904 Hits in 7.5 sec

Contention-based Grant-free Transmission with Extremely Sparse Orthogonal Pilot Scheme [article]

Zhifeng Yuan, Zhigang Li, Weimin Li, Yihua Ma
2021 arXiv   pre-print
Due to the limited number of traditional orthogonal pilots, pilot collision will severely degrade the performance of contention-based grant-free transmission.  ...  To alleviate the pilot collision and exploit the spatial degree of freedom as much as possible, an extremely sparse orthogonal pilot scheme is proposed for uplink grant-free transmission.  ...  However, as there is no scheduling of the transmission resource by the base station (BS), the grant-free transmission is contention-based.  ... 
arXiv:2106.04172v1 fatcat:p6rj6j3adbb7tmdr3vfnt7tefm

Sparse Signal Processing for Grant-Free Massive Connectivity: A Future Paradigm for Random Access Protocols in the Internet of Things

Liang Liu, Erik G. Larsson, Wei Yu, Petar Popovski, Cedomir Stefanovic, Elisabeth de Carvalho
2018 IEEE Signal Processing Magazine  
(unknown) subset of devices are active at any given instant, thus one of the key challenges for providing massive IoT connectivity is to detect the active devices first and then to decode their data with  ...  multiple-output (MIMO) is especially well-suited for massive IoT connectivity in the sense that the device detection error can be driven to zero asymptotically in the limit as the number of antennas at the base  ...  This important result implies that in a massive MIMO system, in which M can be larger than 100, the AMP-based grant-free access scheme is able to detect device activity with extremely high accuracy in  ... 
doi:10.1109/msp.2018.2844952 fatcat:74lj3fosrrfibao6rruslqrhtm

Towards the Standardization of Non-orthogonal Multiple Access for Next Generation Wireless Networks [article]

Yan Chen, Alireza Bayesteh, Yiqun Wu, Bin Ren, Shaoli Kang, Shaohui Sun, Qi Xiong, Chen Qian, Bin Yu, Zhiguo Ding, Sen Wang, Shuangfeng Han, Xiaolin Hou (+3 others)
2018 arXiv   pre-print
For generations of wireless communication systems design, orthogonal multiple access (OMA) schemes in time, frequency, or code domain have been the main choices due to the limited processing capability  ...  This article will provide a systematic overview of the state-of-the-art design of the NoMA transmission based on a unified transceiver design framework, the related standardization progress, and some promising  ...  His research interests include pattern division multiple access, no-orthogonal multiple access and 5G wireless communications system.  ... 
arXiv:1802.03880v1 fatcat:lme7vdtjzjdwfgyanqonbpxleq

Grant-free Non-orthogonal Multiple Access for IoT: A Survey [article]

Muhammad Basit Shahab, Rana Abbas, Mahyar Shirvanimoghaddam, Sarah J. Johnson
2019 arXiv   pre-print
autonomous and grant-free communication, where devices can transmit data whenever they need.  ...  The existing literature on NOMA schemes majorly considers centralized scheduling based HTC, where users are already connected, and various system parameters like spreading sequences, interleaving patterns  ...  III and IV can also be customized to support grant-free communication. 3) Other signature based grant-free NOMA schemes: Some other grant-free transmission schemes motivated by signature based NOMA are  ... 
arXiv:1910.06529v1 fatcat:6ouywssbwjhm3nt5iz6px7h7oa

DNN-Aided Block Sparse Bayesian Learning for User Activity Detection and Channel Estimation in Grant-Free Non-Orthogonal Random Access

Zhaoji Zhang, Ying Li, Chongwen Huang, Qinghua Guo, Chau Yuen, Yong Liang Guan
2019 IEEE Transactions on Vehicular Technology  
In order to address the joint user activity detection (UAD) and channel estimation (CE) problem in the grant-free NORA system, we propose a deep neural network-aided message passing-based block sparse  ...  A grant-free non-orthogonal random access (NORA) system is considered in this paper, which could simultaneously reduce the access delay and support more Machine Type Communication (MTC) devices with limited  ...  A DNN-MP-BSBL algorithm was proposed in this paper for the joint UAD and CE problem in grant-free NORA systems.  ... 
doi:10.1109/tvt.2019.2947214 fatcat:k7mapivt2bdb5hrqvrx2lwbki4

Massive machine-type communications in 5g: physical and MAC-layer solutions

Carsten Bockelmann, Nuno Pratas, Hosein Nikopour, Kelvin Au, Tommy Svensson, Cedomir Stefanovic, Petar Popovski, Armin Dekorsy
2016 IEEE Communications Magazine  
In summary, the sparsity of codebooks, low projection techniques and blind detection with SCMA receiver make SCMA an attractive solution for uplink contention-based grant-free transmission in mMTC with  ...  A crucial component of uplink SCMA grant-free transmission is blind detection.  ... 
doi:10.1109/mcom.2016.7565189 fatcat:iwl6ooby3jcnzjbu67wdgtv2lu

Massive MIMO for Internet of Things (IoT) Connectivity [article]

Alexandru-Sabin Bana, Elisabeth de Carvalho, Beatriz Soret, Taufik Abrão, José Carlos Marinello, Erik G. Larsson, Petar Popovski
2019 arXiv   pre-print
The main conclusion is that massive MIMO can bring benefits to the scenarios with IoT connectivity, but it requires tight integration of the physical-layer techniques with the protocol design.  ...  Exploiting the large number of degrees of freedom (DoFs) of massive MIMO essential for achieving high spectral efficiency, high data rates and extreme spatial multiplexing of densely distributed users.  ...  Pilot sequences Grant mode Device ID SUCRe Orthogonal Grant-based yes pilot RA Orthogonal Grant-free yes coded RA Orthogonal Grant-free yes CS-RA Pseudo-random Grant-free yes Unsourced  ... 
arXiv:1905.06205v1 fatcat:xqe2z6evhrc27cvtxad5iiko4a

Reed-Muller Sequences for 5G Grant-free Massive Access [article]

Huazi Zhang, Rong Li, Jun Wang, Yan Chen, Zhaoyang Zhang
2018 arXiv   pre-print
We propose to use second order Reed-Muller (RM) sequence for user identification in 5G grant-free access.  ...  These two features are essential to meet the massive connectivity (10^7 links/km^2), ultra-reliable and low-latency requirements in 5G, e.g., one-shot transmission (≤ 1ms) with ≤ 10^-4 packet error rate  ...  In order to support low latency, the basic radio resource for grant-free transmission is a contention transmission unit (CTU), defined as a combination of time, frequency and pilot sequence.  ... 
arXiv:1801.05089v1 fatcat:ikw5oez4lzeolcanvhynfca4ji

Massive Access for 5G and Beyond [article]

Xiaoming Chen, Derrick Wing Kwan Ng, Wei Yu, Erik G. Larsson, Naofal Al-Dhahir, Robert Schober
2020 arXiv   pre-print
To tackle this problem, the authors in [89] proposed a transmission control scheme for grant-free random access protocols.  ...  Grant-Free Random Access To overcome the problems of grant-based random access, various grant-free random access protocols have been proposed which allow the active devices to access the wireless network  ... 
arXiv:2002.03491v2 fatcat:e632upafkvhwlm4m2mwhbeleam

Sparse Code Multiple Access for 6G Wireless Communication Networks: Recent Advances and Future Directions [article]

Lisu Yu, Zilong Liu, Miaowen Wen, Donghong Cai, Shuping Dang, Yuhao Wang, Pei Xiao
2021 arXiv   pre-print
disruptive non-orthogonal multiple access (NOMA) scheme for the enabling of massive connectivity.  ...  We propose to apply SCMA to a massively distributed access system (MDAS), whose architecture is based on fiber-based visible light communication (FVLC), ultra-dense network (UDN), and NOMA.  ...  Recently, grant-free NOMA schemes have been considered as a compelling alternative.  ... 
arXiv:2104.01402v1 fatcat:gikrj242bzd2xawdbleyb6ray4

Sparse Code Multiple Access for 6G Wireless Communication Networks: Recent Advances and Future Directions

Lisu Yu, Zilong Liu, Miaowen Wen, Donghong Cai, Shuping Dang, Yuhao Wang, Pei Xiao
2021 IEEE Communications Standards Magazine  
disruptive non-orthogonal multiple access (NOMA) scheme for the enabling of massive connectivity.  ...  We propose to apply SCMA to a massively distributed access system (MDAS), whose architecture is based on fiber-based visible light communication (FVLC), ultra-dense network (UDN), and NOMA.  ...  Fig. 2 : 2 System architecture of massively distributed access system with advanced technologies. Fig. 3 : 3 Time-domain structure of grant-free NOMA scheme.  ... 
doi:10.1109/mcomstd.001.2000049 fatcat:sy55wr2mrrbq7n3trgcszaljq4

Towards Massive Connectivity Support for Scalable mMTC Communications in 5G networks [article]

Carsten Bockelmann, Nuno K. Pratas, Gerhard Wunder, Stephan Saur, Monica Navarro, David Gregoratti, Guillaume Vivier, Elisabeth de Carvalho, Yalei Ji, Cedomir Stefanovic, Petar Popovski, Qi Wang, Malte Schellmann, Evangelos Kosmatos, Panagiotis Demestichas (+3 others)
2018 arXiv   pre-print
The fifth generation of cellular communication systems is foreseen to enable a multitude of new applications and use cases with very different requirements.  ...  Coupling these two technologies facilitates a non-orthogonal grant-free access scheme supporting collision resolution based on MIMO detection techniques on the BS side.  ...  The proposed random access scheme with non-orthogonal TA-free transmission is illustrated in Fig. 8 and can be described as follows: 1) UE establishes downlink synchronization to the primary cell and  ... 
arXiv:1804.01701v1 fatcat:rxmtp2lrjncstjiabqkntm7niu

Channel Estimation for Massive MIMO-OFDM Systems by Tracking the Joint Angle-Delay Subspace

Yu Zhang, Dongming Wang, Jiangzhou Wang, Xiaohu You
2016 IEEE Access  
Simulation results show that the joint angle-delay subspace can be estimated effectively, and the proposed pilot reuse scheme combined with robust MMSE channel estimation offers significant performance  ...  Then, we investigate an interference-free transmission condition that the joint angle-delay subspaces of the users reusing the same pilots are non-overlapping.  ...  Then, we investigated channel estimation for massive MIMO-OFDM with the JADSMs of users, and provided an interference-free transmission condition that the JADSMs of users transmitting the same pilots are  ... 
doi:10.1109/access.2016.2634025 fatcat:obuyetmhwzeobjps74zo6o2bve

Massive Access for Future Wireless Communication Systems [article]

Yongpeng Wu, Xiqi Gao, Shidong Zhou, Wei Yang, Yury Polyanskiy, and Giuseppe Caire
2020 arXiv   pre-print
of potential user devices with sporadic transmission pattern, and the integration of massive access with massive MIMO and other important wireless communication technologies.  ...  The tremendous growth in the number of connected devices requires a fundamental rethinking of the conventional multiple access technologies in favor of new schemes suited for massive random access.  ...  However, the key difference between a coordinated grant-free multiple access and an uncoordinated multiple access is that, in the former scenario, each user is assigned with a dedicated pilot/signature  ... 
arXiv:1910.12678v5 fatcat:qnc3vxft65adlpmfnd4j7nhkza

Compressive Sensing Based Adaptive Active User Detection and Channel Estimation: Massive Access Meets Massive MIMO [article]

Malong Ke, Zhen Gao, Yongpeng Wu, Xiqi Gao, Robert Schober
2020 arXiv   pre-print
Specifically, we design non-orthogonal pseudo-random pilots for uplink broadband massive access, and formulate the active user detection and channel estimation problems as a generalized multiple measurement  ...  Finally, an adaptive access scheme is proposed, which adapts the access latency to guarantee reliable massive access for practical systems with unknown channel sparsity level.  ...  The physical random access channel (PRACH) protocol of Long-Term Evolution is one example of grant-based protocols, and can be classified into two categories: contention-free RA and contention-based RA  ... 
arXiv:1906.09867v3 fatcat:z67q5bos6zctfpeudvzloyhcia
« Previous Showing results 1 — 15 out of 904 results