Quality of Service (QoS): Issues and Recommendations

Quality of Service (QoS): Issues and Recommendations The Effects Of Movement On QoS – As the mobile device moves from a cell protected from one base station to an adjoining cell of a different base station during a connection handover takes place. This hand over time may just result in a short loss of communication which would possibly not be obvious for voice interplay however can outcomes in loss of information for different applications. For mobile computing, the base station may have to provide regional processing, storage or other services as good as communication. Variations in link quality will additionally be caused by atmo ­ circular conditions such as rain or lightning. These effects need additional refined dynamic QoS management than fixed systems. It is therefore the variation in QoS that is that the crucial distinction between mobile systems and communications based on wired networks. This implies for adaptive QoS management that specifies a variety of acceptable QoS levels, instead of attempting to ensure specific values. The QoS management is additionally accountable for cooperation with QoS aware applications to support adaptation, instead of insulating applications from variation in underlying QoS. The effects of quality on QoS need then that algorithms utilized should be capable of managing frequent loss and reappearance of mobile device within the network, and that overhead ought to be reduced in periods of low connectivity. This is in contrast to traditional distributed applications, wherever moderately stable presence and systematically high network quality square measure usually assumed. The Restrictions Of Portable Devices On QoS – Portability of the mobile computing device imposed variety of problems that place limitations on QoS. The main limitation is within the physical size of mobile computers. Systems usually are designed with the limitations of batteries in mind. Current battery technology still needs appreciable area and weight for modest power reserves, and isnt expected to become considerably additional compact in future. This then places limits on the style due to the ought to offer low power consumption as a primary style goal: low power processors, displays and peripherals, and the observe of getting systems powered down or sleeping once not in active use are common measures to reduce power consumption in portable PCs (Personal computer) and PDAs (Personal digital assistant). Low power consumption elements are usually grade of processing power below their higher consumption desktop counterparts, so limiting the complexness of tasks performed. The practice of intermittent activity might seem as frequent failures in some situations. Similarly, mobile technology needs vital power, notably for transmission, thus network association should be intermittent. The second purpose is that of user interfaces: giant screens, large keyboards, and refined and straightforward to use pointer systems are commonplace in a desktop surroundings. These facilitate data wealthy, complicated user interfaces, with precise user management. In portable computers, screen size is reduced, keyboards are typically additional incommodious, and pointer devices less refined. PDAs have tiny, low resolution screens that are usually additional suited to text than graphics and will solely be monochrome. They have stripped miniature keyboards, and pen based mostly, voice, or easy cursor input and selection devices. These limitations in input and show technology need a considerably totally different approach to user interface style. In sush type of environments where users may use a variety of systems in different situations, the interface to applications may then be heterogeneous. QoS management in a mobile environment should enable for scaling of delivered information, and also less complicated user interfaces once connecting using a common combination of portable devices and higher power non-portable devices [1, 6] and field of context aware computing provides groundwork during this area, wherever instead of treating the geographical context (as for mobility), one can treat the choice of end system as giving a resource context. The Effects On Other Non-Functional Parameters – Any style of remote access will increase security risks however wireless based mostly communication is especially likely to unseen undetected therefore mobility complicates traditional security mechanisms. Even nomadic systems can build use of less secure telephone and net based mostly communications than workplace systems using LANs. Some Organizations might place restrictions on what knowledge or services will be accessed remotely, or need a lot of subtle security than is required for workplace systems. In addition, there are legal and moral problems rose within the observance of users locations. Cost is another parameter that might be stricken by the employment of mobile communications. However, whereas wireless connections are frequently more expensive, the basic principles of QoS management in relevancy price are the same as for fixed systems. The only major extra quality is formed by the risk of a bigger range of connection, and therefore price, options, and the risk of performing accounting in multiple currencies. WORK ON MANAGEMENT OF QoS IN MOBILE ENVIRONMENTS Management Adaptivity As declared within the section The Effects of Movement on QoS, one of the key ideas in managing QoS for mobile environments is adaptation to changes in QoS. In the following we tend to discuss 3 categories of change that have to be catered for. Large-grained change is characterized as changes due to varieties of end system, or network connection in use, generally these can vary infrequently, often only between sessions, and therefore are managed mostly at the initialization of interaction with applications, probably by suggests that of context awareness. Hideable changes are those minor fluctuations, some of that could be peculiar to mobile systems, that are sufficiently little in degree and period to be managed by traditional media aware buffering and filtering techniques. Buffering is often used to take away noise by smoothing a variable (bit or frame) rate stream to a constant rate stream. Filtering of packets could differentiate between those containing base and improvement levels of information in multimedia streams, e.g., moving from color to black and white images and are like those in fixed network systems [35]. However, as mobile systems move, connections with totally different base stations have to be set up and connections to remote servers re-routed via the new base stations. This needs moving or putting in filters for these connection, different connection could not give the same QoS as the previous one, and so the needed filter technique could differ. To manage this needs an extension of the traditional interactions for migrating connections between base stations. The choice and handover of management should realize of offered QoS, needed QoS, and the capability of the network to accommodate any needed filters. Wherever the network cannot maintain the current level of service, base stations ought to initiate adaptation in conjunction with handover [14, 41]. Fine-grained change are those changes that are often transient, however vital enough in vary of variation and period to be outside the range of effects that will be hidden by traditional QoS management ways. These include: Environmental effects in wireless networks. Other flows beginning and stopping in a part of the system so affecting resources available. Changes in accessible power inflicting power management Functions to be initiated, or degradation in functions like radio transmission. These types of change should be informed with the applications involved, as they need interation between QoS management and the application for adaptation. In several conditions it is a reasonable to assume that the wireless connection will determine the overall QoS. However, an end-to-end QoS management is still needed, specially for multicast systems, and those using the internet for their connection. The impact of price on patterns of desired adaptivity also becomes more pronounced in mobile systems, wherever connections usually have a charge per unit time or per unit data. Adaptation paths connected with QoS management ought to be able to describe how a lot of the users are willing to pay for a certain level of presentation quality or timeliness. The heterogeneousness inherent in systems that might offer network access through more than one media also will be a issue here, as certain sorts of connection can cost more than others, and cost of connection will vary due to telecoms supplier traffic structures. Resource Management And Reservation – Some researchers contend that resource reservation isnt relevant in mobile systems, as the accessible bandwidth in connections is just too extremely variable for a reservation to be meaningful. However, some resource allocation and admission control would appear reasonable once resources are scarce, even if laborious guarantees of resource provision are not practical. [44, 47] proposes that guarantees be created in admission control on lower bounds of needs, whereas providing best-effort service beyond this. This is achieved by creating advance reservation of minimum levels of resources within the next predicted cell to confirm accessibility and smooth handoff, and maintaining a portion of resources to handle unforeseen events. The issue of resource reservation is given some thought by those engaged on base stations and wired elements of mobile infrastructures, as these high bandwidth elements should be shared by several users, therefore the traditional resource management approach s till applies. Context Awareness – A further aspect of resource management is that of large grained adaptivity, and context awareness. [49] defines situation as the entire set of circumstances close surrounding agent, including the agents own internal state and from this context as the elements of the situation that ought to impact behavior. Context aware adaptation may include migrating data between systems as a results of mobility; dynamic a user interface to reflect location dependent information of interest; choosing a local printer or power conscious scheduling of actions in portable environments. The QoS experienced is also dependant on awareness of context, and applicable adaptation to that context [11]. A elementary paper on context awareness is [13], that emphasizes that context depends on more than location, i.e., vicinity to alternative users and resources or environmental conditions such as lighting, noise or social things. In consideration of QoS presentation, the problems with network connectivity, comm unications price and bandwidth, and location are obvious factors, poignant data for interactions as well as how end systems are used and users preferences, for instance, network bandwidth may be available to supply spoken messages on a PDA (Personal digital assistant) with audio capability, however in several situations text show would still be the most applicable delivery mechanism speech might not be intelligible on a noisy factory floor, and secrecy is also required in conferences with customers. Quality will therefore cover all non-functional characteristics of information poignant any aspect of perceived quality. CONCLUSION We discussed the critical issues faced by QoS in a mobile environment, the time those challenges emerged and the techniques that were put forward to tackle those challenges following literature to discussed work. The Persistence of Memory by Salvador Dalà ­: An Analysis The Persistence of Memory by Salvador Dalà ­: An Analysis The Persistence of Memory is a surreal landscape created in 1931 by the famous Spanish artist, Salvador Dali. This oil painting measures 9 1/2 x 13 inches, or 24.1 x 33 cm and is on display at the Museum of Modern Art in New York (MoMA). It has been displayed in galleries worldwide and is a symbol of Dalis work. The Persistence of Memory contains a light blue horizon, which slowly fades downward from blue to yellow across the top quarter of the painting. Under the skyline sits a body of water, or what looks to be a large lake or a reflecting pool. The body of water traces the skyline until it interacts with neighboring mountains to the right. In front of the mountains there is lone pebble. On the left close to the water, Dali places a reflective, blue, elevated, rectangular platform with dark brown trimming around the edges. Placed in front of this platform, there is another single pebble. A lifeless tree with a hollow top, is in front of it, missing all of its leaves and branches but one. The single branch holds a silver pocket watch which appears to be melting on the end of the branch showing the numbers three through nine. Only one hand of the watch is shown, pointing at the 6. The tree is located on top of a light brown square object that looks desk-like. The brown object takes over the bottom left corner of the painting, and even goes off the canvas. On this object there are two more pocket watches residing. One of them is gold and melted, hanging half way off the light brown cube. The hands of the gold watch are stopped at five of seven and there is a fly on the face near the 1 oclock mark. The fly is also casting a very small shadow, which is shaped more like a human. The other pocket watch is bronze and shut. The exterior of the pocket watch is covered with a swarm of black ants. Unlike the other clocks, this is shut, and the only one that is not warped or melted of the four. The ground in The Persistence of Memory is a dark brown that almost turns black in certain areas. On it lies a white figure on its right side with another silver-colored melting clock on its back. The white figure is human-like, with over emphasized large eyelashes. It has a what looks to be a trade mark Salvador Dali moustache and lips where eyebrows would be on a human face. Its nose is flared and has another small brown object coming out of the right nostril. The white figure has no limbs or other human-like characteristics. The rest of the scenery around the white figure is dark and barren. The Persistence of Memory uses the basic elements of art including a plethora of lines, values, shapes, form, colors, and texture (Glatstein). The lines that Dali uses in the painting vary on the shape which he is working with. Most of the painting contains lines that are relatively thin and similar in width, with the exception of the mountains, and the eyelashes of the white figure. The lines on the mountains are noticeable, and give them a rough realistic approach. On the white figure Dali uses different lengths and widths to create individuality in each lash. He also makes everything detailed down to the very last ant on the bronze watch. The lines that make up the watches are so detailed that they even show each number on the faces. The use of lines also improve the realistic look of the reflection of the mountains in the water. The lines on the platform and brown object are straight and symmetric. He does not leave many visible sketch marks in this painting, so it is not clear o r easy to distinguish his lines from shading. The lines that he does show usually complement the dark shadows of his surrealist landscape. The values and shading in this painting are very drawn out and detailed. The shadows in Dalis Persistence of Memory are the heart and soul of the piece, creating a universe that has never been seen before. Thick values highlight details and color, giving a three dimensional illusion to this piece. On the tree, the values are implied to create the illusion of bark, while the limp clock it is holding on its branch uses value to create a tarnished and three dimensional effect. The brown object also uses shading to get this effect. The watches on the brown cube have detailed shading on and around them, and use color to shade and give a shiny effect. The melting one uses a great deal of color on the face, while the watch with the ants draws attention to the insects covering it. The ground is primarily solid brown, with vivid black shadows overpowering the landscape. This stresses the amount of sunlight that is shown in the landscape, reflecting off of other interacting objects. The mounta ins use a combination of light and darkness mixed with color rather than only black to create this style. Some of the ridges on the mountains are shaded with black, along with other parts of the painting such as the white figure and the brown cube where the two pocket watches are placed. The ants are all black, and have very little shading, while the fly on the other watch only has a blue shadow of a human figure. The white figure has shading throughout its entire body. There is heavy shading on his head, nose eyelashes, and where its body touches the ground. This painting contains a variety of shapes and forms that add to the uniqueness of its style. There are noticeable figures and shapes, and unidentifiable ones throughout the painting. The blue platform in the far corner is a solid three dimensional rectangle, as is the large brown cube in front of it. In these objects the lines are straight and solid, and although the object is not identifiable, the geometric shapes are (Jirousek). The way that the clocks are melting adds a sense of movement and flimsiness. The mountains are recognizable shapes, along with the body of water surrounding them. The tree is easily identified, as are ants and the fly. The white figure is almost cubist, missing parts and anatomical structures, somewhat resembling a Picasso or Braque painting. It still contains human qualities, like the eyelashes and the nose but lacks a solid form. Many of the objects in this painting interact with others, either resting on or touching. The clocks are an example of this be cause they almost mold to whatever object they come into contact with. This painting is three dimensional, geometric, and abstract, and does not stick to all traditional shapes or forms (Jirousek). The color scheme along with the shading work to bring the painting to life. The colors are not vivid or bright, but more saturated and dark. Dali uses shadow and color together to create a different experience. The colors in The Persistence of Memory are primarily warm including a lot of yellow, gold, black, and brown (Warm Colors). The browns on the cube and the scenery range from light to dark. The mountains are a shade of yellow, along with a lot of what the sun touches in the painting. The watches are gold, silver, and bronze and have a shine to them because of the color and shading. There are also cool colors in this piece including blue, white, and silver (The Meaning of Color). The faces of the clocks, tree, the flys shadow, the sky and water are all a blue tint, working with the warm colors to balance the painting. The texture of the painting mainly focuses on senses such as sight and touch. From smooth surfaces to rough and jagged objects, Dali intensifies the visual experience to create an imaginary sense of touch. The blue platform appears to have a smooth reflective surface, with a rough wooden underside. The tree in front of it has a course exterior with deteriorating bark. The clock on its weak branch has a flexible but noodle like appearance to it. The large brown object with the other two clocks on top looks smooth and almost wooden. The pocket watch with the ants on it looks smooth and shiny, but still covered in small black ants. The gold pocket watch looks melted and squishy. The hands on the watch appear to go in every direction and never stay in sync with each other. The mountains in the background look narrow, ancient, dangerous, with noticeable signs of erosion. The water looks still, clear, reflecting the mountains in the landscape. The two pebbles that are separated on the far left and right in the background have a smooth exterior. The white figures skin is smooth as well, although the shading gives the impression that the figures body is wavy and ameba-like. Its moustache and lips where his eyebrow appear to be drawn on and unnatural. The large eyelashes have a rough and soft texture, as does his nose and the rest of his face. Salvador Dalis painting The Persistence of Memory, uses a variety of artistic methods and principles (Glatstein). The emphasis of the piece are the four melting clocks scattered throughout the painting. Some may argue that its his mysterious white figure that draws more attention to the work. The painting carries a strong sense of movement as well. The melting clocks create an optical illusion, giving the viewer the impression that they are actually dripping metal. The ant colony on the bronze watch also creates a sense of motion as they scatter on its surface. The cracked and crumbling mountains add to this movement too, while the water below and the white figure stay completely still. The use of shadows in the picture builds a strong contrast between sources of light and darkness. The lighting projects emphasis on several objects and builds three dimensions using shadow and color. The contrast also brings the three dimensional illusion to life, giving the painting its distinguishin g features. The painting lacks a definite pattern or motif, and the only reoccurring object is the pocket watches. Its scenery changes throughout the piece from geometric objects, to empty space, to mountains. In this piece the vanishing point appears to make sense and the water touching the skyline gives an illusion of distance. The proportion of the other objects in the painting however, do not follow traditional standards. The pocket watches seem ridiculously large and warped in every direction, while the tree holding the silver watch up is similar in size to the pocket watch. The overall unity of Dalis painting brings mixed emotions. The interpretation of the piece always has a critics bias either directly or indirectly. The Persistence of Memory seems to have a darker impact on people because of its style and subject matter. It is not seen as a cheerful or happy painting, but more eerie and disturbing. According to the Salvador Dali Museum this painting is known to cause fear a nd anxiety of the unknown surroundings (Clocking in With Salvador Dali). Dalis creation of this painting was not drug induced, but from melting cheese and bizarre dreams (Rochfort). The message Dali is trying to spread is that life is fast paced and full of choices which sometimes produce unfavorable outcomes, but we move on. The clocks are only stepping stones into the real meaning behind the painting. The silver watch on the tree is symbolic of a time which has recently passed (Being second closest to the white figure). The gold watch symbolizes the best years of life slowly escaping. The closed bronze watch with the ants could symbolize a time which the artist wanted to move on and forget. The one on top of the white figure symbolizes the place that he is at now and currently trying to live through. The pebbles painted on opposite sides of the canvas symbolize separation between a lover. The cracks in the mountains are obstacles that one faces before they can reach a stable point in life and find happiness. The raised blue platform in the back symboliz es the path to a higher quality of life, while the dead tree shows mortality and that nothing lives forever. The flys shadow in the form of a person could be another symbol of Dalis love escaping, or that he wishes to escape reality. Many sources state that Salvador Dali had fallen in Gala, his only love and muse included in her many pieces (Salvador Dali-A Soft Self-Portrait). This piece defines surrealism, breaking many of the norms previously adopted by artists and critics. The painting itself reflects a lot on Salvador Dali, and the way which he viewed life. His artistic style is incredible, and his dream photographs (Clocking in with Salvador Dali) are mind blowing. His use of colors and lighting creates a three dimensional experience that was never seen before. The lifelike qualities and absurd creatures that inhabit the piece make it so good, and separate it from the rest. It has even been noted that the white figure seen in the painting is a self portrait of Dali, (looking at the moustache above its eyelashes) (Clocking in with Salvador Dali). The clocks themselves make The Persistence of Memory an iconic piece and have been emulated and parodied in popular culture as well. It surpasses much of the Modern Art of its time, involving more talent than just throwing paint buckets at a canvas. I was able to see this painting in person at the Philadelphia Art Museum in 2005 when the Dali Exhibit was on display.