Problem Of Medium Access Control Research Articles

A Study of Developments in the Routing Protocols in the Wireless Ad Hoc Networks (WANET)

Abstract: A mobile ad hoc network (manet) is a new name for an obsolete system: a network that doesn't require any pre-existing architecture to function. in the early 1970s, the darpa pr net and suran Programmes were predecessors of this system. the new twitch is the application of this approach in non-military communication circumstances. in addition, the research in this field has recently focused on various advanced aspects of this technology, such as multicasting and security. there have also been a number of unique solutions to "traditional" routing and medium access control problems proposed. this study attempts to characterize the state-of-the-art of networks technology in four areas: routing, intermediate identity management, multicasting, and security. when possible, reviews of the proposed techniques are offered. As part of this research, the Fuzzy based Flexible Energy Efficient Routing protocol (FIE2R) will be presented as a routing system for WANET. The decision maker is in charge of the whole FIE2R procedure, which is separated into two parts. It is the WANET graph start phase, which aids in the second phase's determination of each route's reward. That's from a comprehensive computation of FIE2R using MATLAB and NS2 and a comparative analysis of the same with other networking schemes, the recommended protocol improves performance in terms of energy consumption. Keywords: Adhoc networks, Manet, Wanet, MATLAB. Routing schemes

Survey of medium access control schemes for inter-vehicle communications

Currently, Vehicular Ad-hoc Networks (VANETs) are attracting a lot of attention due to their favorable applications. VANETs are the key to providing safety and efficiency on the roads. The vehicles can communicate with other vehicles to inform the ongoing status of the traffic flow or critical situations like accidents. However, this would entail a reliable and efficient Medium Access Control (MAC) protocol. Due to the high speed of the nodes, the frequent changes in network topology, and particularly the lack of an infrastructure, the design of the MAC for vehicular communications turns into a more challenging task. A lot of research works has been conducted to overwhelm the vehicular MAC problems regarding Quality of Service (QoS) requirements of both safety and non-safety applications covering both Vehicle-to-Infrastructure (V2I) and Vehicle-to-Vehicle (V2V) communications. Recently, a significant number of MAC schemes has been proposed for V2V communications. In this paper, for future studies to be more effective, the outstanding proposed V2V MAC schemes are intended to come under review. Moreover, V2V MAC design approaches are discussed and a qualitative comparison is provided. A novel classification of V2V MAC schemes is then presented, and the characteristics of these schemes along with their strengths and weaknesses are studied. Finally, a comparative summary is given and some open challenges regarding the design of V2V MAC schemes are discussed.

Survey on Reactive Medium Access Control Mechanism for Peer to Peer Heterogeneous Multi Hop Networks

Based on the functionality, wireless multi-hop network (MANETs) can be divided as mobile ad hoc networks, wireless mesh networks (WSN). WSN is similar to MANETs with the application of monitoring, and it is an extension of infrastructure based single-hop wireless network technology. However, these multi-hop technologies have its applications and limitations depending on their implementation and operation. Analysis: In this work our primary focus is to review the current work on developed reactive MAC protocol for multiple -beam smart –antennas in MANETs and WMNs and secondly focus to review the current work on developed efficient and reliable MAC methods for wireless multi-hop networks. Findings: Based on our analysis we find the method to describe the Medium Access Control Problems for Reliable Data Communication. Application: This work is used to develop reactive medium access control mechanism for peer to peer heterogeneous multi hop networks.

Frame-Based Medium Access Control for 5G Wireless Networks

Millimeter wave (mmWave) communications is one of the key technologies for future 5th generation (5G) wireless networks. In this paper, we investigate the problem of medium access control (MAC) in mmWave networks. We develop a frame-based scheduling directional MAC protocol, termed FDMAC, to achieve the goal of leveraging collision-free concurrent transmissions to fully exploit spatial reuse in mmWave networks. The high efficiency of FDMAC is achieved by amortizing the scheduling overhead over multiple concurrent, back-to-back transmissions in a row. The core of FDMAC is a graph coloring-based scheduling algorithm, termed greedy coloring (GC) algorithm, that can compute near-optimal schedules with respect to the total transmission time with low complexity. FDMAC is analyzed and evaluated with simulations.

무선랜 QoS의 성능향상을 위한 최적 파라미터에 관한 연구

IEEE 802.11과 같은 무선 LAN 환경에서 실시간 멀티미디어 통신이 전송 데이터의 많은 부분을 차지하면서 성능 문제와 함께 네트워크의 QoS(Quality of Service)가 중요한 문제로 대두되고 있다. 802.11e MAC(Medium Access Control)은 기존 802.11 MAC의 문제를 해결하기 위해 우선순위 기반의 차별화 서비스를 제공한다. 특히 각 스테이션의 TXOP(Transmission Opportunity)는 한 번에 여러 프레임을 전송할 수 있는 시간을 규정하며 Priority와 함께 네트워크 성능 및 QoS 향상에 중요한 요소가 된다. 따라서 본 논문에서는 스테이션 수의 변화에 따라 네트워크의 최대 성능을 위한 프레임 사이즈와 TXOP, 그리고 Priority 값을 분석하고 최적의 값을 도출한다. 802.11e 표준 파라미터를 사용하여 시뮬레이션을 수행한 결과 Throughput은 스테이션의 수가 5일 때, TXOP Limit의 값이 6.016ms 일 때 가장 좋은 결과를 보였고 공정성은 TXOP Limit의 값이 3.008ms이고 Priority는 우선순위가 가장 높은 CW(Contention Window) 값이 7-15일 때가 아니고 그보다 낮은 CW 15-31일 때 가장 좋은 결과를 나타내었다. Since multimedia data takes large part of realtime transmission in wireless communication environments such as IEEE 802.11, QoS issues became one of the important problems with network performance. 802.11e MAC provides differentiated services based on priority schemes to solve existing 802.11 MAC problems. The TXOP is an important factor with the priority to improve network performance and QoS because it defines the time duration in which multiple frames can be transferred at one time for each station. In this paper, therefore frame sizes, TXOP Limit, and Priority values in accordance with the number of stations are experimented and derived for best network performance and QoS. Using 802.11e standard parameters, simulation results show the best throughput when the number of stations is 5 and TXOP Limit value is 6.016ms. For fairness, the best result is achieved at 3.008ms of TXOP Limit value and 15-31 of CW(Contention Window) that is lower priority than CW 7-15.

On Reservation-Based MAC Protocol for IEEE 802.11 Wireless Ad Hoc Networks With Directional Antenna

In this paper, we study the issues of medium access control (MAC) for multihop wireless networks with directional antennas. Existing solutions to directional antenna MAC problems rarely account for the impact of minor lobes and typically assume that the neighboring nodes' locations are known a priori. As a result, they are not applicable to practical systems or mobile nodes. In this paper, we propose a reservation-based directional medium access control (RDMAC) protocol for multihop wireless networks based on the IEEE 802.11 distributed coordination function. The design objective of RDMAC is to increase the network throughput by reducing interference among neighboring nodes. We then develop an analytical model for RDMAC to investigate the throughput performance of RDMAC under arbitrary node density. The analytical model provides insights into RDMAC parameter settings. We also evaluate the performance of the proposed RDMAC through ns-2 simulations. The results validate the accuracy of our analytical model and show that our mechanism outperforms existing solutions, in terms of higher throughput.

Channel-aware multi-user uplink transmission scheme for SIMO-OFDM systems

The problem of medium access control (MAC) in wireless single-input multiple-output-orthogonal frequency division multiplexing (SIMO-OFDM) systems is addressed. Traditional random access protocols have low overheads and inferior performance. Centralized methods have superior performance and high overheads. To achieve the tradeoff between overhead and performance, we propose a channel-aware uplink transmission (CaUT) scheme for SIMO-OFDM systems. In CaUT, users transmit request-to-send (RTS) at some subcarriers whose channel gains are above a predetermined threshold. Using the channel state information provided by RTS, access point performs user selection with receive beamforming to decide which users can access and then broadcasts the selection results via clear-to-send (CTS) to users. We present a distributed power control scheme by using a simple fixed modulation mode. We optimize the modulation order and channel gain thresholds to maximize the separable packets subject to the bit-error-rate (BER) and temporal fairness requirements and the individual average transmit power constraints. The performance of CaUT scheme is analyzed analytically and evaluated by simulations. Simulation results show that CaUT can achieve more significant throughput performance than traditional random access protocols.

A cross-layer framework for position-based routing and medium access control in heterogeneous mobile ad hoc networks

Many Mobile Ad Hoc Networks (MANETs) are composed of nodes with heterogeneous communication capabilities in terms of transmission power, data rate, battery life, reliability, etc. Heterogeneous MANETS (H-MANETs) often encounter problems in both Medium Access Control (MAC) and routing layers due to link asymmetry. But meanwhile, H-MANETs have many advantages including: scalability, robustness, and connectivity. In this paper we present a two-layer approach which spans the MAC and network layers for H-MANETs to minimize the problems caused by link asymmetry and exploit the advantages of H-MANETs simultaneously. At the network layer, we design a hierarchical Location service (LS) protocol and a node density adaptive position-based routing protocol. At the MAC layer we propose a new MAC protocol which uses two communication channels and closely ties in with the network layer to solve the MAC problems caused by link asymmetry. We evaluate our approach using both probabilistic analysis and simulations.

Efficient MAC in cognitive radio systems: A game-theoretic approach

In this paper, we study the problem of efficient medium access control (MAC) among cognitive radio devices that are equipped with multiple radios and thus are capable of transmitting simultaneously at different frequencies (channels). We assume that radios contend on each channel using the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol. We study two MAC problems: (i) the allocation of the available channels among radios, and (ii) the optimal usage of each allocated channel by the radios occupying it. Both problems are studied in a game-theoretic setting, where devices aim to selfishly maximize their share of the available bandwidth. As for the first problem, we show that the “price of anarchy” is close to 1, that is, Nash equilibria imply nearly system optimal allocations of the available channels. For the second problem, we design a game such that it admits a unique Nash equilibrium that is is both fair and Pareto-optimal. Furthermore, we propose simple mechanisms that enable selfish cognitive radio devices not only to coordinate efficiently on the available channels but also to optimally use every single allocated channel.

Distributed Utility-Based Power Control: Objectives and Algorithms

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> This paper deals with the problem of medium access control (MAC)-layer fair power control in a wireless mesh network with an established network topology. The notion of MAC-layer fairness is defined along similar lines as end-to-end fairness for elastic traffic, except that instead of end-to-end flows, MAC-layer flows are considered, being that one hop flows between neighboring nodes. In this paper, we identify a class of utility functions of link rates that allows for a convex problem formulation. The convexity property is a key prerequisite for implementing power control algorithms in practice. We present a novel distributed algorithmic solution to the power control problem based on gradient-projection methods, prove its global convergence, and provide sufficient conditions for a geometric convergence rate. The main novelty of our scheme lies in the use of the so-called adjoint network in such a way that each transmitter can estimate its current update direction from the received signal power. This mitigates the problem of global coordination of the transmitters when carrying out gradient-projection algorithms in distributed wireless networks. The price for this are possible estimation errors so that the proposed scheme is analyzed within the framework of stochastic approximation. </para>

A Unified MAC Layer Framework for Ad-Hoc Networks With Smart Antennas

Smart antennas represent a broad variety of antennas that differ in their performance and transceiver complexity. The superior capabilities of smart antennas, however, can be leveraged only through appropriately designed higher layer network protocols, including at the medium access control (MAC) layer. Although several related works have considered such tailored protocols, they do so in the context of specific antenna technologies. In this paper, we explore the possibility for a unified approach to medium access control in ad hoc networks with smart antennas. We first present a unified representation of the PHY layer capabilities of the different types of smart antennas, and their relevance to MAC layer design. We then define a unified MAC problem formulation, and derive unified MAC algorithms (both centralized and distributed) from the formulation. Finally, using the algorithms developed, we investigate the relative performance trade-offs of the different technologies under varying network conditions. We also analyze theoretically the performance bounds of the different smart antenna technologies when the available gains are exploited for rate increase and communication range increase.

The medium access control problem for wireless communication networks modelled as hybrid dynamical systems

The paper considers the medium access control problem for a class of wireless communication networks. We apply mathematical models in terms of hybrid dynamical systems to analyze such networks. We introduce the concept of stabilizability for such systems which guarantees that any data packet in the wireless network will reach its destination within finite time. We obtain conditions for a wireless communication network to be stabilizable.

The problem of medium access control in wireless sensor networks

In this article we revisit the problem of scheduled access through a detailed foray into the questions of energy consumption and throughput for MAC protocols in wireless sensor networks. We consider a static network model that rules out simultaneous transmission and reception by any sensor node and consequently requires partitioning of nodes into disjoint sets of transmitters and receivers at any time instant. Under the assumption of circular transmission (reception) ranges with sharp boundaries, a greedy receiver activation heuristic is developed relying on the network connectivity map to determine distinct receiver groups to be activated within disjoint time intervals. To conserve limited energy resources in sensor networks, the time allocation to each receiver group is based on the residual battery energy available at the respective transmitters. Upon activating each receiver group separately, the additional time-division mechanism of group TDMA is imposed to schedule transmissions interfering at the non-intended destinations within separate fractions of time in order to preserve the reliable feedback information. The two-layered time-division structure of receiver activation and group TDMA algorithms offers distributed and polynomial-time solutions (as required by autonomous sensor networks) to the problems of link scheduling as well as energy and throughput-efficient resource allocation in wireless access. The associated synchronization and overhead issues are not considered in this article.

On the medium access control problem in Ad hoc networks with smart antennas

In this paper, we address the problem of medium access control in ad-hoc networks with fully adaptive array antennas, which to the best of our knowledge is one of the first efforts of its kind. We show that, unlike in the case of directional and switched beam antennas, significant performance improvement can be leveraged with just a simple extension to CSMA/CA that we refer to as CSMA/CA (k). We than provide PHY layer based insights into why a MAC scheme that is smarter than CSMA/CA (k), and can achieve significantly better performance is possible in the target environment. Finally, we propose an idealized protocol called SMART-MAC that builds on the insights.

Performance of shared medium access protocols for ATM traffic concentration

AbstractThe paper analyses the problem of Medium Access Control in a Passive Optical Network, used to concentrate ATM user traffic. Feasible solutions for the problem are investigated and two protocols to resolve contention on the shared medium are presented, the single cell and the multiple cell frame based. The performance of the two protocols is evaluated, obtaining indications about the transfer delay introduced by the protocols and the amount of buffering needed at the user side.