Analyzing Uplink Grant-Free Sparse Code Multiple Access System in Massive IoT Networks

Lai, Ke; Lei, Jing; Deng, Yansha; Wen, Lei; Chen, Gaojie; Liu, Wei

doi:10.1109/jiot.2021.3109912

Cited by 10 publications

(4 citation statements)

References 46 publications

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“…At large SNRs, as the ABER is mainly dominated by the largest value of PEP in (14), we assert that improving the minimum distance of d 2 w→ ŵ among all pairs will lead to lower ABER. Hence, we formulate our codebook design of the SCMA system with structure S(V, G; J, M, N, K), V := [V j ] J j=1 and G := [g j ] J j=1 in downlink Rician fading channels as…”

Section: B Design Criteria Of Multi-dimensional Codebookmentioning

confidence: 77%

“…Specifically, [13] introduced a novel uplink grant-free asynchronous flipped SCMA scheme for future S-IoT communication networks. The error performance of grant-free SCMA under codebook collision was analyzed in [14]. Moreover, [15] proposed an SCMA based secure communication scheme for satellite communication from codebook design point of view.…”

Section: Introductionmentioning

confidence: 99%

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A Design of Low-Projection SCMA Codebooks for Downlink Satellite Internet of Things

Luo¹,

Liu²,

Chen³

et al. 2022

Preprint

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This paper presents a systematic investigation on codebook design of sparse code multiple access (SCMA) communication in downlink satellite Internet-of-Things (S-IoT) systems that are generally characterized by Rician fading channels. To serve a huge number of low-end IoT sensors, we aim to develop enhanced SCMA codebooks which enable ultra-low decoding complexity, while achieving good error performance. By analysing the pair-wise probability in Rician fading channels, we deduce the design metrics for multi-dimensional constellation construction and sparse codebook optimization. To reduce the decoding complexity, we advocate the key idea of projecting the multi-dimensional constellation elements to a few overlapped complex numbers in each dimension, called low projection (LP). We consider golden angle modulation (GAM), thus the resultant multi-dimensional constellation is called LPGAM. With the proposed design metrics and based on LPGAM, we propose an efficient approach of multi-stage optimization of sparse codebooks. Numerical and simulation results show the superiority of the proposed LP codebooks (LPCBs) in terms of decoding complexity and error rate performance. In particular, some of the proposed LPCBs can reduce the decoding complexity by 97% compared to the conventional codebooks, and own the largest minimum Euclidean distance among existing codebooks. The proposed LPCBs are available at https://github.com/ethanlq/SCMA-codebook.

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Section: B Design Criteria Of Multi-dimensional Codebookmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

A Design of Low-Projection SCMA Codebooks for Downlink Satellite Internet of Things

Luo¹,

Liu²,

Chen³

et al. 2022

Preprint

Self Cite

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show abstract

“…When two or more UEs transmit their data sharing the same MA physical resource using different pilot sequences but the same codebook, the codebook collision occurs. In this condition, the detector can still decoded these UEs' data carried over the same codebook, as long as different pilot sequences are used [18]. Although a one-to-one mapping or a many-to-one mapping between the pilot sequences and codebooks can be predefined, since it has been verified in [17] that the performance loss due to codebook collision is negligible for a real system, we focus on the pilot sequence collision and consider the one-to-one mapping as [16].…”

Section: Krepmentioning

confidence: 99%

Deep Reinforcement Learning-Based Grant-Free NOMA Optimization for mURLLC

Yan

Deng

Zhou

et al. 2023

IEEE Trans. Commun.

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Grant-free non-orthogonal multiple access (GF-NOMA) is a potential technique to support massive Ultra-Reliable and Low-Latency Communication (mURLLC) service. However, the dynamic resource configuration in GF-NOMA systems is challenging due to random traffics and collisions, that are unknown at the base station (BS). Meanwhile, joint consideration of the latency and reliability requirements makes the resource configuration of GF-NOMA for mURLLC more complex. To address this problem, we develop a novel learning framework for signature-based GF-NOMA in mURLLC service taking into account the multiple access signature collision, the UE detection, as well as the data decoding procedures for the K-repetition GF and the Proactive GF schemes. The goal of our learning framework is to maximize the long-term average number of successfully served users (UEs) under the latency constraint. We first perform a real-time repetition value configuration based on a double deep Q-Network (DDQN) and then propose a Cooperative Multi-Agent learning technique based DQN (CMA-DQN) to optimize the configuration of both the repetition values and the contention-transmission unit (CTU) numbers. Our results show the superior performance of CMA-DQN over the conventional load estimation-based approach (LE-URC) in heavy traffic and demonstrate its capability in dynamically configuring in long term for mURLLC service. In addition, with our learning optimization, the Proactive scheme always outperforms the Krepetition scheme in terms of the number of successfully served UEs, especially under the high backlog traffic scenario.

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“…But GF random access causes collision will results in non‐orthogonal resource sharing between the user equipments (UEs) 19 . PDMA can naturally be incorporated with GF transmission to reduce the collision probability, intelligently overlapping of the UEs at the transmitter allows to separate them at the receiver 20,21 . Therefore, in this article, we analyze the uplink GF PDMA transmission in the uRLLC scenario.…”

Section: Introductionmentioning

confidence: 99%

Uplink grant‐free pattern division multiple access transmission scheme by exploiting poly complementary sequence

Sun

et al. 2021

Trans Emerging Tel Tech

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Non‐orthogonal multiple access (NOMA) technology is a key technology of the future cellular mobile communication system. It provides services for users under different channel conditions through signal superposition transmission and spectrum multiplexing. Pattern division multiple access (PDMA) is a new NOMA technology based on the overall optimization of multi‐user communication system. Since the performance of PDMA mainly depends on the gain of the pattern matrix, we propose a design scheme of uplink PDMA pattern matrix for ultra‐reliable low latency communication (uRLLC). For the interference between users is a common problem in NOMA system, first, we use poly complementary sequence (PCS) as the spread codebook to spread the PDMA transmission signal and reduce interference. Meanwhile, an uplink power control scheme is proposed. It allocates wireless resources reasonably by jointly considering the interference between users and resource blocks within users (JUR), the corresponding outage probability formula is also derived. Simulation results show that compared with the previous researches, the pattern matrix design scheme and JUR power control scheme proposed in this article have greatly improved the transmission performance. The addition of PCS spread spectrum technology can significantly reduce the block error rate and outage probability.

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Analyzing Uplink Grant-Free Sparse Code Multiple Access System in Massive IoT Networks

Cited by 10 publications

References 46 publications

A Design of Low-Projection SCMA Codebooks for Downlink Satellite Internet of Things

A Design of Low-Projection SCMA Codebooks for Downlink Satellite Internet of Things

Deep Reinforcement Learning-Based Grant-Free NOMA Optimization for mURLLC

Uplink grant‐free pattern division multiple access transmission scheme by exploiting poly complementary sequence

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