Apollonio, Pietrofrancesco
(2014)
Erasure error correcting codes applied to DTN communications.
[Laurea magistrale], Università di Bologna, Corso di Studio in
Ingegneria informatica [LM-DM270]
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Abstract
The space environment has always been one of the most challenging for
communications, both at physical and network layer. Concerning the latter,
the most common challenges are the lack of continuous network connectivity,
very long delays and relatively frequent losses. Because of these problems,
the normal TCP/IP suite protocols are hardly applicable. Moreover, in
space scenarios reliability is fundamental. In fact, it is usually not tolerable
to lose important information or to receive it with a very large delay because
of a challenging transmission channel. In terrestrial protocols, such as TCP,
reliability is obtained by means of an ARQ (Automatic Retransmission reQuest)
method, which, however, has not good performance when there are long
delays on the transmission channel. At physical layer, Forward Error Correction Codes (FECs), based on the insertion of redundant information, are an alternative way to assure reliability.
On binary channels, when single bits are flipped because of channel noise,
redundancy bits can be exploited to recover the original information. In the
presence of binary erasure channels, where bits are not flipped but lost, redundancy can still be used to recover the original information. FECs codes,
designed for this purpose, are usually called Erasure Codes (ECs). It is worth
noting that ECs, primarily studied for binary channels, can also be used at
upper layers, i.e. applied on packets instead of bits, offering a very interesting alternative to the usual ARQ methods, especially in the presence of long
delays. A protocol created to add reliability to DTN networks is the Licklider Transmission Protocol
(LTP), created to obtain better performance on long delay links. The aim of this thesis is the application of ECs to LTP.
Abstract
The space environment has always been one of the most challenging for
communications, both at physical and network layer. Concerning the latter,
the most common challenges are the lack of continuous network connectivity,
very long delays and relatively frequent losses. Because of these problems,
the normal TCP/IP suite protocols are hardly applicable. Moreover, in
space scenarios reliability is fundamental. In fact, it is usually not tolerable
to lose important information or to receive it with a very large delay because
of a challenging transmission channel. In terrestrial protocols, such as TCP,
reliability is obtained by means of an ARQ (Automatic Retransmission reQuest)
method, which, however, has not good performance when there are long
delays on the transmission channel. At physical layer, Forward Error Correction Codes (FECs), based on the insertion of redundant information, are an alternative way to assure reliability.
On binary channels, when single bits are flipped because of channel noise,
redundancy bits can be exploited to recover the original information. In the
presence of binary erasure channels, where bits are not flipped but lost, redundancy can still be used to recover the original information. FECs codes,
designed for this purpose, are usually called Erasure Codes (ECs). It is worth
noting that ECs, primarily studied for binary channels, can also be used at
upper layers, i.e. applied on packets instead of bits, offering a very interesting alternative to the usual ARQ methods, especially in the presence of long
delays. A protocol created to add reliability to DTN networks is the Licklider Transmission Protocol
(LTP), created to obtain better performance on long delay links. The aim of this thesis is the application of ECs to LTP.
Tipologia del documento
Tesi di laurea
(Laurea magistrale)
Autore della tesi
Apollonio, Pietrofrancesco
Relatore della tesi
Scuola
Corso di studio
Ordinamento Cds
DM270
Parole chiave
erasure codes, ion, dtn, fec, ec, space communications, ltp
Data di discussione della Tesi
17 Marzo 2014
URI
Altri metadati
Tipologia del documento
Tesi di laurea
(NON SPECIFICATO)
Autore della tesi
Apollonio, Pietrofrancesco
Relatore della tesi
Scuola
Corso di studio
Ordinamento Cds
DM270
Parole chiave
erasure codes, ion, dtn, fec, ec, space communications, ltp
Data di discussione della Tesi
17 Marzo 2014
URI
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