Comprehensive grant-free random access for massive &amp; low latency communication

Abebe, Ameha T.; Kang, Chung G.

doi:10.1109/icc.2017.7996932

Cited by 53 publications

(40 citation statements)

References 8 publications

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“…Thus, in recent discussed 5G standards, the subcarrier space is suggested not to exceed 30kHz [135] for achieving high reliability and low latency. Although GFA can improve system efficiency theoretically, there are many practical considerations for the technique to be used for IoT, which deserve more attentions [136]- [140]. The GFA cannot be implemented without proper channel estimation and synchronization.…”

Section: • Possible 5g Systemmentioning

confidence: 99%

High-Reliability and Low-Latency Wireless Communication for Internet of Things: Challenges, Fundamentals, and Enabling Technologies

Xiao

et al. 2019

IEEE Internet Things J.

213

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As one of the key enabling technologies of emerging smart societies and industries (i.e., industry 4.0), the Internet of Things (IoT) has evolved significantly in both technologies and applications. It is estimated that more than 25 billion devices will be connected by wireless IoT networks by 2020. In addition to ubiquitous connectivity, many envisioned applications of IoT, such as industrial automation, vehicle-to-everything (V2X) networks, smart grids and remote surgery, will have stringent transmission latency and reliability requirements, which may not be supported by existing systems. Thus, there is an urgent need for rethinking the entire communication protocol stack for wireless IoT networks. In this tutorial paper, we review the various application scenarios, fundamental performance limits, and potential technical solutions for high-reliability and lowlatency (HRLL) wireless IoT networks. We discuss physical, MAC and network layers of wireless IoT networks, which all have significant impacts on latency and reliability. For the physical layer, we discuss the fundamental information-theoretic limits for HRLL communications, and then we also introduce a frame structure and preamble design for HRLL communications. Then practical channel codes with finite block length are reviewed. For the MAC layer, we first discuss optimized spectrum and power resource management schemes and then recently proposed grantfree schemes are discussed. For the network layer, we discuss the optimized network structure (traffic dispersion and network densification), the optimal traffic allocation schemes and network coding schemes to minimize latency.

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Section: • Possible 5g Systemmentioning

confidence: 99%

High-Reliability and Low-Latency Wireless Communication for Internet of Things: Challenges, Fundamentals, and Enabling Technologies

Xiao

et al. 2019

IEEE Internet Things J.

213

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“…In this subsection, we consider a random access approach with two stages. Similar to [23] in Stage 1, an active user is to randomly choose a preamble from the pool. Let ψ l be the lth preamble in the pool of L preambles, {ψ 1 , .…”

Section: A Cra-1mentioning

confidence: 99%

“…In the second stage, the preamble can be used as a spreading sequence for MUD, which results in code division multiple access (CDMA) based random access in [19] [20]. As shown in [23], it is possible to use different spreading code (but associated with the preamble in the first stage) for spreading in the second stage.…”

Section: Introductionmentioning

confidence: 99%

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On Throughput of Compressive Random Access for One Short Message Delivery in IoT

Choi

2020

IEEE Internet Things J.

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In this paper, we study compressive random access (CRA) with two stages for machine-type communication (MTC) in cellular Internet-of-Things (IoT). In particular, we consider the case that each user (IoT device or sensor) has only one short message (of the same length) when it is activated to send data in IoT applications. Two different CRA-based random access schemes are discussed (one is conventional and the other is new based on a simplified handshaking process). Based on the throughput analysis, we show that the CRA-based random access scheme with simplified handshaking process can outperform as its length of payload is adaptively decided depending on the number of active users. Simulation results confirm that the derived throughput expressions agree with them and can be used to design a random access system for MTC with each active device or sensor that has one short message.

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“…Given this, the grant-free RA with low signaling overhead attracts much attentions. In grant-free RA, the request-grant procedure is removed and UEs transmits directly the randomly-select pilot along with data [17]- [19]. By doing this, the access delay is minimized, but the transmission interference is also enhanced.…”

Section: Introductionmentioning

confidence: 99%

A Hybrid-Grant Random Access Scheme in Massive MIMO Systems for IoT

2020

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The grant-free random access (RA) can minimize the access delay but also brings severe data transmission interferences. To overcome this defect, we propose a new RA scheme that inserts a base station (BS) broadcasting message after user equipments (UEs) transmitting pilots. In this scheme, UEs can determine whether they have colliders by resolving the broadcasting message, and only non-colliding UEs can transmit data in the following step while colliding UEs keep silent. By doing this, the data interferences from colliding UEs are eliminated without costing much extra time. Since this BS broadcasting message is also used in the legacy grant-based RA, we call the new RA scheme as a hybrid-grant RA. We investigate the hybrid-grant RA in massive multiple-input multiple-output (MIMO) systems and obtain a tight closedform approximation of the spectral efficiency with maximum-ratio-combing (MRC) and zero-forcing (ZF) receivers, respectively. Via simulation, we find that our proposed hybrid-grant RA can obtain a significant gain on the spectral efficiency compared with grant-free RA, especially for ZF receivers. In particular, this gain grows rapidly as the UE number goes up, which means the hybrid-grant RA is more suitable for the system with large amount of UEs and it is a typical scenario in future communications networks. Moreover, we also analyze the optimal pilot length and UE activation probability that maximize the spectral efficiency, which can be used as references for the practical application of the proposed hybrid-grant RA.

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Comprehensive grant-free random access for massive & low latency communication

Cited by 53 publications

References 8 publications

High-Reliability and Low-Latency Wireless Communication for Internet of Things: Challenges, Fundamentals, and Enabling Technologies

High-Reliability and Low-Latency Wireless Communication for Internet of Things: Challenges, Fundamentals, and Enabling Technologies

On Throughput of Compressive Random Access for One Short Message Delivery in IoT

A Hybrid-Grant Random Access Scheme in Massive MIMO Systems for IoT

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