On the Resource Utilization of Multi-Connectivity Transmission for URLLC Services in 5G New Radio

Mahmood, Nurul Huda; Karimi, Ali; Berardinelli, Gilberto; Pedersen, Klaus I.; Laselva, Daniela

doi:10.1109/wcncw.2019.8902865

Cited by 35 publications

(28 citation statements)

References 15 publications

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“…The processing time at the UE is denoted by T up . The frame alignment delay T fa is a random variable uniformly distributed between zero and one TTI [28]. Depending on the packet size, channel quality and scheduling strategy, the transmission time T tx can vary from one to multiple TTIs.…”

Section: Grant-free Access Schemesmentioning

confidence: 99%

Analyzing Grant-Free Access for URLLC Service

Yan

Deng

Elkashlan

et al. 2021

IEEE J. Select. Areas Commun.

136

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5G New Radio (NR) is expected to support new ultra-reliable low-latency communication (URLLC) service targeting at supporting the small packets transmissions with very stringent latency and reliability requirements. Current Long Term Evolution (LTE) system has been designed based on grantbased (GB) (i.e., dynamic grant) random access, which can hardly support the URLLC requirements. Grant-free (GF) (i.e., configured grant) access is proposed as a feasible and promising technology to meet such requirements, especially for uplink transmissions, which effectively saves the time of requesting/waiting for a grant. While some basic GF access features have been proposed and standardized in NR Release-15, there is still much space to improve. Being proposed as 3GPP study items, three GF access schemes with Hybrid Automatic Repeat reQuest (HARQ) retransmissions including Reactive, K-repetition, and Proactive, are analyzed in this paper. Specifically, we present a spatiotemporal analytical framework for the contention-based GF access analysis. Based on this framework, we define the latent access failure probability to characterize URLLC reliability and latency performances. We propose a tractable approach to derive and analyze the latent access failure probability of the typical UE under three GF HARQ schemes. Our results show that under shorter latency constraints, the Proactive scheme provides the lowest latent access failure probability, whereas, under longer latency constraints, the K-repetition scheme achieves the lowest latent access failure probability, which depends on K. If K is overestimated, the Proactive scheme provides lower latent access failure probability than the K-repetition scheme.

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Section: Grant-free Access Schemesmentioning

confidence: 99%

Analyzing Grant-Free Access for URLLC Service

Yan

Deng

Elkashlan

et al. 2021

IEEE J. Select. Areas Commun.

136

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“…1 depicts the resource usage performance gains of sending URLLC payloads, assuming in-resource control channel multiplexing with respect to outage probability targets ranging from P tar out = 10 −4 to P tar out = 10 −7 and for different channel conditions. We assume data and metadata size are D = 32 and M = 16 bytes, respectively [61], [77]. The gains are compared against the baseline scenario with a single transmission in which both data metadata are encoded with the same BLEP equal P d1 e = P m1 e = 1 2 P tar out .…”

Section: Numerical Resultsmentioning

confidence: 99%

“…A new sub-codeword is consecutively transmitted if the UE fails to correctly decode previous received concatenated samples. The success probability following HARQ retransmission is obtained as [77] P I2a succ = (1 − P m1 e ) (1 − P na e ) (1 − P m2 e ) P d1 e − P d12 e ,…”

Section: A In-resource Control Signallingmentioning

confidence: 99%

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On the Multiplexing of Data and Metadata for Ultra-Reliable Low-Latency Communications in 5G

Karimi

Pedersen

Mahmood

et al. 2020

IEEE Trans. Veh. Technol.

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This paper addresses the problem of downlink radio resource management for ultra-reliable low-latency communications (URLLC) in fifth generation (5G) systems. To support low-latency communications, we study performance of two multiplexing schemes namely in-resource control signalling and joint encoding of data and metadata. In the former, the metadata and data are separately encoded and the metadata is sent at the beginning of transmission time prior to the data. Thus, it benefits from a low-complexity receiver structure to decode the data block. The latter takes advantages of transmitting a larger blocklength to enhance the reliability and improve spectrum efficiency by jointly encoding data and metadata as a single codeword. Dealing with small URLLC payloads, the overhead and error of sending metadata are not negligible and have a significant impact on the system performance in terms of resource usage the reliability of transmission. For each scheme, we derive expressions for the outage probability and resource usage by taking into account impacts of the finite blocklength payloads, overhead and error of sending metadata, and probability of error in uplink feedback channel. We propose a novel framework for joint data and metadata link adaptation to minimize the average number of allocated resources, while ensuring the stringent URLLC quality of service requirements. An optimization problem is formulated for each scheme that is mixed-integer nonconvex problem, difficult to solve in polynomial time. Solutions based on successive convex optimization are proposed. Numerical evaluations show that the proposed algorithms perform close to the optimal solution and demonstrate remarkable gains of up to 27% improvement in resource usage. Finally, we present sensitivity analysis of the results for various network parameters.

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“…Inefficiencies of DC-based data duplication with respect to physical-layer duplication have been also proven via measurement campaigns in industrial scenarios [24]. The observed negative impact of data duplication on system-level performance triggered the investigation of suitable system configurations [21], [25], dynamic link activation heuristics [26], and predictive flow control strategies [27], with the aim of achieving as wide as possible support of URLLC exploiting DC-based data duplication. Nevertheless, there is margin for further improvements of reliability-oriented DC in 5G cellular systems.…”

Section: Related Work and Novel Contributionsmentioning

confidence: 95%

System-Level Study of Data Duplication Enhancements for 5G Downlink URLLC

Centenaro

Laselva²,

Steiner³

et al. 2020

IEEE Access

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Data duplication is studied as a fundamental enabler for ultra-reliable low-latency communication (URLLC) in fifth-generation cellular systems. It entails the simultaneous usage of multiple radio links delivering redundant data between a terminal and the network to boost the transmission reliability. However, the improved reliability comes at a cost of reduced spectral efficiency, since the transmission of multiple instances of the data message on different links occupies more radio resources as compared to sending only one instance using a single link. It is therefore crucial to improve the performance of data duplication schemes, with the aim of reducing the radio resource consumption without degrading the reliability gain provided by this transmission paradigm. In this paper, we propose several methods to increase the downlink URLLC capacity supported by data duplication in fifth-generation cellular networks based on the New Radio standard. A single-user analytical model is derived to evaluate a combination of the proposed enhancements. The most promising solution, namely selective data duplication upon failure which entails a massive reduction of the overall number of duplicate transmissions, is finally evaluated by means of extensive multiuser system-level simulation campaigns. The simulation results with background mobile broadband traffic show that, in the investigated scenario, the proposed solution with 4 Mbps offered URLLC traffic outperforms the baseline approach for data duplication with 1 Mbps offered URLLC traffic, thus increasing the amount of URLLC user equipments that can be effectively sustained by the network.

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On the Resource Utilization of Multi-Connectivity Transmission for URLLC Services in 5G New Radio

Cited by 35 publications

References 15 publications

Analyzing Grant-Free Access for URLLC Service

Analyzing Grant-Free Access for URLLC Service

On the Multiplexing of Data and Metadata for Ultra-Reliable Low-Latency Communications in 5G

System-Level Study of Data Duplication Enhancements for 5G Downlink URLLC

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