Instantly Decodable Network Coding: From Centralized to Device-to-Device Communications

From its introduction to its quindecennial, network coding has built a strong reputation for enhancing packet recovery and achieving maximum information flow in both wired and wireless networks. Traditional studies focused on optimizing the throughput of the system by proposing elaborate schemes able to reach the network capacity. With the shift toward distributed computing on mobile devices, performance and complexity become both critical factors that affect the efficiency of a coding strategy. Instantly decodable network coding presents itself as a new paradigm in network coding that trades off these two aspects. This paper review instantly decodable network coding schemes by identifying, categorizing, and evaluating various algorithms proposed in the literature. The first part of the manuscript investigates the conventional centralized systems, in which all decisions are carried out by a central unit, e.g., a base-station. In particular, two successful approaches known as the strict and generalized instantly decodable network are compared in terms of reliability, performance, complexity, and packet selection methodology. The second part considers the use of instantly decodable codes in a device-to-device communication network, in which devices speed up the recovery of the missing packets by exchanging network coded packets. Although the performance improvements are directly proportional to the computational complexity increases, numerous successful schemes from both the performance and complexity viewpoints are identified

Throughput and Delay Optimization of Linear Network Coding in Wireless Broadcast

Linear network coding (LNC) is able to achieve the optimal throughput of packet-level wireless broadcast, where a sender wishes to broadcast a set of data packets to a set of receivers within its transmission range through lossy wireless links. But the price is a large delay in the recovery of individual data packets due to network decoding, which may undermine all the benefits of LNC. However, packet decoding delay minimization and its relation to throughput maximization have not been well understood in the network coding literature. Motivated by this fact, in this thesis we present a comprehensive study on the joint optimization of throughput and average packet decoding delay (APDD) for LNC in wireless broadcast. To this end, we reveal the fundamental performance limits of LNC and study the performance of three major classes of LNC techniques, including instantly decodable network coding (IDNC), generation-based LNC, and throughput-optimal LNC (including random linear network coding (RLNC)). Various approaches are taken to accomplish the study, including 1) deriving performance bounds, 2) establishing and modelling optimization problems, 3) studying the hardness of the optimization problems and their approximation, 4) developing new optimal and heuristic techniques that take into account practical concerns such as receiver feedback frequency and computational complexity. Key contributions of this thesis include: - a necessary and sufficient condition for LNC to achieve the optimal throughput of wireless broadcast; - the NP-hardness of APDD minimization; - lower bounds of the expected APDD of LNC under random packet erasures; - the APDD-approximation ratio of throughput-optimal LNC, which has a value of between 4/3 and 2. In particular, the ratio of RLNC is exactly 2; - a novel throughput-optimal, APDD-approximation, and implementation-friendly LNC technique; - an optimal implementation of strict IDNC that is robust to packet erasures; - a novel generation-based LNC technique that generalizes some of the existing LNC techniques and enables tunable throughput-delay tradeoffs

Rapprochement between instantly decodable and random linear network coding

In this paper, a new network coding model is proposed to unify instantly decodable network coding (IDNC) and random linear network coding (RLNC), which have been considered to be incompatible in the literature. This model is based on a novel definition o

Louis MacNeice and his influence on contemporary Northern Irish poetry

This thesis examines in close detail the influence of Louis MacNeice’s work – primarily his poetry but also his critical prose and radio plays – in the poetry of Derek Mahon, Michael Longley, Paul Muldoon and Ciaran Carson. Rather than following a fixed, unified theory of influence, the thesis explores how individual poems contain echoes – either formally, rhythmically, tonally or imagistically – of the elder poet’s work. The thesis shows how the example of a single, shared creative ancestor may manifest in many different ways. For Derek Mahon, MacNeice is present in the question of how an artist may be of use to their community, even (perhaps especially) in a community or society in which the artist is not valued. Mahon’s poetry also explores similar existential questions, through a shared interest in the work of Samuel Beckett. For Michael Longley, MacNeice presents a vital example for his war poetry through the poem ‘The Casualty’, and for his love poetry through ‘Mayfly’. As single poems of Longley’s reverberate and evolve throughout his oeuvre, so specific poems by MacNeice become touchstones throughout Longley’s poetry. Muldoon’s writing seems interested in MacNeice as a symbol as well as an artistic forebear: MacNeice appears as a dramatic persona in one poem, and remnants of his own poems, particularly ‘Snow’, ghost many of Muldoon’s collections. Carson has had a turbulent relationship with MacNeice through his career, and in his early collections this relationship is defined in negative as much as positive: Carson’s ‘Bagpipe Music’ seems a response to and a rebuke of MacNeice’s poem of the same name. Later, the creative potential of MacNeice’s determination to remain creatively unanchored seems to have been an empowering example. The thesis considers the matter of influence as far more subtle and contextually sensitive than the psychologically fraught, highly combative depiction in many existing theoretical models. Instead, it is interested in how influence works in practice, in individual case studies

Compilation and critique : the essay as a literary, cinematographic and videographic form

This dissertation critically engages the meaning and scope of the category of the ‘essay film’; a term that has gained increasing currency in recent decades in film studies and contemporary art to group a diverse array of moving-image works. Departing from recent literature on the essay film, the essay, as I argue, should be conceived less as a stable generic category, than as a dynamic form and experimental mode of writing and filmmaking, which employs and cuts across diverse literary, cinematic and televisual genres and sub-genres, and which is historically subject to critical transformation as it encounters new social, technological and cultural forms and mediums. The introduction provides a critical survey of some of the leading proponents of the essay film, and outlines a working definition of the essay as a literary and cinematographic form. Chapter 1 examines the history of the essay and criticism as a literary and philosophical form, focusing on the essayistic and critical writings of Michel de Montaigne, the early German Romantics, Walter Benjamin, Theodor W. Adorno and Roland Barthes. Central to the critical and experimental nature of the essay, as the chapter underlines, is the deployment of various indirect, allegorical, and modernist rhetorical and poetic strategies and devices – such as citation, irony, fragmentation, and parataxis – which attempt to engage the reader in the text’s reflective process through the constellation of enigmatic and disjunct moments and perspectives. Chapter 2 explores the emergence of various essayistic forms in the Soviet avant-garde in the 1920s, relating debates around the privileging of literary and photographic documentary montage practices in Soviet Factography to Esfir Shub’s historical compilation films, Dziga Vertov’s experimental newsreels, and Sergei Eisenstein’s project to make a plotless film-essay based on Karl Marx’s Capital. Chapter 3 focuses on Jean-Luc Godard’s film and video essays – from Camera Eye (1967) to Histoire(s) du cinéma (1988-1998) – delineating the crucial shifts in Godard’s various attempts to present a critical discourse on cinema and the media through the montage of image and sound. Chapter 4 investigates the essay films, archival video essays, and essayistic video installations of Harun Farocki, attending to how his works endeavour to render the ciphered social life of images and the historical transformations in technologies and techniques of seeing and imaging available for critical interpretation. Central to my account of the essay as a literary, cinematographic, and videographic form is the question of compilation; namely, how (from Montaigne to Farocki) knowledge and history (whether in the form of text or image) is archived and assembled through the juxtaposition and critical weighing of disparate citations and images. Paramount in relation to Godard and Farocki, as I underscore, is their respective shifts to working with video technology, which afforded both filmmakers the capacity to more freely combine and analyze images from divergent media sources, as well as to devise novel forms of videographic montage based on the construction of historical correspondences between audio-visual elements. I conclude the dissertation with a consideration of the impact of digital technology on contemporary essayistic audio-visual practices, and how issues raised in the preceding chapters – around audio-visual criticism, the spatialization of montage in moving-image installation work, and documentary and archival film practices – have been affected by such technological and cultural shifts