Showing papers on "Media access control published in 2007"

Hop-by-hop congestion control over a wireless multi-hop network

Abstract: This paper focuses on congestion control over multi-hop, wireless networks. In a wireless network, an important constraint that arises is that due to the MAC (Media Access Control) layer. Many wireless MACs use a time-division strategy for channel access, where, at any point in space, the physical channel can be accessed by a single user at each instant of time. In this paper, we develop a fair hop-by-hop congestion control algorithm with the MAC constraint being imposed in the form of a channel access time constraint, using an optimization-based framework. In the absence of delay, we show that this algorithm are globally stable using a Lyapunov-function-based approach. Next, in the presence of delay, we show that the hop-by-hop control algorithm has the property of spatial spreading. In other words, focused loads at a particular spatial location in the network get "smoothed" over space. We derive bounds on the "peak load" at a node, both with hop-by-hop control, as well as with end-to-end control, show that significant gains are to be had with the hop-by-hop scheme, and validate the analytical results with simulation.

UWAN-MAC: An Energy-Efficient MAC Protocol for Underwater Acoustic Wireless Sensor Networks

Abstract: In this paper, we propose a distributed, scalable, energy-efficient media access control (MAC) protocol that works despite long, unknown propagation delays of the underwater acoustic medium. This protocol can be used for delay-tolerant applications such as underwater ecological sensor networks between energy-limited nodes. Our protocol differs significantly from ALOHA, multiple access with collision avoidance (MACA), and the media access protocol for wireless LANs (MACAW) in that energy is the main performance metric in our case rather than bandwidth utilization. We show that under a realistic underwater sensor network scenario, our MAC protocol wastes only 4% of the transmit energy and only 1.5% of the receive energy due to collisions, when the average number of neighbors is four, and the duty cycle is 0.004. This distributed, scalable MAC protocol has the potential to serve as a primer for the development of energy-efficient MAC protocols for future underwater sensor networks.

Topology Control for Wireless Sensor Networks

Abstract: Topology control is one of the most fundamental problems in wireless sensor networks. It is of great importance for prolonging network lifetime, reducing radio interference, increasing the efficiency of MAC (media access control) protocols and routing protocols, among other things. This paper makes a full-scale introduction to the advancement of research on topology control. Firstly, the topology control problem and the design objectives are clearly presented. Secondly, an introduction is made to representative research efforts, along with analyses and comparisons, in two aspects, power control and sleep scheduling, respectively. At the same time, the defects of those efforts are clearly pointed out. Finally, existing problems, open issues and research trends are analyzed and

Multi-wideband communications over multiple mediums

Abstract: A powerline communications device comprises a powerline communications interface and at least one other communications interface configured to communicate over a computing network. The powerline communications interface is further configured to receive electrical power. The computing network may comprise mediums including powerlines, telephone lines, and/or coaxial cables. In some embodiments, the powerline communications interface may communicate with a network apparatus, such as a personal computer, via an Ethernet interface. The powerline interface, the telephone line interface, and/or the coaxial cable interface may all be associated with the same media access control (MAC) address. The powerline communications device may receive a message via a first medium and repeat the message via a second medium based on a quality of service (QoS) metric. In some embodiments, the powerline communications device may communicate using multiple frequency bands.

Rogue router hunter

Abstract: A computer implemented method, data processing system, and computer program product for discovering an unauthorized router in a network. The process in the illustrative embodiments first obtains a physical address of a suspected router or destination device. A data packet is created which comprises at least a destination media access control field, a destination internet protocol field, and a time-to-live field, wherein the destination media access control field comprises the physical address of the destination device, wherein the destination internet protocol field comprises a bogus internet protocol address, and wherein the time-to-live field comprises a value indicating the data packet has exceeded a time limit. The data packet is sent to the destination device using the physical address in the destination media access control field. If a time exceeded message is received from the destination device, the destination device is determined to be enabled for routing.

A component-based architecture for power-efficient media access control in wireless sensor networks

Abstract: The diverse requirements of wireless sensor network applications necessitate the development of multiple media access control (MAC) protocols to meet their varying throughput, latency, and network lifetime needs. Building new MAC protocols has proven to be extremely difficult, however, given the monolithic nature of existing protocol implementations as well as their dependence on a particular radio or processor platform. To address these issues, we propose the MAC Layer Architecture (MLA), a component-based architecture for power-efficient MAC protocol development in wireless sensor networks. MLA consists of optimized, reusable components that implement a common set of features shared by existing MAC protocols, as well as abstractions that encapsulate the intricacies of the hardware platforms they run on. Through an instantiation of MLA in TinyOS 2.0.1, we have implemented five representative MAC protocols. Empirical results show that MLA results in significant code reuse among different protocols, while achieving comparative performance and memory footprints to monolithic implementations of the same protocols.

Media Access Control (MAC) Protocol for Cognitive Wireless Networks

Abstract: A new media access control (MAC) protocol for cognitive wireless networks is described. The new MAC protocol allows each of multiple nodes, such as cell phones and computers with wireless, to determine utilization of a communication spectrum, such as the television broadcast band. The nodes collaborate to achieve a combined view of spectrum utilization in their local vicinity, in which scheduled users and empty time segments are mapped across a wide range of frequencies. Nodes negotiate with each other to reserve idle segments of the spectrum for packet exchange on negotiated frequencies. Control packet structure allows nodes to become prescient of the local spectrum utilization during handshaking. A cognitive device operating under the new MAC has a first radio that both scans the spectrum and monitors a control channel; and a second reconfigurable radio with adjustable parameters, including frequency and bandwidth, for packet transmission.

HYMAC: Hybrid TDMA/FDMA Medium Access Control Protocol for Wireless Sensor Networks

Abstract: We describe HyMAC, a new hybrid MAC layer protocol for wireless sensor networks that is, to the best of our knowledge, the first effort to combine the strengths of both TDMA and FDMA schemes in these constrained networks. While allowing the network to operate in an energy-efficient collision-free manner, HyMAC takes advantage of the multiple frequencies provided in the radio component of recent sensor node hardware platforms such as MICAZ, TELOS and FireFly. We show how HyMAC outperforms protocols such as B-MAC, RT-Link and MMSN achieving high throughput and small bounded end- to-end delay suitable for newer types of sensor network applications such as real-time voice streaming.

MAC Protocol Design for Spectrum-agile Wireless Networks: Stochastic Control Approach

Abstract: Widespread deployment of wireless networks under different services including wireless LANs and sensor networks in a shared spectrum has caused many interference and performance issues in dense networks. Specifically, such coexistence poses significant challenges on media access protocol design. This paper addresses this problem by proposing a distributed spectrum-agile MAC (media access control) protocol. It is a multichannel CSMA-based protocol equipped with a dynamic channel selection algorithm. The dynamic channel selection problem is formulated as a multi-armed bandit problem, and the optimal channel selection rules are derived. Finally the advantage of the new protocol is demonstrated through simulation.

Wireless handoffs between multiple networks

Abstract: The disclosure is directed to an access terminal, and method for selecting an access point for handing off the access terminal. The access terminal may include a processor. The processor may be configured to access a list access points and select one of the access points on the list based on the current traffic state of the access terminal.

Data structures and state tracking for network protocol processing

Abstract: Described are data structures, and methodology for forming same, for network protocol processing. A method for creating data structures for firewalling and network address translating is described. A method for creating data structures for physical layer addressing is described. A method for security protocol support using a data structure is described. A method for creating at least one data structure sized responsive to whether a firewall is activated is described. A data structure for routing packets is described. A method of forming hashing table chains is described. Additionally, method and apparatus for tracking packet states is described. More particularly, Transmission Control Protocol (“TCP”) tracking of states for packets is described. In an embodiment, a division between software states and hardware states is made as a packet is processed by both software and hardware. Additionally, method and apparatus for network protocol processing are described. For example, a packet for network address translation having a media access control header is obtained, from which information, including the media access control header, is obtained. The information is parsed into one or more data structures. It is determined whether a network processing unit is in a first round processing mode, or a second round pass-through mode.

Joint Channel Allocation, Interface Assignment and MAC Design for Multi-Channel Wireless Mesh Networks

Abstract: In a wireless mesh network (WMN) with a number of stationary wireless routers, the aggregate capacity can be increased when each router is equipped with multiple network interface cards (NICs) and each NIC within a router is assigned to a distinct orthogonal frequency channel. In this paper, given the logical topology of the network, we formulate the joint channel allocation, interface assignment, and media access control (MAC) problem as a cross-layer non-linear mixed-integer network utility maximization problem. An optimal joint design, based on exact binary linearization techniques, is proposed which leads to a global maximum. A near-optimal joint design, based on approximate dual decomposition techniques, is also proposed which is of more interest in terms of practical deployment. Performance evaluation is given through a number of numerical examples in terms of network utility maximization and aggregate network throughput.

802.11 mesh architecture

Abstract: A wireless network device comprises a physical layer (PHY) module that sends and receives packets wirelessly, a first media access control (MAC) module that wirelessly communicates with a second wireless network device in an ad-hoc mode via the PHY module, and a second MAC module that wirelessly communicates with an access point in an infrastructure mode via the PHY module

Dynamic resource allocation in OFDMA wireless metropolitan area networks [Radio Resource Management and Protocol Engineering for IEEE 802.16]

Abstract: In this article we present important resource allocation problems in IEEE 802.16 wireless metropolitan area networks employing orthogonal frequency division multiple access. We first highlight the unique aspects of these networks and identify challenges and opportunities provided by the physical and medium access control layers. Next, we concentrate on four interrelated resource allocation problems: dynamic subcarrier allocation, adaptive power allocation, admission control, and capacity planning. We describe solution techniques, provide preliminary results, and discuss open problems for future research

A Cross-Layer Design Approach to Multicast in Wireless Networks

Abstract: We study rate optimization for multicast communications at the media access control (MAC) layer, and explore transport layer erasure coding to enhance multicast reliability in wireless networks. We start with investigating network models with single-input-single-output (SISO) links. For threshold-T based multicast policies, we characterize the optimal transmission rates that maximize the throughput in stable networks and in saturated networks, respectively. We investigate the tradeoff between stability and throughput therein. We then generalize our study to network models with multiple-input-multiple-output (MIMO) links and non-i.i.d. channel links, and investigate the optimal transmission rate. In addition, to ensure multicast reliability while no retransmission is required at the MAC layer, we propose to use transport layer erasure coding for reliability enhancement, where the problem boils down to jointly optimizing the transmission rate and the multicast threshold. We provide a solution to this optimization problem accordingly

Method to select access point and relay node in multi-hop wireless networking

Abstract: A method and apparatus are described for selecting an access point in a wireless network, including initializing a channel index, recording a received signal power and information contained in one of a beacon message and a probe request response message, calculating an access link metric for each candidate access point, the access link metric being between an end device and each candidate access point on the channel indexed by the channel index responsive to the received signal power and information receiving a path metric between each candidate access point and a gateway, estimating a function using the access link metric and the path metric, selecting one of the candidate access points based on the function and establishing a connection with the selected access point. Also described is a method and apparatus for maintaining a connection with an access point.

A Scalable Hybrid Approach to Switching in Metro Ethernet Networks

Abstract: The most common technology in local area networks is the Ethernet protocol. The continuing evolution of Ethernet has propelled it into the scope of metropolitan area networks. Even though Ethernet is fast and simple, the spanning tree in Ethernet is inefficient in terms of network utilization and load balancing. In this work, we compare the performance of spanning tree and link state algorithms in the context of layer 2 switching. In addition, we introduce a hybrid scheme that is customized for metro Ethernet networks. The results show that the hybrid scheme increases utilization and reduces the congestion ratio and delay. The performance gained as compared to RSTP, link state, and MSTP are 20.9%, 9.4%, and 11.4%, respectively. In addition, the hybrid scheme is more scalable than using pure link state.

Methods and apparatus to provide enhanced 911 (E911) services for nomadic users

Abstract: Methods and apparatus provide enhanced 911 (E911) services for nomadic users are disclosed. An example method comprises receiving an Internet protocol (IP) address associated with a voice over internet protocol (VoIP) device and a media access control (MAC) address associated with the VoIP device, detecting when the VoIP device is outside an access network based on the MAC address and the IP address, prompting a user of the VoIP device to provide geographic location information for the VoIP device when the VoIP device is outside the access network, and updating enhanced 911 (E911) information for the VoIP device based on the geographic location information.

Method for controlling a radio access bearer in a communication system

Abstract: A radio access bearer in a mobile communication system is controlled by disposing a radio resource control layer having radio access bearers in a user side, disposing a radio link control layer, a media access control layer, and a physical layer in the user side beneath the radio resource control layer in succession, measuring a traffic volume of the media access control layer and radio link control layer in the user side by using the media access control layer in the user side to produce traffic volume measurements, comparing the traffic volume measurements to at least one of an upper critical value and a lower critical value provided to the media access control layer in the user side from a radio resource control layer in a network side of the communication system through the radio resource control layer in the user side of the system, and forwarding a comparison result and the traffic volume measurements to the radio resource control layer in the network side through the radio resource control layer in the user side, and controlling the radio access bearer in the user side through the radio resource control layer in the network side according to a result of the comparison.

Network address translation for tunnel mobility

Abstract: An access terminal identity based mobility is provided in which a first network tunnel is established between an access gateway and a first access router that provides a first access point for access terminals, and a second network tunnel is established between the access gateway and a second access router that provides a second access point for access terminals. A public address is assigned to the access terminal having a local address assigned by the first or second access router. At the access gateway, source addresses of packets sent from an access terminal to a remote correspondent node are translated by replacing the local address of the access terminal with the public address of the access terminal. The access terminal continuously maintain a communication session with the correspondent node as the access terminal moves from a first location to a second location and switches from accessing the first access router to accessing the second access router. A mapping between the local address and the public address is updated as the access terminal switches from the first access router to the second access router.

Distributed CDMA-based MAC Protocol for Underwater Sensor Networks

Abstract: Underwater sensor networks are typically distributed in nature and the nodes communicate using acoustic waves over a wireless medium. Such networks are characterized by long and variable propagation delays, intermittent connectivity, limited bandwidth and low bit rates. Due to the wireless mode of communication between the sensor nodes, a medium access control (MAC) protocol is required to coordinate access to the shared channel and enable efficient data communication. However, conventional terrestrial wireless network protocols that are based on RF technologies cannot be used underwater. In this paper, we propose PLAN - a MAC Protocol for Long-latency Access Networks that is designed for use in half-duplex underwater acoustic sensor networks. We utilize CDMA as the underlying multiple access technique, due to its resilience to multi-path and Doppler's effects prevalent in underwater environments, coupled with an RTS-CTS handshaking procedure prior to the actual data transmission. Using simulations, we study the performance and efficiency of the proposed MAC protocol in underwater acoustic networks.

Mac address learning in a distributed bridge

Abstract: A method for communication includes configuring a network node (30) having at least first and second line cards 32), the line cards having respective ports (36), to operate as a distributed media access control (MAC) bridge in a Layer 2 network. Each of the line cards has a respective forwarding database (FDB) (58). Upon receiving a data packet on a port of the network node from a MAC source address, the data packet is conveyed to at least the first line card for transmission to the MAC destination address. The MAC source address of the data packet is checked against the records in the FDB of the first line card. If the FDB does not contain a record of an association of the MAC source address with the port on which the data packet was received, the record is added to the FDB of the first line card, which sends a message to at least the second line card informing the second line card of the association.

System architecture for very fast ethernet blade

Abstract: The system of the present invention provides data transmission speeds at or in excess of 10 gigabits per second between one or more source devices and one or more destination devices. The system comprises a media access control (MAC) interface to facilitate receipt and transmission of packets over a physical interface. A first field programmable gate array is coupled to the MAC interface and operative to receive packets from the MAC interface and configured to perform initial processing of packets, which are dispatched to a first memory. A second field programmable gate array is operative to retrieve packets from the first memory and configured to compute an appropriate destination, which is used to dispatch packets to a backplane. A third field programmable gate array is provided that is operative to receive packets from the backplane and configured to organize the packets for transmission, which are dispatched to a second memory. A fourth field programmable gate array is coupled to the MAC interface and operative to retrieve packets from the second memory and configured to schedule the transmission of packets to the MAC interface for transmission to one or more destination devices.

On the design of mobility-tolerant TDMA-based media access control (MAC) protocol for mobile sensor networks

Abstract: Several media access control (MAC) protocols proposed for wireless sensor networks assume nodes to be stationary. This can lead to poor network performance, as well as fast depletion of energy in systems where nodes are mobile. This paper presents several results for TDMA-based MAC protocol for mobile sensor networks, and also introduces a novel mobility-aware TDMA-based MAC protocol for mobile sensor networks. The protocol works by first splitting a given round into a control part, and a data part. The control part is used to manage mobility, whereas nodes transmit messages in the data part. In the data part, some slots are reserved for mobile nodes. We show that the protocol ensures collision-freedom in the data part of a schedule.

Analysis and improvement of contention access protocol in IEEE 802.15.4 star network

Abstract: The wireless standard IEEE 802.15.4 is emerging as a key enabling technology for different wireless sensor network applications. IEEE802.15.4 supports a low data rate wireless sensor network with low power requirement. In this paper, we discuss the performance analysis of IEEE 802.15.4 MAC assuming star topology in the beacon enabled mode. We obtain analytical expressions for channel sensing probabilities and saturation throughput during the contention access period. We have included the packet discard analysis and validated the analytical expressions for these parameters using ns-2 simulation. Further, we also discuss the performance analysis of the MAC when the contention access mechanism of IEEE 802.15.4 is modified to have only one channel sensing. Finally, we discuss adaptation of the frame length for the case with one channel sensing.

E-CSMA: Supporting Enhanced CSMA Performance in Experimental Sensor Networks Using Per-Neighbor Transmission Probability Thresholds

Abstract: A transmitter in a wireless network that uses CSMA, a simple carrier sensing-based MAC protocol, to determine the likelihood of successful packet reception at the intended receiver can easily be misled At the same time, CSMA variants and hybrid MAC protocols based at least in part on carrier sensing have become the de facto standard in wireless sensor networks, underscoring a need to improve its performance We propose to enhance the de facto state of carrier sensing-based MACs in wireless sensor networks by using low cost channel feedback combined with a learning approach to try to better predict the probability of a successful reception, on a per-receiver basis We show results from an experimental wireless sensor network testbed, where our proposal E-CSMA (Enhanced CSMA) provides up to a 55% improvement in network performance

Media access control protocol for multi-hop network systems and method therefore

Abstract: A method and system for wireless communication in which a plurality of media access control (“MAC”) packet data units (“PDUs”) corresponding to a plurality of wireless communication connections are received. The plurality of MAC PDUs is grouped into a relay packet and the relay packet is transmitted. Such grouping and transmission of the relay packet is performed by one or more relay nodes. The traffic control for the transmission can also be based on centralized or decentralized routing control and/or centralized or decentralized QoS control.

A Novel Performance Model for Distributed Prioritized MAC Protocols

Abstract: Distributed prioritized channel access mechanisms have been adopted by the IEEE 802.11e enhanced distributed channel access (EDCA) and the Multiband OFDM Alliance prioritized channel access (PCA) to support service differentiation. In this paper, we propose a novel analytical model for performance study of such mechanisms. The proposed model gives the average frame service time first and then the per station and network normalized throughput, which makes it applicable to both saturated and unsaturated stations. Furthermore, the model is especially helpful in understanding the different effects of the same prioritizing mechanisms in saturated and unsaturated conditions. To the best of our knowledge, there is no similar work reported in the open literature. The accuracy of the analytical model is demonstrated by extensive simulation.

Media access control for ultra-wide band communication

Abstract: Media access control is provided for an ultra-wide band medium. The media access control may employ a peer-to-peer network topology. The media access control may employ a reduced addressing scheme. Concurrent ultra-wide band channels may be established through the use of a pulse division multiple access channelization scheme. Multiple media access control states may be defined whereby each state may be associated with one or more of different channel parameter state information, different duty cycles, and different synchronization status.

IEEE 802.1 AVB and Its Application in Carrier-Grade Ethernet [Standards Topics]

Abstract: Ethernet is increasingly being used in carrier networks to transport real-time traffic, including wireless backhaul network traffic, time-sensitive audio/video applications in access networks, and circuit emulation for legacy services With the replacement of traditional circuit-switched networks with Ethernet-based packet networks, it must be ensured that the application timing and QoS requirements are met The IEEE 8021 Audio/Video Bridging Task Group is developing a comprehensive set of standards to enable high quality, low-latency streaming of time-sensitive applications These standards specify a means of providing time synchronization (IEEE 802IAS), a resource reservation protocol (IEEE 8021Qat), and a set of forwarding and queuing rules that bound the variability of delay in an AVB network (IEEE 8021Qav) These standards are described, including their potential application to carrier-grade Ethernet networks