Pub Date : 2024-09-11DOI: 10.1109/LCOMM.2024.3458422
Andreas Tsouchlos;Holger Jäkel;Laurent Schmalen
In this letter, the proximal decoding algorithm is considered within the context of additive white Gaussian noise (AWGN) channels. An analysis of the convergence behavior of the algorithm shows that proximal decoding inherently enters an oscillating behavior of the estimate after a certain number of iterations. Due to this oscillation, frame errors arising during decoding can often be attributed to only a few remaining wrongly decoded bit positions. In this letter, an improvement of the proximal decoding algorithm is proposed by establishing an additional step, in which these erroneous positions are attempted to be corrected. We suggest an empirical rule with which the components most likely needing correction can be determined. Using this insight and performing a subsequent “ML-in-the-list” decoding, a gain of up to 1 dB is achieved compared to conventional proximal decoding, depending on the decoder parameters and the code.
在这封信中，我们在加性白高斯噪声（AWGN）信道的背景下考虑了近似解码算法。对算法收敛行为的分析表明，近端解码在迭代一定次数后，估计值会出现固有的振荡行为。由于这种振荡，解码过程中出现的帧错误往往只能归因于剩余的几个错误解码位位置。在这封信中，我们提出了一种改进近端解码算法的方法，即增加一个步骤，尝试纠正这些错误位置。我们提出了一个经验规则，通过该规则可以确定最有可能需要纠正的部分。利用这一洞察力并执行后续的 "ML-in-the-list "解码，与传统的近端解码相比，可实现高达 1 dB 的增益，具体取决于解码器参数和代码。
{"title":"List-Based Optimization of Proximal Decoding for LDPC Codes","authors":"Andreas Tsouchlos;Holger Jäkel;Laurent Schmalen","doi":"10.1109/LCOMM.2024.3458422","DOIUrl":"10.1109/LCOMM.2024.3458422","url":null,"abstract":"In this letter, the proximal decoding algorithm is considered within the context of additive white Gaussian noise (AWGN) channels. An analysis of the convergence behavior of the algorithm shows that proximal decoding inherently enters an oscillating behavior of the estimate after a certain number of iterations. Due to this oscillation, frame errors arising during decoding can often be attributed to only a few remaining wrongly decoded bit positions. In this letter, an improvement of the proximal decoding algorithm is proposed by establishing an additional step, in which these erroneous positions are attempted to be corrected. We suggest an empirical rule with which the components most likely needing correction can be determined. Using this insight and performing a subsequent “ML-in-the-list” decoding, a gain of up to 1 dB is achieved compared to conventional proximal decoding, depending on the decoder parameters and the code.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"28 11","pages":"2464-2467"},"PeriodicalIF":3.7,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190002","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-11DOI: 10.1109/LCOMM.2024.3457909
Pinmo Li;Jianping Zheng
In this letter, we study the signature code design and active user identification for the random access in fast fading channels. First, we propose a constant-weight signature code construction by utilizing the on-off pattern of the binary subspace chirps. The constructed code has low fading coherence and large size, and thus guarantees good performance with large number of access users. Second, a practical activity detection based on the generalized approximate message passing is proposed. Finally, the performance of the proposed signature code and activity detection is demonstrated by computer simulations.
{"title":"Random Access in Fast Fading Channels: Signature Code Design and Active User Identification","authors":"Pinmo Li;Jianping Zheng","doi":"10.1109/LCOMM.2024.3457909","DOIUrl":"10.1109/LCOMM.2024.3457909","url":null,"abstract":"In this letter, we study the signature code design and active user identification for the random access in fast fading channels. First, we propose a constant-weight signature code construction by utilizing the on-off pattern of the binary subspace chirps. The constructed code has low fading coherence and large size, and thus guarantees good performance with large number of access users. Second, a practical activity detection based on the generalized approximate message passing is proposed. Finally, the performance of the proposed signature code and activity detection is demonstrated by computer simulations.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"28 11","pages":"2473-2477"},"PeriodicalIF":3.7,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-10DOI: 10.1109/LCOMM.2024.3457617
Heng Dong;Xiaojie Fang;Jun Zhao;Xu Lin;Xuejun Sha;Zhuoming Li
In this letter, we investigate secure communication for the downlink rate-splitting multiple access (RSMA) system by integrating both the spatial domain and weighted fractional Fourier transform (WFRFT) signal domain to enhance its physical layer security (PLS) performance. To counter the external passive eavesdropper, we propose an RSMA-CM-WFRFT scheme to promote the dual use of the common message (CM), thereby improving the secrecy rate of both common and private messages. Specifically, the common message is encoded based on WFRFT, enabling all received power of legitimate users for signal reconstruction, while introducing inter-component interference at the eavesdropper. Furthermore, the inevitable serial interference caused by the WFRFT-encoded CM sequence overlays onto the private message (PM), thus enhancing its security. To counter internal eavesdroppers, we propose an RSMA-PM-WFRFT scheme to achieve parallel encryption by encoding the private message of different users into different WFRFT domains. Additionally, we formulate and solve a non-convex optimization problem aimed at minimizing the required power under both security and reliability constraints. Numerical results demonstrate the superior performance of the two proposed schemes.
{"title":"Secure Communication for RSMA Systems: Integrating Spatial and WFRFT Signal Domains","authors":"Heng Dong;Xiaojie Fang;Jun Zhao;Xu Lin;Xuejun Sha;Zhuoming Li","doi":"10.1109/LCOMM.2024.3457617","DOIUrl":"10.1109/LCOMM.2024.3457617","url":null,"abstract":"In this letter, we investigate secure communication for the downlink rate-splitting multiple access (RSMA) system by integrating both the spatial domain and weighted fractional Fourier transform (WFRFT) signal domain to enhance its physical layer security (PLS) performance. To counter the external passive eavesdropper, we propose an RSMA-CM-WFRFT scheme to promote the dual use of the common message (CM), thereby improving the secrecy rate of both common and private messages. Specifically, the common message is encoded based on WFRFT, enabling all received power of legitimate users for signal reconstruction, while introducing inter-component interference at the eavesdropper. Furthermore, the inevitable serial interference caused by the WFRFT-encoded CM sequence overlays onto the private message (PM), thus enhancing its security. To counter internal eavesdroppers, we propose an RSMA-PM-WFRFT scheme to achieve parallel encryption by encoding the private message of different users into different WFRFT domains. Additionally, we formulate and solve a non-convex optimization problem aimed at minimizing the required power under both security and reliability constraints. Numerical results demonstrate the superior performance of the two proposed schemes.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"28 11","pages":"2498-2502"},"PeriodicalIF":3.7,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-10DOI: 10.1109/LCOMM.2024.3457693
Roberto Garello
In this letter we introduce Serial Bicode and Serial Multicode Direct Sequence Spread Spectrum (DSSS) and we extend them to Code Division Multiple Access (CDMA). To each user are assigned two or more spreading codes. The information is associated to these codes, which are alternated within a single DSSS signal. The performance of the new techniques for incoherent demodulation is analyzed. Additionally, we present the application to the construction of data-less pilot channels for satellite navigation systems. Alternative codes can be used to embed a pattern or a message that, when recognized, allows to quickly solve time ambiguity and simplify initial synchronization for MEO and LEO scenarios.
在这封信中，我们介绍了串行双码和串行多码直接序列扩频（DSSS），并将其扩展到码分多址（CDMA）。我们为每个用户分配了两个或多个扩频码。信息与这些编码相关联，这些编码在一个 DSSS 信号中交替出现。我们分析了非相干解调新技术的性能。此外，我们还介绍了为卫星导航系统构建无数据先导信道的应用。交替编码可用于嵌入图案或信息，当识别到这些图案或信息时，可快速解决时间模糊问题，并简化 MEO 和 LEO 场景的初始同步。
{"title":"Serial Multicode Direct Sequence Spread Spectrum With Applications to Satellite Navigation Pilot Channels","authors":"Roberto Garello","doi":"10.1109/LCOMM.2024.3457693","DOIUrl":"10.1109/LCOMM.2024.3457693","url":null,"abstract":"In this letter we introduce Serial Bicode and Serial Multicode Direct Sequence Spread Spectrum (DSSS) and we extend them to Code Division Multiple Access (CDMA). To each user are assigned two or more spreading codes. The information is associated to these codes, which are alternated within a single DSSS signal. The performance of the new techniques for incoherent demodulation is analyzed. Additionally, we present the application to the construction of data-less pilot channels for satellite navigation systems. Alternative codes can be used to embed a pattern or a message that, when recognized, allows to quickly solve time ambiguity and simplify initial synchronization for MEO and LEO scenarios.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"28 11","pages":"2603-2607"},"PeriodicalIF":3.7,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-10DOI: 10.1109/LCOMM.2024.3456823
Sandushan Ranaweera;Beeshanga Abewardana Jayawickrama;Ying He;Quynh Tu Ngo;Ren Ping Liu
This letter presents an enhanced gradient search algorithm for jointly optimizing signal constellations and bit mappings. This approach stands in contrast to the recent trend of utilizing deep learning (DL) to model communication systems as end-to-end (E2E) systems, which often involve a large number of learnable parameters and high computational complexity during training. We enhance the efficiency of the gradient search algorithm by leveraging the symmetrical properties of the I/Q plane, particularly in higher modulation orders. The resulting constellations are evaluated in terms of bit error rate (BER) performance under additive white Gaussian noise and Rayleigh flat fading channels. Our findings indicate that the optimized constellations obtained via the enhanced gradient search algorithm outperform an attention-empowered DL-based E2E system in terms of BER across both channels, notably in higher signal-to-noise ratio regimes, without encountering error floor issues.
{"title":"On the Joint Optimization of Signal Constellations and Bit Mappings","authors":"Sandushan Ranaweera;Beeshanga Abewardana Jayawickrama;Ying He;Quynh Tu Ngo;Ren Ping Liu","doi":"10.1109/LCOMM.2024.3456823","DOIUrl":"10.1109/LCOMM.2024.3456823","url":null,"abstract":"This letter presents an enhanced gradient search algorithm for jointly optimizing signal constellations and bit mappings. This approach stands in contrast to the recent trend of utilizing deep learning (DL) to model communication systems as end-to-end (E2E) systems, which often involve a large number of learnable parameters and high computational complexity during training. We enhance the efficiency of the gradient search algorithm by leveraging the symmetrical properties of the I/Q plane, particularly in higher modulation orders. The resulting constellations are evaluated in terms of bit error rate (BER) performance under additive white Gaussian noise and Rayleigh flat fading channels. Our findings indicate that the optimized constellations obtained via the enhanced gradient search algorithm outperform an attention-empowered DL-based E2E system in terms of BER across both channels, notably in higher signal-to-noise ratio regimes, without encountering error floor issues.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"28 11","pages":"2513-2517"},"PeriodicalIF":3.7,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-10DOI: 10.1109/LCOMM.2024.3457166
Alireza Soofinezhadmoghaddam;Hamidreza Bakhshi
Joint Hybrid Beamforming (HBF) and Power Allocation (PA) in mmWave nonorthogonal multiple access (NOMA) systems are investigated in this letter. We consider downlink mmWave NOMA systems, in which HBF is done at the Base Station (BS), and all users have only one antenna. At the BS, user grouping uses the K-means-based algorithm according to the user’s channel correlation. Subsequently, inspired by the benefits of Deep Reinforcement Learning (DRL), a novel algorithm based on DRL is proposed to output the HBF matrix and PA of all the users. Simulations represent the superiority of the proposed algorithm in comparison with the state-of-the-art schemes in both perfect Channel State Information (CSI) and imperfect CSI.
{"title":"Joint Power Allocation and Hybrid Beamforming of mmWave NOMA Systems Using DDPG","authors":"Alireza Soofinezhadmoghaddam;Hamidreza Bakhshi","doi":"10.1109/LCOMM.2024.3457166","DOIUrl":"10.1109/LCOMM.2024.3457166","url":null,"abstract":"Joint Hybrid Beamforming (HBF) and Power Allocation (PA) in mmWave nonorthogonal multiple access (NOMA) systems are investigated in this letter. We consider downlink mmWave NOMA systems, in which HBF is done at the Base Station (BS), and all users have only one antenna. At the BS, user grouping uses the K-means-based algorithm according to the user’s channel correlation. Subsequently, inspired by the benefits of Deep Reinforcement Learning (DRL), a novel algorithm based on DRL is proposed to output the HBF matrix and PA of all the users. Simulations represent the superiority of the proposed algorithm in comparison with the state-of-the-art schemes in both perfect Channel State Information (CSI) and imperfect CSI.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"28 11","pages":"2578-2582"},"PeriodicalIF":3.7,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We analyze the outage probability (OP), ergodic capacity (EC), and average bit error probability (ABEP) of L-branch diversity systems using maximal-ratio-combining (MRC) over Multi-cluster-Fluctuating-Two-Ray (MFTR) fading channels, a model well-suited for sub-terahertz bands. We derive exact OP, EC, and ABEP expressions. For this latter metric, we assume M-ary quadrature amplitude modulation (M-QAM), and we also perform its asymptotic analysis to obtain the coding gain and diversity order. Unlike previous works for simpler fading models, our expressions retain consistent complexity regardless of the number of MRC branches and depend on functions available in standard mathematical software. The results show that coding gain relies on fading distribution parameters, L, and M. Meanwhile, diversity order is determined by multiplying L with the number of multipath clusters in the MFTR model.
我们分析了在多簇-波动-双射线（MFTR）衰落信道（一种非常适合亚太赫兹频带的模型）上使用最大比值组合（MRC）的 L 分支分集系统的中断概率（OP）、遍历容量（EC）和平均比特误差概率（ABEP）。我们推导出精确的 OP、EC 和 ABEP 表达式。对于后一种度量，我们假定采用 M-ary 正交振幅调制（M-QAM），并对其进行渐近分析，以获得编码增益和分集阶数。与以往针对更简单的衰减模型的研究不同，我们的表达式保持了一致的复杂性，而与 MRC 分支的数量无关，并且依赖于标准数学软件中可用的函数。结果表明，编码增益取决于衰减分布参数 L 和 M。
{"title":"Performance Evaluation of MRC Systems Over Sub-Terahertz MFTR Fading Channels","authors":"Nathaly Orozco Garzón;Henry Carvajal Mora;Fernando Almeida García;José Vega-Sánchez;Diana Moya Osorio","doi":"10.1109/LCOMM.2024.3455798","DOIUrl":"10.1109/LCOMM.2024.3455798","url":null,"abstract":"We analyze the outage probability (OP), ergodic capacity (EC), and average bit error probability (ABEP) of L-branch diversity systems using maximal-ratio-combining (MRC) over Multi-cluster-Fluctuating-Two-Ray (MFTR) fading channels, a model well-suited for sub-terahertz bands. We derive exact OP, EC, and ABEP expressions. For this latter metric, we assume M-ary quadrature amplitude modulation (M-QAM), and we also perform its asymptotic analysis to obtain the coding gain and diversity order. Unlike previous works for simpler fading models, our expressions retain consistent complexity regardless of the number of MRC branches and depend on functions available in standard mathematical software. The results show that coding gain relies on fading distribution parameters, L, and M. Meanwhile, diversity order is determined by multiplying L with the number of multipath clusters in the MFTR model.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"28 10","pages":"2422-2426"},"PeriodicalIF":3.7,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10669087","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Integrated sensing and communication (ISAC) has been recognized as one of the key techniques for 6G, aiming at realizing smart sensing applications using wireless signals. However, existing investigations are limited to the algorithm design for smart sensing applications, and the parameters affecting sensing performance have not been thoroughly explored. To fill this gap, we study the impact of sensing sequences and communication parameters on the performance with real-world evaluations in this letter. Specifically, we develop a sensing platform based on USRP X310 and propose a novel packet detection algorithm as well as a time synchronization algorithm. Two typical applications, i.e., human pose recognition and dynamic gesture recognition, have been conducted under different sequences and communication parameters. The extensive results indicate that the sensing performance is identical across various sequences, and the relationship between the sensing performance and communication parameters is fully investigated.
{"title":"Experimental Study on ISAC Performance With Different Sensing Sequences","authors":"Diao Wang;Weiwei Chen;Yinghui He;Jianfeng Wang;Haiyan Luo;Guanding Yu","doi":"10.1109/LCOMM.2024.3455779","DOIUrl":"10.1109/LCOMM.2024.3455779","url":null,"abstract":"Integrated sensing and communication (ISAC) has been recognized as one of the key techniques for 6G, aiming at realizing smart sensing applications using wireless signals. However, existing investigations are limited to the algorithm design for smart sensing applications, and the parameters affecting sensing performance have not been thoroughly explored. To fill this gap, we study the impact of sensing sequences and communication parameters on the performance with real-world evaluations in this letter. Specifically, we develop a sensing platform based on USRP X310 and propose a novel packet detection algorithm as well as a time synchronization algorithm. Two typical applications, i.e., human pose recognition and dynamic gesture recognition, have been conducted under different sequences and communication parameters. The extensive results indicate that the sensing performance is identical across various sequences, and the relationship between the sensing performance and communication parameters is fully investigated.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"28 11","pages":"2538-2542"},"PeriodicalIF":3.7,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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