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University of Michigan

1. Weng, Lihua. Error exponent regions for multi-user channels.

Degree: PhD, Electrical engineering, 2005, University of Michigan

In modern communication systems, different users have different requirements for quality of service (QoS). In contrast to existing QoS schemes, there is currently no framework in information theory concerning QoS in multi-user systems. In this work an information-theoretic groundwork is proposed to study communication systems which provide heterogeneous reliabilities for the users. This is done by defining individual codeword error probabilities for the users in the network and obtaining their fundamental tradeoff. This tradeoff is quantified by introducing the concept of the error exponent region. Using this framework, a system can be realized, which can provide a tradeoff of reliabilities among the users for a fixed vector of users' rates. This adds a completely new dimension to the performance tradeoff in such networks, which is unique to multi-terminal communication systems, and is beyond what is given by the conventional performance-versus-rate tradeoff in single-user systems. Although this is a very general concept and can be applied to any multi-terminal communication system, in this work we focus on broadcast and multiple access channels. We show the existence of a tradeoff among the users' error exponents by deriving inner and outer bounds for the error exponent region. Advisors/Committee Members: Anastasopoulos, Achilleas (advisor), Sadanandarao, Sandeep P. (advisor).

Subjects/Keywords: Channels; Diversity Gain; Diversity Gains; Error Exponent; Multi; Multiuser; Regions; User

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Weng, L. (2005). Error exponent regions for multi-user channels. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/125537

Chicago Manual of Style (16th Edition):

Weng, Lihua. “Error exponent regions for multi-user channels.” 2005. Doctoral Dissertation, University of Michigan. Accessed November 25, 2020. http://hdl.handle.net/2027.42/125537.

MLA Handbook (7th Edition):

Weng, Lihua. “Error exponent regions for multi-user channels.” 2005. Web. 25 Nov 2020.

Vancouver:

Weng L. Error exponent regions for multi-user channels. [Internet] [Doctoral dissertation]. University of Michigan; 2005. [cited 2020 Nov 25]. Available from: http://hdl.handle.net/2027.42/125537.

Council of Science Editors:

Weng L. Error exponent regions for multi-user channels. [Doctoral Dissertation]. University of Michigan; 2005. Available from: http://hdl.handle.net/2027.42/125537

2. Giannoulakis, Ioannis. Ανάλυση και σύγκριση αλγορίθμων ευκαιριακού χρονοπρογραμματισμού σε ασύρματα δίκτυα επικοινωνιών: μεθοδολογίες ανάλυσης και αποτελέσματα συγκριτικής αξιολογήσης.

Degree: 2013, National Technical University of Athens (NTUA); Εθνικό Μετσόβιο Πολυτεχνείο (ΕΜΠ)

Wireless communication networks develop rapidly, featuring excessive demand for performance improvements. This thesis studies performance and fairness issues of opportunistic schedulers, widely used in modern wireless standards like HSDPA and HDR. Opportunistic schedulers take into account the condition of the wireless link in order to select a terminal for service during a timeslot, by allocating to it all the available network resources. The main attribute of this type of scheduling is that the average transmission rate does depend on the number of active terminals, in the form of a multiuser diversity gain which acts as a multiplicative factor on the average rate. The above characteristics yield to a State Dependent Processor Sharing (SDPS) model, which in its general form considered here, features separate classes of terminals and a generic form of the state space, as a result of the admission control scheme. From a mathematical point of view, we manage to provide the distribution of the sojourn time for an SDPS system, which is expressed through the exponential of an appropriate M-matrix. The form allows the characterization of the asymptotic decay rate of the sojourn time’s distribution tail and provides easily computable upper and lower bounds. Furthermore, the conducted research studies time-scale separation phenomena, by separating the classes of terminals into a slow and a fast group, according to their average transmission rate. By leveraging on the nearly completely decomposable structure of the full system, we arrive in accurate approximations that offer conceptual and computational simplicity. Additionally, we consider some special important cases of the service rate function and/or the admission control scheme, which allow to determine the effect of the presence of slow class terminals on the performance of the terminals belonging in the fast group of classes. The results and conclusions of the generalized problem have been applied in the practical case of a channel-aware wireless network. A comparison of two basic opportunistic schedulers with respect to performance and fairness issues follows. We result in several conclusions regarding the value and the suitability of each scheduler, the appropriate form of the service pool and the specification of the worst case scenario related to the fast class terminals. Moreover, a new scheduling scheme is proposed, combining the nice properties oh the previous two schedulers. The theoretical findings are compared and verified numerically.

Τα δίκτυα ασύρματων επικοινωνιών γνωρίζουν ιδιαίτερη ανάπτυξη και χαρακτηρίζονται από τη συνεχώς αυξανόμενη ανάγκη για βελτιωμένες επιδόσεις και υψηλούς ρυθμούς μετάδοσης. Η διατριβή ασχολείται με τη μελέτη της επίδοσης σε συστήματα τηλεπικοινωνιών όπως το HSDPA και το HDR που βασίζονται σε αλγορίθμους ευκαιριακού χρονοπρογραμματισμού για την επιλογή του τερματικού που θα εξυπηρετηθεί σε κάθε χρονοσχισμή, λαμβάνοντας υπόψη την κατάσταση της ασύρματης ζεύξης. Βασικό γνώρισμα αυτού του τύπου χρονοπρογραμματισμού αποτελεί το…

Subjects/Keywords: Ευκαιριακός χρονοπρογραμματισμός; Μερισμός εξυπηρετητή με εξάρτηση από την κατάσταση; Κατανομή χρόνου απόκρισης; Διαχωρισμός χρονικής κλίμακας; Κέρδη διαφορισμού πολλαπλών χρηστών; Ασύρματο δίκτυο με παρακολούθηση καναλιού; Αποσύνθεση; Συνάθροιση; Opportunistic scheduling; State-dependent processor sharing; Sojourn time distribution; Time scale separation; Multiuser diversity gains; Channel-aware wireless network; DECOMPOSITION; Aggregation

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Giannoulakis, I. (2013). Ανάλυση και σύγκριση αλγορίθμων ευκαιριακού χρονοπρογραμματισμού σε ασύρματα δίκτυα επικοινωνιών: μεθοδολογίες ανάλυσης και αποτελέσματα συγκριτικής αξιολογήσης. (Thesis). National Technical University of Athens (NTUA); Εθνικό Μετσόβιο Πολυτεχνείο (ΕΜΠ). Retrieved from http://hdl.handle.net/10442/hedi/38661

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Giannoulakis, Ioannis. “Ανάλυση και σύγκριση αλγορίθμων ευκαιριακού χρονοπρογραμματισμού σε ασύρματα δίκτυα επικοινωνιών: μεθοδολογίες ανάλυσης και αποτελέσματα συγκριτικής αξιολογήσης.” 2013. Thesis, National Technical University of Athens (NTUA); Εθνικό Μετσόβιο Πολυτεχνείο (ΕΜΠ). Accessed November 25, 2020. http://hdl.handle.net/10442/hedi/38661.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Giannoulakis, Ioannis. “Ανάλυση και σύγκριση αλγορίθμων ευκαιριακού χρονοπρογραμματισμού σε ασύρματα δίκτυα επικοινωνιών: μεθοδολογίες ανάλυσης και αποτελέσματα συγκριτικής αξιολογήσης.” 2013. Web. 25 Nov 2020.

Vancouver:

Giannoulakis I. Ανάλυση και σύγκριση αλγορίθμων ευκαιριακού χρονοπρογραμματισμού σε ασύρματα δίκτυα επικοινωνιών: μεθοδολογίες ανάλυσης και αποτελέσματα συγκριτικής αξιολογήσης. [Internet] [Thesis]. National Technical University of Athens (NTUA); Εθνικό Μετσόβιο Πολυτεχνείο (ΕΜΠ); 2013. [cited 2020 Nov 25]. Available from: http://hdl.handle.net/10442/hedi/38661.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Giannoulakis I. Ανάλυση και σύγκριση αλγορίθμων ευκαιριακού χρονοπρογραμματισμού σε ασύρματα δίκτυα επικοινωνιών: μεθοδολογίες ανάλυσης και αποτελέσματα συγκριτικής αξιολογήσης. [Thesis]. National Technical University of Athens (NTUA); Εθνικό Μετσόβιο Πολυτεχνείο (ΕΜΠ); 2013. Available from: http://hdl.handle.net/10442/hedi/38661

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.