1,827,837 research outputs found
f-MAC: A Deterministic Media Access Control Protocol Without Time Synchronization
Full text linkNodes in a wireless network transmit messages through a shared medium. Thus, a Media Access Control (MAC) protocol is necessary to regulate and coordinate medium access. For some application areas it is necessary to have a deterministic MAC protocol which can give guarantees on message delay and channel throughput. Schedule based MAC protocols, based on time synchronization among nodes, are currently used to implement deterministic MAC protocols. Time synchronization is difficult and costly, especially in energy constrained sensor networks. In this paper the f-MAC protocol is presented which can give guarantees regarding message delay and channel throughput without the requirement of time synchronization among nodes. The various trade-offs of f-MAC are analysed and discussed and application areas that would benefit from f-MAC are presented
Big Mac parity, income, and trade
Full text linkNontraded inputs account for the lion's share of a Big Mac price (Ong 1997, Parsley and Wei 2003). Major departures from Big Mac PPP may then be explained by the Balassa-Samuelson income differences effect, as shown e.g. by Click (1996). But it has been argued that Click''s result is not robust to changing estimation methods, sample of countries, and time period (Fujiki and Kitamura 2003). Here we address a key theoretical distinction between high and low income countries for the Balassa-Samuelson effect to be properly evaluated. Since this distinction is missing in Click''s analysis, we revisit his finding and take a sample which is distinct (in terms of both set of countries and time period) to meet Fujiki-Kitamura''s criticism. We find that distinguishing high from low income makes no harm to Click''s result. But we also find that openness to trade (viewed as a proxy for trade barriers) helps to explain departures from Big Mac PPP.
A new MAC scheme for very high-speed WLANs
Full text linkWe consider the medium access control (MAC) layer for very high-speed Wireless LANs, which is designed to support rich multimedia applications such as highdefinition television. In such networks, the physical (PHY) layer data rate is proposed to exceed 216Mbps. The legacy MAC layer, however, greatly restricts the performance improvement due to its overhead. It has been shown that MAC utilizes less than 20% of the transportation ability provided by the PHY layer. To mitigate this inefficiency, we propose an Aggregation with Fragment Retransmission (AFR) scheme, which supports transmissions of very large frames and partial retransmissions in the case of errors. Aggregation allows for increased performance despite pertransmission overhead while partial retransmission alleviates the risk of losing the entire frame. Extensive simulations show that AFR fundamentally outperforms the legacy MAC protocol. It is particularly effective for applications with high data rates and large packet sizes such as HDTV and high-rate UDP traffic. For applications with very low data rates and small packet sizes such as Voice over IP, AFR performs slightly better
A Big Mac test of price dynamics and dispersion across euro area
Full text linkBased on the prices of McDonald's Big Mac hamburger in 11 Eurozone countries over the 1986–2009 period, the present article investigates whether the adoption of the euro was accompanied by an increase in inflation and how far it affected developments in price dispersion. Our results indicate that the Eurozone inflation rate after the introduction of the euro is on average significantly higher than prior to the changeover. Additionally, we find no evidence of a further significant reduction in price dispersion since the euro switchover in comparison with the previous period during which progress towards a leveling of existing price differentials had been made.Euro, inflation, price dispersion, Big Mac
Special Collection of Artists’ books of the Museu de Arte Contemporânea from Universidade de Sao Paulo MAC USP
Full text linkThe text deals with the collection of artist books from the Library of MAC USP. It brings the main points of insertion of a new collection in a museum library, mainly focusing their advertising on database so that the collection can be discovered and used by the society. This text also brings the memory of the process of incorporation of this new collection to the work of the Library, and their inclusion in automated cataloging system, making the technology the aim of spread of an unknown collection. We will discuss the types of material, its treatment and the methodology applied. Emphasis will be given to the fact of the new collection is located in a library with the character to be a library belonging to a public university and also be a museum library, having to cope and respond to the needs and university museums
Portability in MAC protocol and transceiver software implementations for LR-WPAN platforms
No full textIn a variety of emerging networked computing system domains over the years, there have been bursts of activity on new medium access control (MAC) protocols, as new communication transceiver technologies with greater data-movement performance or
lower power dissipation have been introduced. To enable implementations flexible to evolving standards and improving application-domain insight, such MAC protocols are typically initially implemented in software, and interface between applications or system software, typically executing on an embedded processor or microcontroller, and the evolving radio transceiver hardware. Many challenges exist in implementing MAC protocols across evolving or competing transceiver hardware implementations and processor architectures. Some of these challenges are peculiar to the requirements of MAC protocols, and others are a result of the plethora of system and processor architectures in the embedded systems domain. This article studies the challenges facing software implementations of MAC protocols running on embedded microcontrollers, and interfacing with radio transceiver hardware. Experience with an implementation of the IEEE 802.15.4 MAC across three hardware platforms with different processor, system, and systems software architectures is presented, focusing on implementation approach and interfaces. Pitfalls are pointed out, and
guidelines are provided for ensuring that new MAC implementations are easily portable
across processor architectures and transceiver hardware.Science Foundation Irelandau ti ke st en SB. 14/10/1
μ-MAC : an energy-efficient medium access control for wireless sensor networks
Full text linkFor the long-term deployment of wireless sensor networks, energy efficient MAC protocols are necessary. The transceiver of a sensor node should only consume energy while actively taking part in communication. Energy consumption in idle mode should be avoided as much as possible. In this paper it is shown how application layer knowledge in the form of flow specifications can be used to improve the energy properties of a MAC protocol. A new protocol, named m-MAC, is proposed and evaluated through simulations
Mac Barnett: 2023 Irma Black Award Silver Medal Acceptance Speech
No full textAuthor Mac Barnett gives an acceptance speech for John\u27s Turn, illustrated by Kate Berube (Candlewick)https://educate.bankstreet.edu/irma_black_awards/1007/thumbnail.jp
The Big Mac Standard: A Statistical Illustration
Full text linkWe demonstrate a statistical procedure for selecting the most suitable empirical model to test an economic theory, using the example of the test for purchasing power parity based on the Big Mac Index. Our results show that supporting evidence for purchasing power parity, conditional on the Balassa-Samuelson effect, depends crucially on the selection of models, sample periods and economies used for estimations.Big Mac Index, Purchasing Power Parity, Panel Data
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