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CAC-MAC: A Cross-Layer Adaptive Cooperative MAC for Wireless Ad Hoc Networks
Chunguang Shi,Haitao Zhao,Shan Wang,Jibo Wei,Linhua Zheng
International Journal of Distributed Sensor Networks , 2012, DOI: 10.1155/2012/785403
Abstract: Cooperative communication has been recently proposed as a way to mitigate fading in wireless networks. A cross-layer adaptive cooperative MAC (CAC-MAC) protocol for IEEE 802.11 DCF-based wireless ad hoc networks is proposed. The novel aspect and core idea of our proposal is a cross-layer adaptive data transmission algorithm considering both the length of data frame at the MAC layer and instantaneous wireless channel conditions. Under this algorithm, direct transmission mode or proper cooperative transmission mode will be adaptively selected for data packets according to both MAC layer and physical layer information. Analytical results demonstrate the effectiveness of the adaptive data transmission algorithm. Simulation studies based on NS2 show that the CAC-MAC protocol can significantly improve network throughput and reduce packet delay compared with legacy IEEE 802.11 protocol, which illustrate a new paradigm for realistic cross-layer cooperative MAC protocol design for next-generation wireless ad hoc networks.
Metric-Based Cooperative Routing in Multihop Ad Hoc Networks  [PDF]
Xin He,Frank Y. Li
Journal of Computer Networks and Communications , 2012, DOI: 10.1155/2012/893867
Abstract: Cooperative communication fully leverages the broadcast nature of wireless channels and exploits time/spatial diversity in a distributed manner, thereby achieving significant improvements in system capacity and transmission reliability. Cooperative diversity has been well studied from the physical layer perspective. Thereafter, cooperative MAC design has also drawn much attention recently. However, very little work has addressed cooperation at the routing layer. In this paper, we propose a simple yet efficient scheme for cooperative routing by using cooperative metrics including packet delivery ratio, throughput, and energy consumption efficiency. To make a routing decision based on our scheme, a node needs to first determine whether cooperation on each link is necessary or not, and if necessary, select the optimal cooperative scheme as well as the optimal relay. To do so, we calculate and compare cooperative routing metric values for each potential relay for each different cooperative MAC scheme (C-ARQ and CoopMAC in this study), and further choose the best value and compare it with the noncooperative link metric. Using the final optimal metric value instead of the traditional metric value at the routing layer, new optimal paths are set up in multihop ad hoc networks, by taking into account the cooperative benefits from the MAC layer. The network performance of the cooperative routing solution is demonstrated using a simple network topology. 1. Introduction Multihop wireless networks in forms of ad hoc networks, mesh networks and sensor networks have become active research topics in recent years in both academia and industry. Different types of nodes are deployed pervasively in various environments such as office buildings, wildlife reserves, battle fields, and metropolitan area networks. However, lots of challenging tasks still remain for building multihop ad hoc networks, despite significant progress achieved so far. Traditional techniques conceived for wired networking provide inefficient performance when applied in wireless ad hoc networks. Efforts are being made to improve the existing techniques and protocols with new features suitable for the wireless paradigms. For example, different from wired transmission, broadcast is an inherent feature in wireless communications, that is, information transmitted from a source node can be overheard by not only the destination node, but also neighboring nodes surrounding the source. In traditional wireless networks, signals received by the neighboring nodes are treated as interference and many techniques
Mac Protocols in Mobile Ad Hoc Networks  [cached]
Nermin Makhlouf,Pavel Vajsar
International Journal of Advances in Telecommunications, Electrotechnics, Signals and Systems , 2012, DOI: 10.11601/ijates.v1i1.4
Abstract: Mobile Ad hoc NETwork (MANET) is a wireless net- work of mobile nodes connected by wireless link without a central control. The Medium Access Control (MAC) protocol is one of the important issues in such network, thereby the presented paper will discuss the MAC protocol used in MANET depending on IEEE 802.11 standard which known as Distributed Coordination Function (DCF).However, the limitation of MANET is that, the collision increases with the rise of nodes number. Therefore paper study the MAC protocol using directional antennas to reduce the collisions, increase the range of transmission and largely reduce the interference between the directions. However, the main problem of using directional antennas is caused by frequent node mobility. So the movement plays a vital role in wireless Ad hoc networks to predict the location of MNs.
Cooperative Multibeamforming in Ad Hoc Networks  [cached]
Chuxiang Li,Xiaodong Wang
EURASIP Journal on Advances in Signal Processing , 2007, DOI: 10.1155/2008/310247
Abstract: We treat the problem of cooperative multiple beamforming in wireless ad hoc networks. The basic scenario is that a cluster of source nodes cooperatively forms multiple data-carrying beams toward multiple destination nodes. To resolve the hidden node problem, we impose a link constraint on the receive power at each unintended destination node. Then the problem becomes to optimize the transmit powers and beam weights at the source cluster subject to the maximal transmit power constraint, the minimal receive signal-to-interference-plus-noise ratio (SINR) constraints at the destination nodes, and the minimal receive power constraints at the unintended destination nodes. We first propose an iterative transmit power allocation algorithm under fixed beamformers subject to the maximal transmit power constraint, as well as the minimal receive SINR and receive power constraints. We then develop a joint optimization algorithm to iteratively optimize the powers and the beamformers based on the duality analysis. Since channel state information (CSI) is required by the sources to perform the above optimization, we further propose a cooperative scheme to implement a simple CSI estimation and feedback mechanism based on the subspace tracking principle. Simulation results are provided to demonstrate the performance of the proposed algorithms.
A Review of MAC Protocol for Mobile Ad Hoc Networks
移动Ad Hoc网络MAC协议研究

HE Min,LIU Xing-Song,ZHAO Dong-Feng,
何敏
,刘心松,赵东风

计算机科学 , 2006,
Abstract: A MANET(Mobile Ad-hoc network)is an autonomous non-infrastructure network system of mobile hosts, which are connected with each other via wireless links.It can provide efficient services for data and multimedia applica- tions.However,as we know that the wireless system is a band-limited system,so the channel allocation algorithm is very important.To improve the efficiency,capability and transmission quality of the wireless resource is the key re- search.This paper provides an overview of various MAC protocols for mobile Ad hoc network by presenting their char- acteristics and functionalities,and then provides a comparison and discussion of their respective merits and drawbacks, which cover most types of MANET MAC protocols.Finally,the future research directions are outlined.
Performance Evaluation of Efficient MAC in Mobile Ad Hoc Wireless Networks
Soni Sweta,Arun Nahar,Sanjeev Sharma
International Journal of Computer Science Issues , 2011,
Abstract: Wireless media is in very much demand because of high mobility of the users and establishing ad hoc network in emergency situations, which requires the designing of an efficient and priority based MAC (Medium Access Protocol) as a resource to support MANET (Mobile Ad hoc Networks) adequately. There are various MAC standards used in MANET. The IEEE 802.11 is one of them MAC layer standard and most frequently applied to such networks presently. We found that the IEEE 802.11 MAC standard is not very much suitable into wireless network scenario because its poor performance results in lower throughput, higher delay ,large number of collisions and poor fair access of cannels. In this paper, we propose a dynamic PBCMAC protocol for wireless ad hoc networks - named as Priority Based Contention-MAC protocol- in which contention window size increases or decreases dynamically and non-uniformly after the collision depending upon the priority levels of nodes in the network. It decides its lower Backoff time as per higher priority level of the nodes to access channel adequately. The simulation result show that PBC-MAC scheme is outperform than the Binary Exponential Backoff (BEB) scheme in the IEEE 802.11 MAC in respect of delay.
Cooperative Transmission in Cognitive Radio Ad Hoc Networks
Juncheng Jia,Shukui Zhang
International Journal of Distributed Sensor Networks , 2012, DOI: 10.1155/2012/863634
Abstract: Cognitive radio technology is the key to realize dynamic spectrum access system and promote the spectrum utilization through exploiting the spectrum holes left by primary users. However, the spatial heterogeneity of spectrum availability imposes special challenges for efficient utilization of the spectrum resources for cognitive radio ad hoc networks (CRAHNs). The cross-layer cooperative transmission scheme is a promising approach to improve the efficiency of spectrum utilization and improve the performance of cognitive radio networks. Such an approach leverages relay-assisted discontiguous OFDM (DOFDM) for data transmission at physical and MAC layers in a basic three-node configuration. With this scheme, a relay node will be selected that can bridge the source and the destination using its common channels between those two nodes. In this paper, we investigate the application of such a cooperative transmission scheme to address the spectrum heterogeneity issue in CRAHNs. In particular, we describe several types of cooperative transmission and formulate a new resource allocation problem with joint relay selection and channel allocation. We propose a heuristic algorithm to solve the resource allocation problem, which is based on the metric of utility-spectrum ratio of transmission groups. Simulations demonstrate the performance improvement of the cooperative transmission over the direct transmission.
Survey of MAC Layer Protocols for vehicular Ad Hoc Network
Vimal Bibhu,Dhirendra Kumar Singh
International Journal of Information Technology and Computer Science , 2012,
Abstract: Vehicular Ad Hoc Network is currently challenge for the wireless networking and its researchers. In this paper we have proposed the survey of the different MAC Layer protocols of the wireless medium those can be implemented in the Vehicular Ad Hoc Networking. The survey is based upon the study of the different protocol on their MAC level and its performance factors is evaluated. The performance factor is extracted from the studied materials and current working conditions of the protocols. These all factors are mobility, accuracy, privacy and confidentiality, safety critical message priority, delay control and suitability on vehicle and roadside. According to analyzed performance factor the IEEE 802.11p Wave is most suitable protocol for the Vehicular Ad Hoc Network but it does not cover up all conditional requirements.
An Energy Efficient MAC Protocol for Fully Connected Wireless Ad Hoc Networks  [PDF]
K. Rahimi Malekshan,W. Zhuang,Y. Lostanlen
Computer Science , 2014,
Abstract: Energy efficiency is an important performance measure of wireless network protocols, especially for battery-powered mobile devices such as smartphones. This paper presents a new energy-efficient medium access control (MAC) scheme for fully connected wireless ad hoc networks. The proposed scheme reduces energy consumption by putting radio interfaces in the sleep state periodically and by reducing transmission collisions, which results in high throughput and low packet transmission delay. The proposed MAC scheme can also address the energy saving in realtime traffics which require very low packet transmission delay. An analytical model is established to evaluate the performance of the proposed MAC scheme. Analytical and simulation results demonstrate that the proposed scheme has a significantly lower power consumption, achieves substantially higher throughput, and has lower packet transmission delay in comparison with existing power saving MAC protocols.
Comparative Study of MAC Protocols for Mobile Ad Hoc Networks
Sanjeev Sharma,R.C. Jain,Sarita Bhadauria,Ramesh Cherukuru
International Journal of Soft Computing , 2012,
Abstract: 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 comparative study of major schemes, integrating various related issues and challenges. We present a classification of MAC protocols and their brief description based on their operating principles and underlying features.
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