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IEEE Wireless Communications and Networking Conference (WCNC)

作者： Denno, Satoshi Yamagami, Taichi Hou, Yafei Okayama Univ Grad Sch Nat Sci & Technol 3-1-1 Tsushima NakaKita Okayama 7008530 Japan

ISBN: (纸本)9781665491228

This paper proposes low complexity resource allocation in frequency domain non-orthogonal multiple access where many devices access with a base station. The number of the devices is assumed to be more than that of the resource for network capacity enhancement, which is demanded in massive machine type communications (mMTC). This paper proposes two types of resource allocation techniques, which are named as "CGVS" and "LLRVS", all of which are based on the MIN-MAX approach. CGVS seeks for nicer resource allocation with only channel gains, while LLRVS applies the message passing algorithm (MPA) for better resource allocation. The proposed resource allocation techniques are evaluated by computer simulation in frequency domain non-orthogonal multiple access. Whereas LLRVS achieves only 0.1dB better performance than CGVS in the multiple access with the overloading ratio of 1.5 at the BER of 10(-4), CGVS can be implemented with 10(-5) smaller computational complexity than LLRVS. CGVS attains a gain of about 10dB at the BER of 10(-4) in the multiple access with the overloading ration of 2.0. The complexity of CGVS is 10(-16) as small as the conventional technique.

关键词： Non-orthogonal access low complexity message passing algorithm subcarrier allocation

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DMPACT: A Data Detection Solution for NOMA-Based Uplink Cell-Free MIMO Networks

DMPACT: A Data Detection Solution for NOMA-Based Uplink Cell...

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2023 IEEE Globecom Workshops, GC Wkshps 2023

作者： Chen, Ti-Yu Yu, Chia-Hao Chiueh, Tzi-Dar Graduate Institute of Electronics Engineering National Taiwan University Taipei Taiwan Mediatek Inc. Hsin-Chu Taiwan

ISBN: (纸本)9798350370218

Cell-free (CF) multiple-input multiple-output (MIMO) technology is garnering significant attention as a promising solution to meet the rising demand for a large number of users with high quality of service (QoS) in the upcoming 5G and 6G wireless communication systems. In CF MIMO networks, all user equipments (UEs) share a single subcarrier, resulting in a non-orthogonal multiple access (NOMA) scheme. Effective detection of the uplink (UL) signals received at multiple sites can significantly improve the system transmission efficiency. In this paper, we proposed a dynamic message-passing algorithm (DMPA) for cell-free MIMO detection. DMPA dynamically allocates detection resources on UEs that are difficult to detect by adjusting the factor graph (FG) of the message-passing algorithm in a timely fashion. Simulation results show that the bit error rate (BER) by DMPA outperforms the existing detectors, indicating that DMPA is very competitive. We further designed three low-complexity techniques and proposed DMPA with constellation truncation (DMPACT) that has 95% lower computational complexity than DMPA with literally no BER loss. The low-complexity techniques include initial constellation truncation according to minimum mean-squared error (MMSE) combining outcomes, truncation of less-likely constellation points based on the Log-Likelihood Ratios (LLR) during DMPA, and refined FG adjustment. Simulation results show that DMPACT can decrease the SNR required for 10-3 BER by 2dB with only doubled computation complexity compared to the widely-used MMSE-SIC detector. © 2023 IEEE.

关键词： cell-free detection low complexity message passing algorithm MIMO NOMA

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Iterative Symbol Decision Schemes for CP-OTFS on Static Multipath Channels

Iterative Symbol Decision Schemes for CP-OTFS on Static Mult...

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International Conference on Computing, Networking and Communications (ICNC)

作者： Tsai, Shuen-Yu Chen, Wei-Chang Chung, Char-Dir Realtek Inc Hsinchu Taiwan Natl Taipei Univ Technol Dept Elect Engn Taipei Taiwan Natl Taiwan Univ Grad Inst Commun Engn Taipei Taiwan

ISBN: (纸本)9781665457194

Orthogonal time frequency space (OTFS) systems have gained great attention in wireless communications due to achievable prominent error performance characteristics on high-mobility and static multipath channels. In this paper, two symbol decision schemes are proposed for the cyclic-prefixed OTFS system on static multipath channels by virtue of iterative decision-feedback hybrid equalization (IDFHE) using linear minimum mean-square-error (LMMSE) equalization rule and message-passing algorithm (MPA) as the respective first-iteration decision rule. The proposed LM-IDFHE and MPA-IDFHE schemes can exploit the advantages that inter-symbol interference is suppressed progressively over iterations and noise power enhancement is avoided at the final iteration. From simulation results, LM-IDFHE and MPA-IDFHE schemes are shown to outperform non-iterative LMMSE, iterative LMMSE, and iterative MPA schemes remarkably in average error performance on Rician multipath channels.

关键词： Orthogonal time frequency space modulation iterative decision-feedback hybrid equalization message passing algorithm static multipath channels

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PySigma: Towards Enhanced Grand Unification for the Sigma Cognitive Architecture 14th

PySigma: Towards Enhanced Grand Unification for the Sigma Co...

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14th International Conference on Artificial General Intelligence (AGI)

作者： Zhou, Jincheng Ustun, Volkan Univ Southern Calif Dept Comp Sci Los Angeles CA 90007 USA Univ Southern Calif Inst Creat Technol Los Angeles CA 90007 USA

ISBN: (纸本)9783030937577;9783030937584

The Sigma cognitive architecture is the beginning of an integrated computational model of intelligent behavior aimed at the grand goal of artificial general intelligence (AGI). However, whereas it has been proven to be capable of modeling a wide range of intelligent behaviors, the existing implementation of Sigma has suffered from several significant limitations. The most prominent one is the inadequate support for inference and learning on continuous variables. In this article, we propose solutions for this limitation that should together enhance Sigma's level of grand unification;that is, its ability to span both traditional cognitive capabilities and key non-cognitive capabilities central to general intelligence, bridging the gap between symbolic, probabilistic, and neural processing. The resulting design changes converge on a more capable version of the architecture called PySigma. We demonstrate such capabilities of PySigma in neural probabilistic processing via deep generative models, specifically variational autoencoders, as a concrete example.

关键词： Sigma Cognitive architecture Probabilistic graphical model message passing algorithm Approximate inference Deep generative model

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Low Complexity MPA Based on Dynamic Threshold and Stability Judgment for SCMA

Low Complexity MPA Based on Dynamic Threshold and Stability ...

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IEEE Global Communications Conference (GLOBECOM)

作者： Zhao, Xiaoyan Wang, Cheng Cai, Songsong Wang, Weidong Beijing Univ Posts & Telecommun Sch Elect Engn Beijing Peoples R China

ISBN: (纸本)9781665435406

Sparse code multiple access (SCMA) is an up-and-coming non-orthogonal multiple access technology. The message passing algorithm (MPA) is utilized for multi-user signal detection in the SCMA system to achieve a performance close to the maximum a posterior algorithm. However, higher iterations will lead to the higher computational complexity of the MPA. In this paper, a dynamic threshold and stability judgment based MPA scheme (DTS-MPA) is proposed to reduce the computational complexity by simplifying the factor graph and reducing the number of iterations. Firstly, an adaptive dynamic threshold is set to minimize the number of iterations in the different channel state information. Secondly, an additional iteration is proposed to determine whether the variable nodes that meet the dynamic threshold reach stable convergence to improve the decoding reliability. Variable nodes that meet the above conditions will be decoded in advance. Numerical results show that the DTS-MPA can significantly reduce the computational complexity of the MPA and achieve a significant trade-off between bit error rate performance and computational complexity.

关键词： Sparse code multiple access message passing algorithm dynamic threshold stability judgment

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A Novel Block-Wise Index Modulation Scheme for High-Mobility OTFS Communications

A Novel Block-Wise Index Modulation Scheme for High-Mobility...

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IEEE/CIC International Conference on Communications in China (ICCC)

作者： Qian, Mi Ge, Yao Wen, Miaowen Ji, Fei South China Univ Technol Sch Elect & Informat Engn Guangzhou 510641 Peoples R China Nanyang Technol Univ Continental NTU Corp Lab Singapore 639798 Singapore

ISBN: (数字)9781665459778

ISBN: (纸本)9781665459778

As a promising technique for high-mobility wireless communications, orthogonal time frequency space (OTFS) has been proved to enjoy excellent advantages with respect to traditional orthogonal frequency division multiplexing (OFDM). However, a challenging problem is to design efficient systems to further improve the performance. In this paper, we propose a novel block-wise index modulation (IM) scheme for OTFS systems, named Doppler-IM with OTFS (DoIM-OTFS), where a block of Doppler resource bins are activated simultaneously. For practical implementation, we develop a low complexity customized message passing (CMP) algorithm for our proposed DoIM-OTFS scheme. Simulation results demonstrate our proposed IINAIVI-OTFS system outperforms traditional OTFS system without IM. The proposed CMP algorithm can achieve desired performance and robustness to the imperfect channel state information (CSI).

关键词： OTFS modulation index modulation message passing algorithm diversity order

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Remote State Estimation With Asynchronous Mission-Critical IoT Sensors

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2021年第3期39卷 835-850页

作者： Tang, Minjie Cai, Songfu Lau, Vincent K. N. Hong Kong Univ Sci & Technol Dept ECE Hong Kong Peoples R China Hong Kong Univ Sci & Technol Shenzhen Res Inst Shenzhen 518000 Peoples R China

In this paper, we consider a mission-critical remote state estimation system with asynchronous massive access of the IoT sensors. We focus on remote state estimation stability of the system in the presence of asynchronous access of the sensors. Exploiting the sparsity in the observation matrix induced by the asynchronous access, we propose a low complexity 2-D message passing state estimation algorithm, where the cyclic loops in the 2-D factor graphs are removed based on the Gaussian-elimination-based quasi-diagonalization of the oversampled aggregated channel matrix of the IoT sensors. As a result, the proposed state estimation scheme is of low complexity and can achieve exact MAP estimation. Using Lyapunov drift analysis, we derive closed-form necessary and sufficient conditions for stability of the mission-critical remote state estimation system. We show that our proposed scheme can achieve significant performance gain over various state-of-the-art baselines for the large-scale system under asynchronous massive access.

关键词： State estimation Sensor systems Wireless sensor networks Wireless communication Timing Mission-critical remote state estimation systems asynchronous massive access Lyapunov analysis large scale system analysis message passing algorithm

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OTFS-SCMA: A Code-Domain NOMA Approach for Orthogonal Time Frequency Space Modulation

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IEEE TRANSACTIONS ON COMMUNICATIONS 2021年第8期69卷 5043-5058页

作者： Deka, Kuntal Thomas, Anna Sharma, Sanjeev Indian Inst Technol Goa Sch Elect Sci Ponda 403401 India Indian Inst Technol BHU Varanasi Dept Elect Engn Varanasi 221005 Uttar Pradesh India

Orthogonal time frequency space (OTFS) modulation is a two-dimensional (2-D) modulation technique that has the potential to overcome the challenges faced by orthogonal frequency division multiplexing (OFDM) in high Doppler environments. The performance of OTFS in a multi-user scenario with orthogonal multiple access (OMA) techniques has been impressive. Due to the requirement of massive connectivity in 5G and beyond, it is essential to devise and examine the OTFS system with the existing non-orthogonal multiple access (NOMA) techniques. This paper proposes a multi-user OTFS system based on a code-domain NOMA technique called sparse code multiple access (SCMA). This system is referred to as the OTFS-SCMA model. The framework for OTFS-SCMA is designed for both downlink and uplink. First, the sparse SCMA codewords are strategically placed on the delay-Doppler plane. The overall overloading factor of the OTFS-SCMA system is equal to that of the underlying basic SCMA system. The receiver in downlink performs the detection in two sequential phases: first, the conventional OTFS detection using the method of linear minimum mean square error (LMMSE) estimation, and then the SCMA detection. We propose a single-phase detector based on a message-passing algorithm (MPA) to detect multiple users' symbols for the uplink. The expressions for the asymptotic diversity orders of the proposed OTFS-SCMA system are derived for downlink and uplink. OTFS-SCMA provides a significant diversity gain over other multiple access systems for OTFS. Based on the diversity analysis, an algorithm is proposed to devise an optimal codeword allocation scheme. The performance of the proposed OTFS-SCMA system is validated through extensive simulations both in downlink and uplink. We consider delay-Doppler planes of different parameters and various SCMA systems of overloading factor up to 200%. The performance of OTFS-SCMA is compared with those of the existing OTFS-OMA, OFDM-SCMA and OTFS-power-domain (PD

关键词： Doppler effect Delays Time-frequency analysis NOMA Uplink Downlink Modulation OTFS SCMA NOMA message passing algorithm delay-Doppler plane

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Over-the-Air Aggregation With Multiple Shared Channels and Graph-Based State Estimation for Industrial IoT Systems

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IEEE INTERNET OF THINGS JOURNAL 2021年第19期8卷 14638-14657页

作者： Tang, Minjie Cai, Songfu Lau, Vincent K. N. Hong Kong Univ Sci & Technol Dept ECE Hong Kong Peoples R China Hong Kong Univ Sci & Technol Shenzhen Res Inst Shenzhen 518000 Peoples R China

We consider remote state estimation for an industrial Internet-of-Things (IoT) system, where the plant dynamics are monitored by a number of distributed industrial IoT sensors. We propose an "estimation friendly" remote state estimation framework, which not only maintains low computational complexity but also provides better estimation stability performance. Specifically, we propose a novel over-the-air-aggregation-based multiple access, which enhances the observability performance of the state estimation system and hence, provides better estimation stability. Additionally, exploiting the sparsity in the observation matrix induced by the over-the-air-aggregation-based multiple access, we propose a low-complexity 2-D message passing state estimation algorithm, where the cyclic loops in the 2-D factor graphs are removed based on the quasi-diagonal transformation of the aggregated channel matrix of the IoT sensors. As a result, the proposed state estimation scheme is of low complexity and can achieve exact maximum a posterior estimation. Using the Lyapunov drift analysis, we derive the closed-form necessary and sufficient conditions for stability of the mission-critical remote state estimation system. The numerical results demonstrate that the proposed scheme has a low computational complexity. Furthermore, it is scalable with the number of sensors and has a low power consumption.

关键词： Sensors State estimation Sensor systems Wireless sensor networks Channel estimation Wireless networks Stability criteria Industrial Internet-of-Things (IoT) system large-scale system analysis Lyapunov analysis message passing algorithm over-the-air-aggregation-based multiple access remote state estimation

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Intelligent Reflecting Surface-Assisted Uplink SCMA System

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IEEE COMMUNICATIONS LETTERS 2021年第8期25卷 2728-2732页

作者： Sharma, Sanjeev Deka, Kuntal Hong, Yi Dixit, Dharmendra IIT BHU Varanasi Dept Elect Engn Varanasi 221005 Uttar Pradesh India IIT Goa Dept Elect Engn Ponda 403401 India Monash Univ Dept Elect & Comp Syst Engn Melbourne Vic 3800 Australia Rajkiya Engn Coll Sonbhadra Dept Appl Sci Sonbhadra 231206 India

Intelligent reflecting surface (IRS) is a promising technique to enhance performance of wireless systems due to its ability to smartly reconfigure the signal propagation environment. Sparse code multiple access (SCMA) is code-domain non-orthogonal multiple access technique suitable for the next-generation wireless networks. In this letter, we consider IRS-assisted uplink SCMA (I-SCMA) for energy and spectrally-efficient wireless systems. message passing algorithm (MPA)-based signal detection is proposed to detect multiple users' symbols in uplink I-SCMA. The diversity orders of I-SCMA for random and coherent phase shifting are derived. The symbol error rate and the sum-rate performance of the uplink I-SCMA system are analyzed. Further, the impact of overloading factor, the number of reflecting surfaces, the number of phase shifts of reflected signals are studied. Simulation results demonstrate the benefits of I-SCMA in terms of the spectral and energy efficiency over conventional SCMA and other NOMA techniques.

关键词： Uplink NOMA Electronic mail Wireless networks Antennas Wireless sensor networks Simulation IRS-assisted SCMA (I-SCMA) SER sum-rate diversity order message passing algorithm

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