Indian National Satellite System Information Technology Essay

Indian National Satellite System Information Technology Essay Our region is unlikely to achieve a degree of stability in the near future. Practically speaking, there will always be social, political and economic turmoil, at least for some time to come. Such a situation remains conducive to all forms of unrest and violence. The natural implication is that there would always be unforeseen emergent situations. I think that aerospace power is the only instrument that possesses the required speed and flexibility, when military intervention would be required. Air Chief Marshall FH Major  [1]   1. It is the capacity of getting others to do what we want, without coercing them because they will then admire our achievements and emulate us. Indias space programme needs to be viewed as the most thus. It is an important factor that has contributed immensely towards giving India its soft power status. India chose space to address the real problems of society and took initiative to develop space technology for the benefit of the nation and the common man, contrary to the path of countries like Soviet Union, US, China and European Union who developed space capabilities having origin in strategic and military domain. Today, India has a robust and self reliant space infrastructure and technological prowess with capability to design and build satellites for providing space services and to launch them using indigenously designed and develop launch vehicles. India has been able to achieve the present capability encompassing IRS, INSAT, PSLV, GSLV and mission to moon in just about forty y ears. The progress, present capability and future plans of ISRO are discussed briefly in succeeding paragraphs. Indian Remote Sensing (IRS) System 2. India established National Natural Resources Management System (NNRMS) in late 1970s under Department of Space (DOS) with an aim to develop indigenous remote sensing satellite system. The major elements of NNMRS encompass conceptualization and implementation of space segments with the necessary ground based data reception, processing and interpretation systems integrating the satellite based remotely sensed data with conventional data for resource management applications. Starting with IRS-1A in March 1988, there are eight remote sensing satellites in operation at present. The details of these satellites are tabulated below. Table 1: Details of Operational IRS Satellite Satellite IRS-1D Ocean sat-1and 2 TES Resource sat-1 Cartosat-1 Cartosat-2 Cartosat-2A,2B IMS-1 Launched in 1997 1999, Sep 09 2001 2003 2005 2007 2008. Jul 10 2008 Vehicle PSLV-C1 PSLV-C2 PSLV-C3 PSL-C5 PSLV-C6 PSLV-C7 PSLV-C9 PSLV-C9 Payload PAN, LISS-III, WIFS Res 5.8m OCM, MSMR PAN Res 1m LISS4, LISS3, MSC Res 5.8m Two PAN Cameras Res 2.5m Two steerable Cameras Res 80cm PAN Res 70cm MSC Res 37m, HySI Res 506m 3. The data from IRS satellites is utilised for applications including land use/ cover mapping, crop acreage and production estimate, wasteland mapping, forest cover mapping, wetland mapping, coastal zone regulation mapping etc. The TES and CARTOSAT series satellites have limited military applications as well with high resolution imagery. 4. The future programmes involve land and water resources series, Resourcesat-2 and 3, Imaging radar application through RISAT-1, DM SAR-1, RISAT-3 and RISAT-4L, Ocean biology and sea state application through Oceansat-2 and 3, cadastral and infrastructure mapping and analysis through Cartosat-3 and 4, TES-HYS and HyS-OP with hyperspectral sensors for application in forestry, agriculture, coatal zone and inland waters, soil and mineral/ rock mapping etc.  [2]   Indian National Satellite System (INSAT) 5. INSAT co-ordination Committee (ISS) was created as an apex body to address the development of Space Communication, Broadcasting and Meteorology and planning their utilization to meet the social needs of India. Due to the non-availability of appropriate launch vehicle for placing a satellite in Geostationary orbit, the INSAT series of satellites had been launched by commercially available launch vehicles till 2001 when India tested GSLV. With 211 transponders onboard 11 active INSAT series satellites, it is the largest domestic satellite communication infrastructure in Asia. It is used for variety of applications such as telecommunication, broadcasting, meteorology and search rescue. The details of operational INSAT satellites are tabulated below. Table2: Details of Operational INSAT Satellites Satellite Launch Vehicle Weight in Kg Payload INSAT-1E 1999 Ariane-4 2550 17 C band transponder, VHRR with 2 km and CCD with 1 km resolution INSAT-3B 2000 Ariane-5 2070 12 C Band and 3 Ku band transponder. S Band mobile satellite service payloads. INSAT-3C 2002 Ariane-5 2750 30 C band and 2 S Band transponder. KALPANA-1 2002 PSLV-C4 1060 Exclusive weather satellite with VHRR and data relay transponder. INSAT-3A 2003 Ariane-5 2950 18 C band, 6 Ku Band transponders. VHRR with 2 km resolution and CCD camera with 1 km resolution. Dedicated transponder for satellite aided search and rescue. GSAT-2 2003 GSLV-D2 2000 4 C Band, 2 Ku Band transponder. Other experimental payloads. INSAT-3E 2003 Ariane-5 2750 36 C Band transponder. EDUSAT 2004 Ariane-5 1950 6 Ku Band, 6 C band transponder. 1 Ku Band beacon to help ground users for accurate antenna pointing and uplink power control. INSAT-4A 2005 Ariane-5 3100 12 C Band, 12 Ku Band transponder for DTH, broadcasting and other community services. INSAT-4B 2007 Ariane-5 3025 12 C Band, 12 Ku Band transponder for DTH, broadcasting and other community services. INSAT-4CR 2007 GSLV-F04 2130 12 Ku Band transponder and 1 KU Band beacon for tracking the satellite. Provides DTH, video picture transmission and digital signal gathering services. 6. With increased demand on bandwidth due to services like 3G, HD TV, Wi-FI and Wi-Max systems, more number of transponders are required which would mean more INSAT satellites. ISRO has been launching INSAT satellites in 2 Ton class which would have to be enhanced to 5-6 Tons. The launch of such satellites would be limited by the present capability of GSLV which is about 4 Ton for GSLV MK-3. ISRO intends to enhance the transponders to 500 by 2012 under 11th plan.  [3]   Satellite Launch Vehicles 7. Unlike the US, USSR and China, Indias launch vehicle development has been strictly a civilian programme like Japan and EU. Under the aegis of Dr APJ Abdul Kalam, India developed the first indigenous launch vehicle SLV (four stage rocket with solid propellant) with the object of placing a 40 Kg satellite into 400 km orbit. Three launches were carried out during early eighties carrying Rohini satellites, two of them being successful. With the expertise gained, ISRO expanded it a PSLV programme was initiated. ASLV (five stage solid propellant) programme was also undertaken simultaneously as a low cost intermediate vehicle for trying critical technologies such as strap-on booster and new guidance system required for PSLV. The payload capability was thus enhanced to 150 Kg. 8. With the success of ASLV, work further progressed on PSLV (four stage rocket alternately solid and liquid propellant stage with six strap on boosters), which was basically meant to be able to place a 1000 Kg IRS series satellite in sun synchronous polar orbit. With continuous upgrades the payload capacity has been increasing (1600 Kg now), 12 out of 14 launches have been successful including the launch of Chandrayan-1. ISRO is further developing PSLV-HP with 2000 Kg payload capacity, which would be used to launch seven navigational satellites.  [4]   9. GSLV programme was started in 1990 to end Indias dependence on the former Soviet Union for launch of heavy satellites. Essentially, to be able to launch a satellite to geostationary orbit, a cryogenic engine rocket stage is required in addition to the liquid propellant stage and solid propellant stage. Indias GSLV programme encountered a roadblock when the technology of cryogenic engine was denied to ISRO in the name of MTCR, stating that the same technology can be used for ICBM. ISRO did get access to the cryogenic engines from Russia without the technology and finally was able to successfully use it in 2001 when GSAT-1 was placed in geostationary orbit on board the first indigenously developed GSLV. Since then several successful launches of GSLV have been conducted placing GSAT-2, EDUSAT and INSAT-4CR in to orbit. 10. With this capability India has achieved the full complement of capabilities needed for the country in space infrastructure creation, including the scientific satellites in near earth orbit, the IRS in polar orbit and INSAT in geostationary orbit. Meanwhile ISRO continues to develop indigenous cryogenic engine and finally in 2007 completed the successful ground trials of the fully indigenous cryogenic engine. The research is further on to develop GSLV MK-3 capable of launching 4400 Kg initially and stepping it up to 6000 Kg.  [5]   Other Developmental Programme 11. Chandrayaan. India became the fifth nation to launch a moon orbiter after US, Russia, EU, Japan and China in 2008. The launch of Chandrayaan-1 onboard the core alone configuration of PSLV-C11 demonstrates the technological capability of ISRO. The most significant success among many is the fact that compared to Chinese and Japanese moon missions launched in 2007, Indias mission costed only half and one fifth respectively, while beaming far better pictures of moon compared to their missions. Another mission to moon Chandrayaan-2 with a land-rover with robotic instruments is planned to be launched in 2011. A manned mission to moon is likely to be planned by the end of next decade.  [6]   12. Satellite Navigation. India has felt the need for an independent navigation system after being dependent on US GPS and the Russian GLONASS for long. A two pronged strategy of developing a wide area GPS augmentation system (GAGAN) and a regional system known as the Indian Regional Navigation Satellite System (IRNSS) has been started. GAGAN is conceived by ISRO and Airport Authority of India to aid civil air traffic in India to enable precise landing. In effect, GAGAN will augment the capabilities of GPS by enhancing the accuracy and reliability presently provided by GPS. Compared to the existing accuracy of 30 m at 50 bits/ sec, accuracy of 6-8 m at 500 bits/ sec would be available. This would be possible with three geostationary satellites having dual frequency GAGAN payload. The final system acceptance has already been done in 2007. The IRNSS project as a fully indigenous effort was started in 2006. It would have seven satellites and would give 2 m accuracy, all weather 24 hour operation over India and the region extending to about 1500-2000 km around it.  [7]   13. Bhuvan. With the capability of excellent imagery, ISRO has planned an Indianised version of Google maps. It would provide a zoom up to 10 m compared to 200 m available through Google Earth. Incorporation of GPS into the online tool is also planned with yearly image up date.  [8]   14. Space capsule Recovery Experiment (SRE). The objective of SRE is to demonstrate the capability to recover an orbiting capsule back to earth. With successful recovery of SRE-1 from Bay of Bengal, which was launched on board PSLV-C7 in Jan 2007 certain critical technologies such as reusable thermal protection system, deceleration and floating system, reentry control and propulsion system, space qualified parachute system, locating aids etc. were tested. It is major milestone in Indias Space Programme. A fully operational recovery capsule will pave the way for indigenous manned flights by India.  [9]   15. Space Situational Awareness. The ISRO Telemetry, Tracking and Command Network (ISTRAC) at Bangalore provides situational awareness and tracking of LEO satellites as well as launch vehicle missions. ISTRAC has its headquarters at Bangalore with network of ground stations at Bangalore, Lucknow, Sriharikota, Port Blair and Thiruvanantpuram in India besides stations at Mauritius, Bearslake (Russia), Brunei and Biak (Indonesia). The Master Control Facility (MCF) of ISRO is at Hassan (Karnataka) and Bhopal (MP) which monitors and controls all GEO satellites. The operations involve continuous tracking, telemetry and commanding, special operations like eclipse management, station keeping manoevres and recovery etc. In addition for Chandrayaan mission, Indian Deep Space Tracking Network (DSTN) is established at Bangalore. It is likely to enhance Indias space situational awareness which would be required especially in the light of Chinas ASAT and micro-satellite capability.  [10]   16. Indias Ballistic Missile Program. The Indian Ballistic Missile Defense Program is an initiative to develop and deploy a multi-layered ballistic missile defense system to protect India from ballistic missile attacks. Introduced in light of the ballistic missile threat from Pakistan, it is a double-tiered system consisting of two interceptor missiles, namely the Prithvi Air Defence (PAD) missile for high altitude interception, and the Advanced Air Defence (AAD) Missile for lower altitude interception. The two-tiered shield should be able to intercept any incoming missile launched 5,000 kilometers away. PAD was tested in November 2006, followed by AAD in December 2007. With the test of the PAD missile, India became the fourth country to have successfully developed an Anti-ballistic missile system, after United States, Russia and Israel. On March 6, 2009, India again successfully tested its missile defense shield, during which an incoming enemy missile was intercepted at an altitude of 75 km. Development of the anti-ballistic missile system began in 1999. Around 40 public and private companies were involved in the development of the systems. They include Bharat Electronics Ltd and Bharat Dynamics Ltd, Astra Microwave, ASL, Larsen Toubro, Vem Technologies Private Limited and Kel Tech. Development of the LRTR and MFCR (Multi-function Fire Control Radar) was led by Electronics and Radar Development Establishment (LRDE). Defence Research and Development Laboratory (DRDL) developed the mission control software for the AAD missile. Research Centre, Imarat (RCI) developed navigation, electromechanical actuation systems and the active radar seeker. Advanced System Laboratory (ASL) provided the motors, jet vanes and structures for the AAD and PAD. High Energy Materials Research Laboratory (HEMRL) supplied the propellants for the missile. 18. Swordfish is the indigenous target acquisition and fire control radar for the BMD system. The LRTR currently has a range of 600 km (370 mi) to 800 km (500 mi) and can spot objects as small as a cricket ball. The DRDO plans to upgrade the capacity of Swordfish to 1,500 km by 2011. Two new anti ballistic missiles that can intercept IRBM/ICBMs are being developed. These high speed missiles (AD-1 and AD-2) are being developed to intercept ballistic missiles with a range of around 5,000 km (3,100 mi). The test trials of these two systems are expected to take place in 2011. The new missile will be similar to the THAAD missile deployed by the U.S.A. These missiles will travel at hypersonic speeds and will require radars with scan capability of over 1,500 km (930 mi) to successfully intercept the target. 19. India is also planning to develop a laser based weapon system as part of its defense to intercept and destroy missiles soon after they are launched towards the country. DRDOs Air Defence Programme Director V. K. Saraswat says that its ideal to destroy a ballistic missile carrying nuclear or conventional warheads in its boost phase. Saraswat further added that it will take another 10-15 years for the premier defence research institute to make it usable on the ground. In 2009, reports emerged of a new missile named the PDV. The PDV is said to be a two solid stage hypersonic anti-ballistic missile similar in class to the THAAD. The PDV is intended to replace the existing PAD in the PAD/AAD combination. It will have an IIR seeker for its kill vehicle as well. The PDV will replace the PAD with a far more capable missile and will complete the Phase 1 of the BMD system, allowing it to be operational by 2013. Phase 2 development will take over for protection against missiles of the 5,000 km (3,100 mi) range class. The PDV is designed to take out the target missile at altitudes above 150 km (93 mi). Buoyed by recent successes DRDO is accelerating the pace of development of the BMD. Finally, with all the previous failures acting as a stepping stone and learning valuables lessons from them, Indias technological prowess has come to the fore and this gives a new confidence and boost to other projects hanging in limbo and some of them can incorporate the technologies developed for this project.  [11]   20. Indias Dedicated Military Satellite Program. DRDO Chief Saraswats stated in Oct 2010 about Indias decision not to be coy about its military satellite program. The shift in policy probably stems from the knowledge that its military satellite program will not attract US sanctions against ISRO as would have happened in the past. We are looking at launching one or two satellites every year to fulfill the requirements of all three military formations, Saraswat said. Once these satellites are operational, we will be able to see troop movements along the borders. The key requirement is high-resolution images with precision. The army, the navy and the air force have varied requirements, and it wont be appropriate to give the exact numbers. Data and commands can be sent through these satellites to cruise missiles. he added. 21. The satellites will be developed and launched by ISRO based on requirements projected by the armed forces. Some of the latest developments are as under:- Communication-Centric Intelligence Satellite (CCI-Sat). The satellite is being developed with a budget of Rs 100 crore by theDefense Electronics Research Laboratory (DLRL) under the Defense Research and Development Organization (DRDO). The existence of the project was revealed in February 2010 by DLRL director G. Bhoopathy. We are in the process of designing and developing a spacecraft fitted with an intelligent sensor that will pick up conversations and communications across the borders, he told reporters in Bangalore before the start of the first international conference on electronic warfare (EWCI 2010).The satellite will feature a Synthetic Aperture Radar (SAR) and be used for imaging and communication. It will be capable of detecting conversations and espionage activities in the region.The satellite will be launched in the lower earth orbit about 500 km above the earth on board the polar satellite launch vehicle (PSLV).The satellite, which will be operational by 2014, will als o serve as a test bed for anti-satellite weapon development.  [12]   Navy Satellite. A dedicated satellite to facilitating Naval communication and network centric warfare will be launched into geostationary orbit by ISRO in 2010, Indian Defense Minister, AK Antony announced during Senior Naval Officers Conference in New Delhi on October 22, 2009. The satellite will facilitate networking of IN warships, submarines and aircraft among themselves as well as with operational centres ashore through high-speed data-links, allowing Maritime threats to be detected and shared in real-time to ensure swift reaction. The multi-band satellite will weigh 2,330 kg. (5,137 lb.). The satellite will provide coverage over a 600 x 1,000 nm area of the Indian Ocean Region (IOR), which India considers to be its primary area of responsibility in terms of maritime security. The project cost is Rs 950 crore. IAF Satellite. The first dedicated IAF satellite is scheduled for launch in FY 2011-12, after the Navy satellite scheduled for launch in FY 2010-11.The satellite will serve as the air forces eye in the skies. It will link up the six AWACS, that the IAF plans acquiring, with each other as well as other ground and air-based radars. CONCLUSION 17. For many in India, militarisation and weaponisation are synonymous and, hence, one can attribute the present state of Indian militarisation of space to this fact. Reacting to the need of the Indian Air Force (IAF) for an Aerospace Command likely to be set up at Akkulam, in Tiruvanathapuram, the then External Affairs Minister, Pranab Mukherjee, stated at the inauguration of the international seminar hosted by the IAF as part of its Platinum Jubilee celebrations on February 5, 2007, There is merit in asking for the creation of separate institutions to oversee the assets that take warfare into space it does not mean that India will go back on international commitments and weaponise space-based assets. Recent developments have shown that we are treading a thin line between current defence related uses of space and its actual weaponisation. While the reaction of the former defence minister underscores the fine line separating the issue of militarisation and weaponisation, the same can not be said of the Chairman of the Indian Space Research Organisation (ISRO) Madhavan Nair. Reacting to the Chinese ASAT test of January 11, 2007, and on the possibility of India doing an encore, he said the country was against militarising space. 18. These statements only underline the fact that there is still a lot of ground to be covered in India on dispelling the myth about militarization and weaponisation being synonymous. However, for the world at large, the common understanding has been that weaponisation is a sub-set of militarisation and there is but a subtle difference between the two. If one envisions a continuum running from space systems being used for civil purposes to satellites providing services to support terrestrial military operations to satellites being integral parts of terrestrial weapon systems, to weapons themselves being deployed in space, weaponisation occurs when the upper range of the spectrum is reached. At its most extreme, space weaponisation would include the deployment in quantity of a full range of space weapons, including satellite-based systems for ballistic missile defence (BMD), space based anti-satellite weapons (ASATs), and a variety of space-to-earth weapons (STEW), and these would pla y a central role in any type of military operation.  [13]   19. There are some 500 operating satellites of various types orbiting the Earth at present. While most communication and military satellites for early warning are in geostationary orbits, there are several satellites in low and medium orbit. Most prominent amongst them is the International Space Station (ISS) (340 km). The use of satellites for the enhancement of security and defence has become ubiquitous, and India is no exception. As an emerging space power with wide-ranging strategic interests, and with a military establishment undergoing large-scale modernisation in order to meet the security challenges of the 21st century, Indias reliance on space systems for its security and defence needs is gradually set to increase. 20. With budding strategic and economic ties with Europe, Russia and the United States, India is well placed to leverage international efforts in a number of aspects of space security and defence. This will not only facilitate meeting its own growing requirements, but will also establish long-term and mutually advantageous programmes with its allies. The environment is absolutely ripe for international policy and industrial collaboration with India at the hub of all activity. 21. Space-based technologies play an increasingly critical role in the maintenance and development of national and international infrastructures. With the benefits of the widespread application of peaceful outer space technology, comes the urgent need for the international community to understand, communicate and cooperatively regulate activities in the outer space. Potential dangers such as the dissemination of dual use technologies, the shift from the militarization of space to the weaponization of space, and the growing problem of space debris are threatening to undermine security in outer space as well as prospects for its peaceful use by humanity as a whole. More than 130 States have interests at stake either as space-faring nations or indirectly benefiting from the use of commercial satellites. There is an international consensus on the general principle of the importance and urgency of preventing an arms race in outer space, as shown by the regular adoption by the UN General A ssembly, without any negative vote, of a number of resolutions since 1990. However, there has been a lack of political and diplomatic action, whereas existing frameworks such as the 1967 Outer Space Treaty and the 1979 Moon Agreement are insufficient for dealing with the challenges that we now foresee. Today, the Space Issue has become an integral part of the Global Security discourse. Almost every country is concerned about certain developments that are taking place in this field as any kind of offensive technological Development can make space security for every nation or for most of them vulnerable. Space Security being a universal issue, it is necessary that there should be an international understanding and cooperation. One can say that the use of Space has become almost indispensable for the world community. It has to be noted that in the civilian arena, the space market is emerging as a big player with lots of scope for business. That is something good for the world economy , the sole threat to it being weaponisation of space. 22. The Anti-Satellite Test (ASAT) by China on 11 January 2007 for instance, in which it shot one of its own satellites to demonstrate its anti-satellite capability. It was an act reminiscent of the 1960s James Bonds films in which disgruntled Chinese Generals destroy satellites by the US and Russia towards world dominance. The facts are still far from that fiction but the ASAT demonstration nonetheless sent shivers in various world capitals. The old Chinese satellite was monitoring weather since 10 May 1999, and its destruction created hundreds of shrapnel, of varying sizes, that are now also orbiting the earth and posing tremendous dangers to satellites. That this kind of technology has existed is known. But its demonstration has brought the issueof weaponization of space to the forefront and has shown that what a country, with destructive technological superiority, can do in Space. Can a country with ASAT technology render the defence mechanisms of other countries almost helpless? Perhaps yes. Can the consequences mean some kind of space war, with its debris literally falling on earth? The answer to that also is perhaps yes. The Chinese test was unanimously criticized as a threat to peace by all the participants, a clear indication of the world communitys desire for peace in the space. Considering all these aspects the need for a focused attention on the various aspects of the Space Security is not far -fetched. 23. There is a need for space faring nations to put their efforts together to launch time-bound, financially-shared programmers to take up societal missions on a large scale, pooling their capabilities in launch vehicles, spacecraft and applications. Such major cooperation itself will act a great measure towards space security, benefiting all without exception. Additionally, it would also help empower the most underprivileged, minimizing communication gaps and reducing threats for conflicts. The use of commercial off-the-shelf technologies widely available from the industrial and indeed leisure industries has enabled the development of a new class of space assets which are low-cost, rapid response and yet highly capable small satellites. The cost, nature of technology and scale of these small satellites brings access to the high ground of space within the reach of virtually every nation. While this can be perceived as a potential threat by some super power, which may view this develo pment as erosion of their historical dominance of space, it can also be argued that increased situational awareness from space and the opportunity for wider participation by developing nations in the exploration of space and its applications should help in a decrease in international tensions. 24. The recent trends and developments in commercial space sector indicated significant growth prospects for this industry. It was insisted that the countries are increasingly looking at the commercial space sector as a critical infrastructure for national security. The wider growth of this industry is possible only with the adaptation of innovative but economical technologies, for otherwise it would remain limited to the countries that have the capability to invest in capital intensive projects. The budding countries like India, should invest in technologies like the Near Space technology which can become an alternative to the many existing high cost space platforms. The countrys indigenous industry needs to look into investments in technologies like the nano-technology and scramjet which can help reduce the cost of various space projects. The main challenge of the 21st century in the advancement of space law is to balance the competing complementary interests of the military, intel ligence, civil and commercial space communities.  [14]  

Existentialism in Waiting for Godot Essay

Existentialism is a philosophy that repudiates the idea of religion or any ‘supreme’ being bringing meaning to life, and advocates the idea that individuals are instrumental in finding a purpose to life through free will, choice, and personal responsibility. Hence in Samuel Becket’s existentialist play Waiting For Godot, he puts forth an idea that all of humanity is wasting their lives in inaction- waiting for the salvation of a deity, when that divine being may or may not even exist. As inferred from the phrase â€Å"existence precedes essence†, there is no pre-existent spirituality or soul; no god, Christian or otherwise; no cosmic compassion for human life; no salvation in heaven and damnation in hell; neither preset destiny nor inevitable fate; and nor is there the transcendence of our worldly existence. Everyone must bear the responsibility for their own existence, since it is not predetermined or shaped by any external force; a subsequent anxiety is one of the aspects of human nature. Nevertheless, the burdens of anxiety and responsibility are often too heavy to bear, and we often seek to shift them on certain individuals, institutions, religions, or even on a ‘Godot’. Existentialism manifests itself in Waiting for Godot through its motifs of despair, absurdity, alienation, and boredom. One of the most prevalent themes is that of loneliness as a consequence of godlessness. In a blank futile universe devoid of purpose, design or care – represented by the featureless Beckettian landscape, human beings are alone, and condemned to be free. Afraid of this isolation Estragon and Vladimir cling together despite their quarrels, and Pozzo and Lucky do not untie themselves. This futility leads to another characteristic of existentialism: despair. Since there is no preset will, Existentialism preaches the individual freedom of choice. Estragon and Vladimir have made the choice of waiting, without any instruction as Vladimir says that Godot â€Å"didn’t say for sure he’d come†. Yet they wait to know exactly how they stand. The boredom of waiting prompts them to ponder over their identity, as inactivity leads the individual to think. Estragon remarks: â€Å"We always find something, eh Didi, to give us the impression that we exist? It is learnt that man needs a rational basis for existence but fails to find one, making his life no better than a wasted passion. The two tramps, Estragon and Vladimir vainly attempt to put order in their lives by waiting for Godot who never arrives, and reiterate that â€Å"Nothing is to be done. † This inaction further questions their very entities, and Estragon anxiously doubts: â€Å"Where do we come in? † Whenever Estragon and Vladimir make a decision, the stage directions dictate that â€Å"They do not move. † and continue to show passivity. Therefore, even their resolution to go is not strong enough to produce action. Many times Estragon says â€Å"Let’s go†, but Vladimir always reminds him that they can’t as they are â€Å"waiting for Godot. †This inability to act renders Vladimir and Estragon unable to determine their own fates. Instead of acting, they can only wait for someone or something to act upon them- referring to the existentialist argument of man’s desperate need to establish his own purpose and meaning to life. Furthermore, Vladimir and Estragon ponder suicide by hanging themselves from the tree, but once again their anxiety stops them, as the latter remarks: â€Å"Don’t let’s do anything. It’s safer. † Kierkegaard’s notion of ‘Dread’ or ‘Angst’ includes ideas of existentialism which talk about a state in which the individual’s freedom of choice places him in a state of anxiety, as he is surrounded by almost infinite possibilities. This could explain the inactivity of both the tramps. They are aware of the different choices they can make but are hesitant, just as they decide to leave at the end of the act but remain motionless. Thus, the end of act 1 firmly asserts the characters’ hopelessness. Beckett infers that people pass time with habits to cope with the existentialist dilemma of the dread or anxiety of their existence. Estragon and Vladimir idly pass their time to escape the pain of waiting and even thinking. Vladimir expresses this idea at the end of the play: â€Å"Habit is a great deadener. † All the events narrated through the course of the play – the Crucifixion story, the suicide plan, playing talk – seem nothing more than silly pastimes. Once during the Pozzo-Lucky encounter, the tramps behave as if they are in a theatre; Vladimir even asks Estragon to keep his seat while going off to the urinal at â€Å"The end of the corridor, on the left. † Pozzo and Lucky’s coming can also well be interpreted as an act to entertain Vladimir and Estragon; a way in which Becket questions whether life itself is just a mere source of entertainment to pass the time while waiting for salvation. However, the distractions end sometime or the other, leaving them again with their futile inaction: â€Å"The essential doesn’t change. † This once again echoes the existentialist theory that life will end in nothingness as it has begun, reducing all of man’s achievements and accomplishments to nothing. Time has little significance in this futile lifecycle. The past often becomes misty to Estragon as he often asks questions like â€Å"What did we do yesterday? † He does not remember Pozzo and Lucky and even the place in Act Two, and shortly, Pozzo fails to recognize the tramps (Estragon and Vladimir) too. The mysterious boy returns with the same message; Godot never comes and tomorrow never seems to arrive. Vladimir, therefore, is right to say that â€Å"time has stopped. † Estragon conveys the horror of this uneventful repetitive existence in â€Å"Nothing happens, nobody comes, nobody goes, it’s awful! â€Å".

Information Technology Dissertations - Internet Media - Free Essay Example

Sample details Pages: 25 Words: 7527 Downloads: 3 Date added: 2017/06/26 Category Internet Essay Type Narrative essay Did you like this example? Chapter 2: Literature Review 2.1 Introduction Multimedia streaming over internet is getting its revolutionary in the communication, entertainment and interactive game industries. The web now becomes a popular medium for video streaming since the user does not have to wait to download a large file before seeing the video or hearing the sound. Instead, the media is sent in a continuous stream and is played as it arrives. Don’t waste time! Our writers will create an original "Information Technology Dissertations Internet Media" essay for you Create order It can integrate all other media formats such as text, video, audio, images and even live radio and TV broadcasts can all be integrated and delivered through a single medium. These applications may require in terms of bandwidth, latency and reliability than traditional data applications to support the growth of multimedia technology in the future [1]. The transportation of multimedia traffic over networks become more complicated because multimedia is becoming cheaper and cheaper and therefore used more and more. Problems with bearing multimedia flows on networks are mainly related to the bandwidth they require and to the strict maximum delay requirements that must be met [2]. This is important when multimedia applications have to provide users with real-time interaction. Because of the rapid growth of Internet usage and the requirement of different applications, the IPv4 is no more relevant to support the future networks. Many new devices, such as mobile phones, require an IP a ddress to connect to the Internet. Thus, there is a need for a new protocol that would provide new services. To overcome to these problems, a new version of Internet Protocol has been introduced. This is called Internet Protocol next generation (IPng or IPv6), which is designed by the IETF [3] to replace the current version Internet Protocol, IP Version 4 (IPv4). IPv6 is designed to solve the problems of IPv4. It does so by creating a new version of the protocol which serves the function of IPv4, but without the same limitations of IPv4. IPv6 is not totally different from IPv4. The differences between IPv6 and IPv4 are including in five major areas which is addressing, routing, security, configuration and support for mobile devices [4]. Like all the development and new inventions, the problems of current Internet Protocol made researcher to develop some new techniques to solve these problems. Even they have tried to make some changes on the current protocol, these changes still didn t help a much. So, at the end the way came to development of a new protocol which is known as IPv6 or IPng. 2.2 OSI 7 Layer Computer networks are complex dynamic systems and difficult task to understand, design, and implement a computer network. Networking protocols need to be established for low level computer communication up to how application programs communicate. Each step in this protocol is called a layer and divided into several layers simplifies the solution. The main idea behind layering is that each layer is responsible for different tasks. The Open System Interconnection (OSI) Reference Model defines seven layers [5]. 1. Physical Layer. This layer deals, for instance, with conversion of bits to electrical signals, bit level synchronization. 2. Data Link Layer. It is responsible for transmitting information across a link, detecting data corruption, and addressing. 3. Network Layer. The layer enables any party in the network to communicate with each other. 4. Transport Layer. It establishes reliable communication between a pair in the system, deals with lost and duplicated packets. 5. Session Layer. This layer is responsible for dialogue control and changing. 6. Presentation Layer. The main task of this layer is to represent data in a way convenient for the user. 7. Application Layer. Applications in this case include Web browsing, file transferring, etc. The Network Layer is the layer that is the most interesting in the context of this project. The following section gives a better view of this layer. 2.3 Network Layer As was mentioned before, this layer is responsible for enabling the communication between any party. The most used method for transporting data within and between communications networks is the Internet Protocol (IP). 2.3.1 Internet Protocol IP is a protocol that provides a connectionless, unreliable, and best-efforts packet delivery system. More details on these network service types are given below [5]. In a connectionless model the data packets are transferred independently from all others and containing full source and the destination address. It is worth mentioning that another type is the connection oriented model. However, the connection-oriented model and its details are beyond the scope of this project and thus will not be pursued in this report. The reader can consult [5] for further information on this type of service. Unreliable delivery means that packets may be lost, delayed, duplicated, delivered non-consecutively (in an order other than that in which they were sent), or damaged in transmission. 2.4 Internet Protocol Version 4 As we know, IPv4 is the current protocol for communication on the Internet. It is the protocol that underlies most communication on networks today, such as TCP/IP and UDP/IP. The largest weakness of IPv4 is its address space [7]. Each IPv4 address only have 32 bits and consists of two parts, defined as network identifier and host identifier [5]. A standard method of displaying an IPv4 address is as decimal value of four octets, each separated a period, for example: 192.168.2.5. Traditionally [6], IP addresses are presented by classfull addressing. 5 classes of address were created, which is A to E. Class A consists of 16,777,214 hosts while class B consists of 65,534 hosts and class C consists of 254 hosts. Class D is reserved for use with multicasting and class E is a block of IP addresses reserved for future use [7]. The class D and E addresses are not used to address public host, so this leaves the rest of the entire range of IP addresses carved up into classes A C. As soon as a site is connected to the Internet, it needs to be given an entire class C. Assuming that many sites only need one or two addresses then this waste over 200 addresses. Once a site reaches over 254 full addressable machines it would need an entire class B, which would waste over 65,000 addresses and so on. This allocation system is obviously insufficient and wastes much of a limited resource. 2.4.1 Header Header is a part of the IP packet[5]. There is a number of fields in an IPv4 header. Below are the some explanations for each field. 2.4.2.1 Version This field (4-bit long) is used to determine the version of IP datagram that is considered. For IPv4 it is set to 4. 2.4.2.12 Internet Header Length (IHL) The Internet Header Length is the length of the header. 2.4.2.3 Type of Service Theoretically, this field (1 octet long) should indicate something special about the protocol. However, it has never really been used. 2.4.2.4 Total Length Total is the le ngth of data in the fragment plus the header. 2.4.2.5 Identification This field is useful for fragmentation only. Its purpose is to enable the destination node to perform reassembly. This implies that the destination node must know which fragments belong to each other, i.e. the source, destination, and protocol fields should match. 2.4.2.6 Offset Offset indicates the point at which this fragment belongs in the reassembly packet. The field is related to fragmentation mechanism and has similar vulnerabilities as the identification field. 2.4.2.7 Time to Live TTL measures the time duration of the datagram presence in a network. This guarantees that no datagram exists forever in the network. 2.4.2.8 Protocol This field identifies the transport protocols, for example UDP or TCP. Since the field contains an arbitrary value that indicates some protocol, encapsulation of one datagram into another (IP tunneling) is possible. 2.4.2.9 Header Checksum The checksum is used to detect transmission errors. However, this field was removed in IPv6. 2.4.2.10 Source Address. This field specifies the source address. 2.4.2.11 Destination Address The destination address (4 octets long) is specified in this field. No attacks related to this field are known. 2.4.2.12 Options The field (variable size) was designed to improve the IP communication. There are several options defined for this field. Among them are: security, source routing, and route recording. 2.4.2.13 Padding The field (variable size) is used to fill the IP header with zeros if the header length is less than 32 bits. 2.5 Internet Protocol Version 6 IPv6 is a new version that is specified in RFC2460 [5] to overcome the weakness of the current protocol in certain aspect. It uses a 128 bit long address field which is 4 times longer than Ipv4 addresses. This size of address space removes one of the worst issues with IPv4 and IPv6 doesnt have classes of addresses. In general, IPv4 and IPv6 have a similar in their basic framework and also many differences. At a first view, there are obviously differences in the addresses between IPv4 and IPv6. IPv6 addresses range from 0000:0000:0000:0000:0000:0000:0000:0000 to ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff. In addition to this preferred format, IPv6 addresses may be specified in two other shortened formats: Omit leading zeros Specify IPv6 addresses by omitting leading zeros. For example, IPv6 address 1050:0000:0000:0000:0005:0600:300c:326b may be written as 1050:0:0:0:5:600:300c:326b. Double colon Specify IPv6 addresses by using double colons (::) in place of a series of zeros. For example, IPv6 address ff06:0:0:0:0:0:0:c3 may be written as ff06::c3. Double colons may be used only once in an IP address. The IPv6 addresses are similar to IPv4 except that they are 16 octets long. A critical fact to be observed is that the present 32-bit IP addresses may be accommodated in IPv6 as a special case of IPv6 addressing. The standard representation of IPv6 addresses is a hexadecimal value of 16-bit each separated by a colon. Not only does IPv6 have different address representation, but it also discards the previous concept of network classes. The 6-byte addresses are very popular in the 802 LANs. The next generation of LANs will use 8-byte address space specified by the Institute of Electrical and Electronics Engineers (IEEE) [9]. Thus, the IPv6 addresses should be 8 bytes long. 2.5.1 IPv6Header Some of  IPv4 header fields excluded in IPv6, and some of  them has been made optional. As a result of this the packet processing time and packet header size is reduced. The header consists of two parts, which are: the basic IPng header and IPng extension headers. 2.5.2.1 Version Th is field (4-bit long), same as in IPv4 case, is used to determine the version of IP datagram and is set to 6 in the present case. This field is the same in both versions. The reasoning for this is that these two protocols should coexist during the transition period. 2.5.2.2 Flow Label This field is 20 bits long and, as yet, there is no specific functionality assigned to it. 2.5.2.3 Payload Length Only IPv6 has this field. Since the header length is constant in IPv6, just one field is needed. This field replaces IHL and Total Length fields in IPv4. It carries information about the length of data (the headers are not included). 2.5.2.4 Next Header Next Header field replaces the Protocol field in the IPv4 header. 2.5.2.5 Hops limit This field is a hop count that decrements. This field redefines the Time to Life field present in IPv4. 2.5.2.6 Source Address The source address is indicated by this field (16 octets long). No attacks related to this field have been experienced. 2.5.2.7 Destination Address This field (16 octets long) specifies the destination address. No attacks related to this field are known. IPv6 brings major changes to the IP header. IPv6s header is far more flexible and contains fewer fields, with the number of fields dropping from 13 to 8. Fewer header fields result in a cleaner header format and Quality of Service (QoS) that was not present in IPv4. IP option fields in headers have been replaced by a set of optional extensions. The efficiency of IPv6s header can be seen by comparing the address to header size. Even though the IPv6 address is four times as large as the IPv4 address, the header is only twice as large. Priority traffic, such as real time audio or video, can be distinguished from lower priority traffic through a priority field [8]. Based on the [27] experiment, it clearly show the brake-down of the various headers in both IPv4 and IPv6, it is evident that the overhead incurred is minimal be tween IPv4 and IPv6. In theory, the performance overhead between these two protocols is so minimal that the benefits of IPv6 should quickly overshadow the negatives. Table 1: Packet breakdown and overhead incurred by header information 2.6 Streaming Overview In recent years, there has been major increasing in multimedia streaming application such as audio and video broadcast over internet. The increasing number of internet subscribers with broadband access from both work and home enables multimedia applications with high quality can be delivered to the user. However, since the best effort internet is unreliable with a high packet lost and inconsistency in packet arrival, it does not provide any QoS control. This is a crucial part when dealing with real-time multimedia traffic. The multimedia streaming is a real-time application includes audio and video which is stored in stream server and streamed its content to client upon request. The example includes continuous media server, digital library, and shopping and entertainment services. Prior to streaming, video was usually downloaded. Since, it took a long time to download video files, streaming was invented with the intention of avoiding download delays and enhancing user experience . In streaming, video content is played as it arrives over the network, in the sense that there is no wait period for a complete download. Real-time streaming has a timing constraint such that the data are played continuously. If the packet data are not arrive in time, the playback is paused and will cause the in smoothness in multimedia presentation and its definitely annoying to the user. Because of this factor, multimedia streaming require isochronous processing and QoS [10] from end to end view. The lack of QoS has not prevented the rapid growth of real-time streaming application and this growth is expected to continue and multimedia traffic will form a higher portion of of the internet load. Thus, the overall behavior of these applications will have a significant impact on the other internet traffic. 2.7 Downloading Versus Streaming Application Basically downloading applications such as FTP involve downloading a file before it is viewed by a user. The examples of multimedia downloading applications are downloading an MP3 song to an IPod or any portable device, downloading a video file to a computer via P2P application such as BitTorrent. Downloading is usually a simple and easiest way to deliver media to a user. However, downloading has two potentially important disadvantages for multimedia applications. First, a large buffer is required whenever a large media file such as MPEG-4 movie is downloaded. Second, the amount of time required for the download can be relatively large, (depends on the network traffic), thereby requiring the user to wait minutes or even hours before being able to view the content. Thus, while downloading is simple and robust, it provides only limited flexibility both to users and to application designers. In contrast, in the streaming mode actually is by split the media bit stream into separate packet which can be transmitted independently. This enables the receiver to decode and play back the parts of the bit stream that are already received. The transmitter continues to send multimedia data packet while the receiver decodes and simultaneously plays back other, already received parts of the bit stream. This enables low delay between the current data is sent by the transmitter to the moment it is viewed by the user. Low delay is of paramount importance for interactive applications such as video conferencing, but it is also important both for video on demand, where the user may desire to change channels or programs quickly, and for live broadcast, but the delay must be finite. Another advantage of streaming is its relatively low storage requirements and increased flexibility for the user, compared to downloading. However, streaming applications, unlike downloading applications, have deadlines and other timing requirements to ensure continuous real-time media play out. This leads to new challenges for designing communication systems to best support multimedia streaming applications. [12] 2.8 Standard/Protocols for Streaming A good streaming protocol is required to achieve a quality of continuous playback in multimedia streaming over the internet with the short delay when a user downloading a multimedia content over the internet. The streaming protocol provides a service such as transport, and QoS control mechanism including quality adaptation, congestion control and error control. The streaming protocol is built on the top of network level protocol and the transport level protocol. The multimedia streaming protocol is based on IP network and â€Å"User Datagram Protocol† (UDP) is mainly used, despite of some streaming application using TCP. Like TCP, UDP is a transport layer protocol, but UDP is a connectionless transport protocol. UDP does not guarantee a reliable transmission and in order arrival packet. Under UDP also, there is no guarantee that is packet will arrive to its destination [16]. The UDP packet may get lost in the network when there is a lot of network traffic. Therefore, UDP is not suitable for data packet transfer where a guarantee delivery is important.UDP is never used to send important data such as webpage, database information, etc; UDP is commonly used for streaming audio and video. Streaming media such as Windows Media audio files (.WMA), Real Player (.RM), and others format use UDP because it offers speed. The reason UDP is faster than TCP is because there is no form of flow control or error correction. The data sent over the Internet is affected by collisions, and errors will be present. Remember that UDP is only concerned with speed. This is the main reason why streaming media is not high quality. However, UDP is the ideal transport layer protocol for streaming application which the priority is to transfer the packet from the sender to its destination and does not contribute any delay which is the result of the transmission of lost packets. Since UDP does not guarantee in packet delivery, the client needs to rely Real time Transport Protoco l (RTP) [10]. The RTP provides the low-level transport functions suitable for applications transmitting real-time data, such as video or audio, over multicast or unicast services The RTP standard consists of two elementary services, transmitted over two different channels. One of them is the real-time transport protocol which carries the data and the other works as control and monitor channel named RTP control protocol (RTCP) [13]. RTP packets are encapsulated within UDP datagrams. This step incorporates a high throughput and efficient bandwidth usage. The RTP data packets contain a 12 byte header followed by the payload, which can be a video frame, set of audio samples etc. The header includes a payload type indicating the kind of data contained in the packet (e.g. JPEG video, MP3 audio, etc), a timestamp (32 bits), and a sequence number to allow ordering and loss detection of RTP packets [11]. According to the standard [14], the transport of RTP streams can use both UDP and TCP tr ansport protocols, with a strong preference for the datagram oriented support offered by UDP. The primary function of RTCP is to provide feedback on the quality of the data distribution. The feedback may be directly useful for control of adaptive encodings along with fault diagnostics in the transmission. In summary, RTP is a data transfer protocol while RTCP is control protocol. The Real-time Streaming Protocol (RTSP) [25] is a client-server signaling system based on messaging in ASCII format. It establishes procedures and controls, either one or more time-synchronized streams continuous media such as audio and video. The protocol is intentionally similar in syntax and operation to HTTP and therefore hires the option of using proxies, tunnels and caches. RTSP and works well both for large audiences, and single-viewer media-on-demand. RTSP provides control functionality such as pause, fast forward, reverse and absolute positioning and works much like a VCR remote control. The nec essary additional information in the negotiation is conducted in the Session Description Protocol (SDP), sent as an attachment of RTSP appropriate response [13]. The Requirement for Multimedia Application Various multimedia applications have different requirements for QoS describes in the following QoS parameters such as throughput, delay, delay variation (jitter) and packet loss. In most cases, the application of QoS requirements can be determine by the user which are the factors that affect the quality of applications [17]. For example, from experimenting concluded that acceptable quality, one-way delay requirements for interactive voice should be less than 250 ms. This delay includes the value of the delays imposed on all components of the communication channels, as a source of delay, transmission delays, delays in the network and the determination of the delay. There are some factors which affect QoS application requirements such as interactive and noninteractive applications, User/Application characteristics (delay tolerance and intolerance, adaptive and nonadaptive characteristics) and application criticality (Mission-critical and non-mission-critical applications) [15]. The t hree types for this application requirement will be discuss in next section. 2.10.1 Interactive and Noninteractive Applications An interactive application involves some form of between two parties such as people-to-people, people-to-machine or machine-to-machine. An example of interactive applications is: People-to-people application such as IP telephony, interactive voice/video, videoconferencing People-to-machine application such as Video-on-demand (VOD), streaming audio/video Machine-to-machine application: Automatic machine control The time elapsed between interactions is essential to the success of an interactive application. The degree of interactivity determines the level of severity or delay the requirement. For example, interactive voice applications, which involve human interaction (conversation) in real time, are stringent requirements of delay (in order of milliseconds). Streaming (play), video applications involve less interaction and do not require real-time response. Applications streaming, therefore, are more relaxed requirements of delay (in order of seconds). Often applications tolerance delay is determined by users tolerance delay (ie, higher delay tolerance leads to more relaxed delay requirements). Jitter delay is also related to QoS support for interactive tasks. The delay jitter can be corrected by de-jittering techniques buffer. However, the buffer introduces delay in the original signal, which also affects the interactivity of the task. In general, an application with strict requirements delay also has a strict delay jitter requirements [15]. 2.10.2 Tolerance and Intolerance Tolerance and intolerance also one of the key that affect in QoS parameter values require by the user. Latency tolerance and intolerance determines the strictness of the delay requirement. As we already mentioned, streaming multimedia applications are more latency tolerant than interactive multimedia applications. The level of latency tolerance extremely depends based on users satisfaction, expectation, and the urgency of the application such as mission critical. Distortion tolerance to the commitment of the application quality depends on users satisfaction, users expectation, and the application media types. For example, users are more tolerant to video distortion than to audio distortion. In this case, during congestion, the network has to maintain the quality of the audio output over the quality of the video output [15]. 2.10.3 Adaptive and Nonadaptive Characteristics Adaptive and nonadaptive aspects mostly describe the mechanisms invoked by the applications to adapt to QoS degradation and the common adaptive techniques are rate adaptation and delay adaptation. Rate adaptive application can adjust the data rate injected into the network. During network congestion, the applications reduce the data rate by dropping some packets, increasing the codec data compression, or changing the multimedia properties. This technique may cause degradation of the perceived quality but will keep it within acceptable levels. Delay-tolerant adaptive applications are tolerate to a certain level of delay jitter by deploying the de-jittered buffer or adaptive playback technique. Adaptation is trigged by some form of implicit or explicit feedback from the network or end user [15]. 2.10.4 Application Criticality Mission-critical aspects reflect the importance of application usage, which determines the strictness of the QoS requirements and Failing the mission may result in dis astrous consequences. For example: Air Traffic Control Towers (ATCTs): The Traffic controller is responsible to guide the pilot for direction, takeoff and landing process. Life and death of the pilot and passenger may depend on the promptness and accuracy of the Air Traffic Control (ATC) system. E Banking system: The failure of this system may lead to the losses to the bank and user is unable to make an online transaction (view account summary, account history, transaction status, manage cheques and transfer funds online) and to make a online payment ( loans, bills, and credit card) and other transaction. 2.10.6 Examples of Application Requirements Video applications can be classified into two groups: interactive video (i.e., video conferencing, long-distance learning, remote surgery) and streaming video (i.e., RealVideo, Microsoft ASF, QuickTime, Video on Demand, HDTV). As shown in table 2, video applications bandwidth requirements are relatively high depending on the video codec. Video codec Bandwidth Requirement Uncompressed HDTV 1.5 Gbps HDTV 360 Mbps Standard definition TV (SDTV) 270Mbps Compressed MPEG2 25-60 Mbps Broadcast quality HDTV 19.4 Mbps MPEG 2 SDTV 6 Mbps MPEG 1 1.5 Mbps MPEG 4 5 kbps 4 Mbps H.323 (h.263) 28 kbps 1 Mbps Table 2 : Video Codec Bandwidth Requirement [15] 2.11 Packet Delay Delay has a direct impact on users satisfaction. Real-time media applications require the delivery of information from the source to the destination within a certain period of time. Long delays may cause incidents such as data missing the playback point, which can degrade the quality of service of the application. Moreover, it can cause user frustration during interactive tasks. For example, the International Telecommunication Union (ITU) considers network delay for voice applications in Recommendation G.114 and defines three bands of one-way delay as shown in table 2. Range in Millisecond (ms) Description 0 150 Acceptable for most user application. 150 400 Acceptable provided that administrators are aware of the transmission time and the impact it has on the transmission quality of user applications. 400 Unacceptable for general. However in certain cases this limit exceeds. Table 3: Standard for delay limit for voice In the data transmission process, each packet is moving from its source to its destination. The process of data transmission usually starts with a packet from a host (source), passes through a several series of routers, and reaches at another host (destination). The packet usually may expose from several different types of delay at each node along the path while it is traveling form one node (host or router) to another node (host or router). The most important of these delays are the nodal processing delay, queuing delay, transmission delay, and propagation delay; together these delays accumulate to give the total nodal delay [18]. 2.11.1 Types Of delay As a part of end -to-end route between source and destination, packet is sent from upstream node through router A to router B. When the packet arrives at router A , router A examines the packets header in order to place it in appropriate link. Then router A directs it to that pa rticular link. Processing Delay: This delay requires time to consider the package of header and to determine the direction of the packet is part of the processing delay. Processing delays may include other factors such as the time needed to check for errors in the bit level package that occurred in the transmission of the packet of bits from upstream unit to router A. delays in processing high-speed routers are usually in the order of microseconds or less. Then nodal processing, router directs the packet that precedes a link to router B. Queuing Delay (buffering): On the queue, a packet experience queue delay, as it waits to be transferred to the link. The queue delay of a package, will depend on the number of previously-arriving packets are pending and awaiting transfer to the link. The delay of a certain packets can vary greatly from the packet to the packet. If the queue is empty, and no other packets are being transferred, then the packet, the queue delay is zero. On the o ther hand, if the traffic is heavy and many other packages are also ready to be transferred row will be a long delay. In queue delays may be on the order of microseconds to milliseconds in practice. Transmission Delay: Assuming that packets are transmitted in first-come-first served (FIFO) manner, as is common in packet-switched networks, our packet can be transmitted only after all before the packets are sent. Denote the length of the packet by L bits, and denote the transmission rate of the link from router A to router B by R bits/sec. The rate R is determined by the transmission rate of the link to router B. For example, for a 10 Mbps Ethernet link, the rate is R = 10 Mbps; for a 100 Mbps Ethernet link, the rate is R = 100 Mbps. The transmission delay (also called the store-and-forward delay, is L/R. This is the amount of time to push (that is, transfer) all the packets of bits into the link. Transmission delay, typically on the order of microseconds to milliseconds in practic e. Propagation Delay: Once a bit is pushed into the connection, it needs to spread the router B. The time required to propagate from the beginning of connection to the router B is the propagation delay. A bit propagates the speed of propagation of the link. The propagation speed depends on the physical link (ie, fiber optic, twisted pair of copper wires, and so on) and is in the range of 2 †¢ 108 meters/sec to 3 †¢ 108 meters/sec which is equal to, or slightly less, the speed of light. The propagation delay is the distance between two routers divided by the propagation speed. That is, the propagation delay is d/s, where d is the distance between router A and router B and s is the propagation speed of the link. Once the last bit of the packet propagates to node B, it and all the preceding bits of the packet are stored in router B. The whole process then continues with router B now performing the forwarding. In wide-area networks, propagation delays are on the order of milliseconds. If we let dproc, dqueue, dtrans, and dprop denote the processing, queuing, transmission, and propagation delays, then the total nodal delay is given by dnodal = dproc+ dqueue + dtrans + dprop. The contribution of these delay components can vary significantly. 2.11.2 End to end delay Multimedia streaming require bound to bound delay so that multimedia data packet can arrive at the client in time to be decode and played. The definition of end to end delay for a streaming system. Ti is the transmission time of packet i from the server. PLi is the play out time of packet i in the player. Ai is the arrival time of packet i. If packet i arrive in time, it is used for the playback. However if packet i does not arrive in time, it cannot used for the playback and will cause a multimedia dropout problem. The outcome of the multimedia dropout is a deprivation of the multimedia playback because the streaming buffer does not have enough playtimes in which the conten t can be played. Furthermore, if the multimedia packet arrives too slowly and beyond a delay bound, then it will not be used in real time playback. As a result, such a packet are rendered useless even though they have successfully arrived at the client and such multimedia data packets are waste of network resources, and create a congested network traffic [10]. 2.11.3 Delay Jitter Multimedia streaming require a bound end to end delay in order to provide a continuous and smooth multimedia playback to users. However, the end to end delay may varies with the network condition. Therefore it is unpredictable and difficult to control. If the end to end delay is not bounded, it will causes a delay jitter problem. Figure 9 above shows the packet arrival time in the client buffer. PLi is the layout time of packet i while Ai is the arrival time of packet i to the client buffer. EAi is the expected arrival time of packet i. This is related to the end to end delay of a streaming packet tra nsferred from the server to the client. The delay can be defined as the difference between the arrival time Ai and expected arrival time EAi, i.e. Ji = |Ai EAi| The delay jitter problem complicated the synchronization problem between packets from a single media stream, or between packet from a different media stream. When there is too much delay jitter when streamed over the network renders the stream is useless when received by the client and this leads to degradation in the QoS. This is because it is difficult to re-adjust the timing relationship between multimedia packets from the same/several media stream so as to ensure a synchronized playback of information. The conflicting goals in minimizing delay and removing delay jitter have engendered various scheme capable of adapting a delay jitter buffer size that match the time varying requirement of the network delay jitter removal [10]. There are several techniques to deal with with delay jitter at the receiver end [12]. As shown in Figure 10, the packets travel through the network and experience different end-to-end delays, reaching the destination with timing distortions (incomplete or delayed signal) relative to the original traffic. For example, in technique A, the receiver playbacks the signal as soon as the packets arrive. The playback point is changed from the original timing reference. This introduces distortion in the playback signal. In technique B, the receiver playbacks the signal based on the original timing reference. The late packets that miss the playback point will be ignored. This also introduces distortion. In technique C a de-jittered buffer is used. All packets will be stored in the buffer and held for some time (offset delay) before they are retrieved by the receiver with the original timing reference. The reliability of the signal will be maintained as long as there are packets available in the buffer. Large delay jitter requires large buffer space to hold the packets and smoo th out the jitter. A large buffer may lead to large delays, which will be eventually constrained by the application delay requirement. In summary, there is a tradeoff between the following three factors: de-jittered buffer space, delay requirement, and fidelity of the playback signal. The other alternative is by using gateway and data method for minimizing the increase of delay by dejitterizing [20]. A gateway for interconnecting two network, may comprised: a receiver for receiving from a first network a plurality of data units in at least one form; a controller for temporary storing the data units received by the receiver and for outputting the data units on the basis of the dejitterizing capability of destination terminal served by a second network, thereby reducing jitter among delays of the data units; and transmitter for sending data units to the output by the controller to the destination terminal through the second network. 2.12 Quality Of service (QoS) And Technical Issues in Multimedia Networks QoS is used to describe overall experience an application or a user will receive over network and usually referring to network operator or Internet service provider (ISP) commitment in providing and maintaining acceptable value of parameter or characteristic of user application requirement and user expectation [16]. Providing QoS guarantee sometimes can be difficult in networks that offer best effort service such as internet. IP does not guarantee about when data will arrive, or how much data it can deliver. â€Å"According the recommendation of the Telecommunication standardization sector of International Telecommunication Union (ITU-T), Quality of Service is defined as â€Å"the collective effect of service performance which determines the degree of satisfaction of a user of that serviceâ€Å"[21]. QoS has become an issue when designing multimedia streaming system. QoS parameters have to be presented in all components in such systems, from an application to a communication lev el in order to insure a certain level of QoS to a user. An element of a generalized QoS framework have been identified such as OoS principles, QoS specification which is capturing applications QoS requirements, and QoS mechanisms which provide desired end-to-end QoS. As we already mentioned, a different system such as application and network is formulated in different parameter. Thus it is a crucial to interpret user/application QoS into network. Like in video streaming, it has different bit rates and a relation between bit rate of a stream and required bandwidth to carry the stream is obvious e.g. the higher bit rate, the higher bandwidth is needed. These applications have tight resource requirements and can benefit from non-interference to provide forms of progress guarantees. Video stream places high demands for QoS, performance, and reliability on storage servers and communication networks. The necessary traffic management components to support QoS are [22]: Admission control: The admission control component takes into account resource reservation requests and the available capacity to determine whether to accept a new request with its QoS requirements. Scheduling: The scheduling component provides QoS by allocating resources depending on the service requirements. This requires mapping the user-defined QoS requirement to resource allocations for providing the service. Resource management: QoS can be provided using over-provisioning of a network, which increases the cost incurred by the provider. Efficient resource management is a cost-effective solution for the provider and it ensures that applications will get the specified QoS during the course of its execution. Congestion control: Congestion control is required to avoid anything bad from happening inside a network domain. Some applications may not follow the standard protocol description and try to steal resources, thereby deteriorating the QoS of other applications. Mechanisms are needed to recover from congestion and control flows accordingly. Policing/Shaping: Users might send traffic at a rate higher than the agreement. Policing is necessary to monitor these situations, and shaping makes the traffic smooth and reduces its variations over time IP version 6 also includes QoS measures which were developed for IP version 4 but the principles are most the same. QoS makes use of both the Traffic Class and Flow Label headers to categorize network traffic into different priority groups [29]. The Flow Label header is used to uniquely identify a â€Å"flow† of IP packets, such as those belonging to a specific connection. Each flow label is unique per Source and Destination address pair. This allows QoS levels to be requested on a per-flow basis, rather than per individual packet, giving the potential for the sender to request special handling for time-critical data [28]. 2.12.1 End To End QoS Service Level Service levels refer to the end-to-end QoS capabilities, which means that the ability of a network for providing specific services required by the traffic on the network end or alongside. The services vary in their level of quality of service discipline, which describes how the service can be bound by specific ban dwidth, delay, jitter and loss characteristics. There are three levels of QoS services and can be categorize as follows [15] [23]: 2.12.1.1 Quantitative (Guaranteed Services/IntServ) Quantitative (guaranteed) services also call hard QoS, ensure the provision of the quantitative application requirements. The main protocol that works with this architecture is the Reservation Protocol (RSVP) which has a complicated operation and also inserts significant network overhead [26]. This is an absolute the reservation of network resource for specific traffic. The services guaranteed to ensure the performance of network (i.e. bandwidth, delay, delay jitter), in statistical terms or deterministic. For example, networks to guarantee the minimum bandwidth provided to guarantee an application or bound to delay the delivery of packages within a certain value and suitable for applications that guarantee overall performance as mission critical and interactive applications [15]. 2.12.1.12 Qua litative (Differentiated Services/DiffServ) Qualitative (differentiated) services, also called as soft QoS, provide statistical preference not a hard and fast guarantee. DiffServ architecture is more flexible and efficient as it tries to provide Quality of Service via a different approach [26]. Some traffic is treated better delay to one class of applications than to another class of applications. An application that belongs to a higher priority class will receive service before applications that belong to a lower priority class. 2.12.1.13 Best Effort Services (Lack of QoS Service) Make the greatest efforts to provide network services, without any guarantees of performance. All traffic treated equally. Service is adequate for data traffic such as FTP, e-mail and web pages. It does not require a minimum bandwidth or time delivery. 2.13 QoS Parameter Certain applications can tolerate some degree of traffic loss while others cannot. All these requirements are expressed using QOS parameters which are usually grouped according to several criteria. The Qos parameter below may relevant in multimedia application: Throughput (bandwidth) Delay Delay variation (jitter) Packetloss 2.13.1 Throughput (Bandwidth) From the application point of view, throughput or bandwidth basically refers to the data rate (bits per second) generated by the application. Throughput is measured in the number of bits per second. Bandwidth is considered to be the network resource that needs to be properly managed and allocated to applications. The throughput required by an application depends on the application characteristics. For example, in a streaming video application, different video properties generate different throughput (see table 1). A user can select the video quality by varying the following video properties such as frame size (pixel), frame rate (number of frame per second), colour depth (possible colors represented by a pixel) and compression (MPEG1, MPEG2, MPEG4) [15]. 2.13.2 Delay As we already discuss in section 2.11, Delay has a direct impact on users satisfaction. Real-time media applications require the delivery of information from the source to the des tination within a certain period of time. Long delays may cause incidents such as data missing the playback point, which can degrade the quality of service of the application. The delay consists of four types which is processing delay, queuing delay, transmission delay and propagation delay (refer to section 2.11.1 for explanation). 2.13.3. Delay Variation (jitter) As we already covered about this subtopic, refer to section 2.11.3 for explanation. 2.13.4 Packet Loss Packet loss has directly impact the overall quality of the application. It undermines the reliability of data or disrupts the service. At the network level, packet loss can be caused by network congestion, which results in data packets. Another cause of the loss is caused by bit errors that occur because of a communication channel noise such as in a wireless medium channel. There are several techniques identify to recover from packet loss or error such as retransmission packages, the correction of errors in t he physical layer, or codec to the application layer, which may offset or conceal the loss [15]. 2.14 Congestion-Management Congestion management use marking on each packet to determine in which queue to place packets, mechanisms queuing algorithms each interface must have a queuing mechanism to prioritize transmission of packets.â€Å"Queuing algorithms take effect when congestion is experienced. By definition, if the link is not congested, then there is no need to queue packets. In the absence of congestion, all packets are delivered directly to the interface† [23]. Congestion may occur at any point where there re-points of speed mismatches, aggregation or confluence, queuing manages congestion to provide bandwidth and delay guarantees. Congestion management is sophisticated queuing technology, there are algorithms of queuing or congestion management QoS features: FIFO (first in, first out) PQ (priority queuing) WFQ (weighted fair queuing) WRR(weight round robin) 2.14.1 FIFO (First-in-First-Out) First-in-First-Out (FIFO) is probably the simplest queuing strategy: all packets are stored in a single queue in the order of their arrival and are served sequentially, regardless which QoS requirements they have. FIFO provides best effort service [15] and there is no service differentiation is possible and, therefore, no advantage can be taken from the lower QoS demand of tolerant traffic in order to increase the link utilization [24]. 2.14.2 PQ (priority queuing) PQ ensures that important traffic gets the fastest handling at each point where it is used. It was designed to give strict priority to important traffic. In PQ, each packet is placed in one of four queues—high, medium, normal, or low—based on an assigned priority. Packets that are not classified by this priority list mechanism fall into the normal queue [23]. The queues with higher priorities are served exhaustively before queues with lower priority. In particular, the tail of the waiting time distribution can be non-exponential because a majority of high priority traffic can delay low priority traffic extensively [24]. 2.14.3 WFQ (weighted fair queuing) Weight Fair Queue schedules packets based on the weight ratio of each queue [15]. â€Å"WFQ is one of Ciscos premier queuing techniques†. It is a flow-based queuing algorithm that creates bit-wise fairness by allowing each queue to be serviced fairly in terms of byte count. For example, if queue 1 has 100-byte packets and queue 2 has 50-byte packets, the WFQ algorithm will take two packets from queue 2 for every one packet from queue 1. This makes service fair for each queue: 100 bytes each time the queue is serviced [23]. WFQ ensures that queues do not starve for bandwidth and that traffic gets predictable service. Low-volume traffic streams which comprise the majority of traffic receive increased service, transmitting the same number of bytes as high-volume streams. WFQ is d esigned to minimize configuration effort, and it automatically adapts to changing network traffic conditions. [23]. 2.13.4 WRR (weight round robin) Round Robin (RR) takes turns for servicing its queues and every queue receives the same share of bandwidth. With WRR, weights are assigned to the queues and some queues can be served more frequently by prescribing. a serving cycle. The network capacity is shared among queues 0 and 1 with a ratio of 2:1 by using the serving cycle 0-0-1. If a queue has nothing to send, the next queue in the cycle is served [24].

The Concepts of Limit and Predatory Pricing - 1927 Words

Discuss the concepts of limit and predatory pricing. Explain how imperfect knowledge of other firms’ costs or financial conditions can lead to limit or predatory pricing. Limit pricing is when an incumbent firm sets a â€Å"low price with the purpose of deterring entry†. Predatory pricing is when an incumbent sets an â€Å"‘irrationally’ low price [possibly below cost] so other firms can’t compete† forcing existing firms to exit the market. Both pricing strategies require at least two periods: the first to deter entry/force exit of a rival; the second to reap the benefits of lower competition. Although both are examples of illegal anti-competitive behaviour, only the latter is usually pursued with litigation. In order to engage in limit pricing, an†¦show more content†¦In the first period Indep sets the price. Pevin observes this, then decides whether to enter in the second period. Indep knows its own cost function, but Pevin does not know Indep’s. Furthermore, both firms know this. Although Pevin does not know whether Indep has a high or low unit cost, it does know the probability that Indep is a high-cost (inefficient) and low-cost (efficient) type. In the first period there are three possible scenarios: * Indep is efficient and sets a low monopoly price – earning  £100m * Indep is inefficient and sets a high monopoly price – earning  £60m * Indep is inefficient and sets a low monopoly price – earning  £40m In the second period, if Pevin abstains from entry, Indep sets the optimal price for its type earning  £100m (efficient) or  £60m (inefficient). Pevin earns zero profit. But, if Pevin enters, Indep earns  £50m (efficient) or  £20m (inefficient). Moreover, Pevin earns  £20m if Indep is inefficient and loses  £20m if Indep is efficient. Although it may seem irrational for an inefficient Indep to set a low first period price, it may do so to influence Pevin’s entry strategy. 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