Author: Yun-Jung LuPublisher:
ISBN:
Category :
Languages : en
Pages : 142
Book Description
Multi-channel Mac Protocols with Bandwidth Utilization Enhancement in Wireless Ad Hoc Networks
Author: Yun-Jung LuControl-channel Reuse-based Multi-channel MAC Protocol for Ad Hoc Networks
Author: Divya SardanaPublisher:
ISBN:
Category :
Languages : en
Pages : 81
Book Description
Ad hoc networks have become a popular type of wireless network in the present world. In order to match with the increasing demand of ad hoc networks, a lot of research is being done towards solving the issues related to the design of ad hoc networks. The design of a Medium Access Control (MAC) protocol for ad hoc networks is one such issue. Traditional MAC protocols involve the use of a single channel as the wireless medium. However, throughput of a single channel MAC degrades as the node traffic in the system increases. One of the interesting approaches towards alleviating this problem is the use of more than one channel as the underlying medium. The use of multiple channels allows more than one communication to take place simultaneously thereby improving the throughput of the system. Multiple channels have been mostly used in the literature by assigning one of the channels as the control channel used only for control packet transfer and the rest of the channels as data channels used for Data packet transfer. Using such an approach towards designing a multi-channel MAC protocol leads to a poor utilization of the available bandwidth. In this thesis, we propose a multi-channel MAC protocol called as Control-channel Reuse based Multi-channel MAC (CRM-MAC) which aims at improving the overall bandwidth utilization. We illustrate the efficacy of our protocol through elaborate simulations.
Throughput Analysis and Enhancement of Multi-Channel MAC Protocol in Ad-Hoc Networks
Author: 高譓翔Cooperative Multi-channel MAC Protocols for Wireless Ad Hoc Networks
Author: Yuhan MoonPublisher:
ISBN:
Category : Ad hoc networks (Computer networks)
Languages : en
Pages : 151
Book Description
Today, many wireless networks are single-channel systems. However, as the interest in wireless services increases, the contention by nodes to occupy the medium is more intense and interference worsens. One direction with the potential to increase system throughput is multi-channel systems. Multi-channel systems have been shown to reduce collisions and increase concurrency thus producing better bandwidth usage. However, the well-known hidden- and exposed-terminal problems inherited from single-channel systems remain, and a new channel selection problem is introduced. In this dissertation, Multi-channel medium access control (MAC) protocols are proposed for mobile ad hoc networks (MANETs) for nodes equipped with a single half-duplex transceiver, using more sophisticated physical layer technologies. These include code division multiple access (CDMA), orthogonal frequency division multiple access (OFDMA), and diversity. CDMA increases channel reuse, while OFDMA enables communication by multiple users in parallel. There is a challenge to using each technology in MANETs, where there is no fixed infrastructure or centralized control. CDMA suffers from the near-far problem, while OFDMA requires channel synchronization to decode the signal. As a result CDMA and OFDMA are not yet widely used. Cooperative (diversity) mechanisms provide vital information to facilitate communication set-up between source-destination node pairs and help overcome limitations of physical layer technologies in MANETs. In this dissertation, the Cooperative CDMA-based Multi-channel MAC (CCM-MAC) protocol uses CDMA to enable concurrent transmissions on each channel. The Power-controlled CDMA-based Multi-channel MAC (PCC-MAC) protocol uses transmission power control at each node and mitigates collisions of control packets on the control channel by using different sizes of the spreading factor to have different processing gains for the control signals. The Cooperative Dual-access Multi-channel MAC (CDM-MAC) protocol combines the use of OFDMA and CDMA and minimizes channel interference by a resolvable balanced incomplete block design (BIBD). In each protocol, cooperating nodes help reduce the incidence of the multi-channel hidden- and exposed-terminal and help address the near-far problem of CDMA by supplying information. Simulation results show that each of the proposed protocols achieve significantly better system performance when compared to IEEE 802.11, other multi-channel protocols, and another protocol CDMA-based.
Medium Access Protocol (MAC) Design for Wireless Multi-hop Ad Hoc and Sensor Networks
Author: Afef SayadiPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Wireless multi-hop ad hoc and sensor networks provide a promising solution to ensure ubiquitous connectivity for the Future Internet. Good network connectivity requires designing a reliable Medium Access Control (MAC) protocol, which is a challenging task in the ad hoc and sensor environments. The broadcast and shared nature of the wireless channel renders the bandwidth resources limited and expose the transmissions to relatively high collisions and loss rates. The necessity to provide guaranteed Quality of Service (QoS) to the upper layers triggered the design of conflict-free MAC protocols. The TDMA synchronization constraint is basically behind the rush of MAC protocol design based on a fixed frame size. This design shows inflexibility towards network variations and creates a network dimensioning issue that leads to a famine risk in case the network is under-dimensioned, and to a waste of resources, otherwise. Moreover, the alternative dynamic protocols provide more adaptive solutions to network topology variations at the expense of a fair access to the channel. Alongside with the efficient channel usage and the fair medium access, reducing the energy consumption represents another challenge for ad hoc and sensor networks. Solutions like node activity scheduling tend to increase the network lifetime while fulfilling the application requirements in terms of throughput and delay, for instance. Our contributions, named OSTR and S-OSTR, address the shortcomings of the medium access control protocol design in the challenging environment of wireless multi-hop ad hoc and sensor networks, respectively. For OSTR the idea consists in adopting a dynamic TDMA frame size that increases slot-by-slot according to the nodes arrival/departure to/from the network, and aiming to achieve a minimum frame size. For this end, OSTR couples three major attributes: (1) performing slot-by-slot frame size increase, (2) providing a spatial reuse scheme that favors the reuse of the same slot if possible, (3) and ensuring an on-demand frame size increase only according to the node requirements in terms of throughput. To tackle different frame sizes co-existence in the network, OSTR brings a cooperative solution that consists in fixing an appointment, a date when the frame size in the network is increased. Concerning S-OSTR, it is an amendment of OSTR for wireless sensor networks. It brings the idea of a dynamic active period, since it deploys a dynamic frame size that is built slot-by-slot according to nodes arrival to the network. S-OSTR enforces the slot-by-slot frame size increase by a node activity scheduling to prolong the inactivity period in the network, and hence prolong the overall network lifetime for wireless sensor networks. Our contributions are both based on the new dynamic TDMA frame size increase that consists in increasing the frame size slot-by-slot aiming to achieve a shorter frame size, and hence improve the channel utilization, and reduce the energy consumption. The performance analysis of OSTR and S-OSTR shows that they present good potentials to support QoS requirements, to provide energy-efficiency, to ensure fair medium access, to accommodate network topology changes and finally, to enhance robustness against scalability. The impact of this new TDMA frame size increase technique on the medium access control protocol performance is highlighted through multiple simulations of OSTR and S-OSTR. Multiple comparative studies are also handled to point out the effectiveness of this new technique and the soundness of our contributions.
An Enhanced Medium Access Control Protocol for Ad Hoc Networks
Author: Priyadarshini SabutPublisher: LAP Lambert Academic Publishing
ISBN: 9783838393476
Category :
Languages : en
Pages : 60
Book Description
Ad hoc Networks are the most popular networks and are useful in many application environments due to less cost and easy deployment at anytime anywhere. The efficiency of these networks depends on the performance and reliability of the medium access control (MAC) protocol applied in such networks. The IEEE 802.11 DCF MAC protocol for ad hoc networks suffers from the problem of bandwidth sharing due to presence of hidden and exposed nodes. This book discusses a MAC protocol that not only overcomes the problem of hidden and exposed nodes but also allows the hidden nodes to transmit and exposed nodes to receive without interfering with the ongoing transmission in their vicinity, thereby improving channel utilization. The proposed protocol outperforms IEEE 802.11 DCF MAC in terms of throughput and packet delivery ratio with a little cost of control overhead.
Multichannel Medium Access Control Protocol with Cooperative Channel Selection for Ad Hoc Networks
Author: Jai MondhePublisher:
ISBN:
Category :
Languages : en
Pages : 150
Book Description
A mobile ad hoc network is a collection of mobile terminals equipped with wireless transceivers that form an autonomous network without any pre-planned infrastructure or centralized administration. Wireless hosts in an ad hoc network typically share a single common channel for communication. The Medium Access Control (MAC) allows the hosts to resolve contention while randomly accessing the channel and plays a key role in determining the efficiency of channel usage in the network. Usage of multiple channels improves the throughput of the MAC protocol in ad hoc networks by allowing multiple nodes to transmit concurrently on different non-overlapping channels. Efficient channel selection schemes can reduce the contention in each channel leading to smaller number of collisions, backoffs, and retransmissions. This research explores a new channel selection scheme that is based on maximizing the signal to interference ratio at the receiver as well as minimizing the interference caused to all other active receivers in the vicinity of the sender. An implementation of this "cooperative" channel selection technique is proposed employing receiver-initiated busy-tones and signal power measurements at the sending and receiving nodes respectively. Simulation based performance results are presented.
A New Multi-channel MAC Protocol for Wireless Ad Hoc Networks with Single Transceiver
Author: Musa Aykut CanbolatPublisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 74
Book Description
Although IEEE 802.11a/b/g standards allow use of multiple channels, only a single channel is popularly used, due to the lack of efficient protocols that enable use of Multiple Channels. There are some papers challenging this problem. Some of them have requirements that will increase the cost, like requirement of multiple transceivers. Some others address the problem with single transceivers, but are very hard to be employed in highly mobile Ad Hoc networks due to network-wide synchronization requirements. In this Thesis, multiple channel use in a wireless network with single transceiver nodes is addressed, and attempted to be solved with a new efficient Ad Hoc network MAC protocol, which intends to remove the requirement of network-wide synchronization.
Medium Access Control Protocols for Multi-hop Wireless Ad Hoc Networks
Author: Venkatesh RajendranMAC Protocol Design in Full-Duplex Enabled Wireless Networks
Author: Liqun FuPublisher: Springer Nature
ISBN: 3031572963
Category :
Languages : en
Pages : 158
Book Description