This paper presents a multi-overloading-factor sparse code multiple access (SCMA) decoder IC for 5G massive machine-type communications. This design supports three different overloading factors. We applied the delayed...
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ISBN:
(纸本)9798350304206
This paper presents a multi-overloading-factor sparse code multiple access (SCMA) decoder IC for 5G massive machine-type communications. This design supports three different overloading factors. We applied the delayed update technique and an early-stop method to the message-passingalgorithm (MPA) for better pipeline and decoding efficiency. Moreover, novel techniques, such as common term reuse, approximate distance, and sum/max circuit sharing, significantly reduce the circuit complexity and critical path delays. At 560MHz, the 40nm decoder IC achieves 2.777 Gbps/mm(2) area efficiency and 46.8pJ/b energy with 152.7Mbps throughput. The decoder can achieve maximum energy efficiency of 28pJ/b when working at 0.66V Vdd and 360MHz clock rate.
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 th...
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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-passingalgorithm (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.
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 th...
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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 multip...
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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 messagepassing (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).
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 b...
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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.
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 perform...
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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.
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 asynchro...
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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 messagepassing 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.
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 Do...
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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-passingalgorithm (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
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&...
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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 messagepassing 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.
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)...
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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.
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