Improving the encoding and the decoding process of low-density parity-check codes for novel applications

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Improving the encoding and the decoding process
of low-density parity-check codes for novel
applications

• Miss Insah Bhurtah
• Main Supervisor Prof. K.M.S. Soyjaudah
• Associate Supervisor Dr C Catherine

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Overview

• Introduction
• Digital Communications
• Digital Communication Block
• Low-Density Parity-Check Codes (LDPC Codes)
• Objectives Of The Research
• Methodology
• Encoding of LDPC Codes
• Decoding of LDPC Codes
• Evolving Wireless Networks Outside The Internet
• Delay Tolerant Networks (DTNs)
• Ongoing Research

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Introduction

• In the field of digital communications,
• coding is used to transmit data correctly.
• It ensures that a sent original
• message is obtained at a receiver.
• Planning to do coding in Delay
• Tolerant Networks (DTNs) and
• Interplanetary Networks (IPNs)
• Aim is to improve the performance of
• low-density parity-check codes for application
  in DTNs and IPNs.

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Digital Communications

• It involves the transmission of information from
  source to a sink.
• It works by the physical transmission of data
  over a point-to-point or point-to-multipoint
  medium

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Digital Communication Block
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Digital Communication Block

• Data from the source passes into a noisy channel.
• Channel coding Redundancy added to the data
  before transmission and the same redundancy used
  to correct errors introduced by the channel to
  get the original data at the receiver.
• Many types of error-correcting codes used such as
  turbo codes and low-density parity-check codes
  being among the best.
• In this research, channel encoding and decoding,
  and low-density parity-check codes are dealt.

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Low-Density Parity-Check Codes (LDPC codes)

• (LDPC) codes are the second generation of
  modern codes, following turbo codes.
• They were first defined by Gallager in 1962, but
  were not practical at that time.
• Rediscovered after the turbo code revolution in
  1994
• Many improvements have been made in the last few
  years through extensive research.
• Advances in LDPC coding enabled better
  performance than turbo codes to be achieved. In
  2003, an LDPC code beat six turbo codes to turn
  into the new DVB-S2 standard for the satellite
  transmission of digital television.

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Objectives Of The Research

• Adapting LDPC codes for novel applications such
  as Delay Tolerant Networks (DTNs) and
  Interplanetary Networks (IPNs).
• DTN overlay of regional networks that
  accommodates long delays between and within them.
• IPN interplanetary internet currently being
  developed for space communication.
• Expanding the usage of LDPC codes in high
  generation wireless communication systems such as
  WiMax.

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Methodology

• Development of matrix creation techniques for
• creation of high rate LDPC codes
• Improving performance by improving specific-edge
• connections and local topologies of the
  bipartite graph
• Designing of very low error rates LDPCs to their
• effective use in satellite transmission, IPNs
  and DTNs.
• Devising of algorithms to enhance wireless
• transmission.
• Use of C/C programming language to design
• algorithms to reduce the error floor in
  bipartite
• graphs.

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Encoding Of LDPC Codes

• Encoding is to transform the data into a format
  so that it can be transmitted into the channel.
• It is carried out by the equation, where t is the
  transmitted codeword, s the source sequence and
  the generator-transpose matrix of the code GT

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Decoding Of LDPC Codes

• Decoding involves getting the original message
  back.
• It is done over the bipartite graph having two
  sets of vertices.

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Decoding Of LDPC Codes

• Check vertices are connected to bit vertices by
  edges allowing flow of information.

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Decoding Of LDPC Codes

• Performance curves of LDPC show the presence of
  an error floor during the decoding process.

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Evolving Wireless Networks Outside The Internet
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Evolving Wireless Networks Outside The Internet

• Todays internet connectivity relies primarily on
  wired links.
• Communication outside of the internet
  power-limited mobile wireless, satellite,
  interplanetary communications are developing.
• Future space missions crewed by people motivate
  interest in interplanetary internet.
• Long and variable delays, arbitrarily long
  periods of disconnection and high error rates.

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Delay-Tolerant Networks (DTNs)
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Delay-Tolerant Networks (DTNs)

• DTNs Network of regional networks. Overlay on
  top of regional networks.
• Accommodate long delays, intermittent
  connectivity (no end-to-end path between source
  and destination), long or variable delays from
  node to node
• Moving communicating bodies (interplanetary
  space, earth mobile wireless communication),
  links shut down by intervening bodies to conserve
  energy or preserve secrecy.
• DTNs solve these problems by store-and-forward
  message switching.
• Design of error correction codes can provide
  large reductions in delay.

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Ongoing Research

• Literature Review of past publications.
• Designing of algorithms in C/C language to
  generate matrices for encoding.
• Studying of decoding algorithms.

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Thank you for your kind attention