Роль графічного дизайнера у сучасному суспільстві

У статті досліджується тема особливостей графічного дизайнера як професії. Описано сфери діяльності графічного дизайнера та аспекти, які графічному дизайнеру потрібно розвивати, щоб стати успішним.The article analyses the main peculiarities of graphic designer as a profession. The spheres of activity for graphic designers and aspects that graphic designer need to develop have been described in the given research

Testbed implementation of the meta-MAC protocol

The meta-MAC protocol is a systematic and automatic method to dynamically combine any set of existing MAC protocols into a single higher layer MAC protocol. We present a proof-of-concept implementation of the meta-MAC protocol by utilizing a programmable wireless MAC processor (WMP) on top of a commodity wireless card in combination with a host-level software module. The implementation allows us to combine, with certain constraints, a number of protocols each represented as an extended finite state machine. To illustrate the combination principle, we combine protocols of the same type but with varying parameters in a wireless mesh network. Specifically, we combine TDMA protocols with all possible slot assignments. We demonstrate that an implementation of the meta-MAC protocol over the WMP rapidly converges to non-conflicting TDMA slot assignments for the nodes

Demo - MAC learning: Enabling automatic combination of elementary protocol components

Cognition as a way to deal with the challenges of future wireless networks has been largely considered by the recent literature, with a main focus on physical layer adaptability and dynamic spectrum access. In this demo, we show how a simple cognition mechanism can be also applied at the MAC layer, by exploiting the emerging paradigm of programmable wireless cards. The idea is using the formal definition of simple MAC protocol components and platform-independent representation of channel events gathered from the wireless node, for emulating the behavior of protocols which are not currently running on the network, learning about their expected performance, and dynamically reconfiguring the wireless node. We demonstrate that programmable nodes, employing our cognition scheme, can find in a distributed way a con-conflicting schedule with other neighbor nodes and can switch from contention-based to scheduled-based protocols as a function of the network load

Making WiFi work in multi-hop topologies: Automatic negotiation and allocation of airtime

We propose a solution for mitigating the performance impairments of CSMA/CA protocols in multi-hop topologies based on the dynamic adaptation of the contention process experienced by nodes in a wireless network. A distributed protocol is used to negotiate the channel airtime for a node as a function of the traffic requirements of its neighbourhood, taking into account bandwidth reserved for the control operations. A mechanism is provided for a node to tune its contention window depending on its allocated airtime. Different from previous schemes, a node's contention window is fixed in size unless the traffic requirements of its neighbourhood change. The scheme is implemented on legacy commercial 802.11 devices. Extensive experimental results, performed on the CREW European testbed, demonstrate the effectiveness of the approach

Realizing airtime allocations in multi-hop Wi-Fi networks: A stability and convergence study with testbed evaluation

REACT is a distributed resource allocation protocol used to negotiate a max–min allocation of airtime for multi-hop ad hoc wireless networks. Two approaches are proposed for a node to realize its REACT allocation in a contention-based MAC protocol. This is achieved by tuning its contention window to a value that corresponds to its allocation. Only a change in the allocation, due to a change in local traffic requirements or local network views, results in re-tuning. The approaches for tuning are implemented in commercial Wi-Fi devices and their stability and convergence are studied experimentally in the w-iLab.t wireless network testbed. These properties are also studied analytically to support the experimental results. In addition, REACT is extended to support airtime reservations for multi-hop flows. With a reservation in place, multi-hop TCP flows exhibit improved performance metrics when running over REACT than when running over 802.11 DCF in the w-iLab.t testbed