9 research outputs found
Soft-Feedback OMP for the Recovery of Discrete-Valued Sparse Signals
Publication in the conference proceedings of EUSIPCO, Nice, France, 201
Advances in the recovery of binary sparse signals
Recently, the recovery of binary sparse signals from compressed linear systems has received attention due to its several applications. In this contribution, we review the latest results in this framework, that are based on a suitable non-convex polynomial formulation of the
problem. Moreover, we propose novel theoretical results. Then, we show numerical results that highlight the enhancement obtained through the non-convex approach with respect to the state-of-the-art methods
Efficient recovery algorithm for discrete valued sparse signals using an ADMM approach
Motivated by applications in wireless communications, in this paper we propose a reconstruction algorithm for sparse signals whose values are taken from a discrete set, using a limited number of noisy observations. Unlike conventional compressed sensing algorithms, the proposed approach incorporates knowledge of the discrete valued nature of the signal in the detection process. This is accomplished through the alternating direction method of the multipliers which is applied as a heuristic to decompose the associated maximum likelihood detection problem in order to find candidate solutions with a low computational complexity order. Numerical results in different scenarios show that the proposed algorithm is capable of achieving very competitive recovery error rates when compared with other existing suboptimal approaches.info:eu-repo/semantics/publishedVersio
μ¬λ¬Ό ν΅μ μμ μμΆ μΌμ±μ μ΄μ©ν λκ·λͺ¨ μ°κ²°λ°©λ²μ λν μ°κ΅¬
νμλ
Όλ¬Έ (λ°μ¬)-- μμΈλνκ΅ λνμ : 곡과λν μ κΈ°Β·μ 보곡νλΆ, 2019. 2. μ΄κ΄λ³΅.Massive machine-type communication (mMTC) has become one of the most important requirements for next generation (5G) communication systems with the advent of the Internet-of-Things (IoT). In the mMTC scenarios, grant-free non-orthogonal multiple access (NOMA) on the transmission side and compressive sensing-based multi-user detection (CS-MUD) on the reception side are promising because many users sporadically transmit small data packets at low rates. In this dissertation, we propose a novel CS-MUD algorithm for active user and data detection for the mMTC systems. The proposed scheme consists of a MAP-based active user detector (MAP-AUD) and a MAP-based data detector (MAP-DD). By exchanging extrinsic information between MAP-AUD and MAP-DD, the proposed algorithm improves the performance of the active user detection and the reliability of the data detection. In addition, we extend the proposed algorithm to exploit group sparsity. By jointly processing the multiple received data with common activity, the proposed algorithm demonstrates dramatically improved performance. We show by numerical experiments that the proposed algorithm achieves a substantial performance gain over existing algorithms.μ¬λ¬Ό μΈν°λ· (Internet of Things, IoT) μλμ λλμ ν¨κ», λκ·λͺ¨ μ¬λ¬Ό ν΅μ (massive machine-type communications, mMTC)μ μ°¨μΈλ 무μ ν΅μ νμ€μ μ£Όμ μꡬ μ¬νλ€ μ€μ νλκ° λμλ€. λκ·λͺ¨ μ¬λ¬Ό ν΅μ νκ²½μμλ λ§μ μμ μ¬λ¬Ό κΈ°κΈ°(machine-type device)λ€μ΄ λλΆλΆ λΉνμ± μνλ‘ λ°μ΄ν°λ₯Ό μ μ‘νμ§ μλ€κ° κ°λμ© νμ± μνλ‘ μ νλμ΄ μμ ν¬κΈ°μ λ°μ΄ν°λ₯Ό μ μ‘νλ€. κ·Έλ¬λ―λ‘, κΈ°μ§κ΅(base station, BS)μΌλ‘λΆν°μ μ€μΌμ₯΄λ§μ κΈ°λ°μΌλ‘ μ§κ΅(orthogonal) μκ°/μ£Όνμ μμμ ν λΉλ°μ ν λ°μ΄ν° μ‘μμ μ΄ μ΄λ£¨μ΄μ§λ κΈ°μ‘΄μ ν΅μ λ°©μμ, μ€μ μ μ‘νλ €λ λ°μ΄ν° λλΉ λ§μ λΆκ°μ μΈ μ μ΄ μ 보λ₯Ό νμλ‘ νκ³ λν λ°μ΄ν°μ μ§μ°μ μ λ°μν€λ―λ‘ λκ·λͺ¨ μ¬λ¬Ό ν΅μ μ μ ν©νμ§ μλ€. λμ , μ μ‘λ¨μμλ μ€μΌμ₯΄λ§ μμ΄, μ¦ κΈ°μ§κ΅μΌλ‘ λΆν°μ μΉμΈ μμ΄(grant-free), λΉμ§κ΅ μμμ λ€μ€ μ μνκ³ (non-orthogonal multiple access, NOMA), μμ λ¨μμλ λ€μ€ μ¬μ©μ κ²μΆ(multi-user detection, MUD)μ μ΄μ©νμ¬ λ°μ΄ν°μ μΆ©λμ λ³΅μ‘°ν΄ λ΄λ λ°©μμ΄ λκ·λͺ¨ μ¬λ¬Ό ν΅μ μ μ ν©νλ€. μ΄ λ, μ¬λ¬Ό κΈ°κΈ°λ€μ΄ μ μ‘νλ λ°μ΄ν°μ ν¬μ νΉμ±μ κ°μνλ©΄, μμΆ μΌμ± κΈ°λ°μ λ€μ€ μ¬μ©μ κ²μΆ λ°©λ²(compressive sensing-based multi-user detection, CS-MUD)μ΄ μΌλ°μ μΈ λ€μ€ μ¬μ©μ κ²μΆ λ°©λ²λ³΄λ€ λ μ’μ μ±λ₯μ λ°νν μ μλ€.
λ³Έ λ
Όλ¬Έμμλ, κΈ°μ‘΄ λ°©μλ³΄λ€ λ μ’μ μ±λ₯μ κ°μ§ μλ‘μ΄ μμΆ μΌμ± κΈ°λ°μ λ€μ€ μ¬μ©μ κ²μΆ λ°©λ²μ μ μνλ€. λΆμ° μ€λͺ
νλ©΄, κ°μ₯ ν° μ¬ν νμ± νλ₯ μ κ°μ§ μ¬μ©μλ₯Ό μ°Ύκ³ (maximum a posteriori probability-based active user detection, MAP-AUD), μμ μ¬ν νλ₯ κ΄μ μμ κ°μ₯ νλ₯ μ΄ λμ λ°μ΄ν°λ₯Ό μΆμ νλ€(maximum a posteriori probability-based data detection, MAP-DD). μ΄ λ, MAP-AUDμ MAP-DD λΈλ‘μ μλ‘ μΈμ¬μ μ 보(extrinsic information)λ§μ μ£Όκ³ λ°λλ°, μ΄ μΈμ¬μ μ 보λ μλλ°©μ μ¬μ μ λ³΄κ° λκ³ , μ΄ μ¬μ μ 보λ₯Ό μ΄μ©νμ¬ λ€μ μ¬ν νλ₯ κ΄μ μμ μ΅μ μ ν΄λ₯Ό ꡬνλ€. μ΄λ¬ν λ°λ³΅ μνμ ν΅ν΄ κ° λΈλ‘μ κ²μΆμ μ νλμ μ±λ₯μ λμ¬ λκ°λ€.
μ΄ λ°©λ²μ ν¨ν· λ¨μλ‘ νμ₯λ μ μλ€. κ°κ°μ μ¬λ¬Ό κΈ°κΈ°λ€μ΄ μ μ‘νλ €λ λ°μ΄ν°λ μ¬λ¬κ°μ μ¬λ³Όλ‘ ꡬμ±λ ν¨ν·μ΄λ©°, ν ν¨ν· λ΄μ κ°κ°μ μ¬λ³Όμ 곡ν΅λ νμ±λλ₯Ό κ°μ§κ² λλ€. μ¬κΈ°μ, μ΄ κ³΅ν΅λ νμ±λλ₯Ό μ΄μ©νλ©΄, νμ± μ¬λ¬Ό κΈ°κΈ°μ μ΄λ€μ μ μ‘ λ°μ΄ν° μΆμ μ μ νλλ₯Ό λμΌ μ μλ€. νμ§λ§, μ΄λ 곡λ μ΅μ ν(joint optimization) λ¬Έμ λ‘ λ§€μ° λ³΅μ‘ν μ°μ°μ νμλ‘ νλ€. λ³Έ λ
Όλ¬Έμμλ, ν¨ν· λ΄μ μμμ νλμ μ¬λ³Όμμ μΆμ λ μ¬λ¬Ό κΈ°κΈ°μ νμ±λλ λ€λ₯Έ μ¬λ³Όμ νμ±λλ₯Ό μΆμ νλλ° μ¬μ μ 보(a priori information)λ‘ μ΄μ©λ μ μλ€λ μ μ μ°©μνμ¬, 볡μ‘ν 곡λ μ΅μ ν λ¬Έμ λ₯Ό λΉκ΅μ μ°μ°λμ΄ μ μ λΆλΆ μ΅μ ν(subproblem optimization) λ¬Έμ λ‘ λ¨μν μν€κ³ , μ΄λ€ κ°μ λ©μμ§ μ λ¬ (massage-passing) κΈ°λ²μ ν΅ν΄ 곡λ μ΅μ νμ ν΄μ κ·Όμ ν ν΄λ₯Ό ꡬνλ λ°©λ²μ μ μνλ€. μ΄ λ, λΆλΆ μ΅μ ν λ¬Έμ μ ν΄λ²μ΄ λ°λ‘ μμ μ€λͺ
ν MAP-AUD/MAP-DD λ°©λ²μ΄λ€.
λ§μ§λ§μΌλ‘, λͺ¨μ μ€νμ ν΅ν΄ μ μνλ λ°©λ²μ΄ κΈ°μ‘΄ λ°©λ²κ³Ό λΉκ΅νμ λ λ§€μ° ν¬κ² μ±λ₯μ΄ ν₯μλ¨μ 보μλ€. νΉν, μ μνλ λ°©λ²μ μ 체 μ¬μ©μ μ λλΉ μ΄μ© κ°λ₯ν μμμ΄ μ μ λμΌμλ‘ λ ν° μ±λ₯ ν₯μμ΄ μλλ°, μ΄λ μ°¨μΈλ 무μ ν΅μ μμ μ¬λ¬Ό ν΅μ μ΄ κ³ λ €νλ λ¨μ λ©΄μ λΉ μ¬λ¬Ό κΈ°κΈ°μ μ(10^6κ°/km^2)λ₯Ό κ³ λ €νμ λ, μ μνλ λ°©λ²μ΄ λκ·λͺ¨ μ¬λ¬Ό ν΅μ μ μμ£Ό ν¨μ©μ±μ΄ νΌμ 보μ¬μ€λ€.Contents
Abstract i
Contents ii
List of Tables iv
List of Figures v
1 Introduction 1
2 MAP-based Active User and Data Detection 7
2.1 System Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 MAP-based Active User and Data Detection . . . . . . . . . . . . . . 9
2.2.1 Activity Log-Likelihood Ratios . . . . . . . . . . . . . . . . 11
2.2.2 MAP-based Active User Detection . . . . . . . . . . . . . . . 12
2.2.3 MAP-based Data Detection . . . . . . . . . . . . . . . . . . 16
2.2.4 Inversion of Covariance Matrices . . . . . . . . . . . . . . . 20
2.2.5 Comments on Complexity . . . . . . . . . . . . . . . . . . . 23
3 Group Sparsity-Aware Active User and Data Detection 28
3.1 Extraction of Extrinsic User Activity Information . . . . . . . . . . . 28
3.2 Modified Active User and Data Detection . . . . . . . . . . . . . . . 32
4 Numerical Results 35
4.1 Simulation Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.2 Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
5 Conclusion 55
Abstract (In Korean) 61
Acknowlegement 63Docto