The Value of Source Study of Hamlet by Shakespeare

Introduction The content of this essay revolves around the Hamlet play staged and sensationalized by William Shakespeare. With substantial reference to varied sources, the prodigy hatched a theatrical drama piece of Hamlet, depicting a code of revenge, patricide, tragedy, and regicide (Sanchez 21).Advertising We will write a custom essay sample on The Value of Source Study of Hamlet by Shakespeare specifically for you for only $16.05 $11/page Learn More This paper bears significant valuation for the sources that Shakespeare alluded to in the production of this play. Sanchez attests that he studied previous works and literature of preeminent playwrights persistently fixating on Francois Belleforest borrowing insightful chapters and verses (1). Belleforest’s work is a replication of Saxo Grammaticus’s Danish legend on Amleth, accompanied with a selection of changes (Sanchez 7). Shakespeare still made some alterations in his adaptations to emp ower his performance, regardless of character references and tributes. This essay seeks to delineate these alterations and, over and above that, explain their instrumental significance. This article starts by narrating Hamlet’s story then outlines Shakespeare’s modifications mainly by way of character analysis and the language borrowed. Body Background Facts: Shakespeare’s Literature of Hamlet Hamlet is a fiction plot with a premise that convenes tragedy and revenge within the Elsinore Castle, in the Kingdom of Denmark (Stopes, Belleforest, and Shakespeare 3). The fortress summons Prince Hamlet, the protagonist, home from Germany to grace his father’s funeral with his presence. On arrival, the Prince gets wind of the marriage between his mother, Gertrude, and his uncle, Claudius, which agitates him. He fathoms foul play and attests his suspicions through an epiphany by his father’s ghost that appears to him recounting how Claudius murdered him in h is nap. The Ghost taxes Hamlet to compensate his death by killing his executioner, Claudius, to be at ease. However, Hamlet is somewhat unsure of the ghost’s credibility and decides to engage a troupe of players to stage a play called The Murder of Gonzago to affirm his notion.Advertising Looking for essay on british literature? Let's see if we can help you! Get your first paper with 15% OFF Learn More The tactic is so successful that it strikes Claudius’ conscience; he is remorseful and leaves to pray and ask for cleansing (Stopes, Belleforest, and Shakespeare 4). The affirmation of the stage play rekindles the intense passion for vengeance and retribution within Hamlet for his father’s death (Stopes, Belleforest, and Shakespeare 5). This vengeance, however, is all words but no action, and as the prince contemplates on how to achieve revenge, he instigates six ancillary deaths within the palace. According to Stopes, Belleforest, and Shakespeare (5 ), Hamlet first stabs Polonius, the king’s chief counselor, who was eavesdropping on a conversation between the Prince and the Queen behind the tapestry. The next victims are Hamlet’s schoolmates, Rosencrantz, and Guildenstern, whose demise Hamlet himself arranges by instructing the King of England to hang the two (Stopes, Belleforest, and Shakespeare 6). Ophelia, tormented by Polonius’ decease and Hamlet’s antic disposition, drowns while singing bawdy melodies, lamenting over her spurned lover (Stopes, Belleforest, and Shakespeare 6). Next is Laertes, Ophelia’s sister, who declares to finish off Hamlet, as he is entirely responsible for both his father and sister’s demise. Stopes, Belleforest, and Shakespeare assert that Laertes, in consultation with Claudius, concocts various strategies to kill the Prince, one of them being a ‘fencing match’ (7).Advertising We will write a custom essay sample on The Value of Source Study of Hamlet by Shakespeare specifically for you for only $16.05 $11/page Learn More In the course of the contest, Laertes uses a poisoned sword blade to maim the Prince but releases it after that. Hamlet sees an opening here to reciprocate the attack by Laertes and, therefore, collects the same blade; he uses it to impale his adversary. In a show of victory, the queen drinks from a contaminated glass of wine that Claudius had specially prepared and poisoned for Hamlet (Stopes, Belleforest, and Shakespeare 8). The toxic substance kills her instantly. In an aggravated maneuver, Hamlet grabs the sword, using it to wound Claudius in concurrence with forcing the wine down his throat, in light of Gertrude’s demise. After that, he announces that Prince Fortinbras should rule over Denmark’s throne. He also advocates his friend, Horatio, to retell the preceding events, after which he relinquishes life (Stopes, Belleforest, and Shakespeare 9). In reverence , Fortinbras secures Hamlet’s burial procession withal full military honors. What Changes Has Shakespeare Made to the Archetype Work of Amleth? I have researched that Shakespeare evidently altered some descriptions here and there to personalize Hamlet from looking through Nash’s book, Christ Tears Over Jerusalem. Sanchez clarifies that Shakespeare’s plays inferred from preexistent playwrights, tragedians, and dramatists who composed classic pieces of literature (4). These masterpieces were inclusive of mythologies, folktales, daily life, songs, and history emanating from varied localities such as Greek, Italian, Roman, Germany, and English.Advertising Looking for essay on british literature? Let's see if we can help you! Get your first paper with 15% OFF Learn More Shakespeare collected and remodeled these works, introducing new viewpoints and ideas to the existent compositions, affirms Sanchez (10). The reforms were all in a bid to create finer plot devices to advance the visual and speculative perceptions altogether. The Ghost Stopes, Belleforest, and Shakespeare (7) compare the spirits in the plays of Antonio’s Revenge and Hamlet to elucidate Shakespeare’s variations of King Hamlet’s apparition. By the exploitation of profound readings and assessment of the two works, Hamlet and Antonio’s Revenge implement the character of a ghost in their explanations (Stopes, Belleforest, and Shakespeare 9). The plot in Antonio’s Revenge is fundamentally similar to that of Shakespeare’s Hamlet as it encompasses vindictiveness by a son, whose father’s ghost emerges and commands revenge. Nonetheless, there exist definite divergences in the specters’ properties. The Significance of The Ghost’s Ch aracter Alteration Andrugio’s ghost materializes before both Antonio- the protagonist- and his mother alike, such that the two can see the specter’s impression in the same way (Stopes, Belleforest, and Shakespeare 10). Over and above that, this apparition even has a conversation with both Antonio and his mother, Maria. To Antonio, the ghost has come compelling him to take vengeance on his account, against his murderer, Piero (Stopes, Belleforest, and Shakespeare 11). On the other hand, Andrugio’s ghost relates to Maria in a rather comical and somewhat haunting way, explain Stopes, Belleforest, and Shakespeare (11). The play depicts Andrugio’s ghost seating on the edge of Maria’s bed chastising her by way of rebuking her loose ways, seeing that she has already been intimate with the villain. He proceeds to explain to her that her gender is frail and subsequently soothes her fears. Stopes, Belleforest, and Shakespeare analyze that the gap between the mortal human and the dead narrows down significantly and almost plummets them into one form (9). This plot device is in contradiction with that of Shakespeare’s Hamlet, as the ghoul does not show itself before Hamlet’s mother, Gertrude. Stopes, Belleforest, and Shakespeare note that Shakespeare modified the ghost of King Hamlet to only converse with the prince and beseeched him to get the appropriate revenge for his demise (11). He also points out that the ghoul does not interact directly with the Queen and instead reaches out to her through Hamlet, additionally warning him to care for her as her sex is fragile. In this context, the gap between the supernatural worlds versus the earthly humans remains as vast as it should be. In regards to the intended significance, Stopes, Belleforest, and Shakespeare report that Shakespeare designed the role of the ghost to appear to Hamlet relentlessly to enhance the melancholy motif of the play (12). The central theme envisaged re volves around revenge, and the protagonist aims to achieve his vengeance on the villain by faking madness. By slightly changing the scenario, Stopes, Belleforest, and Shakespeare (11) say that Shakespeare succeeded in consummating the original concept of ‘Hero-as-Fool.’ The leading role feigns a deranged character to avoid the rogue from suspecting his motives. By virtue of the ghost emerging incessantly before Hamlet, the rest of the observers, his mother included, believe without a doubt that Hamlet is not mentally right. The significance of the ghost in Shakespeare’s Hamlet holding conversation with the Prince only, also creates a mood of mystery and confusion (Stopes, Belleforest, and Shakespeare 12). The fact that the apparition comes back from Purgatory gives rise to mockery because Protestants such as Hamlet doubt the entire doctrine of the underworld (Stopes, Belleforest, and Shakespeare 13). This element of disbelief causes the prince to question the gho st’s reliability, thus attaining the aspect of delay in the outline. Ophelia Francois Belleforest sketched the individuality of Ophelia in Saxo Grammaticus’ Danish legend, in his very own rendition. Likewise, Shakespeare paints the same character of Ophelia that Polonius and Claudius use as a convenient tool to spy on Hamlet and examine if he was crazy (Stopes, Belleforest, and Shakespeare 15). In as much as Shakespeare and Saxo portray Ophelia as the lead character’s mistress, some notable differences surface as expounded below. The Significance of Ophelia’s Character Alteration In the Danish legend, Saxo imaged Amleth- the exponent- and Ophelia as foster siblings who shared a very strong likeness to each other. Their closeness was visible when Feng, the antihero, send Ophelia to observe Amleth, and she declined to reveal any information about him whatsoever (Stopes, Belleforest, and Shakespeare 16). After this point, Saxo does not comment on her again i n the play and thus, it is not coherent to the audience what befalls her after that. Secondly, mention is that when Amleth sailed to England, he married Herminthrud, who betrayed him later on. The duplicity and infidelity that Herminthrud inflicted on her husband drove him to detest women and utter profanities about them in general (Stopes, Belleforest, and Shakespeare 16). Shakespeare tweaked Saxo’s thesis marginally in various ways, for example; he stated that Ophelia was Hamlet’s sweetheart and not his foster sister (Stopes, Belleforest, and Shakespeare 17). Shakespeare employed this strategy to pull off the elements of betrayal by way of guiding Ophelia to betray her lover, Hamlet. In the setting of Hamlet, Ophelia sells out the prince repeatedly when at first; she deserts him under the instructions of Polonius, her father. The second time is when she reports Hamlet’s questionable behavior towards her, to her father and Claudius as well (Stopes, Belleforest, and Shakespeare 18). By her act of disloyalty towards him, he reproves of her conduct and shuns her away to a nunnery (Stopes, Belleforest, and Shakespeare 17). Her behavior hurts him, and he decides to humiliate her by refusing to wed her and instead calls her a ‘breeder of sinners.’ In light of her treachery, Hamlet becomes more alert to the people around him, more so, the ones he considers as precious and cherished (Stopes, Belleforest, and Shakespeare 18). In this setting, Shakespeare brought Ophelia into play to scrutinize Hamlet’s resolve of revenge and feigned madness, as Hamlet trusts her enough to divulge his secrets to her. Another significance of revising Ophelia’s individuality is visible in Shakespeare’s elimination of Herminthrud in Hamlet. If he included her in the plot, he would have first had to pause and acquaint her to his audience, hence disrupting the flow of the story. In view of this, he thus observed the rule of flow and coh erency in this narration. Unlike Saxo, who described Herminthrud’s character trait, Shakespeare omitted her intentionally to capitalize on the story’s code of revenge by having Hamlet attack Ophelia (Stopes, Belleforest, and Shakespeare 15). Ophelia thus serves as a scapegoat and takes the blame for all the female characters’ offenses. In addition, the omission of Herminthrud allowed Shakespeare to justify why Ophelia developed madness. Stopes, Belleforest, and Shakespeare argue that the unsympathetic attitude that Hamlet brandish on Ophelia only mirrors the contempt Amleth harbored against women (14). Gertrude Saxo and Shakespeare both incorporated the character of Geruth and Gertrude respectively as that persona that makes merry with the villain. This detail is apparent from the plays’ descriptions that both these personalities marry the antiheroes who have just killed their husbands (Stopes, Belleforest, and Shakespeare 25). By virtue of their union, t hey display an indecent show of incest that devastates both their spouses’ specters, as well as their sons. Despite the legends’ striking resemblance, there are several nonconformities in these characters’ distinctive attributes, verifying that Shakespeare reconstructed his version. The Significance of Gertrude’s Character Alteration The tale of Amleth presents Geruth as a very mild dignitary who suffered under her former husband’s- King Orvendil- quick temper before his death (Stopes, Belleforest, and Shakespeare 27). Her circumstances are so lamentable that her remarriage to Feng calls for deliverance; Saxo sculpts her as Feng’s pushover, whom he forces into marrying him after dispatching her husband, Orvendil. Later on, her son Amleth berated her to rectify her transgressions of conjugating with the villain, who doubled up as her spouse’s murderer and her brother-in-law. Amleth is successful in his castigations as she repents and v ows to help him enact his attack on Feng; Saxo per contra does not cite her again in the play. By contrast, Shakespeare’s Hamlet is quite the edited restatement of the earlier Amleth legend. Before all else, Shakespeare fails to establish Gertrude’s stand on the regicide issue meted out on King Hamlet, her husband (Stopes, Belleforest, and Shakespeare 26). Shakespeare’s indecisive angle enabled him to stage a theatrical aspect of a riddle, as his viewers are inquisitive of whether the queen willingly married Claudius, or he forced her into it. This part of the play also serves as a brainteaser- a quality that is profitable to any play or work of literature. Along the storytelling, Shakespeare records that Hamlet also rebukes his mother, Gertrude, for coupling with Claudius and more so, allying with the bully. Shakespeare also included a supplementary section where the Prince exhibited pictures of Claudius to the queen, in an effort to mark out Claudius’ f laws- a feature lacking in the Amleth legend. Following Hamlet’s admonitions, Gertrude apologizes for her actions and promises him that she will suppress the details of their meeting, never to disclose it to anyone. Unlike Geruth, Stopes, Belleforest, and Shakespeare (26) remark that Gertrude breaks her promise and confesses the solemn secret to Claudius, her second husband. There is a valid reason Shakespeare allowed the queen, Gertrude, to break her promise and betray him to Claudius. Stopes, Belleforest, and Shakespeare state that the betrayal served to enlighten why the Prince set sail for England (28). Hamlet reluctantly embarked on a sea voyage to England, under the king’s strict bidding, as he- Claudius- dreaded that Hamlet was out to kill him. In addition to this, he also required some space and time to account for Polonius’ decease to his children, Ophelia, and Laertes. Claudius also coerced the prince into exile, as he wanted to scheme a dark and cover t plan for killing Hamlet, by drafting letters to the King of England. Gertrude’s betrayal is thus paramount to the unfolding of affairs in Hamlet’s storyline; Shakespeare demonstrated her imperfect portrait of motherhood (Stopes, Belleforest, and Shakespeare 24). Additionally, Shakespeare contradicted Saxo by retaining Gertrude’s character in Hamlet, almost until the end of the narrative, where she died after drinking the contaminated wine. The author hangs on to her to maximize on the plot and theme of tragedy and a total catastrophe by reporting on her regrettable death (Stopes, Belleforest, and Shakespeare 24). The passing of the Queen amplified the element of calamity in the genre of tragic stories by resulting in an even more tragic ending. Hamlet The Danish legend and Hamlet both reverberate a similar sentiment- that of retaliation and the implementation of an eye for an eye. The playwrights appoint their champions as Amleth and Hamlet indicatively to acc omplish a counter play motif (Stopes, Belleforest, and Shakespeare 29). In their capacity as the leading role, they execute their assigned duties by way of donning a camouflage of madness to avoid suspicions by their uncles and bring their mission to fruition. Stopes, Belleforest, and Shakespeare (29) analyze that in their paths for vengeance, they trigger the annihilation of other members of the royalty, either deliberately or not. Beyond the correspondence between the two tales, Shakespeare still progressed to change some parts to modify Hamlet. Below is an outline of the revisions he made together with their distinct significances. The Significance of Hamlet’s Character Alteration In Saxo’s rendition, Amleth first appears at a junior age, such that he is feeble and powerless to take any action upon his father’s regicide. Feng’s deed of eradicating and regarding Orvendil’s regicide, as a deserved performance inspires Amleth to yearn for revenge ( Stopes, Belleforest, and Shakespeare 30). He formulates a strategically viable approach that he will administer on Feng when he becomes of age. In his laid out plan, he plots to eradicate Feng together with all those nobles that tolerated his uncle’s injustice. When he finally avenges King Orvendil’s death, Amleth continues to live, taking over the reins of kingship to implement peace in his kingdom (Stopes, Belleforest, and Shakespeare 31). In Hamlet, Shakespeare presents Hamlet as a young adult, approximately thirty years, who is still pursuing his university studies in Germany. Unlike Amleth, Hamlet is of age; he is fully able to maneuver and act towards his goal (Stopes, Belleforest, and Shakespeare 31). Regardless of his grown-up status, Hamlet is still hesitant to obtain payback; as a result perfecting the delay acts employed as plot devices in Shakespeare’s play. Shakespeare also circumvents from imaging Hamlet as intentionally conspiring to cause seven o ther subsidiary deaths encompassing Ophelia, Gertrude, and Laertes (Stopes, Belleforest, and Shakespeare 32). Instead, he brings out these deaths as a mere coincidence and a victim of the occurrences at the palace, all in an attempt to magnify the concept of tragedy. Uncalculated misfortunes are the core of a tragic story; therefore, Shakespeare endears to the expectations of his audience (Stopes, Belleforest, and Shakespeare 33). Furthermore, the ultimate collapse of the protagonist at the end of the narrative multiplies the effect of adversity. Fortinbras The Significance of Fortinbras’ Character Alteration Fortinbras, the Prince of Norway, is a sovereignty personification that makes an entry in Shakespeare’s Hamlet to take over governance from the ruins encountered in Denmark (Stopes, Belleforest, and Shakespeare 32). Stopes, Belleforest, and Shakespeare (46) write that Saxo’s report does not feature Fortinbras. The reason for this omission is that Amleth def eated Feng and his nobles and, therefore, took his rightful capacity as the new king of his empire. In Hamlet’s production, Shakespeare orchestrates the death of Hamlet to record tragedy at its highest peak, explain Stopes, Belleforest, and Shakespeare (33). The crowning fall of the Prince compelled Shakespeare to usher in a new ruler, Fortinbras, who would reign with utmost justice and peace. Another cause of incorporating Fortinbras in the play was that Hamlet likened himself to Fortinbras; By virtue of being a Prince, Hamlet qualified him as sufficient to preside over the throne. Additionally, Fortinbras prevailed under the same state of affairs as Hamlet, and his uncle displaced him as the king yet he, as the prince, was the inheritor of the crown. The unfortunate event aggravated the Norwegian prince to the point he also seeks revenge on his father’s slayer, provide Stopes, Belleforest, and Shakespeare (34). Given that they experienced the same dilemma, Hamlet adv ocated for Fortinbras’ appointment to the throne assuming that he would carry out his ambition. Claudius Shakespeare ventures to mirror Feng, from the Amleth legend, in his recount of Hamlet by embodying him as Claudius (Stopes, Belleforest, and Shakespeare 21). Claudius is a tyrant ruler and traitor; a mannerism perceptible in the way he dispatches his brother, marries his wife and conspires to put his nephew to death. As explained below, Shakespeare still customized Claudius’ character. The Significance of Claudius’ Character Alteration In Saxo’s tale, the playwright starts the folk tale by unfolding the details of the ruling history ongoing before Amleth’s tragedy (Stopes, Belleforest, and Shakespeare 23). He narrates the bitter and tense association between the two co-rulers, Feng, and Orvendil. When Orvendil triumphs in a war against Koller of Norway and becomes Jutland’s sole leader, Feng becomes jealous and massacres him in quite a sc andalous manner. Feng strikes one as a very hard-hearted and unsympathetic figure. So cruel is he that he makes public his murderous deeds to the absolute court of Jutland then disguises the act by claiming that it was a righteous act (Stopes, Belleforest, and Shakespeare 22). By contrast, Shakespeare embarks on the story midway, presenting Hamlet as a full-grown man who is thirty years of age (Stopes, Belleforest, and Shakespeare 25). Shakespeare deletes the ruling history of King Hamlet’s reign, thus allocating the readers the task of unraveling whether Claudius and King Hamlet were also joint leaders. Secondly, Claudius, unlike Feng, does not announce his cause of regicide, thus adding an interesting twist to the play that involves discerning the grounds of the sudden fate of the king. Stopes, Belleforest, and Shakespeare (22) offer that Shakespeare injects some mystification into the drama piece. Hamlet only becomes aware of the atrocity through the ghost’s divinat ion. Hamlet’s rage and crave for revenge intensify as he now realizes that the death was not accidental. The Names ‘Amleth’ and ‘Hamlet’ The title of Shakespeare’s drama play is reflective of the protagonist’s name, Hamlet, the Prince of Denmark (Stopes, Belleforest, and Shakespeare 13). In the course of lifting the name of his titular character from Saxo’s journal, Shakespeare reshuffles and circulates the etymological significance of the heading ‘Amleth.’ He decides to reposition the letter ‘H’ from the end to the beginning of the name, to read as ‘Hamlet’ in place of ‘Amleth.’ Shakespeare is steadfast in the rebirth of the name ‘Hamlet’ to revolutionize and answer to the call of modernity. The reason for his intended modernization is that he was working in a neoteric period or rather, in the Elizabethan era (Stopes, Belleforest, and Shakespeare 14). His audienceà ¢â‚¬â„¢s generation appealed to developments and reformations of outdated literary works. Language Borrowed For a long time, the wide-ranging perception has been that Shakespeare conceived entirely new words and phrases, advances Sanchez (12). The public deduce that he originated most of the terms and expressions used today, thus exalting him as the father of the modern-day language (Sanchez 14). Sanchez states that this impression is all wrong and even quotes that researchers have disputed this understanding in favor of the reality that Shakespeare merely borrowed terminologies from his predecessors (15). They argue that he possessed a great skill of acquiring language from earlier poets, novelists, and composers such as Thomas Nash. However, he did not just borrow heedlessly; instead, he transformed their meaning in the context of the texts he was writing. Explained below are two of the terms he adopted in his play, Hamlet. The Use of the Term ‘Nunnery’ and its Signif icance In the making of Hamlet, Shakespeare renovated the meaning of the utterance ‘nunnery.’ A meticulous study of Nash’s Christ’s Tears Over Jerusalem qualifies me to say that Shakespeare repeated the word from the celebrated pamphleteer, Thomas Nash. Nash first assimilated the ‘nunnery’ expression in his book Christ’s Tears Over Jerusalem to mean an Institute of courtesans and concubines (Nash 19). In Hamlet, Shakespeare slots this term in the phrase â€Å"Get thee to a nunnery,† uttered by Hamlet when he advises Ophelia to sign into a convent (Sanchez 32). Shakespeare utilizes this terminology, but he does not blend it to mean a brothel or bawdyhouse as Nash did. Stopes, Belleforest, and Shakespeare explain that Shakespeare instead projects its literal definition of a religious community (18). Shakespeare’s aim of changing the meaning is to enable him to make Hamlet urge Ophelia to liberate herself from the fleshly wor ld full of dishonest men. Moreover, Hamlet uses this term while rebuking Ophelia of her betrayal, which he suspects of her (Stopes, Belleforest, and Shakespeare 16). The Use of the Phrase ‘Mind’s Eye’ and its Significance A reading of Sanchez (57) reveals that Shakespeare takes on another idiomatic expression from a writer known as Chaucer (1390). The phrase in question here is ‘mind’s eye.’ Chaucer accommodated the set expression in his account, The Man of Law’s Tale, wording it as â€Å"It were with thilke eyen of his mynde† (Sanchez 58). In the negation of Chaucer’s expression, Shakespeare reverses the arrangement and sequence of the statement to appear as â€Å"mind’s eye.† Shakespeare integrates this saying in Horatio’s reply when he, together with the castle’s guards, glimpse King Hamlet’s apparition on the palace walls. â€Å"A mote it is to trouble the mind’s eye,† c autions Horatio. Sanchez deciphers this to mean that Horatio was warning the guards to acknowledge the ghoul’s appearance (61). In other terms, he was predicting that its sheer emergence could bring disaster to the castle. Shakespeare applies the word ‘eye’ here to represent the castle and not the conventional meaning of ‘one’s optical memory.’ Conclusion Despite the fact that he borrowed concepts and models from his predecessors, Shakespeare was a great tragedian himself in devising his plays and drama sets. Sanchez (5) reports that in his play of Hamlet, Shakespeare generously adapts Saxo Grammaticus’ story thesis based on Amleth. However, he makes some structural changes, primarily in the qualities and traits of his characters among other elements. He remodels the characters of Hamlet, Ophelia, Claudius, Gertrude, Fortinbras, and the ghost in conjunction with the language borrowed (Sanchez 15). Shakespeare’s revisions are just : he only implemented them to blend with the tendencies affixed in tragic stories (Sanchez 56). Works Cited Nash, Thomas. Christ’s Tears Over Jerusalem: Whereunto is Annexed. A Comparative Admonition to London. London: From the Private Press of Longman, Hurst, Rees, Orme, and Brown, Printed by T. Davison, 1815. Print. Sanchez, Isabel 2012, â€Å"The Root of the Recycled: A Comparative Analysis of Shakespeare’s â€Å"Hamlet† and the Mythological â€Å"Ur-Hamlet†Ã¢â‚¬ . Masters thesis, Florida International Univ., 2012. FIU Electronic Theses and Dissertations. Web. Stopes, Charlotte, Francois Belleforest and William Shakespeare. Why Does Shakespeare’s ‘Hamlet’ Differ from the ‘Amleth’ Story of Belleforest? [From the Transactions of the Royal Society of Literature, Vol. 33]. London: Adlard Son, 1914. Print. This essay on The Value of Source Study of Hamlet by Shakespeare was written and submitted by user Brooke C. to help you with your own studies. You are free to use it for research and reference purposes in order to write your own paper; however, you must cite it accordingly. You can donate your paper here.

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Englsih - Rhetorical Appeals analysis (logos, ethos, pathos) - Essay Example The commercial appeals to viewers by implying that when we drive, we are responsible not only for our lives but the lives of others as well. Consequently, when we drive too fast, the consequences can be very tragic. As the commercial showed that the reckless driver was sentenced by the court, accountability is the lesson projected here. Ironically, the last scene showing the cemetery shows that we cannot bring back the dead and suffer the consequences. All throughout, emotions was effectively used to convey the message to the public. The commercial chosen was about transport safety that showed the difference in driving at higher speed when you hit a person. The theme of the commercial was â€Å"The faster you go the bigger the mess†. This commercial was one of the most discussed commercial in Poland. It showed two simultaneous situations ( split frame )with the same characters. The first one showed two joggers of which one was almost hit by a speeding car at 50m/h. The jogger was unhurt but run away scared after the car stopped. The other frame showed the same woman being hit by the car and thrown a few meters resulting to her death. In the end, the left frame showed 50m/h while the right frame showed 67m/h. The commercial has used logos argument since it directly argues to the audience that a difference of 17m/h can result to fatality. It rationally persuades viewers to drive in a certain limit. The commercial was balanced in using pathos and logos although the emphasis was more on the effect of the incr eased speed rate. The commercial that uses an Ethos argument well is the South African advertisement of BMW titled †Innovation†, although it was originally titled †Kinetic Sculptures†. The main endorser is world-class sculptor Theo Jensen who creates moving sculptures. Indeed, he is an authority when it comes to

Petrol market Essay Example | Topics and Well Written Essays - 1500 words

Petrol market - Essay Example 105). The amounts of external costs incorporate the direct physical, psychological, as well as emotional damage to others. Along with this, treatment costs are sometimes borne by the third parties (who are directly affected by the Alcohol consumption) by means of private or public insurance. It has been estimated by researchers that the total amounts of costs associated with the alcohol consumption resulting from welfare as well as health services, and also from insurance, enforcement, as well as penal costs and also from loss of costs of production accumulate to the total social cost by the amount of 1–3% of GDP in different European countries, including Poland. These amounts of loss of GDP by creation of negative effects of car accidents on the generation of greater amount of social costs are creating negative externalities to the people of the country (Bielinska-Kwapisz and Mielecka-Kubien, 2010, p. 1). As an outcome of the higher level of road accidents people are getting scared of traveling by road and thus they are expected to demand lesser amount of petrol. This reduces the demand for oil given the price of the petrol. Hence, the demand curve for petrol will shift down from AD1 to AD2 (Figure 1). Thus the equilibrium market price of petrol will fall and the producers will end up producing lesser amounts of output, selling at lower level of price and thus making lesser amount of profit. This also hampers the consumers by reduction in the amount of sales tax generated from the sales of petrol. This reduction in tax earning of the government reduces the amount of government spending on the development of road infrastructures and creates the negative externality to the consumers (Veal, 2002, p. 190). The externality is considered to be negative due to the fact that greater levels of accidents by some of the consumers to lack of proper road protections and infrastructures, which are to be implemented by the government, consumers are getting worse off. And also this fact is regarded as externality because of the fact that the generation of greater amount of negative effects upon the utility level of the consumers has not entirely been reasoned with the inefficient behavior of the people, in general. Rather these negative effects are largely generated by the lack of efficient government intervention into the process of development of higher degree of secured and well-protected road infrastructure Batta, 2008, p. 81). However this negative externality is also related to the misbehavior of the consumers of alcohol also. Greater accidents are made by the drunken car drivers for which the innocent people are paying the price in terms of their lives. This fact is also regarded as the negative externality to a large number of people (Bielinska-Kwapisz and Mielecka-Kubien, 2010, p. 5). Figure 1: Negative externality in the Petrol market Answer 2: Figure 2: Tax on petrol and reduction in negative externality The level of negative externali ty can easily be removed with the help of greater level of tax imposed on the petrol consumption. This higher level of tax on the purchase and use of petrol will increase the amount of tax revenues earned by the government of the country under consideration. This higher volume of tax revenues will thus give the government of the country to make higher amount of public expenditure on the developmen

Mobile Ad Hoc Networks (MANETs)

Mobile Ad Hoc Networks (MANETs) Introduction What is Mobile Ad Hoc Network? With rapid development of wireless technology, the Mobile Ad Hoc Network (MANET) has emerged as a new type of wireless network. MANET is a collection of wireless mobile nodes (e.g. laptops) that dynamically function as a network without the use of any existing infrastructure and centralized administration. It is an autonomous system where each node operates not only as an end system but also as a router to forward packets for other nodes. Since the nodes in MANET move around, the wireless links break and re-establish frequently. Furthermore, most of mobile nodes are resource limited in computing capability and battery power and therefore traditional computing content routing protocols are not suitable for MANET. Several ad hoc routing protocols have been proposed for each node acting as router and maintaining routing information. There are many other applications of MANET. For examples, MANET can be used to provide emergency Services when the network is impaired due to the damaging of existing infrastructure [8]. Computer scientists have predicted a world of ubiquitous computing in which computers will be all around us, constantly performing mundane tasks to make our lives a little easier. These ubiquitous computers connect in mobile ad hoc mode and change the environment or react to the change of the environment where they are suited. MANET is also found useful in the so-called sensor dust network to coordinate the activities and reports of a large collection of tiny sensor devices which could offer detailed information about terrain or environmental dangerous conditions. Problem Statement and Motivation Most current ad hoc routing protocols assume that the wireless network is benign and every node in the network strictly follows the routing behavior and is willing to forward packets for other nodes. Most of these protocols cope well with the dynamically changing topology. However, they do not address the problems when misbehavior nodes present in the network.A commonly observed misbehavior is packet dropping. In a practical MANET, most devices have very limited computing and battery power while packet forwarding consumes a lot of such resources. Thus some of the mobile devices would not like to forward the packets for the benefit of others and they drop packets not destined to them. On the other hand, they still make use of other nodes to forward packets that they originate. These misbehaved nodes are very difficult to identify because we cannot tell that whether the packets are dropped intentionally by the misbehaved nodes or dropped due to the node having moved out of transmission range or other link error. Packet drop significantly decreases the network performance.Traditional security mechanisms are generally not suitable for MANET because: The network lacks central infrastructure to apply traditional security mechanism such as access control, authentication and trusted third party. Limited bandwidth, battery lifetime, and computation power prohibits the deployment of complex routing protocols or encryption algorithms. New security models or mechanisms suitable for MANET must be found. Network topologies and memberships are constantly changing. Thus new intrusion detection system and entity recognition mechanisms that are suitable for mobile ad hoc networks must be designed to avoid or mitigate the behavior to the networks. Trust management systems have been recently introduced as a security mechanism in MANET. In a trust management system, a communicating entity collects evidence regarding competence, honesty or security of other network participants with the purpose of making assessment or decisions regarding their trust relationships. Here trust Objective and Sub-tasks means the confidence of an entity on another entity based on the expectation that the other entity will perform a particular action important to the trustor, irrespective of the ability to monitor or control that other entity . For example, a trust-based routing protocol can collect the evidence of nodes misbehaving, form trust values of the nodes and select safest routes based on the trust metrics.Reputations systems are often seen as a derivation of trust management system. In the reputation system, an entity forms its trust on another entity based not only on the selfobserved evidence but also on the second hand information from third parties. One of the influential reputation systems is the DSR protocol. In the trust management system, reputation system and other trust-based systems, route selection is based on the sending nodes prior experience with other nodes in the network. Its opinions about how other entities are honest are constantly changing. Thus, we call the trust manag ement systems and their derivations as dynamic feedback mechanisms. The dynamic feedback mechanisms are usually applied on the current ad hoc routing protocols to rate the trust about other nodes in the network and make routing decisions based on the trust matrix, which is formed according to the evidence collected from previous interactions. By incorporating the dynamic feedback mechanism in the routing protocol, misbehaved nodes are identified and avoided to forward packets. In this way,misbehavior can be mitigated. Objective and Sub-tasks The primary objective of this thesis is to Investigate the state of the art of dynamic feedback mechanisms and protocols analyze, implement and evaluate DSR protocols to see how it improves the network performance and what are the side effects of introducing the mechanism to the mobile ad hoc network. Following tasks must be done to achieve the primary objective. Study the preliminary knowledge that is required to carry out the main tasks. For example, to understand DSR protocol one must have some knowledge of Bayesian analysis; to do performance analysis one must learn the methodologies of conducting performance analysis and processing simulation data. Investigate security issues of mobile ad hoc network and current dynamic feedback mechanisms or protocols that are used to solve or mitigate the issues. Investigate and learn how to use the network simulation tool. There are several popular network simulation tools available and we need to choose the one that best suits our needs. The selected network simulator should be studied so that we can use it as platform to implement protocol and conduct simulations. Analyze and implement the DSR protocol based on Dynamic Source Routing protocol (DSR); evaluate the network performance. Structure of the Report Since we have almost gone through the chapter one, we only briefly present the content of the subsequent chapters in this section. Preliminary Information State of the Art Analysis Design Implementation and Tests Performance Analysis Conclusion and Future Work Preliminary information we have introduced the MANET. This chapter presents other preliminary information and concepts that will be used in other parts of the thesis. Firstly four general modes of routing operations are introduced and compared. The DSR protocol, which is used as underlying routing protocol in the thesis, is explained in detail. Secondly Bayesian estimation and Beta function are explained to pave the way for the analysis of the reputation model of DSR in the chapter 4. Thirdly some techniques regarding simulation and performance analysis are presented. Finally, several popular network simulation tools are discussed and compared. Mobile Ad Hoc Network Routing Protocols Nowadays there are various routing protocols proposed for the MANET. The most popular ones are DSDV (Destination-Sequenced Distance Vector), TORA (Temporally- Ordered Routing Algorithm), DSR (Dynamic Source Routing) and AODV (Ad-hoc On Demand Distance Vector). These routing protocols can be categorized in different routing operation modes. Mode of Routing Operations These two modes concern whether or not nodes in an ad hoc network should keep track of routes to all possible destinations, or instead keep track of only those destinations of immediate interest Proactive protocols store route information even before it is needed. This kind of protocols has advantage that communications with arbitrary destination experience minimal delay. However it also suffers from the disadvantage that additional control traffic is needed to continually update stale route information. This could significantly increase routing overhead especially for the MANET where the links are often broken. Reactive protocols, on the contrary, acquire routing information only when it is actually needed. However, the latency of the communication increases tremendously especially when a node communicates to another at the first time. Source routing vs. Hop-by-hop routing These two modes concern whether the source node decides the route for a packet to be forwarded to the destination or the intermediate nodes are allowed to decide the next hop until the packet arrives at the destination. In the source routing protocols, the source node decides the route and puts the route information in the packet header. All the intermediate nodes forward the packet along the route faithfully. This kind of protocols has advantage that the intermediate nodes are not required to maintain the routing information. But it suffers from the disadvantage that the packet size grows because of source routing information carried in each packet. In the hop-by-hop routing protocols, it is sufficient for the source to know only how to get to the next hop and intermediate nodes find their own next-hops until the destination. In contrast to source routing protocols, hop-by-hop routing protocols do not increase packet size but they requires all the intermediate nodes to maintain rout ing information. Table 2-1 Categories of routing protocols has compared the performance of these four routing protocols . The results show that DSR has best throughput performance (above 95%) at all mobility rates and movement speeds. Thus we will use DSR as basic routing protocol in this thesis. The Dynamic Source Routing Protocol (DSR) John et al. proposed the dynamic source routing protocol (DSR) [1] which is a routing protocol for use in multi-hop wireless ad hoc networks of mobile nodes. DSR is an ondemand protocol, in which route are only discovered when data need to be transmitted to a node where no route has yet been discovered. The advantage of this on-demand routing protocol is that there are not any periodic routing advertisement and reducing the routing overhead. DSR is also a source routing protocol, allowing multiple routes to any destination and allows each sender to select and control the routes used in routing the packets. DSR is composed of the two main mechanisms: Route Discovery and Route Maintenance which are explained below. Route Discovery Route Discovery aims at finding routes from a source node to destination. Figure 2-1 illustrates the procedure of Route Discovery. When a source node S wants to send a data packet to some destination node D, it first searches its route cache to find whether there is a route to D. If there is no route to D, then S will initiate a Route Discovery and send out Route Request message which is propagated to all the nodes within its transmission range. At the mean time, it saves the data packet in its send buffer. The Route Request message contains the addresses of source node and destination node, a unique route request identifier and a route record which records all the intermediate nodes that this route request packet has traveled through. S appends itself to the beginning of the route record when it initiates the message. When a node receives the Route Request message, it compares the destination address in the message with its own address to judge whether itself is the destination node. If it is not, it will append its own address in the route record and propagate the message to other nodes. If the node is the destination node, it will send a Route Reply message to the source node and the message contains the source route record which is accumulated when the Route Request message is forwarded along its way to the destination. When the destination sends the Route Reply, if it uses MAC protocols such as IEEE 802.11 that require a bidirectional link, it just reverse the source route record and use it as route to send Route Reply to the source node. Otherwise it should find the route by searching its route cache or sending out a Route Request which piggybacks the Route Reply for the source node. When the source node receives the Route Reply message, it puts the returned route into its route cache. From t hen on all the packets destined to the same destination will use this route until it is broken. Route Maintenance Since the ad hoc network is dynamic and the topology of the network changes frequently, the existing routes maintained by nodes in their route cache are often broken. After forwarding a packet, a node must attempt to confirm the reachability of the next-hop node. If the node does not receive any confirmation from the next hop during a certain period of time, it will retransmit the packet. If after a maximum number of retransmission it still does not receive any confirmation, it will think the link to the next hop is broken and will send a Route Error message to the source node. DSR proposes three acknowledge mechanisms to confirm that data can flow over the link from that node to the next hop: Link-layer acknowledgement which is provided by MAC layer protocol such as IEEE 802.11. Passive acknowledgement in which a node hears the next-hop node forwarding the packet and thus confirms the reachability of the link. Network-layer acknowledgement in which a node sends an explicit acknowledgement request to its next-hop node. Passive Acknowledgement Passive Acknowledgement (PACK) is important in DSR protocol because it is used to detect whether the next hop forwards the packet or drops it. We explain it in detail in this section. Passive acknowledgement is used with the assumption that: Network links operates bi- directionally. The network interface is in the promiscuous mode. When a node taps a new packet in promiscuous mode after it originates or forwards a packet, it consider it as an acknowledgement of the first packet if both of following check success. The Source Address, Destination Address, Protocol, Identification, and Fragment Offset fields in the IP header of the two packets MUST match. If either packet contains a DSR Source Route header, both packets MUST contain one, and the value in the Segments Left field in the DSR Source Route header of the new packet MUST be less than that in the first packet. If no matched packet is found during PACK timeout, the node will consider the link between the next hop and itself is broken and will send Route Error message to the source node. Additional features DSR has additional features such as replying to route requests using cached routes, caching overheard routing information, packet salvaging and flow state extension and etc. We will introduce them in section 4.1 and discuss how they will impact the performance of network, how they will interact with DSR and whether they will be enabled in our simulation. Performance Analysis Techniques This section introduces the performance analysis techniques and methodologies that will be used in the performance evaluation. Factors and Primary Factors There are many parameters that will influence the simulation results and need to be carefully chosen in the simulations. Some parameters are chosen based on experience values or the conditions of the network we want to simulate. Others need to be tuned to optimize the network performance. We distinguish the two kinds of parameters as follows: Factors are the variables that affect the simulation result and have several alternatives. Normally they are decided based on experience. Primary factors are the factors whose effects need to be quantified. This kind of factors usually needs to be adjusted through simulation. Data Measurement The key step of the network performance analysis is to interpret the simulation result and summarize the characteristic of the network. To avoid the inaccurate simulation results due to an extreme scenario, we usually run simulations on several different scenarios. The data set of these simulations are called sample. A single number must be presented to give the key characteristic of the sample and this single number is called an average of the data. There are three alternatives to summarize a sample Mean is obtained by taking the sum of all observations and dividing this sum by the number of observations in the sample. Median is obtained by sorting the observations in an increasing order and taking the observation that is in the middle of series. If the number of the observations is even, the mean of the middle two values is used as a median. Mode is obtained by plotting a histogram and specifying the midpoint of the bucket where the histogram peaks. Confidence Interval for the Mean In our performance evaluation, the main objective is to compare the simulation results of DSR and Standard DSR to see whether there is any performance improvement. However, most simulation results are random in some degree due to the particularity of the node movement scenarios and we cannot tell whether the two systems are different. One way to minimize the random effect is to repeat the simulations with different scenarios as many times as possible and get a large sample space. Unfortunately, due to the time limitation we cannot conduct many simulations. points out that using confidence interval we can tell whether the two systems are different with smaller sample space. The confidence interval for the mean can be calculated using If the confidence intervals of the simulation results of the two systems have no overlap, then we can claim the two systems are different and one system is superior or inferior to the other. GloMoSims source and binary code can be downloaded only by academic institutions for research purposes. Commercial users must use QualNet, the commercial version of GloMoSim. OPNET Modeler OPNET Modeler is commercial network simulation environment for network modeling and simulation. It allows the users to design and study communication networks, devices, protocols, and applications with flexibility and scalability [30]. It simulates the network graphically and its graphical editors mirror the structure of actual networks and network components. The users can design the network model visually.The modeler uses object-oriented modeling approach. The nodes and protocols are modeled as classes with inheritance and specialization. The development language is C. Comparison When choosing a network simulator, we normally consider the accuracy of the simulator. Unfortunately there is no conclusion on which of the above three simulator is the most accurate one. David Cavin et al. has conducted experiments to compare the accuracy of the simulators and it finds out that the results are barely comparable [31]. Furthermore, it warns that no standalone simulations can fit all the needs of the wireless developers. It is more realistic to consider a hybrid approach in which only the lowest layers (MAC and physical layers) and the mobility model are simulated and all the upper layers (from transport to application layers) are executed on a dedicated hosts (e.g. cluster of machines). Although there is no definite conclusion about the accuracy of the three network simulators, we have to choose one of them as our simulation environment. We compare the simulators using some metrics and the results are summarized After comparing the three simulators, we decide to choose ns2 as network simulator in our thesis because Ns2 is open source free software. It can be easily downloaded and installed. The author of the thesis has used ns2 in another network related course and gotten familiar with the simulation. Ns2 uses TCL and C++ as development languages for which the author has some programming experience. The author of the DSR protocol has conducted simulation on GloMoSim and gotten performance results. We want to do the simulation on a different simulation to form comparison. State of the Art In this chapter we will introduce the start of the art security solutions in MANET with emphasis on dynamic feedback mechanisms. Firstly, we will present the general security issues/requirements of MANET to pave the way for the future investigation. Then we will discuss the state of the art security mechanisms for MANET such as payment system,trust management system, reputation system, etc. Finally, we will summarize all the security solutions we discussed in this chapter. Security Issues in Mobile Ad Hoc Network Due to lack of central infrastructural and wireless links susceptible to attacks, security in ad hoc network has inherent weakness. In section 1.2 we have discussed the reasons why mobile ad hoc network imposes security challenges that cannot be solved by traditional security mechanisms. In this section, we present the general security properties required by ad hoc network. Following are general security properties regarding ad hoc network Confidentiality: The confdiantiality property is to protect certain information from unauthorized disclosure. The information includes not only the application data that send over the routing protocol, but also the routing information itself as well as network topology and geographical location. Integrity: The integrity ensures that the transmitted message and other system asset are modified only by authorized parties. In the routing level, it requires all nodes in the network following correct routing procedure. The main challenge of ensuring integrity is that without central infrastructure and powerful computing capabilities, it is difficult to apply existing cryptography and key management systems. Availability: The availability property requires that the services or devices are exempt from denial of service, which is normally done by interruption, network or server overload. Typical examples or denial of service attack are radio jamming, in which a misbehaved node transmit radio to interference other nodes communications, and battery exhaustion, in which a misbehaved node interact with a node for no other purpose than to consume its battery energy. Authentication: The authentication property requires that the communication entitys identification is recognized and proved before communication starts. Access control: This property requires restricting resources, services or data to special identities according to their access rights or group membership. Non-repudiation: This property ensures that when data are sent from sender to receiver, the sender cannot deny that he has sent the data and the receiver cannot deny that he has received the data. Mobile nodes may conduct different misbehavior for different purposes. Po-Wah Yau classifies the misbehaved nodes into following categories. Failed nodes are simply those unable to perform an operation; this could be because power failure and environmental events. Badly failed nodes exhibit features of failed nodes but they can also send false routing messages which are a threat to the integrity of the network. Selfish nodes are typified by their unwillingness to cooperate as the protocol requires whenever there is a personal cost involved. Packet dropping is the main attack by selfish nodes. Malicious nodes aim to deliberately disrupt the correct operation of the routing protocol, denying network service if possible. These four types of misbehaved nodes actually can be categorized in two aspects: whether their misbehaviors are intentional or unintentional, and the severity of the results. Payment Systems Payment systems provide economic incentives for the cooperation in MANET. They consider that each node in MANET is its own authority and tries to maximize the benefits it gets from the network. Thus each node tends to be selfish, dropping packets not destined to them but make use of other nodes to forward their own packets. The purpose of payment systems is to encourage the cooperation within the MANET by economic incentives. There are several variations of payment systems proposed. Nuglets Nuglets is a virtual currency mechanism for charging (rewarding) server usage (provision). Nodes that use a service must pay for it (in nuglets) to nodes that provide the service. A typical service is packet forwarding which is provided by intermediate nodes to the source and the destination of the packet. Therefore either the source or the destination should pay for it. There are two models for charging for the packet forwarding service: the Packet Purse Model (PPM) and the Packet Trade Model (PTM). In the Packet Purse Model, the sender pays for the packet. It loads the packet with a number of nuglets when sending the packet. Each intermediate forwarding node acquires some nuglets from the packet that covers its forwarding costs. If a packet does not have enough nuglets to be forwarded, then it is discarded. If there are nuglets left in the packet once it reaches destination, the nuglets are lost. In the Packet Trade Model, the destination pays for the packet. Each intermediate node buys the packet from previous one for some nuglets and sells it to the next one for more nuglets until the destination buys it. Either of the two models has advantages and disadvantages. While the Packet Purse Model deters nodes from sending useless data and avoids the network overloading, the Packet Trade Model can lead to an overload of the network and the destination receives packets it does not want. On the other hand, in the Packet Purse Model it is difficult to estimate the number of nuglets th at are required to reach a given destination. But thePacket Purse Model does not need to consider this problem. To take advantages of the two models and avoid the disadvantages, a hybrid model is suggested. In this model, the sender loads the packet with some nuglets before sending it.The packet is handled according to the Packet Purse Model until it runs out of nuglets. Then it is handled according to the Packet Trade Model until the destination buys it. Counter To address the problems encountered by the nuglets approach such as difficulty in estimating pre-load nuglets and possible network overload, another payment approach based on credit counter is suggested. In this approach, the current state of each node is described by two variables b and c, where b is the remaining battery power and cstands for the value of its nuglet counter. More precisely, b is the number of packets that the node can send using its remaining energy and c is the number of packets a node canoriginate. A node can originate a number of packets N only when the condition c=N holds. When a node forwards a packet, nuglet counter c is increased by one and b is reduced by one. Thus in order to originate packets, each node must earn credits by forwarding packets. The counter solution requires tamper resistant hardware security module. Spirit S. Zhong et al. proposed Sprite [19], a credit-based system for MANET. As opposed to Nuglets or Counter they do not require tamper-proof hardware to prevent the fabrication of payment units. Instead, they introduce a central Credit Clearance Service (CCS). The basic scheme of the system is as follows. When a node receives a message the node keeps a receipt of the message and reports to the CCS when the node has a fast connection to Credit Clearance Service (CCS). The CCS then determines the charge and credits to each node involved in the transmission of a message, depending on the reported receipts of a message. In this scheme, the sender charges money. A node that has forwarded a message is compensated, but the credit that a node receives depends on whether or not its forwarding action is successful. Forwarding is considered successful if and only if the next node on the path reports a valid receipt to the CCS. Discussion on the Payment Systems The payment systems we describe in above sections either assumes a tamper resistant hardware module is available to ensure that the behavior of the node is not modified or requires a central authority server to determine the charge and credit to each node involved in the transmission of a message. Tamper resistant hardware may not be appropriate for most mobile devices because it demands advanced hardware solution and increases the cost of the devices. Lacking of central authority server is right the inherent property of MANET that causes security challenges so it is also not appropriate. Furthermore, all the approaches described above suffer from locality problems [20] that nodes in different locations of the network will have different chances for earning virtualcurrency, which may not be fair for all nodes. Usually nodes at the periphery of the network will have less chance to be rewarded. Reputation System Reputation systems have emerged as a way to reduce the risk entailed in interactions among total strangers in electronic marketplace. Centralized reputation systems have been adopted by many on-line electronic auctions such as eBay to collect and store reputation ratings from feedback providers in a centralized reputation database. Decentralized reputation systems used by MANET, on the other hand, do not use centralized reputation database. Instead, in these reputation systems, each node keeps the ratings about other node and updating the ratings by direct observation of the behaviorsof neighboring nodes or second hand information from other trusted nodes. Identifies three goals for reputation systems: To provide information to distinguish between a trust-worthy principal and an untrustworthy principals. To encourage principals to act in a trustworthy manner To discourage untrustworthy principals from participating in the service the reputation mechanism is present to protect. Most of the reputation systems in MANET are based on trust management system. Trust is such a subjective and dynamic concept that different entities can hold different opinions on it even while facing the same situation. Trust management system can work without reputation system. For example, a mobile node can form opinion about other nodes by direct experience with the nodes.We can unify reputation system and trust management system to dynamic feedback mechanisms. Former one is a global reputation system and mobile nodes share their own experiences of interaction with other nodes. The later one is a local reputation system in which mobile nodes rating the trustability of other nodes based on its own observation. DSR DSR is a reputation system aiming at coping with misbehavior in MANET. The idea is to detect the misbehaved nodes and isolate them fromcommunication by not using them for routing and forwarding and by not allowing the misbehaved nodes to use itself to forward packets. DSR stands for Cooperation Of Nodes: Fairness In Dynamic Ad-hoc Network. It usually works as an extension to on demand routing Mobile Ad Hoc Networks (MANETs) Mobile Ad Hoc Networks (MANETs) Introduction What is Mobile Ad Hoc Network? With rapid development of wireless technology, the Mobile Ad Hoc Network (MANET) has emerged as a new type of wireless network. MANET is a collection of wireless mobile nodes (e.g. laptops) that dynamically function as a network without the use of any existing infrastructure and centralized administration. It is an autonomous system where each node operates not only as an end system but also as a router to forward packets for other nodes. Since the nodes in MANET move around, the wireless links break and re-establish frequently. Furthermore, most of mobile nodes are resource limited in computing capability and battery power and therefore traditional computing content routing protocols are not suitable for MANET. Several ad hoc routing protocols have been proposed for each node acting as router and maintaining routing information. There are many other applications of MANET. For examples, MANET can be used to provide emergency Services when the network is impaired due to the damaging of existing infrastructure [8]. Computer scientists have predicted a world of ubiquitous computing in which computers will be all around us, constantly performing mundane tasks to make our lives a little easier. These ubiquitous computers connect in mobile ad hoc mode and change the environment or react to the change of the environment where they are suited. MANET is also found useful in the so-called sensor dust network to coordinate the activities and reports of a large collection of tiny sensor devices which could offer detailed information about terrain or environmental dangerous conditions. Problem Statement and Motivation Most current ad hoc routing protocols assume that the wireless network is benign and every node in the network strictly follows the routing behavior and is willing to forward packets for other nodes. Most of these protocols cope well with the dynamically changing topology. However, they do not address the problems when misbehavior nodes present in the network.A commonly observed misbehavior is packet dropping. In a practical MANET, most devices have very limited computing and battery power while packet forwarding consumes a lot of such resources. Thus some of the mobile devices would not like to forward the packets for the benefit of others and they drop packets not destined to them. On the other hand, they still make use of other nodes to forward packets that they originate. These misbehaved nodes are very difficult to identify because we cannot tell that whether the packets are dropped intentionally by the misbehaved nodes or dropped due to the node having moved out of transmission range or other link error. Packet drop significantly decreases the network performance.Traditional security mechanisms are generally not suitable for MANET because: The network lacks central infrastructure to apply traditional security mechanism such as access control, authentication and trusted third party. Limited bandwidth, battery lifetime, and computation power prohibits the deployment of complex routing protocols or encryption algorithms. New security models or mechanisms suitable for MANET must be found. Network topologies and memberships are constantly changing. Thus new intrusion detection system and entity recognition mechanisms that are suitable for mobile ad hoc networks must be designed to avoid or mitigate the behavior to the networks. Trust management systems have been recently introduced as a security mechanism in MANET. In a trust management system, a communicating entity collects evidence regarding competence, honesty or security of other network participants with the purpose of making assessment or decisions regarding their trust relationships. Here trust Objective and Sub-tasks means the confidence of an entity on another entity based on the expectation that the other entity will perform a particular action important to the trustor, irrespective of the ability to monitor or control that other entity . For example, a trust-based routing protocol can collect the evidence of nodes misbehaving, form trust values of the nodes and select safest routes based on the trust metrics.Reputations systems are often seen as a derivation of trust management system. In the reputation system, an entity forms its trust on another entity based not only on the selfobserved evidence but also on the second hand information from third parties. One of the influential reputation systems is the DSR protocol. In the trust management system, reputation system and other trust-based systems, route selection is based on the sending nodes prior experience with other nodes in the network. Its opinions about how other entities are honest are constantly changing. Thus, we call the trust manag ement systems and their derivations as dynamic feedback mechanisms. The dynamic feedback mechanisms are usually applied on the current ad hoc routing protocols to rate the trust about other nodes in the network and make routing decisions based on the trust matrix, which is formed according to the evidence collected from previous interactions. By incorporating the dynamic feedback mechanism in the routing protocol, misbehaved nodes are identified and avoided to forward packets. In this way,misbehavior can be mitigated. Objective and Sub-tasks The primary objective of this thesis is to Investigate the state of the art of dynamic feedback mechanisms and protocols analyze, implement and evaluate DSR protocols to see how it improves the network performance and what are the side effects of introducing the mechanism to the mobile ad hoc network. Following tasks must be done to achieve the primary objective. Study the preliminary knowledge that is required to carry out the main tasks. For example, to understand DSR protocol one must have some knowledge of Bayesian analysis; to do performance analysis one must learn the methodologies of conducting performance analysis and processing simulation data. Investigate security issues of mobile ad hoc network and current dynamic feedback mechanisms or protocols that are used to solve or mitigate the issues. Investigate and learn how to use the network simulation tool. There are several popular network simulation tools available and we need to choose the one that best suits our needs. The selected network simulator should be studied so that we can use it as platform to implement protocol and conduct simulations. Analyze and implement the DSR protocol based on Dynamic Source Routing protocol (DSR); evaluate the network performance. Structure of the Report Since we have almost gone through the chapter one, we only briefly present the content of the subsequent chapters in this section. Preliminary Information State of the Art Analysis Design Implementation and Tests Performance Analysis Conclusion and Future Work Preliminary information we have introduced the MANET. This chapter presents other preliminary information and concepts that will be used in other parts of the thesis. Firstly four general modes of routing operations are introduced and compared. The DSR protocol, which is used as underlying routing protocol in the thesis, is explained in detail. Secondly Bayesian estimation and Beta function are explained to pave the way for the analysis of the reputation model of DSR in the chapter 4. Thirdly some techniques regarding simulation and performance analysis are presented. Finally, several popular network simulation tools are discussed and compared. Mobile Ad Hoc Network Routing Protocols Nowadays there are various routing protocols proposed for the MANET. The most popular ones are DSDV (Destination-Sequenced Distance Vector), TORA (Temporally- Ordered Routing Algorithm), DSR (Dynamic Source Routing) and AODV (Ad-hoc On Demand Distance Vector). These routing protocols can be categorized in different routing operation modes. Mode of Routing Operations These two modes concern whether or not nodes in an ad hoc network should keep track of routes to all possible destinations, or instead keep track of only those destinations of immediate interest Proactive protocols store route information even before it is needed. This kind of protocols has advantage that communications with arbitrary destination experience minimal delay. However it also suffers from the disadvantage that additional control traffic is needed to continually update stale route information. This could significantly increase routing overhead especially for the MANET where the links are often broken. Reactive protocols, on the contrary, acquire routing information only when it is actually needed. However, the latency of the communication increases tremendously especially when a node communicates to another at the first time. Source routing vs. Hop-by-hop routing These two modes concern whether the source node decides the route for a packet to be forwarded to the destination or the intermediate nodes are allowed to decide the next hop until the packet arrives at the destination. In the source routing protocols, the source node decides the route and puts the route information in the packet header. All the intermediate nodes forward the packet along the route faithfully. This kind of protocols has advantage that the intermediate nodes are not required to maintain the routing information. But it suffers from the disadvantage that the packet size grows because of source routing information carried in each packet. In the hop-by-hop routing protocols, it is sufficient for the source to know only how to get to the next hop and intermediate nodes find their own next-hops until the destination. In contrast to source routing protocols, hop-by-hop routing protocols do not increase packet size but they requires all the intermediate nodes to maintain rout ing information. Table 2-1 Categories of routing protocols has compared the performance of these four routing protocols . The results show that DSR has best throughput performance (above 95%) at all mobility rates and movement speeds. Thus we will use DSR as basic routing protocol in this thesis. The Dynamic Source Routing Protocol (DSR) John et al. proposed the dynamic source routing protocol (DSR) [1] which is a routing protocol for use in multi-hop wireless ad hoc networks of mobile nodes. DSR is an ondemand protocol, in which route are only discovered when data need to be transmitted to a node where no route has yet been discovered. The advantage of this on-demand routing protocol is that there are not any periodic routing advertisement and reducing the routing overhead. DSR is also a source routing protocol, allowing multiple routes to any destination and allows each sender to select and control the routes used in routing the packets. DSR is composed of the two main mechanisms: Route Discovery and Route Maintenance which are explained below. Route Discovery Route Discovery aims at finding routes from a source node to destination. Figure 2-1 illustrates the procedure of Route Discovery. When a source node S wants to send a data packet to some destination node D, it first searches its route cache to find whether there is a route to D. If there is no route to D, then S will initiate a Route Discovery and send out Route Request message which is propagated to all the nodes within its transmission range. At the mean time, it saves the data packet in its send buffer. The Route Request message contains the addresses of source node and destination node, a unique route request identifier and a route record which records all the intermediate nodes that this route request packet has traveled through. S appends itself to the beginning of the route record when it initiates the message. When a node receives the Route Request message, it compares the destination address in the message with its own address to judge whether itself is the destination node. If it is not, it will append its own address in the route record and propagate the message to other nodes. If the node is the destination node, it will send a Route Reply message to the source node and the message contains the source route record which is accumulated when the Route Request message is forwarded along its way to the destination. When the destination sends the Route Reply, if it uses MAC protocols such as IEEE 802.11 that require a bidirectional link, it just reverse the source route record and use it as route to send Route Reply to the source node. Otherwise it should find the route by searching its route cache or sending out a Route Request which piggybacks the Route Reply for the source node. When the source node receives the Route Reply message, it puts the returned route into its route cache. From t hen on all the packets destined to the same destination will use this route until it is broken. Route Maintenance Since the ad hoc network is dynamic and the topology of the network changes frequently, the existing routes maintained by nodes in their route cache are often broken. After forwarding a packet, a node must attempt to confirm the reachability of the next-hop node. If the node does not receive any confirmation from the next hop during a certain period of time, it will retransmit the packet. If after a maximum number of retransmission it still does not receive any confirmation, it will think the link to the next hop is broken and will send a Route Error message to the source node. DSR proposes three acknowledge mechanisms to confirm that data can flow over the link from that node to the next hop: Link-layer acknowledgement which is provided by MAC layer protocol such as IEEE 802.11. Passive acknowledgement in which a node hears the next-hop node forwarding the packet and thus confirms the reachability of the link. Network-layer acknowledgement in which a node sends an explicit acknowledgement request to its next-hop node. Passive Acknowledgement Passive Acknowledgement (PACK) is important in DSR protocol because it is used to detect whether the next hop forwards the packet or drops it. We explain it in detail in this section. Passive acknowledgement is used with the assumption that: Network links operates bi- directionally. The network interface is in the promiscuous mode. When a node taps a new packet in promiscuous mode after it originates or forwards a packet, it consider it as an acknowledgement of the first packet if both of following check success. The Source Address, Destination Address, Protocol, Identification, and Fragment Offset fields in the IP header of the two packets MUST match. If either packet contains a DSR Source Route header, both packets MUST contain one, and the value in the Segments Left field in the DSR Source Route header of the new packet MUST be less than that in the first packet. If no matched packet is found during PACK timeout, the node will consider the link between the next hop and itself is broken and will send Route Error message to the source node. Additional features DSR has additional features such as replying to route requests using cached routes, caching overheard routing information, packet salvaging and flow state extension and etc. We will introduce them in section 4.1 and discuss how they will impact the performance of network, how they will interact with DSR and whether they will be enabled in our simulation. Performance Analysis Techniques This section introduces the performance analysis techniques and methodologies that will be used in the performance evaluation. Factors and Primary Factors There are many parameters that will influence the simulation results and need to be carefully chosen in the simulations. Some parameters are chosen based on experience values or the conditions of the network we want to simulate. Others need to be tuned to optimize the network performance. We distinguish the two kinds of parameters as follows: Factors are the variables that affect the simulation result and have several alternatives. Normally they are decided based on experience. Primary factors are the factors whose effects need to be quantified. This kind of factors usually needs to be adjusted through simulation. Data Measurement The key step of the network performance analysis is to interpret the simulation result and summarize the characteristic of the network. To avoid the inaccurate simulation results due to an extreme scenario, we usually run simulations on several different scenarios. The data set of these simulations are called sample. A single number must be presented to give the key characteristic of the sample and this single number is called an average of the data. There are three alternatives to summarize a sample Mean is obtained by taking the sum of all observations and dividing this sum by the number of observations in the sample. Median is obtained by sorting the observations in an increasing order and taking the observation that is in the middle of series. If the number of the observations is even, the mean of the middle two values is used as a median. Mode is obtained by plotting a histogram and specifying the midpoint of the bucket where the histogram peaks. Confidence Interval for the Mean In our performance evaluation, the main objective is to compare the simulation results of DSR and Standard DSR to see whether there is any performance improvement. However, most simulation results are random in some degree due to the particularity of the node movement scenarios and we cannot tell whether the two systems are different. One way to minimize the random effect is to repeat the simulations with different scenarios as many times as possible and get a large sample space. Unfortunately, due to the time limitation we cannot conduct many simulations. points out that using confidence interval we can tell whether the two systems are different with smaller sample space. The confidence interval for the mean can be calculated using If the confidence intervals of the simulation results of the two systems have no overlap, then we can claim the two systems are different and one system is superior or inferior to the other. GloMoSims source and binary code can be downloaded only by academic institutions for research purposes. Commercial users must use QualNet, the commercial version of GloMoSim. OPNET Modeler OPNET Modeler is commercial network simulation environment for network modeling and simulation. It allows the users to design and study communication networks, devices, protocols, and applications with flexibility and scalability [30]. It simulates the network graphically and its graphical editors mirror the structure of actual networks and network components. The users can design the network model visually.The modeler uses object-oriented modeling approach. The nodes and protocols are modeled as classes with inheritance and specialization. The development language is C. Comparison When choosing a network simulator, we normally consider the accuracy of the simulator. Unfortunately there is no conclusion on which of the above three simulator is the most accurate one. David Cavin et al. has conducted experiments to compare the accuracy of the simulators and it finds out that the results are barely comparable [31]. Furthermore, it warns that no standalone simulations can fit all the needs of the wireless developers. It is more realistic to consider a hybrid approach in which only the lowest layers (MAC and physical layers) and the mobility model are simulated and all the upper layers (from transport to application layers) are executed on a dedicated hosts (e.g. cluster of machines). Although there is no definite conclusion about the accuracy of the three network simulators, we have to choose one of them as our simulation environment. We compare the simulators using some metrics and the results are summarized After comparing the three simulators, we decide to choose ns2 as network simulator in our thesis because Ns2 is open source free software. It can be easily downloaded and installed. The author of the thesis has used ns2 in another network related course and gotten familiar with the simulation. Ns2 uses TCL and C++ as development languages for which the author has some programming experience. The author of the DSR protocol has conducted simulation on GloMoSim and gotten performance results. We want to do the simulation on a different simulation to form comparison. State of the Art In this chapter we will introduce the start of the art security solutions in MANET with emphasis on dynamic feedback mechanisms. Firstly, we will present the general security issues/requirements of MANET to pave the way for the future investigation. Then we will discuss the state of the art security mechanisms for MANET such as payment system,trust management system, reputation system, etc. Finally, we will summarize all the security solutions we discussed in this chapter. Security Issues in Mobile Ad Hoc Network Due to lack of central infrastructural and wireless links susceptible to attacks, security in ad hoc network has inherent weakness. In section 1.2 we have discussed the reasons why mobile ad hoc network imposes security challenges that cannot be solved by traditional security mechanisms. In this section, we present the general security properties required by ad hoc network. Following are general security properties regarding ad hoc network Confidentiality: The confdiantiality property is to protect certain information from unauthorized disclosure. The information includes not only the application data that send over the routing protocol, but also the routing information itself as well as network topology and geographical location. Integrity: The integrity ensures that the transmitted message and other system asset are modified only by authorized parties. In the routing level, it requires all nodes in the network following correct routing procedure. The main challenge of ensuring integrity is that without central infrastructure and powerful computing capabilities, it is difficult to apply existing cryptography and key management systems. Availability: The availability property requires that the services or devices are exempt from denial of service, which is normally done by interruption, network or server overload. Typical examples or denial of service attack are radio jamming, in which a misbehaved node transmit radio to interference other nodes communications, and battery exhaustion, in which a misbehaved node interact with a node for no other purpose than to consume its battery energy. Authentication: The authentication property requires that the communication entitys identification is recognized and proved before communication starts. Access control: This property requires restricting resources, services or data to special identities according to their access rights or group membership. Non-repudiation: This property ensures that when data are sent from sender to receiver, the sender cannot deny that he has sent the data and the receiver cannot deny that he has received the data. Mobile nodes may conduct different misbehavior for different purposes. Po-Wah Yau classifies the misbehaved nodes into following categories. Failed nodes are simply those unable to perform an operation; this could be because power failure and environmental events. Badly failed nodes exhibit features of failed nodes but they can also send false routing messages which are a threat to the integrity of the network. Selfish nodes are typified by their unwillingness to cooperate as the protocol requires whenever there is a personal cost involved. Packet dropping is the main attack by selfish nodes. Malicious nodes aim to deliberately disrupt the correct operation of the routing protocol, denying network service if possible. These four types of misbehaved nodes actually can be categorized in two aspects: whether their misbehaviors are intentional or unintentional, and the severity of the results. Payment Systems Payment systems provide economic incentives for the cooperation in MANET. They consider that each node in MANET is its own authority and tries to maximize the benefits it gets from the network. Thus each node tends to be selfish, dropping packets not destined to them but make use of other nodes to forward their own packets. The purpose of payment systems is to encourage the cooperation within the MANET by economic incentives. There are several variations of payment systems proposed. Nuglets Nuglets is a virtual currency mechanism for charging (rewarding) server usage (provision). Nodes that use a service must pay for it (in nuglets) to nodes that provide the service. A typical service is packet forwarding which is provided by intermediate nodes to the source and the destination of the packet. Therefore either the source or the destination should pay for it. There are two models for charging for the packet forwarding service: the Packet Purse Model (PPM) and the Packet Trade Model (PTM). In the Packet Purse Model, the sender pays for the packet. It loads the packet with a number of nuglets when sending the packet. Each intermediate forwarding node acquires some nuglets from the packet that covers its forwarding costs. If a packet does not have enough nuglets to be forwarded, then it is discarded. If there are nuglets left in the packet once it reaches destination, the nuglets are lost. In the Packet Trade Model, the destination pays for the packet. Each intermediate node buys the packet from previous one for some nuglets and sells it to the next one for more nuglets until the destination buys it. Either of the two models has advantages and disadvantages. While the Packet Purse Model deters nodes from sending useless data and avoids the network overloading, the Packet Trade Model can lead to an overload of the network and the destination receives packets it does not want. On the other hand, in the Packet Purse Model it is difficult to estimate the number of nuglets th at are required to reach a given destination. But thePacket Purse Model does not need to consider this problem. To take advantages of the two models and avoid the disadvantages, a hybrid model is suggested. In this model, the sender loads the packet with some nuglets before sending it.The packet is handled according to the Packet Purse Model until it runs out of nuglets. Then it is handled according to the Packet Trade Model until the destination buys it. Counter To address the problems encountered by the nuglets approach such as difficulty in estimating pre-load nuglets and possible network overload, another payment approach based on credit counter is suggested. In this approach, the current state of each node is described by two variables b and c, where b is the remaining battery power and cstands for the value of its nuglet counter. More precisely, b is the number of packets that the node can send using its remaining energy and c is the number of packets a node canoriginate. A node can originate a number of packets N only when the condition c=N holds. When a node forwards a packet, nuglet counter c is increased by one and b is reduced by one. Thus in order to originate packets, each node must earn credits by forwarding packets. The counter solution requires tamper resistant hardware security module. Spirit S. Zhong et al. proposed Sprite [19], a credit-based system for MANET. As opposed to Nuglets or Counter they do not require tamper-proof hardware to prevent the fabrication of payment units. Instead, they introduce a central Credit Clearance Service (CCS). The basic scheme of the system is as follows. When a node receives a message the node keeps a receipt of the message and reports to the CCS when the node has a fast connection to Credit Clearance Service (CCS). The CCS then determines the charge and credits to each node involved in the transmission of a message, depending on the reported receipts of a message. In this scheme, the sender charges money. A node that has forwarded a message is compensated, but the credit that a node receives depends on whether or not its forwarding action is successful. Forwarding is considered successful if and only if the next node on the path reports a valid receipt to the CCS. Discussion on the Payment Systems The payment systems we describe in above sections either assumes a tamper resistant hardware module is available to ensure that the behavior of the node is not modified or requires a central authority server to determine the charge and credit to each node involved in the transmission of a message. Tamper resistant hardware may not be appropriate for most mobile devices because it demands advanced hardware solution and increases the cost of the devices. Lacking of central authority server is right the inherent property of MANET that causes security challenges so it is also not appropriate. Furthermore, all the approaches described above suffer from locality problems [20] that nodes in different locations of the network will have different chances for earning virtualcurrency, which may not be fair for all nodes. Usually nodes at the periphery of the network will have less chance to be rewarded. Reputation System Reputation systems have emerged as a way to reduce the risk entailed in interactions among total strangers in electronic marketplace. Centralized reputation systems have been adopted by many on-line electronic auctions such as eBay to collect and store reputation ratings from feedback providers in a centralized reputation database. Decentralized reputation systems used by MANET, on the other hand, do not use centralized reputation database. Instead, in these reputation systems, each node keeps the ratings about other node and updating the ratings by direct observation of the behaviorsof neighboring nodes or second hand information from other trusted nodes. Identifies three goals for reputation systems: To provide information to distinguish between a trust-worthy principal and an untrustworthy principals. To encourage principals to act in a trustworthy manner To discourage untrustworthy principals from participating in the service the reputation mechanism is present to protect. Most of the reputation systems in MANET are based on trust management system. Trust is such a subjective and dynamic concept that different entities can hold different opinions on it even while facing the same situation. Trust management system can work without reputation system. For example, a mobile node can form opinion about other nodes by direct experience with the nodes.We can unify reputation system and trust management system to dynamic feedback mechanisms. Former one is a global reputation system and mobile nodes share their own experiences of interaction with other nodes. The later one is a local reputation system in which mobile nodes rating the trustability of other nodes based on its own observation. DSR DSR is a reputation system aiming at coping with misbehavior in MANET. The idea is to detect the misbehaved nodes and isolate them fromcommunication by not using them for routing and forwarding and by not allowing the misbehaved nodes to use itself to forward packets. DSR stands for Cooperation Of Nodes: Fairness In Dynamic Ad-hoc Network. It usually works as an extension to on demand routing