E2MaC: an energy efficient MAC protocol for multimedia traffic

Energy efficiency is an important issue for mobile computers since they must rely on their batteries. We present a novel MAC protocol that achieves a good energy efficiency of wireless interface of the mobile and provides support for diverse traffic types and QoS. The scheduler of the base station is responsible to provide the required QoS to connections on the wireless link and to minimise the amount of energy spend by the mobile. The main principles of the E2MaC protocol are to avoid unsuccessful actions, minimise the number of transitions, and synchronise the mobile and the base-station. We will show that considerable amounts of energy can be saved using these principles. In the protocol the actions of the mobile are minimised. The base-station with plenty of energy performs actions in courtesy of the mobile. We have paid much attention in reducing the cost of a mobile for just being connected. The protocol is able to provide near-optimal energy efficiency (i.e. energy is only spent for the actual transfer) for a mobile within the constraints of the QoS of all connections in a cell, and only requires a small overhead

Congestion Avoidance Energy Efficient MAC Protocol for Wireless Sensor Networks

Wireless Sensor Network (WSNs) are generally energy-constrained and resource-constrained. When multiple simultaneous events occur in densely deployed WSNs, nodes near the base station can become congested, decreasing the network performance. Additionally, multiple nodes may sense an event leading to spatially-correlated contention, further increasing congestion. In order to mitigate the effects of congestion near the base station, an energy-efficient Media Access Control (MAC) protocol that can handle multiple simultaneous events and spatially-correlated contention is needed. Energy efficiency is important and can be achieved using duty cycles but they could degrade the network performance in terms of latency. Existing protocols either provide support for congestion near the base station or for managing spatially-correlated contention. To provide energy-efficiency while maintaining the networks performance under higher traffic load, we propose an energy-efficient congestion-aware MAC protocol. This protocol provides support for congestion near the base station and spatially-correlated contention by employing a traffic shaping approach to manage the arrival times of packets to the layers close to the base station. We implemented our protocol using the ns-2 simulator for evaluating its performance. Results show that our protocol has an improvement in the number of packets received at the base station while consuming less energy

Warkworth 12-m VLBI Station: WARK12M

This report summarizes the geodetic VLBI activities in New Zealand in 2010. It provides geographical and technical details of WARK12M - the new IVS network station operated by the Institute for Radio Astronomy and Space Research (IRASR) of Auckland University of Technology (AUT). The details of the VLBI system installed in the station are outlined along with those of the collocated GNSS station. We report on the status of broadband connectivity and on the results of testing data transfer protocols; we investigate UDP protocols such as 'tsunami' and UDT and demonstrate that the UDT protocol is more efficient than 'tsunami' and 'ftp'. In general, the WARK12M IVS network station is fully equipped, connected and tested to start participating in regular IVS observational sessions from the beginning of 2011.Comment: 5 pages, 1 figure, Accepeted for the IVS 2010 Annual Repor

Energy Efficient Location Aided Routing Protocol for Wireless MANETs

A Mobile Ad-Hoc Network (MANET) is a collection of wireless mobile nodes forming a temporary network without using any centralized access point, infrastructure, or centralized administration. In this paper we introduce an Energy Efficient Location Aided Routing (EELAR) Protocol for MANETs that is based on the Location Aided Routing (LAR). EELAR makes significant reduction in the energy consumption of the mobile nodes batteries by limiting the area of discovering a new route to a smaller zone. Thus, control packets overhead is significantly reduced. In EELAR a reference wireless base station is used and the network's circular area centered at the base station is divided into six equal sub-areas. At route discovery instead of flooding control packets to the whole network area, they are flooded to only the sub-area of the destination mobile node. The base station stores locations of the mobile nodes in a position table. To show the efficiency of the proposed protocol we present simulations using NS-2. Simulation results show that EELAR protocol makes an improvement in control packet overhead and delivery ratio compared to AODV, LAR, and DSR protocols.Comment: 9 Pages IEEE format, International Journal of Computer Science and Information Security, IJCSIS 2009, ISSN 1947 5500, Impact factor 0.423, http://sites.google.com/site/ijcsis

Telemedicine System Using Voice Video And Data Encapsulation And De-encapsulation For Communicating Medical Information Between Central Monitoring Stations And Remote Patient Monitoring Stations

The present invention provides a packet-based telemedicine system for communicating video, voice and medical data between a central monitoring station and a patient monitoring station which is remotely-located with respect to the central monitoring station. The patient monitoring station obtains digital video, voice and medical measurement data from a patient and encapsulates the data in packets and sends the packets over a network to the central monitoring station. Since the information is encapsulated in packets, the information can be sent over multiple types or combinations of network architectures, including a Community access Television (CATV) network, the Public Switched Telephone Network (PSTN), the Integrated Services Digital Network (ISDN), the Internet, a local area network (LAN), a wide are network (WAN), over a wireless communications network, or over an asynchronous transfer mode (ATM) network. Thus, a separate transmission protocol is not required for each different type of transmission media. Rather, a single transport/network layer protocol is used for encapsulating the information in packets at the sending end and for de-encapsulating the information at the receiving end. Furthermore, by sending the information in packets, the video, voice and measurement data can be integrated and sent over a single network.Georgia Tech Research Corporatio

A Markovian Analysis of IEEE 802.11 Broadcast Transmission Networks with Buffering

The purpose of this paper is to analyze the so-called back-off technique of the IEEE 802.11 protocol in broadcast mode with waiting queues. In contrast to existing models, packets arriving when a station (or node) is in back-off state are not discarded, but are stored in a buffer of infinite capacity. As in previous studies, the key point of our analysis hinges on the assumption that the time on the channel is viewed as a random succession of transmission slots (whose duration corresponds to the length of a packet) and mini-slots during which the back-o? of the station is decremented. These events occur independently, with given probabilities. The state of a node is represented by a two-dimensional Markov chain in discrete-time, formed by the back-off counter and the number of packets at the station. Two models are proposed both of which are shown to cope reasonably well with the physical principles of the protocol. The stabillity (ergodicity) conditions are obtained and interpreted in terms of maximum throughput. Several approximations related to these models are also discussed