79,511 research outputs found
High Rate Single-Symbol Decodable Precoded DSTBCs for Cooperative Networks
Distributed Orthogonal Space-Time Block Codes (DOSTBCs) achieving full
diversity order and single-symbol ML decodability have been introduced recently
for cooperative networks and an upper-bound on the maximal rate of such codes
along with code constructions has been presented. In this report, we introduce
a new class of Distributed STBCs called Semi-orthogonal Precoded Distributed
Single-Symbol Decodable STBCs (S-PDSSDC) wherein, the source performs
co-ordinate interleaving of information symbols appropriately before
transmitting it to all the relays. It is shown that DOSTBCs are a special case
of S-PDSSDCs. A special class of S-PDSSDCs having diagonal covariance matrix at
the destination is studied and an upper bound on the maximal rate of such codes
is derived. The bounds obtained are approximately twice larger than that of the
DOSTBCs. A systematic construction of S-PDSSDCs is presented when the number of
relays . The constructed codes are shown to achieve the upper-bound
on the rate when is of the form 0 modulo 4 or 3 modulo 4. For the rest of
the values of , the constructed codes are shown to have rates higher than
that of DOSTBCs. It is also shown that S-PDSSDCs cannot be constructed with any
form of linear processing at the relays when the source doesn't perform
co-ordinate interleaving of the information symbols.Comment: A technical report of DRDO-IISc Programme on Advanced Research in
Mathematical Engineerin
A lightweight McEliece cryptosystem co-processor design
Due to the rapid advances in the development of quantum computers and their susceptibility to errors, there is a renewed interest in error correction algorithms. In particular, error correcting code-based cryptosystems have reemerged as a highly desirable coding technique. This is due to the fact that most classical asymmetric cryptosystems will fail in the quantum computing era. Quantum computers can solve many of the integer factorization and discrete logarithm problems efficiently. However, code-based cryptosystems are still secure against quantum computers, since the decoding of linear codes remains as NP-hard even on these computing systems. One such cryptosystem is the McEliece code-based cryptosystem. The original McEliece code-based cryptosystem uses binary Goppa code, which is known for its good code rate and error correction capability. However, its key generation and decoding procedures have a high computation complexity. In this work we propose a design and hardware implementation of an public-key encryption and decryption co-processor based on a new variant of McEliece system. This co-processor takes the advantage of the non-binary Orthogonal Latin Square Codes to achieve much smaller computation complexity, hardware cost, and the key size.Published versio
A Lightweight McEliece Cryptosystem Co-processor Design
Due to the rapid advances in the development of quantum computers and their
susceptibility to errors, there is a renewed interest in error correction
algorithms. In particular, error correcting code-based cryptosystems have
reemerged as a highly desirable coding technique. This is due to the fact that
most classical asymmetric cryptosystems will fail in the quantum computing era.
Quantum computers can solve many of the integer factorization and discrete
logarithm problems efficiently. However, code-based cryptosystems are still
secure against quantum computers, since the decoding of linear codes remains as
NP-hard even on these computing systems. One such cryptosystem is the McEliece
code-based cryptosystem. The original McEliece code-based cryptosystem uses
binary Goppa code, which is known for its good code rate and error correction
capability. However, its key generation and decoding procedures have a high
computation complexity. In this work we propose a design and hardware
implementation of an public-key encryption and decryption co-processor based on
a new variant of McEliece system. This co-processor takes the advantage of the
non-binary Orthogonal Latin Square Codes to achieve much smaller computation
complexity, hardware cost, and the key size.Comment: 2019 Boston Area Architecture Workshop (BARC'19
OFDM based Distributed Space Time Coding for Asynchronous Relay Networks
Recently Li and Xia have proposed a transmission scheme for wireless relay
networks based on the Alamouti space time code and orthogonal frequency
division multiplexing to combat the effect of timing errors at the relay nodes.
This transmission scheme is amazingly simple and achieves a diversity order of
two for any number of relays. Motivated by its simplicity, this scheme is
extended to a more general transmission scheme that can achieve full
cooperative diversity for any number of relays. The conditions on the
distributed space time block code (DSTBC) structure that admit its application
in the proposed transmission scheme are identified and it is pointed out that
the recently proposed full diversity four group decodable DSTBCs from precoded
co-ordinate interleaved orthogonal designs and extended Clifford algebras
satisfy these conditions. It is then shown how differential encoding at the
source can be combined with the proposed transmission scheme to arrive at a new
transmission scheme that can achieve full cooperative diversity in asynchronous
wireless relay networks with no channel information and also no timing error
knowledge at the destination node. Finally, four group decodable distributed
differential space time block codes applicable in this new transmission scheme
for power of two number of relays are also provided.Comment: 5 pages, 2 figures, to appear in IEEE International Conference on
Communications, Beijing, China, May 19-23, 200
Quasi-orthogonal space-frequency coding in non-coherent cooperative broadband networks
© 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.So far, complex valued orthogonal codes have been used differentially in cooperative broadband networks. These codes however achieve less than unitary code rate when utilized in cooperative networks with more than two relays. Therefore, the main challenge is how to construct unitary rate codes for non-coherent cooperative broadband networks with more than two relays while exploiting the achievable spatial and frequency diversity. In this paper, we extend full rate quasi-orthogonal codes to differential cooperative broadband networks where channel information is unavailable. From this, we propose a generalized differential distributed quasi-orthogonal space-frequency coding (DQSFC) protocol for cooperative broadband networks. Our proposed scheme is able to achieve full rate, and full spatial and frequency diversity in cooperative networks with any number of relays. Through pairwise error probability analysis we show that the diversity gain of our scheme can be improved by appropriate code construction and sub-carrier allocation. Based on this, we derive sufficient conditions for the proposed code structure at the source node and relay nodes to achieve full spatial and frequency diversity.Peer reviewe
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