively reviews MAC protocols for WBANs. Firstly, 802.15.4 and 802.15.6 based MAC Superframe structures are investigated focusing on design objectives. Secondly, different multiple access techniques such as TDMA, CSMA/CA, Slotted Aloha and Hybrid are explored in terms of design goals. Thirdly, a two-layered taxonomy is presented for MAC protocols. First layer classification is based on multiple access techniques, whereas second layer classification is based on design objectives and characteristics of MAC protocols. Critical and qualitative analysis is carried out for each considered MAC protocol. Comparative study of different MAC protocols is also performed. Finally, some open research challenges in the area are identified with initial research directions.