4,519 research outputs found
General Strong Polarization
Arikan's exciting discovery of polar codes has provided an altogether new way
to efficiently achieve Shannon capacity. Given a (constant-sized) invertible
matrix , a family of polar codes can be associated with this matrix and its
ability to approach capacity follows from the {\em polarization} of an
associated -bounded martingale, namely its convergence in the limit to
either or . Arikan showed polarization of the martingale associated with
the matrix to get
capacity achieving codes. His analysis was later extended to all matrices
that satisfy an obvious necessary condition for polarization.
While Arikan's theorem does not guarantee that the codes achieve capacity at
small blocklengths, it turns out that a "strong" analysis of the polarization
of the underlying martingale would lead to such constructions. Indeed for the
martingale associated with such a strong polarization was shown in two
independent works ([Guruswami and Xia, IEEE IT '15] and [Hassani et al., IEEE
IT '14]), resolving a major theoretical challenge of the efficient attainment
of Shannon capacity.
In this work we extend the result above to cover martingales associated with
all matrices that satisfy the necessary condition for (weak) polarization. In
addition to being vastly more general, our proofs of strong polarization are
also simpler and modular. Specifically, our result shows strong polarization
over all prime fields and leads to efficient capacity-achieving codes for
arbitrary symmetric memoryless channels. We show how to use our analyses to
achieve exponentially small error probabilities at lengths inverse polynomial
in the gap to capacity. Indeed we show that we can essentially match any error
probability with lengths that are only inverse polynomial in the gap to
capacity.Comment: 73 pages, 2 figures. The final version appeared in JACM. This paper
combines results presented in preliminary form at STOC 2018 and RANDOM 201
Polar Codes for Arbitrary DMCs and Arbitrary MACs
Polar codes are constructed for arbitrary channels by imposing an arbitrary
quasigroup structure on the input alphabet. Just as with "usual" polar codes,
the block error probability under successive cancellation decoding is
, where is the block length. Encoding and
decoding for these codes can be implemented with a complexity of .
It is shown that the same technique can be used to construct polar codes for
arbitrary multiple access channels (MAC) by using an appropriate Abelian group
structure. Although the symmetric sum capacity is achieved by this coding
scheme, some points in the symmetric capacity region may not be achieved. In
the case where the channel is a combination of linear channels, we provide a
necessary and sufficient condition characterizing the channels whose symmetric
capacity region is preserved by the polarization process. We also provide a
sufficient condition for having a maximal loss in the dominant face.Comment: 32 pages, 1 figure. arXiv admin note: text overlap with
arXiv:1112.177
๋น๋์ผ ๋ถํฌ ๋ณ๋ ฌ ์ฑ๋์ ์ํ ํด๋ผ ๋ถํธ ๊ธฐ๋ฒ๊ณผ ์ธ๋ฑ์ค ์ฝ๋๋ฅผ ์ํ ์ฐ๊ณ ํด๋ผ ๋ถํธ ์ค๊ณ ๊ธฐ๋ฒ
ํ์๋
ผ๋ฌธ (๋ฐ์ฌ)-- ์์ธ๋ํ๊ต ๋ํ์ : ์ ๊ธฐยท์ปดํจํฐ๊ณตํ๋ถ, 2015. 8. ์ด์ ์ฐ.๋ณธ ๋
ผ๋ฌธ์ Part I์ ๋น๋ํ ๋์นญ ์ด์ง ์ด์ฐ ๋ฌด๊ธฐ์ต ์ฑ๋์์ ์ฑ๋ ์ฉ๋์ ๋ฌ์ฑ ํ๋ ํด๋ผ ๋ถํธ์ ์ค๊ณ ๊ธฐ๋ฒ ๋ฐ ์ฆ๋ช
๊ณผ Part II์ ๋น๋ํ ์ด์ง ๋
๋ฆฝ ๋ฌด๊ธฐ์ต ์ฑ๋์์ ์ธ๋ฑ์ค ๋ถํธ์ ํด๋ผ ๋ถํธ์ ์ฐ๊ณ๊ธฐ๋ฒ์ ํตํ ์ต์ ์ ์ ์ก๋ฅ ์ ๋ฌ์ฑํ๋ ์ฐ๊ณ ๊ธฐ๋ฒ์ ๋ํ ์ค๊ณ๋ก ๊ตฌ์ฑ๋๋ค.
Part I์์๋ ๋จผ์ ๊ฐ ์ฑ๋์ ํต๊ณ์ ํน์ฑ์ ๋๋ณํ๋ ์ฑ๋ ํ๋ผ๋ฏธํฐ๊ฐ ๊ฒฐ์ ์ ์ธ ํํ๋ก ๋ถํธ๊ธฐ์ ๋ณตํธ๊ธฐ์ ์ฃผ์ด์ง๋ ๊ฒฝ์ฐ๋ ๋ํด ๋ค๋ฃจ๋ฉฐ,
๋๋ฒ์งธ๋ก ์ด ํ๋ผ๋ฏธํฐ๋ค์ด ๊ฒฐ์ ์ ์ด ์๋ ๋๋คํ ๊ฐ์ผ๋ก์จ ์ฃผ์ด์ง๋ ๊ฒฝ์ฐ์ ๋ํ์ฌ ์ ํฉํ ํด๋ผ ๋ถํธ ๊ธฐ๋ฒ์ ๋ํด ๊ธฐ์ ํ๋ค.
ํ์๋ ๋ค์ ๋๊ฐ์ง์ ํ์ ๊ฒฝ์ฐ๋ก ๋๋๋๋ฐ ํ๋๋ ๋ชจ๋ ํ๋ผ๋ฏธํฐ๋ค์ด ๋จ ํ๋์ ํ๋ฅ ๋ถํฌ์ ๋ํ ์คํ๊ฐ์ธ ๊ฒฝ์ฐ์ด๊ณ ,
๋๋ค๋ฅธ ํ๊ฐ์ง๋ ๊ฐ ํ๋ผ๋ฏธํฐ๋ค์ด ๊ฐ๊ฐ์ ์๋ก ๋ค๋ฅธ ํ๋ฅ ๋ถํฌ์ ์คํ๊ฐ์ธ ๊ฒฝ์ฐ์ด๋ค.
ํด๋ผ ๋ถํธ๋ฅผ ์ด์ฉํ์ฌ ๊ฒฐ์ ์ ์ธ ๊ฒฝ์ฐ์ ๋๋คํ ์คํ๊ฐ์ผ๋ก ์ฃผ์ด์ง๋ ๋ชจ๋ ๊ฒฝ์ฐ์ ๋ํ์ฌ ํ๊ท ์ฑ๋ ์ฉ๋์ ๋ฌ์ฑ ํ ์์์์ ์ฆ๋ช
ํ๋ค.
์ด์ ๋ํด ๊ฒฐ์ ์ ์ฑ๋ ํ๋ผ๋ฏธํฐ๊ฐ ๊ฐ์ ๋ ์์คํ
์์ ์ฑ๋ ์
๋ ฅ์ผ๋ก ์ฌ์ฉ๋๋ ์ ๋ณด ๋ฒกํฐ์ ์นํ ์ฐ์ฐ์ ์ค์์ฑ์ ๋ํ์ฌ ๋
ผํ๋ค.
์ ์ ํ ์นํ ์ฐ์ฐ์ ์ด๋ก ์ ์ํ๊ฐ์ธ ์ฑ๋์ฉ๋์ ๋ํ ์๋ ด์๋๋ฅผ ํฅ์ ์ํฌ์ ์์์ ์์๋ฅผ ํตํด ๋ณด์ด๊ณ ํด๋ฆฌ์คํฑ ์นํ ์๊ณ ๋ฆฌ์ฆ์ ๊ฐ๋ฐํ์ฌ
๋ฌ์ฑ ์ ์ก๋ฅ ๋๋ ์์คํ
์ ๋ขฐ๋๋ฅผ ํฅ์ ์ํฌ์ ์์์ ๋ณด์ธ๋ค.
Part II์์๋ ํด๋ผ ๋ถํธ์ ์ธ๋ฑ์ค ๋ถํธ๋ฅผ ์ ํฉ์์ผ ์ผ์ข
์ ์ฐ๊ณ๋ ์์ค-์ฑ๋ ๋ถํธ ์ค๊ณ ๊ธฐ๋ฒ์ ๊ฐ๋ฐํ๊ณ ์ ์๋ ๊ธฐ๋ฒ์ด ์ต์ ์ ์ ์ก๋ฅ ์ ๋ฌ์ฑํจ์ ๋ณด์ธ๋ค.
๋จผ์ ์ธ๋ฑ์ค ๋ถํธ์์ ์์ ๋
ธ๋์์ ์ก์ ๋
ธ๋๋ก ์ ๋ฌ๋๋ ๋ถ๊ฐ์ ๋ณด๋ฅผ ํตํด ๊ทธ๋ ค์ง๋ ๊ทธ๋ํ๊ฐ ์์ ๊ทธ๋ํ์ผ๋ ํญ์ ์ต์ ์ ๋ฌ์ฑ ๊ธฐ๋ฒ์ด ์กด์ฌํจ์ ๋ณด์ด๊ณ ,
์ด๋ฅผ ์์์ ๋ถ๊ฐ์ ๋ณด ํจํด์ด ์ฃผ์ด์ง๋ ๊ฒฝ์ฐ๋ก ํ์ฅํ๋ค.
์์ ๊ทธ๋ํ๊ฐ ๊ทธ๋ ค์ง๋ ๊ฒฝ์ฐ์ ๋ฌ๋ฆฌ ์์์ ํจํด์ผ๋ก ์ฃผ์ด์ง๋ ๊ฒฝ์ฐ๋ ๋ถ๊ฐ์ ๋ณด๋ค์ด ํน์ ์กฐ๊ฑด์ ๋ง์กฑํ๋ ๊ฒฝ์ฐ์ ํํ์ฌ ์ต์ ์ ์ก๋ฅ ์ ๋ฌ์ฑํ๊ฒ๋จ์ ๋ณด์ด๊ณ ์ด๋ฅผ ๋ง์กฑํ๋ ์ธ๋ฑ์ค-ํด๋ผ ๋ถํธ ์ค๊ณ ๊ธฐ๋ฒ์ ์ ์ํ๋ค.
๋ง์ง๋ง์ผ๋ก ๋ถ๊ฐ์ ๋ณด๊ฐ ๊ฒฐ์ ์ ์ผ๋ก ์ฃผ์ด์ง์ง ์๊ณ ์กด์ฌ์ฑ์ ํํํ๋ ํ๋ฅ ๋ก์จ ์ฃผ์ด์ง๋ ๊ฒฝ์ฐ ์ ์๋ ์ฐ๊ณ๊ธฐ๋ฒ์ ์ด์ฉํ ํ๊ท ์ ์ก๋ฅ ์ ๋ํ์ฌ ๋
ผํ๋ค.Abstract i
Contents iv
List of Figures viii
List of Tables xii
I Polar codes for Non i.i.d. Parallel channels 1
Chapter 1 Introduction
1.1 Backgrounds
1.2 Scope and Organization
Chapter 2 Polar codes with deterministic non-identically distributed channels
2.1 Non-identical channels with deterministic CP
2.1.1 The evolution of Symmetric Capacities
2.1.2 Achievable Scheme based on the symmetric capacity
2.1.3 The evolution of Bhattacharayya Parameters
2.1.4 Supermartingale Zn
2.1.5 Convergence of Zn
2.2 Channel mapping via the Interleaver Q
2.2.1 Exhaustive Search Method with Grouping
2.2.2 Heuristic method
2.3 Link failures: Puncturing operation
2.4 Polarizations on non-independent channels
2.5 Summary
Chapter 3 Non-identical Binary Erasure Channels with random Erasure
probabilities with Single distribution
3.1 Non-identical Binary Erasure Channels with random Erasure probabilities
with Single distribution
3.1.1 Proof of Theorem 2
3.1.2 The Achievable Polar coding scheme
3.2 Random Erasure probabilities with non-identical distributions
3.2.1 Case1: Variable coding structure
3.2.2 Case2: Fixed coding structure
3.3 Summary
II Polar codes schemes for Index Coded Systems
Chapter 4 Nested Polar codes structures for Index codes
4.1 Introduction to Index codes
4.2 Nested structures for NC and Polar codes
4.3 ICPC for fully connected SI
4.3.1 General channel setting
4.3.2 Degraded channel setting
4.3.3 IC gain analysis
4.4 ICPC for Arbitrary SI
4.4.1 Proof of the Lemma 6
4.4.2 Proof of the Theorem 5
4.4.3 Achievable ICPC scheme for degraded structures
4.4.4 Proof of the Corollary 2
4.4.5 The ICPC scheme
4.4.6 Example: Partially Perfect Graph
4.5 ICPC for Probabilistic Side Information
4.5.1 Random ICPC for non-identical B-DMCs
4.5.2 Expected rate maximization
4.5.3 Expected achievable rate via Random graph
4.6 Summary
Chapter 5 Conclusions 121
Appendix A
A.1 Proof of (2.25)
A.2 Proof of (2.36)
A.3 Proof of (2.37)
A.4 Proof of the number of equivalent channel combinations
Bibliography
Abstract in Korean 138Docto
Channel Polarization on q-ary Discrete Memoryless Channels by Arbitrary Kernels
A method of channel polarization, proposed by Arikan, allows us to construct
efficient capacity-achieving channel codes. In the original work, binary input
discrete memoryless channels are considered. A special case of -ary channel
polarization is considered by Sasoglu, Telatar, and Arikan. In this paper, we
consider more general channel polarization on -ary channels. We further show
explicit constructions using Reed-Solomon codes, on which asymptotically fast
channel polarization is induced.Comment: 5 pages, a final version of a manuscript for ISIT201
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